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Encyclopedia > Adaptation
Part of the Biology series on
Evolution
Mechanisms and processes

Adaptation
Genetic drift
Gene flow
Mutation
Natural selection
Speciation Look up adaptation in Wiktionary, the free dictionary. ... Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, knowledge), also referred to as the biological sciences, is the study of living organisms utilizing the scientific method. ... This article is about evolution in biology. ... Image File history File links Tree_of_life. ... The mechanisms and processes of evolutionary change includes natural selection, genetic drift, gene flow, mutation, adaptation and speciation. ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... In population genetics, gene flow (also known as gene migration) is the transfer of alleles of genes from one population to another. ... For linguistic mutation, see Apophony. ... For other uses, see Natural selection (disambiguation). ... 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. ...

Research and history

Evidence
History
Modern synthesis
Social effect / Objections While on board HMS Beagle, Charles Darwin collected numerous specimens, many new to science, which supported his later theory of evolution by natural selection. ... Evolutionary thought has roots in antiquity as philosophical ideas conceived during the Ancient Greek and Roman eras, but until the 18th century, biological thought was dominated by essentialism, the idea that living forms are static and unchanging in time. ... The modern evolutionary synthesis refers to a set of ideas from several biological specialities that were brought together to form a unified theory of evolution accepted by the great majority of working biologists. ... The theory of transmutation had early origins in the speculations and hypotheses of Erasmus Darwin, and Jean-Baptiste Lamarck. ... There have been numerous objections to evolution since alternative evolutionary ideas came to be hotly debated around the start of the nineteenth century. ...

Evolutionary biology fields

Cladistics
Ecological genetics
Evolutionary development
Human evolution
Molecular evolution
Evolutionary history of life
Phylogenetics
Population genetics
It has been suggested that Clade be merged into this article or section. ... Ecological genetics is the study of genetics (itself a field of biology) from an ecological perspective. ... Evolutionary developmental biology (evolution of development or informally, evo-devo) is a field of biology that compares the developmental processes of different animals in an attempt to determine the ancestral relationship between organisms and how developmental processes evolved. ... For the history of humans on Earth, see History of the world. ... Molecular evolution is the process of the genetic material in populations of organisms changing over time. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... Phylogenetic groups, or taxa, can be monophyletic, paraphyletic, or polyphyletic. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

Biology Portal · v  d  e 

An adaptation is a positive characteristic of an organism that has been favored by natural selection.[1] The concept is central to biology, particularly in evolutionary biology. The term adaptation is also sometimes used as a synonym for natural selection,[citation needed] but most biologists discourage this usage. Life on Earth redirects here. ... For other uses, see Natural selection (disambiguation). ... Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, knowledge), also referred to as the biological sciences, is the study of living organisms utilizing the scientific method. ... This article or section does not cite any references or sources. ...

Contents

Overview

Organisms that are adapted to their environment are able to:

  • Obtain air, water, food and nutrients.
  • Cope with physical conditions such as temperature, light and heat.
  • Defend themselves from their natural enemies.
  • Reproduce.
  • Respond to changes around them.

Adaptations enable living organisms to cope with environmental stresses and pressures. Adaptation can be structural or behavioral. Structural adaptations are special body parts of an organism that help it to survive in its natural habitat (e.g., skin color, shape, body covering). Behavioral adaptations are special ways a particular organism behaves to survive in its natural habitat. Physiological adaptations are systems present in an organism that allow it to perform certain biochemical reactions (e.g., making venom, secreting slime, being able to keep a constant body temperature).


Adaptations are traits that have been selected for by natural selection. The underlying genetic basis for the adaptive trait did not arise as a consequence of the environment; the genetic variant pre-existed and was subsequently selected because it provided the bearer of that variant some advantage. The first experimental evidence of the pre-existing nature of genetic variants was provided by Joshua Lederberg and colleagues who developed fluctuation analysis, a method to show the random fluctuation of pre-exisitng genetic changes that conferred resistance to antibiotics by the bacterium Escherichia coli E. coli redirects here. ...


While many traits have obvious adaptive purposes, it is worthwhile to point out that many traits are not adaptive, that is, there is no obvious reason scientists can divine for the presence of a certain trait. This situation is common and there are many causes: the utility of a trait is lost and hence does not now appear adaptive, the utility of a trait is unknown, the trait is a consequence of another trait that is adaptive (the Spandrel idea). This observation underscores two other important points: genetic variants arise randomly and hence traits can appear randomly and that because the environment for all living things is constantly in flux, the utility of adaptations will naturally ebb and flow.


Organisms that are not suitably adapted to their environment will either have to move out of the habitat or die out. The term die out in the context of adaptation simply means that the death rate over the entire species (population, gene pool ...) exceeds the birth rate for a long enough period for the species to disappear; due to individual phenotypic plasticity, individuals will be more or less successful. The opposite is selection which in this context means that the birth rate of those carrying the adaptive trait and the hence the underlying genetic variant exceeds over time the birth rate of those that do not carry the adaptive trait. We dont have an article called Phenotypic plasticity Start this article Search for Phenotypic plasticity in. ...


Adaptation vs. acclimation

There is a great difference between adaptation and acclimation. Adaptation occurs over many generations; it is a gradual process caused by natural selection. Acclimatization generally occurs within a single lifetime and copes with issues that are less threatening. For example, if a human was to move to a higher altitude, respiration and physical exertion would become a problem, but after spending time in high altitude conditions one may acclimate to the pressure and function and no longer notice the change. This ability to acclimate is an adaptation, but not the acclimation itself. Acclimation is a change occurring in an individual as a result to prolonged exposure of a particular environmental condition, such as a horse shedding its winter coat to produce a lighter summer coat. ... Gradualism is the belief that changes occur, or ought to occur, slowly in the form of gradual steps (see also incrementalism) In politics, the concept of gradualism is used to describe the belief that change ought to be modified in small, discrete increments rather than abrubt changes such as revolutions...


A counter-adaptation is an adaptation that has evolved due to the selective pressure of another adaptation. This occurs in an evolutionary arms race, where a new adaptation giving one species an advantage is countered by the appearance and spread of a new feature that reduces the effectiveness of the first adaptation. An evolutionary arms race is an evolutionary struggle between a predator species and its prey (including parasitism) that is said to resemble an arms race. ...


Theories

Jean-Baptiste Lamarck
Jean-Baptiste Lamarck

The theory of adaptation was first put forth by Jean-Baptiste Lamarck. His theories are also referred to as the inheritance of acquired traits. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Portrait of Jean-Baptiste Lamarck Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 – December 18, 1829) was a French soldier, naturalist, academic and an early proponent of the idea that evolution occurred and proceeded in accordance with natural laws. ... The theory of the inheritance of acquired traits was formulated by the French naturalist Jean-Baptiste Lamarck. ...


Lamarck's theory was for a time held as an alternative scientific explanation for evolutionary change observed by Darwin in the The Origin of Species. The classic giraffe analogy offers the best delineation between the two. For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... Charles Darwins Origin of Species (publ. ...

  • According to Darwin, more long-necked giraffes reproduce than short-necked giraffes and as such giraffes today have long necks.
  • According to Lamarck, it was giraffes stretching their necks in response to higher leaves that resulted in giraffes having long necks. (This trait being passed on to the next generation)

Although neither theory in its conception could provide a complete description of the mechanism of transmission of trait variation (i.e., particulate inheritance), many recognized Darwin's theory immediately upon publication as a more complete and empirically supported theory. Modern genetics have since established the fundamental implausibility of Lamarckian inheritance, due to the one-way nature of transcription. However, see epigenetics and Baldwinian evolution for analogous processes in modern evolutionary theory. For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 - December 28, 1829) was a major 19th century naturalist, who was one of the first to use the term biology in its modern sense. ... Epigenetics is a term in biology used today to refer to features such as chromatin and DNA modifications that are stable over rounds of cell division but do not involve changes in the underlying DNA sequence of the organism. ... Baldwinian evolution is a theory proposed by United States psychologist James Mark Baldwin which states that organisms can pass on learned abilities to their offspring. ...


Although the vast majority of genetic variants arising from errors of DNA replication or recombination do not confer any advantage to an individual organism, the multitude of variation contained within the collective genomes of a species provides much material for natural selection to work upon allowing many adaptations to be manifest.


See also

Adaptationism is the view that all or most traits are optimal adaptations. ... Four of the 13 finch species found on the Galápagos Archipelago, and thought to have evolved by an adaptive radiation that diversified their beak shapes to adapt them to different food sources. ... In biology, co-adaptation, or coadaptation refers to the mutual adaptation of: Species: see mutualism, symbiosis organs: see the evolution of the eye. ... An exaptation is a biological adaptation where the biological function currently performed by the adaptation was not the function performed while the adaptation evolved under earlier pressures of natural selection. ... Dual inheritance theory, (or DIT), in sharp contrast to the notion that culture overrides biology, posits that humans are products of the interaction between biological evolution and cultural evolution. ... The gene-centered view of evolution, gene selection theory or selfish gene theory holds that natural selection acts through differential survival of competing genes, increasing the frequency of those alleles whose phenotypic effects successfully promote their own propagation. ... In psychology, habituation is an example of non-associative learning in which there is a progressive diminution of behavioral response probability with repetition of a stimulus. ... The selfish gene theory postulates that natural selection will increase the frequency of those genes whose phenotypic effects ensure their successful replication. ... Lamarckism or Lamarckian evolution refers to the once widely accepted idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring (also known as based on heritability of acquired characteristics or soft inheritance). It is named for the French biologist Jean-Baptiste Lamarck, who... The neutral theory of molecular evolution (also, simply the neutral theory of evolution) is an influential theory that was introduced with provocative effect by Motoo Kimura in the late 1960s and early 1970s. ... In evolutionary biology, preadaptation describes a situation where an organism uses a preexisting anatomical structure inherited from an ancestor for a potentially unrelated purpose. ... A spandrel is a phenotypic characteristic that evolved as a side effect of a true adaptation. ...

References

  1. ^ Sterelny, K. & Griffiths, P. E. (1999) Sex and Death: An Introduction to Philosophy of Biology p.217 University of Chicago Press. ISBN O-226-77304-3

 
 

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