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Encyclopedia > Evidence of evolution
While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection.
While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection.

The wide range of evidence of evolution provides a wealth of information on the natural processes by which the variety of life on Earth developed. HMS Beagle (1841 watercolor by Owen Stanley) The two-dimensional work of art depicted in this image is in the public domain in the United States and in those countries with a copyright term of life of the author plus 100 years. ... HMS Beagle (1841 watercolor by Owen Stanley) The two-dimensional work of art depicted in this image is in the public domain in the United States and in those countries with a copyright term of life of the author plus 100 years. ... HMS Beagle was a Cherokee class 10-gun brig of the Royal Navy, named after the beagle, a breed of dog. ... Charles Robert Darwin (12 February 1809 – 19 April 1882) was an eminent English naturalist who achieved lasting fame by convincing the scientific community that species develop over time from a common origin. ... The Galápagos Islands hold 13 species of finches that are closely related and differ most markedly in the shape of their beaks. ...


Fossils are important for estimating when various lineages developed. As fossilization is an uncommon occurrence, usually requiring hard body parts and death near a site where sediments are being deposited, the fossil record only provides sparse and intermittent information about the evolution of life. Evidence of organisms prior to the development of hard body parts such as shells, bones and teeth is especially scarce, but exists in the form of ancient microfossils of a few soft-bodied organisms. Three small ammonite fossils, each approximately 1. ... Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ... It has been suggested that this article or section be merged into Fossil. ... This article is about evolution in biology. ... The scientific method or process is fundamental to the scientific investigation and acquisition of new knowledge based upon physical evidence. ...


Comparison of the genetic sequence of organisms has revealed that organisms that are phylogenetically close have a higher degree of sequence similarity than organisms that are phylogenetically distant. Further evidence for common descent comes from genetic detritus such as pseudogenes, regions of DNA that are orthologous to a gene in a related organism, but are no longer active and appear to be undergoing a steady process of degeneration. Since metabolic processes do not leave fossils, research into the evolution of the basic cellular processes is also done largely by comparison of existing organisms. Many lineages diverged at different stages of development, so it is theoretically possible to determine when certain metabolic processes appeared by comparing the traits of the descendants of a common ancestor. In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... A group of organisms is said to have common descent if they have a common ancestor. ... A pseudogene is a nucleotide sequences that is similar to a normal gene, but is not expressed as a functional protein. ... Orthologs are genes in different species which evolved from a common ancestral gene. ... Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ...

Contents

Evidence from paleontology

An insect trapped in amber.

When organisms die, they often decompose rapidly or are consumed by scavengers, leaving no permanent evidences of their existence. However, occasionally, some organisms are preserved. The remains or traces of organisms from a past geologic age embedded in rocks by natural processes are called fossils. They are extremely important for understanding the evolutionary history of life on Earth, as they provide direct evidence of evolution and detailed information on the ancestry of organisms. Paleontology is the study of past life based on fossil records and their relations to different geologic time periods. Download high resolution version (980x1360, 144 KB) Resin This image shows resin with an insect (an ant?). Photographer André Karwath aka Aka Date 2005-04-23 License GNU FDL Camera data Camera Nikon D70 Lens Tamron SP AF 90mm/2. ... Download high resolution version (980x1360, 144 KB) Resin This image shows resin with an insect (an ant?). Photographer André Karwath aka Aka Date 2005-04-23 License GNU FDL Camera data Camera Nikon D70 Lens Tamron SP AF 90mm/2. ... For other uses, see Amber (disambiguation). ... Spoilage redirects here. ... Harvestman eating the tail of a five-lined skink The word scavenger, in zoology, refers to animals that consume already dead organic life-forms. ... // For other uses, see time scale. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... Three small ammonite fossils, each approximately 1. ... This timeline of the evolution of life outlines the major events in the development of life on the planet Earth. ... Paleontology, palaeontology or palæontology (see spelling differences) is the study of the history and development of life on Earth, including that of ancient plants and animals, based on the fossil record (evidence of their prehistoric existence as typically preserved in sedimentary rocks). ...


For fossilization to take place, the traces and remains of organisms must be quickly buried so that weathering and decomposition do not occur. Skeletal structures or other hard parts of the organisms are the most commonly occurring form of fossilized remains (Paul, 1998), (Behrensmeyer, 1980) and (Martin, 1999). There are also some trace "fossils" showing moulds, cast or imprints of some previous organisms. One half of a bronze mould for casting a socketed spear head dated to the period 1400-1000 BC. There are no known parallels for this mould. ...


As an animal dies, the organic materials gradually decay away, such that the bones become porous. If the animal is subsequently buried in mud, mineral salts will infiltrate into the bones and gradually fill up the pores. The bones will harden into stones and be preserved as fossils. This process is known as petrification. If dead animals are covered by wind-blown sand, and if the sand is subsequently turned into mud by heavy rain or floods, the same process of mineral infiltration may occur. Apart from petrification, the dead bodies of organisms may be well preserved in ice, in hardened resin of coniferous trees (amber), in tar, or in anaerobic, acidic peat. Fossilization can sometimes be a trace, an impression of a form. Examples include leaves and footprints, the fossils of which are made in layers that then harden. Grays Anatomy illustration of a human femur. ... In computer gaming, a MUD (Multi-User Dungeon or Domain or Dimension) is a multi-player computer game that combines elements of role-playing games, hack and slash style computer games and social chat rooms. ... Minerals are natural compounds formed through geological processes. ... In geology, petrifaction or petrification is the process by which organic material is converted into stone or a similar substance. ... Patterns in the sand Sand is a granular material made up of fine rock particles. ... For the singer, see Rain (singer). ... Picture of flooding in Amphoe Sena, Ayutthaya Province, Thailand For other uses, see Flood (disambiguation). ... Snowflakes by Wilson Bentley, 1902 Ice is the name given to any one of the 14 known solid phases of water. ... Resin of a pine Insect trapped in resin. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, also known as division Coniferae, are one of 13 or 14 division level taxa within the... For other uses, see Amber (disambiguation). ... In databases, ACID stands for Atomicity, Consistency, Isolation, and Durability. ... Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetation matter. ... Look up Trace in Wiktionary, the free dictionary. ...


Fossil records

Fossil trilobite. Trilobites were hard-shelled animals, related to living crabs and shrimp, that first appeared in significant numbers 500 mya, dying out 250 mya.
Fossil trilobite. Trilobites were hard-shelled animals, related to living crabs and shrimp, that first appeared in significant numbers 500 mya, dying out 250 mya.

It is possible to find out how a particular group of organisms evolved by arranging its fossil records in a chronological sequence. Such a sequence can be determined because fossils are mainly found in sedimentary rock. Sedimentary rock is formed by layers of silt or mud on top of each other; thus, the resulting rock contains a series of horizontal layers, or strata. Each layer contains fossils which are typical for a specific time period during which they were made. The lowest strata contain the oldest rock and the earliest fossils, while the highest strata contain the youngest rock and more recent fossils. Download high resolution version (878x1041, 124 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (878x1041, 124 KB) Wikipedia does not have an article with this exact name. ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Nektaspida (doubtful order) Trilobites are extinct arthropods in the class Trilobita. ... Superfamilies Dromiacea Homolodromioidea Dromioidea Homoloidea Eubrachyura Raninoidea Cyclodorippoidea Dorippoidea Calappoidea Leucosioidea Majoidea Hymenosomatoidea Parthenopoidea Retroplumoidea Cancroidea Portunoidea Bythograeoidea Xanthoidea Bellioidea Potamoidea Pseudothelphusoidea Gecarcinucoidea Cryptochiroidea Pinnotheroidea * Ocypodoidea * Grapsoidea * An asterisk (*) marks the crabs included in the clade Thoracotremata. ... Superfamilies Alpheoidea Atyoidea Bresilioidea Campylonotoidea Crangonoidea Galatheacaridoidea Nematocarcinoidea Oplophoroidea Palaemonoidea Pandaloidea Pasiphaeoidea Procaridoidea Processoidea Psalidopodoidea Stylodactyloidea True shrimp are small, swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. ... In astronomy, geology, and paleontology, mya is an acronym for million years ago and is used as a unit of time to denote length of time before the present. ... The Dodo, shown here in illustration, is an often-cited[1] example of modern extinction. ... This article or section does not cite its references or sources. ... Silt is soil or rock derived granular material of a specific grain size. ... Goldenville Strata exposed at a quarry in Bedford, Canada. ... A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. ...


A succession of animals and plants can also be seen from fossil records. Fossil evidence supports the theory that organisms tend to progressively increase in complexity. By studying the number and complexity of different fossils at different stratigraphic levels, it has been shown that older fossil-bearing rocks contain fewer types of fossilized organisms, and they all have a simpler structure, whereas younger rocks contain a greater variety of fossils, often with increasingly complex structures. Succession is the act or process of pooing or of following in order or sequence. ... Stratigraphy, a branch of geology, is basically the study of rock layers and layering (stratification). ...


In the past, geologists could only roughly estimate the ages of various strata and the fossils found. They did so, for instance, by estimating the time for the formation of sedimentary rock layer by layer. Today, by measuring the proportions of radioactive and stable elements in a given rock, the ages of fossils can be more precisely dated by scientists. This technique is known as radiometric dating. Radioactive decay is the set of various processes by which unstable atomic nuclei emit subatomic particles (radiation). ... The periodic table of the chemical elements (this version outdated on October 13, 2006) A chemical element, or element for short, is a pure substance that cannot be decomposed into any simpler substance. ... Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances. ...


Throughout the fossil record, many species that appear at an early stratigraphic level disappear at a later level. This is interpreted in evolutionary terms as indicating the times at which species originated and became extinct. Geographical regions and climatic conditions have varied throughout the Earth's history. Since organisms are adapted to particular environments, the constantly changing conditions favoured species which adapted to new environments through the mechanism of natural selection. The Galápagos Islands hold 13 species of finches that are closely related and differ most markedly in the shape of their beaks. ...


According to fossil records, some modern species of plants and animals are found to be almost identical to the species that lived in ancient geological ages. They are existing species of ancient lineage that have remained morphologically (and probably also physiologically) somewhat unchanged for a very long time. Consequently, they are called "living fossils" by laypeople. Examples of "living fossils" include the tuatara, the nautilus, the horseshoe crab, the coelacanth, the ginkgo, the Wollemi pine, and the metasequoia. Comparative anatomy is the study of similarities and differences in organisms. ... Leonardo da Vincis Vitruvian Man, an important early achievement in the study of physiology. ... Living fossil is a term for any living species (or clade) of organism which closely resembles species otherwise only known from fossils and has no close living relatives. ... Species Sphenodon punctatus (Gray, 1842) Sphenodon guntheri Buller, 1877 Sphenodon diversum (extinct) The tuatara is a reptile of the family Sphenodontidae, endemic to New Zealand. ... Genera Allonautilus Nautilus Nautilus (from Greek nautilos, sailor) is the common name of any marine creatures of the cephalopod family Nautilidae, the sole family of the suborder Nautilina. ... Binomial name Limulus polyphemus Linnaeus, 1758 The horseshoe crab (Limulus polyphemus) is a chelicerate arthropod, therefore it is more closely related to spiders and scorpions than crabs. ... This article or section does not cite its references or sources. ... Binomial name Ginkgo biloba L. The Ginkgo (Ginkgo biloba), frequently misspelled as Gingko, and sometimes known as the Maidenhair Tree, is a unique tree with no close living relatives. ... Binomial name Wollemia nobilis The Wollemi Pine (Wollemia nobilis) is a remarkable coniferous tree that was discovered in 1994 in a remote series of narrow, steep-sided sandstone gorges in a mild temperate-zone rainforest wilderness area of the Wollemi National Park in New South Wales, 150 kilometers north-west... Binomial name Metasequoia glyptostroboides Hu & Cheng Metasequoia glyptostroboides (Dawn Redwood) is a fast growing tree in the conifer family Cupressaceae native to the Sichuan-Hubei region of China. ...


Extent of the Fossil Record

Despite the relative rarity of suitable conditions for fossilization, approximately 250,000 fossil species are known[4]. The number of individual fossils this represents varies greatly from species to species, but many millions of fossils have been recovered: for instance, more than three million fossils from the last Ice Age have been recovered from the La Brea Tar Pits in Los Angeles[5]. Many more fossils are still in the ground, in various geological formations known to contain a high fossil density, allowing estimates of the total fossil content of the formation to be made. An example of this occurs in South Africa's Beaufort Formation (part of the Karoo Supergroup, which covers most of South Africa), which is rich in vertebrate fossils, including therapsids (reptile/mammal transitional forms)[6]. It has been estimated[7] that this formation contains 800 billion vertebrate fossils. Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... La Brea Tar Pits in Los Angeles Countys Miracle Mile District. ... Groups Biarmosuchia Dinocephalia Anomodontia Theriodontia    Cynodontia       (...mammals) Therapsids, previously known as the mammal-like reptiles, are a group of synapsids. ... A transitional fossil or transitional form is the fossilized remains of a life form that illustrates an evolutionary transition. ...


Evolution of the horse

Further information: Evolution of the horse
Evolution of the horse showing reconstruction of the fossil species obtained from successive rock strata. The foot diagrams are all front views of the left forefoot. The third metacarpal is shaded throughout. The teeth are shown in longitudinal section.
Evolution of the horse showing reconstruction of the fossil species obtained from successive rock strata. The foot diagrams are all front views of the left forefoot. The third metacarpal is shaded throughout. The teeth are shown in longitudinal section.

Due to an almost-complete fossil record found in North American sedimentary deposits from the early Eocene to the present, the horse provides one of the best examples of evolutionary history (phylogeny). Evolution of the horse, showing reconstruction of the fossil species obtained from successive rock strata. ... Image File history File links Download high resolution version (1146x1392, 351 KB) Evolution of horse File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (1146x1392, 351 KB) Evolution of horse File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Evolution of the horse, showing reconstruction of the fossil species obtained from successive rock strata. ... The metacarpus is the intermediate part of the hand skeleton that is located between the fingers distally and the carpus which forms the connection to the forearm. ... World map showing North America A satellite composite image of North America. ... The Eocene epoch (55. ... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus, sometimes seen as a subspecies of the Wild Horse, Equus ferus caballus) is a large odd-toed ungulate mammal, one of ten modern species of the genus Equus. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ...


This evolutionary sequence starts with a small animal called the Hyracotherium which lived in North America about 54 million years ago, then spread across to Europe and Asia. Fossil remains of Hyracotherium show it to have differed from the modern horse in three important respects: it was a small animal (the size of a fox), lightly built and adapted for running; the limbs were short and slender, and the feet elongated so that the digits were almost vertical, with four digits in the forelimbs and three digits in the hindlimbs; and the incisors were small, the molars having low crowns with rounded cusps covered in enamel. This little horse lived 50 million years ago the person who discovered it called Mole Beast or Hyracotherium later they found another one but called it Dawn Horse the name was given to another Hyracotherium but it also goes by Eohippus. ... World map showing the location of Europe. ... World map showing the location of Asia. ... Fox is a general term applied to any one of roughly 27 species of small to medium-sized omnivorous canids in the tribe vulpini with sharp features and a brush-like tail. ... A forelimb is an anterior limb on an animals body. ... A hind limb is a posterior limb on an animal. ... Incisors are the first kind of tooth in heterodont mammals. ... Molar may refer to: Molar (tooth), the fourth kind of tooth in mammals. ... In common parlance, a cusp is an important moment usually regarded as a decision point upon which consequent events are determined. ... The word enamel can mean more than one thing: Tooth enamel Vitreous enamel Enamel (markup language) Enameled wire This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...


The probable course of development of horses from Hyracotheium to Equus (the modern horse) involved at least 12 genera and several hundred species. The major trends seen in the development of the horse to changing environmental conditions may be summarized as follows: For other uses of the word, please see Genus (disambiguation). ... In biology, a species is one of the basic units of biodiversity. ...

  • Increase in size (from 0.4 m to 1.5 m);
  • Lengthening of limbs and feet;
  • Reduction of lateral digits;
  • Increase in length and thickness of the third digit;
  • Increase in width of incisors;
  • Replacement of premolars by molars; and
  • Increases in tooth length, crown height of molars.

Fossilized plants found in different strata show that the marshy, wooded country in which Hyracotherium lived became gradually drier. Survival now depended on the head being in an elevated position for gaining a good view of the surrounding countryside, and on a high turn of speed for escape from predators, hence the increase in size and the replacement of the splayed-out foot by the hoofed foot. The drier, harder ground would make the original splayed-out foot unnecessary for support. The changes in the teeth can be explained by assuming that the diet changed from soft vegetation to grass. A dominant genus from each geological period has been selected to show the progressive development of the horse. However, it is important to note that there is no evidence that the forms illustrated are direct descendants of each other, even though they are related. Incisors are the first kind of tooth in heterodont mammals. ... The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. ... Molar may refer to: Molar (tooth), the fourth kind of tooth in mammals. ... Freshwater marsh in Florida In geography, a marsh is a type of wetland, featuring grasses, rushes, reeds, typhas, sedges, cat tails, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. ... A hawk consuming its prey, a small rodent. ... Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants, and is, by far, the most abundant biotic element of the biosphere. ... Caution: Grass should never be eaten For other uses, see Grass (disambiguation). ...


Limitations

The fossil record is an important source for scientists when tracing the evolutionary history of organisms. However, because of limitations inherent in the record, there are not fine scales of intermediate forms between related groups of species. This lack of continuous fossils in the record is a major limitation in tracing the descent of biological groups. Furthermore, there are also much larger gaps between major evolutionary lineages. These gaps are often referred to as "missing links". A transitional fossil or transitional form is the fossilized remains of a life form that illustrates an evolutionary transition. ...


There is a gap of about 100 million years between the early Cambrian period and the later Ordovician period. The early Cambrian period was the period from which numerous fossils of sponges, cnidarians (e.g., corals), echinoderms (e.g., brittle stars), molluscs (e.g., snails) and arthropods (e.g., trilobites) are found. In the later Ordovician period, the first animal that really possessed the typical features of vertebrates, the Australian fish, Arandaspis appeared. Thus few, if any, fossils of an intermediate type between invertebrates and vertebrates have been found, although likely candidates include the Burgess Shale animal, Pikaia gracilens, and its Maotianshan Shales relatives, Myllokunmingia, Yunnanozoon, Haikouella lanceolata, and Haikouichthys. The Cambrian is a major division of the geologic timescale that begins about 542 ± 1. ... The Ordovician period is the second of the six (seven in North America) periods of the Paleozoic era. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from the Greek poros pore and ferro to bear) are animals of the phylum Porifera. ... Classes Anthozoa - Corals and sea anemones Cubozoa - Sea wasps or box jellyfish Hydrozoa - Hydroids, hydra-like animals Scyphozoa - Jellyfish Cnidaria is a phylum containing some 10,000 species of relatively simple animals found exclusively in aquatic environments (most species are marine). ... Subclasses Alcyonaria Zoantharia See text for orders. ... Classes Asteroidea Blastoidea (extinct) Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Phylum Echinodermata, from the Greek for spiny skin) are a phylum of marine animals found at all depths. ... Orders Oegophiurida Ophiurida Phrynophiurida Brittle starfishs are echinoderms, closely related to sea stars. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ... Subphyla and Classes Subphylum Trilobitomorpha Trilobita - trilobites (extinct) Subphylum Chelicerata Arachnida - spiders,scorpions, etc. ... Orders Agnostida Redlichiida Corynexochida Lichida Phacopida Proetida Asaphida Harpetida Ptychopariida Nektaspida (doubtful order) Trilobites are extinct arthropods in the class Trilobita. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... Arandaspis prionotolepis is an extinct species of jawless fish that lived in the Ordovician period, about 500 million years ago. ... Invertebrate is a term that describes any animal without a spinal column. ... The Burgess Shale (named after Mount Burgess, close to where the Shale was found) is a black shale exposure found high up in the Canadian Rockies in Yoho National Park near the town of Field, British Columbia. ... Pikaia gracilens is an extinct animal known from the Middle Cambrian fossil found near Mount Pika in the Burgess Shale of British Columbia. ... The Myllokummingia is a primitive, probably agnathid (jawless) fish from the Lower Cambrian Maotianshan shales of China thought to be a vertebrate (see external links). ... The Yunnanozooan is a suspected chordate or hemichordate from the Lower Cambrian beds of Xiangchiang in Yunnan province, China. ... The Haikouichthys is a primitive fish-like animal from the Lower Cambrian Maotianshan shales of China. ...


Some of the reasons for the incompleteness of fossil records are:

  • In general, the probability that an organism becomes fossilized after death is very low;
  • Some species or groups are less likely to become fossils because they are soft-bodied;
  • Some species or groups are less likely to become fossils because they live (and die) in conditions that are not favourable for fossilization to occur in;
  • Many fossils have been destroyed by land movements and erosion;
  • Some fossil remains are complete, but most are fragmentary;
  • Some evolutionary change occurs in populations at the limits of a species' ecological range, and as these populations are likely to be small, the probability of fossilization is lower (see punctuated equilibrium);
  • Similarly, when environmental conditions change, the population of a species is likely to be greatly reduced, such that any evolutionary change induced by these new conditions is less likely to be fossilized;
  • Most fossils convey information about external form, but little about how the organism functioned;
  • Using present-day biodiversity as a guide, this suggests that the fossils unearthed represent only a fraction of the large number of species of organisms that lived in the past.

Punctuated equilibrium (or punctuated equilibria) is a theory in evolutionary biology which states that most sexually reproducing species will show little to no evolutionary change throughout their history. ...

Evidence from comparative anatomy

Comparative study of the anatomy of groups of animals or plants reveals that certain structural features are basically similar. For example, the basic structure of all flowers consists of sepals, petals, stigma, style and ovary; yet the size, colour, number of parts and specific structure are different for each individual species. Comparative anatomy is the study of similarities and differences in the anatomy of organisms. ... A Phalaenopsis flower A flower, (<Old French flo(u)r<Latin florem<flos), also known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). ... Flower of the Primrose Willowherb (Ludwigia octovalvis) showing petals and sepals A sepal is one member or part of the calyx of a flower. ... It has been suggested that Corolla be merged into this article or section. ... Amaryllis style and stigmas A carpel is the female reproductive organ of a flower; the basic unit of the gynoecium. ... You may be looking for one of the following: Dimensions: length, width, height Clothing measurements such as shoe size or dress size Geometry Measurement Gelatinous or glutinous substance made from glue, wax, clay or similar Or the following command-line Unix tool: Size (Unix) This is a disambiguation page: a... Color is an important part of the visual arts. ... A number is an abstract entity that represents a count or measurement. ...


Homologous structures and divergent (adaptive) evolution

If widely separated groups of organisms are originated from a common ancestry, they are expected to have certain basic features in common. The degree of resemblance between two organisms should indicate how closely related they are in evolution: Several equivalence relations in mathematics are called similarity. ...

  • Groups with little in common are assumed to have diverged from a common ancestor much earlier in geological history than groups which have a lot in common;
  • In deciding how closely related two animals are, a comparative anatomist looks for structures that are fundamentally similar, even though they may serve different functions in the adult Such structures are described as homologous and suggest a common origin.
  • In cases where the similar structures serve different functions in adults, it may be necessary to trace their origin and embryonic development. A similar developmental origin suggests they are the same structure, and thus likely to be derived from a common ancestor.

When a group of organisms share a homologous structure which is specialized to perform a variety of functions in order to adapt different environmental conditions and modes of life are called adaptive radiation. The gradual spreading of organisms with adaptive radiation is known as divergent evolution. Missing link is a term for a transitional form from the fossil record that connects an earlier species to a later one, or which connects two different species to an earlier ancestor. ... Look up Structure in Wiktionary, the free dictionary. ... A young woman who is 18 years old. ... In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. ... Adaptive radiation describes the rapid speciation of a single or a few species to fill many ecological niches. ... Divergent evolution occurs when a biological characteristic (such as a structure in two or more species or two or more genes) has a common evolutionary origin, but that characteristic has diverged over evolutionary time. ...


Pentadactyl limb

Figure 5a: The principle of homology illustrated by the adaptive radiation of the forelimb of mammals. All conform to the basic pentadactyl pattern but are modified for different usages. The third metacarpal is shaded throughout; the shoulder is crossed-hatched.

The pattern of limb bones called pentadactyl limb is an example of homologous structures (Fig. 5a). It is found in all classes of tetrapods (i.e. from amphibians to mammals). It can even be traced back to the fins of certain fossil fishes from which the first amphibians are thought to have evolved. The limb has a single proximal bone (humerus), two distal bones (radius and ulna), a series of carpals (wrist bones), followed by five series of metacarpals (palm bones) and phalanges (digits). Throughout the tetrapods, the fundamental structures of pentadactyl limbs are the same, indicating that they originated from a common ancestor. But in the course of evolution, these fundamental structures have been modified. They have become superficially different and unrelated structures to serve different functions in adaptation to different environments and modes of life. This phenomenon is clearly shown in the forelimbs of mammals. For example: Image File history File links Download high resolution version (2222x1578, 768 KB) Created by Jerry Crimson Mann 06:25, 2 August 2005 (UTC). ... Image File history File links Download high resolution version (2222x1578, 768 KB) Created by Jerry Crimson Mann 06:25, 2 August 2005 (UTC). ... In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. ... In biology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of an animal. ... Groups See text. ... Subclasses and Orders Order Temnospondyli - extinct Subclass Lepospondyli - extinct Subclass Lissamphibia   Anura   Caudata   Gymnophiona Amphibians (class Amphibia; from Greek αμφις both and βιος life) are a taxon of animals that include all living tetrapods (four-legged vertebrates) that do not have amniotic eggs, are ectotherms, and generally spend part of their time... Subclasses Allotheria* Order Multituberculata (extinct) Order Volaticotheria (extinct) Order Palaeoryctoides (extinct) Order Triconodonta (extinct) Prototheria Order Monotremata Theria Infraclass Marsupialia Infraclass Eutheria The mammals are the class of vertebrate animals characterized by the production of milk in females for the nourishment of young, from mammary glands present on most species... A fin is a surface used to produce lift and thrust or to steer while traveling in water, air, or other fluid media. ... The humerus is a long bone in the arm or fore-legs (animals) that runs from the shoulder to the elbow. ... Remote Authentication Dial In User Service (RADIUS) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... The ulna (Elbow Bone) [Figs. ... In human anatomy, the carpal bones are the bones of the human wrist. ... In human anatomy, the wrist is the flexible and narrower connection between the forearm and the hand. ... Human right hand The hands (med. ... The Kataeb Party, better known in English-speaking countries as the Phalange, is a Lebanese political party that was first established as a Maronite nationalist youth movement in 1936 by Pierre Gemayel. ...

  • In the monkey, the forelimbs are much elongated to form a grasping hand for climbing and swinging among trees.
  • In the pig, the first digit is lost, and the second and fifth digits are reduced. The remaining two digits are longer and stouter than the rest and bear a hoof for supporting the body.
  • In the horse, the forelimbs are adapted for support and running by great elongation of the third digit bearing a hoof.
  • The mole has a pair of short, spade-like forelimbs for burrowing.
  • The anteater uses its enlarged third digit for tearing down ant hills and termite nests.
  • In the whale, the forelimbs become flippers for steering and maintaining equilibrium during swimming.
  • In the bat, the forelimbs have turned into wings for flying by great elongation of four digits, and the hook-like first digit remains free for hanging from trees.

For other uses, see Monkey (disambiguation). ... This article is about the pig genus. ... Genera 17 genera, see text Moles are members of the family (Talpidae) of mammals in the order Soricomorpha that live underground, burrowing holes. ... A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. ... Families Cyclopedidae Myrmecophagidae Anteaters are the four mammal species of the suborder Vermilingua commonly known for eating ants and termites. ... Subfamilies Aenictogitoninae Agroecomyrmecinae Amblyoponinae (incl. ... Families Mastotermitidae Kalotermitidae Termopsidae Hodotermitidae Rhinotermitidae Serritermitidae Termitidae Termites, sometimes known as white ants, are a group of eusocial insects usually classified at the taxonomic rank of order, Isoptera. ... A Fin whale The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. ... Look up flipper in Wiktionary, the free dictionary. ... Suborders Megachiroptera Microchiroptera See text for families. ... WING ESPN 1410 is an commercial AM radio station in Dayton, Ohio operating with 5,000 watts at 1410 kHz with studios, offices and transmitter located on David Road in Kettering. ... Look up Hook in Wiktionary, the free dictionary. ... The coniferous Coast Redwood, the tallest tree species on earth. ...

Insect mouthparts

Figure 5b: Adaptive radiation of insect mouthparts: a, antennae; c, compound eye; lb, labrium; lr, labrum; md, mandibles; mx, maxillae.
Figure 5b: Adaptive radiation of insect mouthparts: a, antennae; c, compound eye; lb, labrium; lr, labrum; md, mandibles; mx, maxillae.

The basic structures are the same which include a labrum (upper lip), a pair of mandibles, a hypopharynx (floor of mouth), a pair of maxillae and a labium. These structures are enlarged and modified; others are reduced and lost. The modifications enable the insects to exploit a variety of food materials (Fig. 5b): Image File history File links Download high resolution version (898x857, 240 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Download high resolution version (898x857, 240 KB) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Adaptive radiation describes the rapid speciation of a single or a few species to fill many ecological niches. ... For other uses, see Antenna. ... Compound eye of a dragonfly Compound eye of Antarctic krill as imaged by an electron microscope A compound eye is a visual organ found in certain arthropods such as insects and crustaceans. ... A labrum (Latin for lip) is the large vessel of a warm bath in the Roman thermae. ... It has been suggested that this article or section be merged with jaw. ... In human anatomy, the hypopharynx is the bottom part of the pharynx, and is the part of the throat that connects to the esophagus. ... The maxillae are the largest bones of the face, except for the mandible, and form, by their union, the whole of the upper jaw. ... Anterior view of an adult woman with pubic hair removed, showing labia majora. ...


(A) Primitive state — biting and chewing: e.g. grasshopper. Strong mandibles and maxillae for manipulating food. Families Superfamily: Tridactyloidea Cylindrachaetidae Ripipterygidae Tridactylidae Superfamily: Tetrigoidea Tetrigidae Superfamily: Eumastacoidea Chorotypidae Episactidae Eumastacidae Euschmidtiidae Mastacideidae Morabidae Proscopiidae Thericleidae Superfamily: Pneumoroidea Pneumoridae Superfamily: Pyrgomorphoidea Pyrgomorphidae Superfamily: Acridoidea Acrididae Charilaidae Dericorythidae Lathiceridae Lentulidae Lithidiidae Ommexechidae Pamphagidae Pyrgacrididae Romaleidae Tristiridae Superfamily: Tanaoceroidea Tanaoceridae Superfamily: Trigonopterygoidea Trigonopterygidae Xyronotidae Grasshoppers are herbivorous insects of...


(B) Ticking and biting: e.g. honey bee. Labium long to lap up nectar; mandibles chew pollen and mould wax. The honeybee is a colonial insect that is often maintained, fed, and transported by farmers. ... In Greek mythology, nectar and ambrosia are the food of the gods. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... candle wax This page is about the substance. ...


(C) Sucking: e.g. butterfly. Labrum reduced; mandibles lost; maxillae long forming sucking tube. Families Superfamily Hesperioidea: Hesperiidae Superfamily Papilionoidea: Papilionidae Pieridae Nymphalidae Lycaenidae Riodinidae A butterfly is an insect of the order Lepidoptera, it belongs to either the Hesperioidea (the skippers) or Papilionoidea (all other butterflies) Superfamilies. ...


(D) Piercing and sucking, e.g. female mosquito. Labrum and maxillae form tube; mandibles form piercing stylets; labrum grooved to hold other parts. This article or section does not cite its references or sources. ...


Analogous structures and convergent evolution

Figure 6: Inverted retina of vertebrate (left) and non-inverted retina of octopus (right)
Figure 6: Inverted retina of vertebrate (left) and non-inverted retina of octopus (right)

Under similar environmental conditions, fundamentally different structures in different groups of organisms may undergo modifications to serve similar functions. This phenomenon is called convergent evolution. Similar structures, physiological processes or mode of life in organisms apparently bearing no close phylogenetic links but showing adaptations to perform the same functions are described as analogous, for example: Image File history File links Created by Jerry Crimson Mann 07:07, 2 August 2005 (UTC). ... Image File history File links Created by Jerry Crimson Mann 07:07, 2 August 2005 (UTC). ... In evolutionary biology, convergent evolution is the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. ... Analogy is either the cognitive process of transferring or giving information from a particular subject (the analogue or source) to another particular subject (the target), or a linguistic expression corresponding to such a process. ...

  • Wings of bats, birds and insects;
  • the jointed legs of insects and vertebrates;
  • tail fin of fish, whale and lobster;
  • eyes of the vertebrates and cephalopod molluscs (squid and octopus). Fig. 6 illustrates difference between an inverted and non-inverted retina, the sensory cells lying beneath the nerve fibres. This results in the sensory cells being absent where the optic nerve is attached to the eye, thus creating a blind spot. The octopus eye has a non-inverted retina in which the sensory cells lie above the nerve fibres. There is therefore no blind spot in this kind of eye. Apart from this difference the two eyes are remarkably similar, an example of convergent evolution.
See also: Evolution of the eye

Suborders Megachiroptera Microchiroptera See text for families. ... Aves redirects here. ... Orders See taxonomy Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species — more than all other animal groups combined [1]. Insects may be found in nearly all environments on the planet, although only a... Orders See taxonomy Insects (Class Insecta) are a major group of arthropods and the most diverse group of animals on the Earth, with over a million described species — more than all other animal groups combined [1]. Insects may be found in nearly all environments on the planet, although only a... Classes and Clades See below Male and female Superb Fairy-wren Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... A fin is a surface used to produce lift and thrust or to steer while traveling in water, air, or other fluid media. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... A Fin whale The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. ... For the magazine, see Lobster (magazine) Subfamilies and Genera Neophoberinae Acanthacaris Thymopinae Nephropsis Nephropides Thymops Thymopsis Nephropinae Homarus Nephrops Homarinus Metanephrops Eunephrops Thymopides Clawed lobsters comprise a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans. ... A human eye. ... Classes and Clades See below Male and female Superb Fairy-wren Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... Orders Subclass Nautiloidea †Plectronocerida †Ellesmerocerida †Actinocerida †Pseudorthocerida †Endocerida †Tarphycerida †Oncocerida †Discosorida Nautilida †Orthocerida †Ascocerida †Bactritida Subclass †Ammonoidea †Goniatitida †Ceratitida †Ammonitida Subclass Coleoidea †Belemnoidea †Aulacocerida †Belemnitida †Hematitida †Phragmoteuthida Neocoleoidea (most living cephalopods) Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida The cephalopods (Greek plural (kephalópoda); head-foot) are the mollusk class Cephalopoda... Suborders Myopsina Oegopsina Squid are a large, diverse group of marine cephalopods. ... Suborders †Pohlsepia (incertae sedis) †Proteroctopus (incertae sedis) †Palaeoctopus (incertae sedis) Cirrina Incirrina Synonyms Octopoida Leach, 1817 The octopus (Greek , eight-legs) is a cephalopod of the order Octopoda that inhabits many diverse regions of the ocean, especially coral reefs. ... Human eye cross-sectional view. ... An axon, or nerve fiber, is a long slender projection of a nerve cell, or neuron, which conducts electrical impulses away from the neurons cell body or soma. ... MRI scan of human eye showing optic nerve. ... The term blind spot has several meanings. ... Compound eye of Antarctic krill. ...

Vestigial organs

Main article: Vestigial structure The human vermiform appendix is a vestigial structure; it no longer retains its original function. ...


A further aspect of comparative anatomy is the presence of vestigial organs. Organs that are smaller and simpler in structure than corresponding parts in the ancestral species are called vestigial organs. They are usually degenerated or underdeveloped. The existence of vestigial organs can be explained in terms of changes in the environment or modes of life of the species. Those organs are thought to be functional in the ancestral species but have now become unnecessary and non-functional. Examples are the vestigial hind limbs of whales, the haltere (vestigial hind wings) of flies and mosquitos, vestigial wings of flightless birds such as ostriches, and the vestigial leaves of some xerophytes (e.g. cactus) and parasitic plants (e.g. dodder). It must be noted however, that vestigial structures have lost the original function but may have another one. For example the halteres in dipterists help balance the insect while in flight and the wings of ostriches are used in mating rituals. Halteres, (singular halter or haltere) from the Greek word for dumbbells, are small knobbed structures homologous to wings and flapped to maintain stability when flying. ... WING ESPN 1410 is an commercial AM radio station in Dayton, Ohio operating with 5,000 watts at 1410 kHz with studios, offices and transmitter located on David Road in Kettering. ... Suborders Nematocera Brachycera Dance fly male Empis tesselata The flesh fly, Sarcophaga carnaria Close-up of the head of a blow-fly. ... Binomial name Struthio camelus Linnaeus, 1758 The present-day distribution of ostriches. ... Foliage redirects here. ... A xerophyte describes a plant that has structural (xeromorphic) and physiological adaptations which enable them to survive, or even thrive, in areas with very little free moisture. ... Genera See Taxonomy of the Cactaceae A cactus (plural cactus, cacti, or cactuses) is any member of the succulent plant family Cactaceae. ... The term Dodder may refer to a number of topics: The parasitic Cuscuta plant. ... Suborders Archidiptera Eudiptera Brachycera Diptera are insects in which the hind wings are reduced to halteres. ... Dates romantically sharing a chili cheese dog, in a dream sequence Courtship (sometimes called dating or going steady) is the process of selecting and attracting a mate for marriage. ...


Evidence from geographical distribution

Biologists have discovered many puzzling facts about the presence of certain species on various continents and islands (biogeography). Color-coded regions of the world based on the seven commonly-recognised continents Dymaxion map by Buckminster Fuller shows land masses with minimal distortion as nearly one continuous continent A continent is one of several large landmasses on Earth. ... Biogeography is the science which deals with patterns of species distribution and the processes that result in such patterns. ...


Continental distribution

All organisms are adapted to their environment to a greater or lesser extent. If the abiotic and biotic factors within a habitat are capable of supporting a particular species in one geographic area, then one might assume that the same species would be found in a similar habitat in a similar geographic area, e.g. in Africa and South America. This is not the case. Plant and animal species are discontinuously distributed throughout the world: Habitat (from the Latin for it inhabits) is the place where a particular species lives and grows. ... A world map showing the continent of Africa. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ...

Even greater differences can be found if Australia is taken into consideration though it occupies the same latitude as South America and Africa. Marsupials like the kangaroo can be found in Australia, but are totally absent from Africa and are only represented by the opossum in South America and the Virginia Opossum in North America: The Old World consists of those parts of Earth known to Europeans, Asians, and Africans before the voyages of Christopher Columbus; it includes Europe, Asia, and Africa (collectively known as Africa-Eurasia), plus surrounding islands. ... Genera and Species Loxodonta Loxodonta cyclotis Loxodonta africana Elephas Elephas maximus Elephas antiquus † Elephas beyeri † Elephas celebensis † Elephas cypriotes † Elephas ekorensis † Elephas falconeri † Elephas iolensis † Elephas planifrons † Elephas platycephalus † Elephas recki † Stegodon † Mammuthus † Elephantidae (the elephants) is a family of pachyderm, and the only remaining family in the order Proboscidea... Binomial name Panthera leo (Linnaeus, 1758) Distribution of Lions in Africa Synonyms Felis leo (Linnaeus, 1758) The lion (Panthera leo) is a mammal of the family Felidae and one of four big cats in the genus Panthera. ... Binomial name Giraffa camelopardalis Linnaeus, 1758 The Giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species. ... Binomial name Puma concolor (Linnaeus, 1771) Cougar range map Synonyms Felis concolor The cougar (Puma concolor), also known as the puma or mountain lion, is a large, solitary cat found in the Americas. ... For other uses, see Jaguar (disambiguation). ... This article does not cite its references or sources. ... Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ... Orders Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name Marsupial derives) in which it rears its young through early infancy. ... Species Macropus rufus Macropus giganteus Macropus fuliginosus Macropus antilopinus A kangaroo is any of several large animals of the Macropodidae, a marsupial family that also includes the wallabies, tree-kangaroos, wallaroos, pademelons and the Quokka, some 63 living species in all. ... This article or section should be merged with Virginia_opossum The word opossum (usually pronounced without the leading O, or with only a very slight schwa) refers either to the Virginia Opossum in particular, or more generally to any of the other marsupials of magnorder Ameridelphia. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... Binomial name Didelphis virginiana (Kerr, 1792) The Virginia Opossum (Didelphis virginiana) is the only marsupial found in North America. ... World map showing North America A satellite composite image of North America. ...

  • The echidna and platypus, the only living representatives of primitive egg-laying mammals (monotremes), can be found only in Australia and are totally absent in the rest of the world.
  • On the other hand, Australia has very few placental mammals except those that have been introduced by human beings.

Species Genus Tachyglossus    T. aculeatus Genus Zaglossus    Z. attenboroughi    Z. bruijnii    Z. bartoni    Z. hacketti (extinct)    Z. robustus (extinct) Echidnas, sometimes also referred to as spiny anteaters, are the only surviving monotremes apart from the Platypus. ... Binomial name Ornithorhynchus anatinus (Shaw, 1799) Platypus range (indicated by darker shading)[3] The Platypus (Ornithorhynchus anatinus) is a semi-aquatic mammal endemic to eastern Australia and Tasmania. ... Families †Kollikodontidae Ornithorhynchidae - Platypus Tachyglossidae - Echidnas †Steropodontidae Monotremes (monos, single + trema, hole; refers to the cloaca) are mammals that lay eggs instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). ...

Explanation

Figure 7: Diagrams to the land bridge between continents in past geological time (A) and the barriers formed (B) due to the submergence of land bridges.
Figure 7: Diagrams to the land bridge between continents in past geological time (A) and the barriers formed (B) due to the submergence of land bridges.

The main groups of modern mammal arose in Northern Hemisphere and subsequently migrated to three major directions: Image File history File links Download high resolution version (1082x379, 100 KB) Created by Jerry Crimson Mann 10:07, 2 August 2005 (UTC). ... Image File history File links Download high resolution version (1082x379, 100 KB) Created by Jerry Crimson Mann 10:07, 2 August 2005 (UTC). ... This article or section does not cite its references or sources. ... The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and about 88-90% of the human population. ...

  • to South America via the land bridge in the Bering Strait and Isthmus of Panama; A large number of families of South American marsupials became extinct as a result of competition with these North American counterparts.
  • to Africa via the Strait of Gibraltar; and
  • to Australia via South East Asia to which it was at one time connected by land

The shallowness of the Bering Strait would have made the passage of animals between two northern continents a relatively easy matter, and it explains the present-day similarity of the two faunas. But once they had got right down into the southern continents, they presumably became isolated from each other by various types of barriers. This article or section does not cite its references or sources. ... Satellite photo of the Bering Strait http://209. ... The Isthmus of Panama. ... The Strait of Gibraltar as seen from space. ... Fauna is a collective term for animal life. ...

  • The submerging of the Isthmus of Panama: isolates the South American fauna
  • the Mediterranean Sea and the North African desert: partially isolate the African fauna; and
  • the submerging of the original connection between Australia and South East Asia: isolates the Australian fauna

Once isolated, the animals in each continent have shown adaptive radiation (Fig. 7) to evolve along their own lines. Composite satellite image of the Mediterranean Sea. ...


Evidence for migration and isolation

Map of the world showing distribution of present members of camel. Solid black lines indicate possible migration routes.
Map of the world showing distribution of present members of camel. Solid black lines indicate possible migration routes.

The fossil record for the camel indicated that evolution of camels started in North America, from which they migrated across the Bering Strait into Asia and hence to Africa, and through the Isthmus of Panama into South America. Once isolated, they evolved along their own lines, giving the modern camel in Asia and Africa and llama in South America. Image File history File links Created by Jerry Crimson Mann 10:57, 2 August 2005 (UTC). ... Image File history File links Created by Jerry Crimson Mann 10:57, 2 August 2005 (UTC). ... Species Camelus bactrianus Camelus dromedarius Camels are even-toed ungulates in the genus Camelus. ...


Continental drift

The same kinds of fossils are found from areas known to be adjacent to one another in the past but which, through the process of continental drift, are now in widely divergent geographic locations. For example, fossils of the same types of ancient amphibians, arthropods and ferns are found in South America, Africa, India, Australia and Antarctica, which can be dated to the Paleozoic Era, at which time these regions were united as a single landmass called Gondwana. [8] Sometimes the descendants of these organisms can be identified and show unmistakable similarity to each other, even though they now inhabit very different regions and climates. Plates in the crust of the earth, according to the plate tectonics theory Continental drift, proposed as a theory by Alfred Wegener in 1912, is the movement of the Earths continents relative to each other. ... The Palaeozoic is a major division of the geologic timescale, one of four geologic eras. ... Pangaea was formed by the merging of two continents, Laurasia and Gondwana East African and Kuungan Orogens 550 Ma reconstruction showing final stages of assembly The southern supercontinent Gondwana (originally Gondwanaland) included most of the landmasses which make up todays continents of the southern hemisphere, including Antarctica, South America...


Oceanic island distribution

Most small isolated islands only have native species that could have arrived by air or water; like birds, insects and turtles. The few large mammals present today were brought by human settlers in boats. Plant life on remote and recent volcanic islands like Hawaii could have arrived as airborne spores or as seeds in the droppings of birds. After the explosion of Krakatoa a century ago and the emergence of a steaming, lifeless remnant island called Anak Krakatoa (child of Krakatoa), plants arrived within months and within a year there were moths and spiders that had arrived by air. The island is now ecologially hard to distinguish from those around it that have been there for millions of years.


Evidence from comparative embryology

Comparative embryology shows how embryos start off looking the same. As they develop, their similarities slowly decrease until they take the form of their particular class. This article or section is in need of attention from an expert on the subject. ... Categories: Biology stubs | Developmental biology ...


For example, adult vertebrates are diverse, yet their embryos are quite similar at the very early pharyngula stage. Gill slits still form in early embryos of reptiles, birds, and mammals. In fish embryos, a two-chambered heart, some veins, and parts of arteries develop and persist in adult fishes. The same structures form early in human embryos but do not persist as such in adults. Classes and Clades See below Male and female Superb Fairy-wren Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... Pharyngula is the name of a stage in embryonic development. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... The heart and lungs, from an older edition of Grays Anatomy. ...


Evidence from comparative physiology and biochemistry

See also: Archaeogenetics, Common descent, Last universal ancestor, Most recent common ancestor, Nothing in Biology Makes Sense Except in the Light of Evolution, Speciation, Timeline of evolution, Timeline of human evolution, Universal Code (Biology)

Archaeogenetics, a term coined by Colin Renfrew, refers to the application of the techniques of molecular population genetics to the study of the human past. ... A group of organisms is said to have common descent if they have a common ancestor. ... Last universal ancestor (LUA), the hypothetical latest living organism from which all currently living organisms descend. ... The most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. ... Nothing in Biology Makes Sense Except in the Light of Evolution is a 1973 essay by the evolutionary biologist and Russian Orthodox Christian Theodosius Dobzhansky, criticising Young Earth creationism and espousing evolutionary creationism. ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ... This timeline of the evolution of life outlines the major events in the development of life on the planet Earth. ... The timeline of human evolution outlines the major events in the development of humans species and the evolution of humans ancestors. ... In biology, universal code is short for the idea of the universal genetic code. In all known living creatures, instructions for making proteins are encoded in DNA. Three bases of DNA (the codon) select an amino acid. ...

Evolution of widely distributed proteins and molecules

All known extant organisms make use of DNA and/or RNA. ATP is used as metabolic currency by all extant life. The Genetic code is the same for almost every organism, meaning that a piece of RNA in a bacterium codes for the same protein as in a human cell. The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... Ribonucleic acid (RNA) is a nucleic acid polymer consisting of nucleotide monomers. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... RNA codons. ... Ribonucleic acid (RNA) is a nucleic acid polymer consisting of nucleotide monomers. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ...


A classic example of biochemical evidence for evolution is the variance of the protein Cytochrome c in living cells. The variance of cytochrome c of different organisms is measured in the number of differing amino acids, each differing amino acid being a result of a base pair substitution, a mutation. If each differing amino acid is assumed to be the result of one base pair substitution, it can be calculated how long ago the two species diverged by multiplying the number of base pair substitutions by the estimated time it takes for a substituted base pair of the cytochrome c gene to be successfully passed on. For example, if the average time it takes for a base pair of the cytochrome c gene to mutate is N years, the number of amino acids making up the cytochrome c protein in monkeys differ by one from that of humans, this leads to the conclusion that the two species diverged N years ago. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Cytochrome c, or cyt c (horse heart: PDB 1HRC) is a small heme protein found loosely associated with the inner membrane of the mitochondrion. ... Phenylalanine is one of the standard amino acids. ... It has been suggested that mutant be merged into this article or section. ...


Comparison of the DNA sequences allows organisms to be grouped by sequence similarity, and the resulting phylogenetic trees are typically congruent with traditional taxonomy, and are often used to strengthen or correct taxonomic classifications. Sequence comparison is considered a measure robust enough to be used to correct erroneous assumptions in the phylogenetic tree in instances where other evidence is scarce. For example, neutral human DNA sequences are approximately 1.2% divergent (based on substitutions) from those of their nearest genetic relative, the chimpanzee, 1.6% from gorillas, and 6.6% from baboons.[1] Genetic sequence evidence thus allows inference and quantification of genetic relatedness between humans and other apes.[2][3] The sequence of the 16S rRNA gene, a vital gene encoding a part of the ribosome, was used to find the broad phylogenetic relationships between all extant life. The analysis, originally done by Carl Woese, resulted in the three-domain system, arguing for two major splits in the early evolution of life. The first split led to modern Bacteria and the subsequent split led to modern Archaea and Eukaryote. In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species in the genus Pan. ... Type species Troglodytes gorilla Savage, 1847 distribution of Gorilla Species Gorilla gorilla Gorilla beringei The gorilla, the largest of the living primates, is a ground-dwelling omnivore that inhabits the forests of Africa. ... Type species Simia hamadryas Linnaeus, 1758 Species Papio hamadryas Papio papio Papio anubis Papio cynocephalus Papio ursinus The five baboon species are some of the largest non-hominid members of the primate order; only the Mandrill and the Drill are larger. ... A non-coding RNA (ncRNA) is any RNA molecule that functions without being translated into a protein. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Carl Richard Woese (born July 15, 1928, Syracuse, New York) is an American microbiologist famous for defining the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese and which is now standard practice. ... The three-domain system is a biological classification introduced by Carl Woese in 1990 that emphasizes his separation of prokaryotes into two groups, originally called Eubacteria and Archaebacteria. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Phyla / Classes Phylum Crenarchaeota Phylum Euryarchaeota     Halobacteria     Methanobacteria     Methanococci     Methanopyri     Archaeoglobi     Thermoplasmata     Thermococci Phylum Korarchaeota Phylum Nanoarchaeota Archaea (; from Greek αρχαία, ancient ones; singular Archaeum, Archaean, or Archaeon), also called Archaebacteria (), is a major division of living organisms. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ...


The proteomic evidence also supports the universal ancestry of life. Vital proteins, such as the ribosome, DNA polymerase, and RNA polymerase, are found in everything from the most primitive bacteria to the most complex mammals. The core part of the protein is conserved across all lineages of life, serving similar functions. Higher organisms have evolved additional protein subunits, largely affecting the regulation and protein-protein interaction of the core. Other overarching similarities between all lineages of extant organisms, such as DNA, RNA, amino acids, and the lipid bilayer, give support to the theory of common descent. The chirality of DNA, RNA, and amino acids is conserved across all known life. As there is no functional advantage to right- or left-handed molecular chirality, the simplest hypothesis is that the choice was made randomly by early organisms and passed on to all extant life through common descent. Further evidence for reconstructing ancestral lineages comes from junk DNA such as pseudogenes, "dead" genes which steadily accumulate mutations.[4] The term proteome was coined by Mark Wilkins in 1995 (1) and is used to describe the entire complement of proteins in a given biological organism or system at a given time, i. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... 3D structure of the DNA-binding helix-hairpin-helix motifs in human DNA polymerase beta A DNA polymerase is an enzyme that assists in DNA replication. ... RNAP from pictured during elongation. ... In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles (or coassembles) with other protein molecules to form a multimeric or oligomeric protein. ... Protein-protein interactions refer to the association of protein molecules and the study of these associations from the perspective of biochemistry, signal transduction and networks. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... Ribonucleic acid (RNA) is a nucleic acid polymer consisting of nucleotide monomers. ... Phenylalanine is one of the standard amino acids. ... A diagonal molecular slab from the DPPC lipid bilayer simulation1; color scheme: PO4 - green, N(CH3)3 - violet, water - blue, terminal CH3 - yellow, O - red, glycol C - brown, chain C - grey. ... The term chiral (pronounced ) is used to describe an object which is non-superimposable on its mirror image. ... In molecular biology, junk DNA is a collective label for the portions of the DNA sequence of a chromosome or a genome for which no function has yet been identified. ... A pseudogene is a nucleotide sequences that is similar to a normal gene, but is not expressed as a functional protein. ...


There is also a large body of molecular evidence for a number of different mechanisms for large evolutionary changes, among them: genome and gene duplication, which facilitates rapid evolution by providing substantial quantities of genetic material under weak or no selective constraints; horizontal gene transfer, the process of transferring genetic material to another cell that is not an organism's offspring, allowing for species to acquire beneficial genes from each other; and recombination, capable of reassorting large numbers of different alleles and of establishing reproductive isolation. The Endosymbiotic theory explains the origin of mitochondria and plastids (e.g. chloroplasts), which are organelles of eukaryotic cells, as the incorporation of an ancient prokaryotic cell into ancient eukaryotic cell. Rather than evolving eukaryotic organelles slowly, this theory offers a mechanism for a sudden evolutionary leap by incorporating the genetic material and biochemical composition of a separate species. Evidence supporting this mechanism has recently been found in the protist Hatena: as a predator it engufes a green algae cell, which subsequently behaves as an endosymbiont, nourishing Hatena, which in turn loses it's feeding apparatus and behaves as an autotroph.[5][6] Schematic of a region of a chromosome before and after a duplication event Gene duplication occurs when an error in homologous recombination, a retrotransposition event, or duplication of an entire chromosome leads to the duplication of a region of DNA containing a gene [1]. The significance of this process for... Horizontal gene transfer (HGT), also Lateral gene transfer (LGT), is any process in which an organism transfers genetic material to another cell that is not its offspring. ... It has been suggested that chromosomal crossover be merged into this article or section. ... An important concept in evolutionary biology, reproductive isolation is a category of mechanisms that prevent two or more populations from exchanging genes. ... The endosymbiotic theory concerns the origins of mitochondria and plastids (e. ... Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) (from Greek μιτος or mitos, thread + κουδριον or khondrion, granule) is a membrane-enclosed organelle, found in most eukaryotic cells. ... Plastids are a class of membrane-bound organelles found in plant and algal cells. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Schematic of typical animal cell, showing subcellular components. ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ... Schematic of typical animal cell, showing subcellular components. ... Typical phyla Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: ) are a diverse group of organisms, comprising those eukaryotes that are not animals... Hatena (or mysterious) is a new creature discovered in Japan. ... An endosymbiont is any organism that lives within the body or cells of another organism, i. ... Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph Flowchart to determine if a species is autotroph, heterotroph, or a subtype An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces organic compounds from carbon dioxide as a carbon source, using either light or...


Since metabolic processes do not leave fossils, research into the evolution of the basic cellular processes is done largely by comparison of existing organisms. Many lineages diverged when new metabolic processes appeared, and it is theoretically possible to determine when certain metabolic processes appeared by comparing the traits of the descendants of a common ancestor or by detecting their physical manifestations. As an example, the appearance of oxygen in the earth's atmosphere is linked to the evolution of photosynthesis. Overview of the citric acid cycle The citric acid cycle, one of the central metabolic pathways in aerobic organisms. ...


Out of Africa hypothesis of human evolution

Mathematical models of evolution, pioneered by the likes of Sewall Wright, Ronald Fisher and J. B. S. Haldane and extended via diffusion theory by Motoo Kimura, allow predictions about the genetic structure of evolving populations. Direct examination of the genetic structure of modern populations via DNA sequencing has recently allowed verification of many of these predictions. For example, the Out of Africa theory of human origins, which states that modern humans developed in Africa and a small sub-population migrated out (undergoing a population bottleneck), implies that modern populations should show the signatures of this migration pattern. Specifically, post-bottleneck populations (Europeans and Asians) should show lower overall genetic diversity and a more uniform distribution of allele frequencies compared to the African population. Both of these predictions are borne out by actual data from a number of studies.[citation needed] Sewall Green Wright ForMemRS (December 21, 1889 – March 3, 1988) was an American geneticist known for his influential work on evolutionary theory. ... Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a British statistician, evolutionary biologist, and geneticist. ... John Burdon Sanderson Haldane (November 5, 1892 – December 1, 1964), who normally used J.B.S. as a first name, was a British geneticist and evolutionary biologist. ... The heat equation or diffusion equation is an important partial differential equation which describes the variation of temperature in a given region over time. ... Motoo Kimura (木村資生, born on November 13, 1924 in Okazaki, Aichi Prefecture - November 13, 1994) was a highly influential Japanese mathematical biologist, working in the field of theoretical population genetics. ... In paleoanthropology, the single-origin hypothesis (or Out-of-Africa model, or Replacement Hypothesis) is one of two accounts of the origin of anatomically modern humans, Homo sapiens. ... A population bottleneck (or genetic bottleneck) is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. ...


External link

Evidence from antibiotic and pesticide resistance

The development and spread of antibiotic resistant bacteria, like the spread of pesticide resistant forms of plants and insects is evidence for evolution of species, and of change within species. Thus the appearance of vancomycin resistant Staphlococcus aureus, and the danger it poses to hospital patients is a direct result of evolution through natural selection. Similarly the appearance of DDT resistance in various forms of Anopheles mosqitoes, and the appearance of myxomatosis resistance in breeding rabbit populations in Australia, are all evidence of the existence of evolution in situations of evolutionary selection pressure in species in which generations occur rapidly. Antibiotic resistance is the ability of a micro-organism to withstand the effects of an antibiotic. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... A cropduster spreading pesticide. ... Vancomycin (INN) (IPA: ) is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. ... Binomial name Staphylococcus aureus Staphylococcus aureus (also known as golden staph) is a bacterium, frequently living on the skin or in the nose of a healthy person, that can cause illnesses ranging from minor skin infections (such as pimples, boils, and cellulitis) and abscesses, to life-threatening diseases such as... Some Species Anopheles atroparvus Anopheles beklemishevi Anopheles coustani Anopheles crypticus Anopheles culicifacies Anopheles farauti Anopheles fluviatilis Anopheles forattinii Anopheles funestus Anopheles gambiae Anopheles grabhamii Anopheles hailarensis Anopheles halophylus Anopheles hyrcanus Anopheles introlatus Anopheles kosiensis Anopheles latens Anopheles maculipennis Anopheles minimus Anopheles moucheti Anopheles nili Anopheles ovengensis Anopheles pampanae Anopheles peytoni... Myxomatosis (from the Greek μύξα (mucus), and ματώνω (to bleed)) is a disease which infects only rabbits. ... Evolutionary pressure or selection pressure can be formalized as an external pressure applied to a process, thereby pushing that process in a distinct direction. ...


Evidence from studies of complex iteration

"It has taken more than five decades, but the electronic computer is now powerful enough to simulate evolution" [9] assisting bioinformatics in its attempt to solve biological problems. Map of the human X chromosome (from the NCBI website). ...


Computer science allows the iteration of self changing complex systems to be studied, allowing a mathematically exact understanding of the nature of the processes behind evolution; providing evidence for the hidden causes of known evolutionary events. The evolution of specific cellular mechanisms like spliceosomes that can turn the cell's genome into a vast workshop of billions of interchangeable parts that can create tools that create tools that create tools that create us can be studied for the first time in an exact way. Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... The word iteration is sometimes used in everyday English with a meaning virtually identical to repetition. ... There are many definitions of complexity, therefore many natural, artificial and abstract objects or networks can be considered to be complex systems, and their study (complexity science) is highly interdisciplinary. ... A spliceosome is a complex of RNA and many protein subunits called snRNPs, that removes the non-coding introns from unprocessed mRNA. Spliceosomes are unique to eukaryotic mRNA as the mRNA of prokaryotes lack introns. ...


For example, Christoph Adami et al. make this point in Evolution of biological complexity:

To make a case for or against a trend in the evolution of complexity in biological evolution, complexity needs to be both rigorously defined and measurable. A recent information-theoretic (but intuitively evident) definition identifies genomic complexity with the amount of information a sequence stores about its environment. We investigate the evolution of genomic complexity in populations of digital organisms and monitor in detail the evolutionary transitions that increase complexity. We show that, because natural selection forces genomes to behave as a natural "Maxwell Demon," within a fixed environment, genomic complexity is forced to increase. [10]

For example, David J. Earl and Michael W. Deem make this point in Evolvability is a selectable trait: Maxwells demon is an 1867 thought experiment by the Scottish physicist James Clerk Maxwell, meant to raise questions about the possibility of violating the second law of thermodynamics. ...

Not only has life evolved, but life has evolved to evolve. That is, correlations within protein structure have evolved, and mechanisms to manipulate these correlations have evolved in tandem. The rates at which the various events within the hierarchy of evolutionary moves occur are not random or arbitrary but are selected by Darwinian evolution. Sensibly, rapid or extreme environmental change leads to selection for greater evolvability. This selection is not forbidden by causality and is strongest on the largest-scale moves within the mutational hierarchy. Many observations within evolutionary biology, heretofore considered evolutionary happenstance or accidents, are explained by selection for evolvability. For example, the vertebrate immune system shows that the variable environment of antigens has provided selective pressure for the use of adaptable codons and low-fidelity polymerases during somatic hypermutation. A similar driving force for biased codon usage as a result of productively high mutation rates is observed in the hemagglutinin protein of influenza A. [11]

"Computer simulations of the evolution of linear sequences have demonstrated the importance of recombination of blocks of sequence rather than point mutagenesis alone. Repeated cycles of point mutagenesis, recombination, and selection should allow in vitro molecular evolution of complex sequences, such as proteins." [12] Evolutionary molecular engineering, also called directed evolution or in vitro molecular evolution involves the iterated cycle of mutation, multiplication with recombination, and selection of the fittest of individual molecules (proteins, DNA, and RNA). Natural evolution can be relived showing us possible paths from catalytic cycles based on proteins to based on RNA to based on DNA. [13] [14] [15] [16] This article needs to be cleaned up to conform to a higher standard of quality. ... Genera Influenzavirus A Influenzavirus B Influenzavirus C Isavirus Thogotovirus Influenzavirus A is a genus of a family of viruses called Orthomyxoviridae in virus classification. ...


Evidence from speciation

Hawthorn fly

An interesting example of evolution at work is the case of the hawthorn fly, Rhagoletis pomonella, which appears to be undergoing sympatric speciation.[7] Different populations of hawthorn fly feed on different fruits. A distinct population emerged in North America in the 19th century some time after apples, a non-native species, were introduced. This apple-feeding population normally feeds only on apples and not on the historically preferred fruit of hawthorns. The current hawthorn feeding population does not normally feed on apples. Scientists are investigating whether or not the apple-feeding subspecies may further evolve into a new species. Binomial name Rhagoletis pomonella Walsh, 1867 The Apple Maggot (Rhagoletis pomonella), also known as railroad worm, is a pest of several fruits, mainly apples. ... Sympatry is one of three theoretical models for the phenomenon of speciation. ... For other uses, see Apple (disambiguation). ... Species See text Crataegus (Hawthorn) is a large genus of in the family Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. ... In zoology, as in other branches of biology, subspecies is the rank immediately subordinate to a species. ...


Some evidence, such as the fact that six out of thirteen allozyme loci are different, that hawthorn flies mature later in the season and take longer to mature than apple flies; and that there is little evidence of interbreeding (researchers have documented a 4-6% hybridization rate) suggests that this is occurring. The emergence of the new hawthorn fly is an example of evolution in progress.[8] In biochemistry, isozymes (or isoenzymes) are isoforms (closely related variants) of enzymes. ...


References

  1. ^ Two sources: 'Genomic divergences between humans and other hominoids and the effective population size of the common ancestor of humans and chimpanzees'. and 'Quantitative Estimates of Sequence Divergence for Comparative Analyses of Mammalian Genomes' "[1] [2]"
  2. ^ The picture labeled "Human Chromosome 2 and its analogs in the apes" in the article Comparison of the Human and Great Ape Chromosomes as Evidence for Common Ancestry is literally a picture of a link in humans that links two separate chromosomes in the nonhuman apes creating a single chromosome in humans. It is considered a missing link, and the ape-human connection is of particular interest. Also, while the term originally referred to fossil evidence, this too is a trace from the past corresponding to some living beings which when alive were the physical embodiment of this link.
  3. ^ The New York Times report Still Evolving, Human Genes Tell New Story, based on A Map of Recent Positive Selection in the Human Genome, states the International HapMap Project is "providing the strongest evidence yet that humans are still evolving" and details some of that evidence.
  4. ^ Pseudogene evolution and natural selection for a compact genome. "[3]"
  5. ^ Okamoto N, Inouye I. (2005). "A secondary symbiosis in progress". Science 310 (5746): 287. 
  6. ^ Okamoto N, Inouye I. (2006). "Hatena arenicola gen. et sp. nov., a Katablepharid Undergoing Probable Plastid Acquisition.". Protist Article in Print. 
  7. ^ Feder et al (2003). "Evidence for inversion polymorphism related to sympatric host race formation in the apple maggot fly, Rhagoletis pomonella.". Genetics 163 (3): 939-953. 
  8. ^ Berlocher, S.H. and G.L. Bush. 1982. An electrophoretic analysis of Rhagoletis (Diptera: Tephritidae) phylogeny. Systematic Zoology 31:136-155; Berlocher, S.H. and J.L. Feder. 2002. Sympatric speciation in phytophagous insects: moving beyond controversy? Annual Review of Entomology 47:773-815; Bush, G.L. 1969. Sympatric host race formation and speciation in frugivorous flies of the genus Rhagoletis (Diptera: Tephritidae). Evolution 23:237-251; Prokopy, R.J., S.R. Diehl and S.S. Cooley. 1988. Behavioral evidence for host races in Rhagoletis pomonella flies. Oecologia 76:138-147. Proc. Natl. Acad. Sci. USA - Vol. 94, pp. 11417-11421, October 1997 - Evolution article Selective maintenance of allozyme differences among sympatric host races of the apple maggot fly.
  • Darwin, Charles November 24, 1859. On the Origin of Species by means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life. London: John Murray, Albemarle Street. 502 pages. Reprinted: Gramercy (May 22, 1995). ISBN 0-517-12320-7
  • Mayr, Ernst. What Evolution Is. Basic Books (October, 2002). ISBN 0-465-04426-3
  • Gigerenzer, Gerd, et al., The empire of chance: how probability changed science and everyday life (New York: Cambridge University Press, 1989).
  • Williams, G.C. (1966). Adaptation and Natural Selection: A Critique of some Current Evolutionary Thought. Princeton, N.J.: Princeton University Press.
  • Biological science, Oxford, 2002.
  • CJ Clegg, 1999, Genetics and Evolution, John Murray. ISBN 0-7195-7552-4
  • Y.K. Ho, 2004, Advanced-level Biology for Hong Kong, Manhattan Press. ISBN 962-990-635-X
  • Paul, Christopher R. C. (1998) The Adequacy of the Fossil Record, John Wiley & Sons, ISBN 0-471-96988-5
  • Behrensmeyer, Anna K. (1980) Fossils in the making: Vertebrate taphonomy and paleoecology, University of Chicago Press, ISBN 0-226-04169-7
  • Martin, Ronald E. et al. eds. (1999) Taphonomy: A Process Approach, Cambridge University Press, ISBN 0-521-59833-8

The New York Times is an internationally known daily newspaper published in New York City and distributed in the United States and many other nations worldwide. ... The goal of the International HapMap Project is to develop a haplotype map of the human genome, also referred to as the HapMap, which will describe the common patterns of human genetic variation. ... November 24 is the 328th day (329th on leap years) of the year in the Gregorian Calendar. ... 1859 (MDCCCLIX) is a common year starting on Saturday of the Gregorian calendar (or a common year starting on Monday of the Julian calendar). ... The 1859 edition of On the Origin of Species First published in 1859, The Origin of Species (full title On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life) by British naturalist Charles Darwin is one of the pivotal... John Murray is a British publishing house, renowned for the roster of authors it has published in its history, including Jane Austen, Lord Byron and Charles Darwin. ... View of Clarendon House, now demolished. ...

External links


  Results from FactBites:
 
Evidence of evolution - Wikipedia, the free encyclopedia (4781 words)
This process ly life is sparse before the evolution of organisms with hard body parts, such as shell, bone, and teeth, but exists in the form of ancient microfossils and the fossilization ded in rocks by natural processes are called fossils.
A classic example of biochemical evidence for evolution is the variance of the protein Cytochrome c in living cells.
The evolution of specific cellular mechanisms like spliceosomes that can turn the cell's genome into a vast workshop of billions of interchangeable parts that can create tools that create tools that create tools that create us can be studied for the first time in an exact way.
Evolution - Wikipedia, the free encyclopedia (9300 words)
Evolution occurs whenever a new species of bacterium evolves that is resistant to antibiotics which had been lethal to prior strains.
Further evidence for common descent comes from genetic detritus such as pseudogenes, regions of DNA which are orthologous to a gene in a related organism, but are no longer active and appear to be undergoing a steady process of degeneration.
The claim that evolution results in moral progress is not part of modern evolutionary theory – that claim is associated with Social Darwinism, which held that the subjugation of the poor, and of minority groups, was favored by evolution.
  More results at FactBites »

 
 

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