FACTOID # 28: Austin, Texas has more people than Alaska.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Experimental evolution

In evolutionary biology, the field of experimental evolution is concerned with testing the theory of evolution in controlled experiments. Evolution can be observed in the laboratory as organisms adapt to new environmental conditions. With modern microbiological tools, it is possible to pinpoint the mutations that selection acts upon and what brought about the adaptations and to find out how exactly these mutations work. Because of the large number of generations required for adaptation to occur, evolution experiments are typically carried out with microorganisms such as bacteria or viruses. However, laboratory studies with rodents have shown that notable adaptations can occur within as few as 10-20 generations (see below) and experiments with wild guppies have observed adaptations within comparable numbers of generations 1. Evolutionary biology is a subfield of biology concerned with the origin and descent of species, as well as their change, multiplication, and diversity over time. ... This article is about biological evolution. ... In the scientific method, an experiment (Latin: ex-+-periri, of (or from) trying), is a set of actions and observations, performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ... An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... It has been suggested that mutant be merged into this article or section. ... Selection is hierachically classified into natural and artificial selection. ... The eye is an adaptation. ... Generation (From the Greek γιγνμαι), also known as procreation, is the act of producing offspring. ... A cluster of Escherichia coli bacteria magnified 10,000 times. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus is a microscopic particle (ranging in size from 20 - 300 nm) that can infect the cells of a biological organism. ... Families Many, see text The order Rodentia is the most numerous of all the branches on the mammal family tree. ... For other uses of this word, see Guppy (disambiguation). ...

Contents

Evolution experiments throughout human history

This Chihuahua mix and Great Dane show the wide range of dog breed sizes created using artificial selection.
This Chihuahua mix and Great Dane show the wide range of dog breed sizes created using artificial selection.

Unwittingly, humans have carried out evolution experiments for as long as they have been domesticating plants and animals. Selective breeding of plants and animals has led to varieties that differ dramatically from their original wild-type ancestors. Examples are the cabbage varieties, maize, or the large number of different dog breeds. The power of human breeding to create varieties with extreme differences from a single species was already recognized by Charles Darwin. In fact, he started out his book The Origin of Species with a chapter on variation in domestic animals. In this chapter, Darwin discussed in particular the pigeon. He wrote: Image File history File links IMG013biglittledogFX_wb. ... Image File history File links IMG013biglittledogFX_wb. ... This article or section does not adequately cite its references or sources. ... This small dog of unknown parentage may be part Chihuahua or Miniature Pinscher. ... The Great Dane is a breed of dog known for its large size and gentle personality. ... This Chihuahua mix and Great Dane show the wide range of dog breed sizes created using artificial selection. ... Percentages are relative to US recommendations for adults. ... Corn redirects here. ... Trinomial name Canis lupus familiaris The dog Canis lupus is a type of canine, a mammal in the order Carnivora. ... For other people of the same surname, and places and things named after Charles Darwin, see Darwin. ... British naturalist Charles Darwins book, The Origin of Species, is one of the pivotal works in scientific literature and arguably the pre-eminent work in biology. ...

"Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would place the English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail in the same genus; more especially as in each of these breeds several truly-inherited sub-breeds, or species as he might have called them, could be shown him.
(...) I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects."

Early experimental evolution

Drawing of the incubator used by Dallinger in his evolution experiments
Drawing of the incubator used by Dallinger in his evolution experiments

One of the first to carry out a controlled evolution experiment was William Dallinger. In the late 19th century, he cultivated small unicellular organisms in a custom-built incubator over a time period of seven years (1880-1886). Dallinger slowly increased the temperature of the incubator from an initial 60 °F up to 158 °F. The early cultures had shown clear signs of distress at a temperature of 73 °F, and were certainly not capable of surviving at 158 °F. The organisms Dallinger had in his incubator at the end of the experiment, on the other hand, were perfectly fine at 158 °F. However, these organisms would not grow anymore at the initial 60 °F. Dallinger concluded that he had clearly found evidence for Darwinian adaptation in his incubator, and that the organisms had adapted to live in a high-temperature environment. Unfortunately, Dallinger's incubator was accidentally destroyed in 1886, and Dallinger could not continue this line of research. Image File history File links Download high resolution version (491x740, 83 KB)Image of an incubator used by W. H. Dallinger. ... Image File history File links Download high resolution version (491x740, 83 KB)Image of an incubator used by W. H. Dallinger. ... Rev. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... Year 1880 (MDCCCLXXX) was a leap year starting on Thursday (link will display the full calendar). ... 1886 (MDCCCLXXXVI) is a common year starting on Friday (click on link to calendar) // Events January 18 - Modern field hockey is born with the formation of The Hockey Association in England. ...


Modern experimental evolution

From the 1880s to 1980, experimental evolution was intermittently practiced by a variety of evolutionists, including the highly influential Theodosius Dobzhansky. Like other experimental research in evolutionary biology during this period, much of this work lacked extensive replication and was carried out only for relatively short periods of evolutionary time. Theodosius Grigorevich Dobzhansky (Russian — Феодосий Григорьевич Добржанский; sometimes anglicized to Theodore Dobzhansky; January 25, 1900 - December 18, 1975) was a noted geneticist and evolutionary biologist. ...


But by 1980, a variety of evolutionists realized that the key to successful experimentation lay in extensive parallel replication of evolving lineages as well as a larger number of generations of selection. One of the first of a new wave of experiments using this strategy was the laboratory "evolutionary radiation" of Drosophila melanogaster populations that Michael R. Rose started in February, 1980. This system started with ten populations, five cultured at later ages, and five cultured at early ages. Since then more than 200 different populations have been created in this laboratory radiation, with selection targeting multiple characters. Some of these highly differentiated populations have also been selected "backward" or "in reverse," by returning experimental populations to their ancestral culture regime. Hundreds of people have worked with these populations over the better part of three decades. Much of this work is summarized in the papers collected in the book Methuselah Flies, listed below. Binomial name Drosophila melanogaster Meigen, 1830 [1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ...


Lenski's long-term evolution experiment with Escherichia coli

On February 15, 1988, Richard Lenski started a long-term evolution experiment with the bacterium E. coli. The experiment continues to this day, and is by now probably the largest controlled evolution experiment ever undertaken. Since the inception of the experiment, the bacteria have grown for more than 40,000 generations. Lenski and colleagues regularly publish updates on the status of the experiments. A detailed list of publications and experimental protocols can be found on the project homepage. February 15 is the 46th day of the year in the Gregorian Calendar. ... 1988 (MCMLXXXVIII) was a leap year starting on Friday of the Gregorian calendar. ... Richard E. Lenski (born August 13, 1956) is an American evolutionary biologist. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ...


Garland's long-term experiment with laboratory house mice

In 1993, Theodore Garland, Jr. and colleagues started a long-term experiment that involves selective breeding for high voluntary activity levels on running wheels PDF. This experiment also continues to this day (> 45 generations), and a detailed list of publications can be found here. Mice from the four replicate "High Runner" lines evolved to run ~3-fold more revolutions per day as compared with the four unselected Control lines, mainly by running faster rather than for more minutes/day. A [movie] illustrates the dramatic differences in wheel-running behavior. Binomial name Mus musculus Linnaeus, 1758 Mus musculus is the common house mouse. ... 1993 (MCMXCIII) was a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... Generations redirects here. ...


The HR mice exhibit an elevated maximal aerobic capacity [VO2max] when tested on a motorized treadmill and a variety of other traits that appear to be adaptations that facilitate high levels of sustained endurance running (e.g., larger hearts, more [symmetrical] hindlimb bones). They also exhibit alterations in motivation and the reward system of the brain. Pharmacological studies point to alterations in dopamine function. The High Runner lines have been proposed as a model to study human attention-deficit hyperactivity disorder (ADHD), and administration of Ritalin reduces their wheel running approximately to the levels of Control mice. A biological adaptation is an anatomical structure, physiological process or behavioral trait of an organism that has evolved over a period of time by the process of natural selection such that it increases the expected long-term reproductive success of the organism. ... // Endurance or aerobic exercise consists of performing low- to medium-intensity exercise for very long periods of time. ... Hearts could be: Hearts, a four-player card game. ... It has been suggested that Base motive be merged into this article or section. ... A reward is something that an animal will work to obtain, for example, food. ... In animals, the brain, or encephalon (Greek for in the head), is the control center of the central nervous system. ... Pharmacology (in Greek: pharmacon is drug, and logos is science) is the study of how chemical substances interfere with living systems. ... Dopamine is a chemical naturally produced in the body. ... DISCLAIMER Please remember that Wikipedia is offered for informational use only. ... Methylphenidate (C14H19NO2), or MPH, is an amphetamine-like prescription stimulant commonly used to treat Attention Deficit Hyperactivity Disorder (ADHD) in children and adults. ...


Experimental evolution today

Today, there is a vibrant experimental evolution community. New papers on experimental evolution appear frequently in important scientific journals. This article or section does not cite its references or sources. ...


A list of laboratories that study experimental evolution can be found here.


University of California Network for Experimental Research on Evolution]


Further reading

  • Bennett, A. F. 2003. Experimental evolution and the Krogh Principle: generating biological novelty for functional and genetic analyses. Physiological and Biochemical Zoology 76, 1-11. PDF
  • Dallinger, W. H. 1887. The president's address. J. Roy. Microscop. Soc., 185-199.
  • Elena, S. F., and R. E. Lenski. 2003. Evolution experiments with microorganisms: the dynamics and genetic bases of adaptation. Nature Reviews Genetics 4, 457-469.
  • Garland, T., Jr. 2003. Selection experiments: an under-utilized tool in biomechanics and organismal biology. Pages 23-56 in V. L. Bels, J.-P. Gasc, A. Casinos, eds. Vertebrate biomechanics and evolution. BIOS Scientific Publishers, Oxford, U.K. PDF
  • Gibbs, A. G. 1999. Laboratory selection for the comparative physiologist. Journal of Experimental Biology 202, 2709-2718.
  • Lenski, R. E. 2004. Phenotypic and genomic evolution during a 20,000-generation experiment with the bacterium Escherichia coli. Plant Breeding Reviews 24, 225-265.
  • Lenski, R. E., M. R. Rose, S. C. Simpson, and S. C. Tadler. 1991. Long-term experimental evolution in Escherichia coli. I. Adaptation and divergence during 2,000 generations. American Naturalist 138, 1315-1341.
  • Phage experimental evolution (a collection of phage experimental evolution references with numerous links to full text articles)
  • Reznick, D. N., M. J. Bryant, D. Roff, C. K. Ghalambor, and D. E. Ghalambor. 2004. Effect of extrinsic mortality on the evolution of senescence in guppies. Nature 431, 1095-1099.
  • Rose, M. R., H. B. Passananti, and M. Matos, eds. 2004. Methuselah flies: A case study in the evolution of aging. World Scientific Publishing, Singapore.
  • Swallow, J. G., and T. Garland, Jr. 2005. Selection experiments as a tool in evolutionary and comparative physiology: insights into complex traits - An introduction to the symposium. Integrative and Comparative Biology 45, 387-390. PDF

Bacteriophage (phage) are the viruses of bacteria and, as probably the most numerous organisms on Earth, are exceptionally abundant in many natural environments. ...

See also


  Results from FactBites:
 
evol1-38 (11848 words)
Evolution of the Loop and Lophophore in Terebratuloid Brachiopods.
Evolution of Polygamy in the Long-billed Marsh Wren.
Evolution and Symbiosis in the Genus CkloreUa and Relat@d Algae.
The evolution of experimental psychology (613 words)
Experimental psychology became not a subject matter but a cluster of methods that could be used in any area of psychology.
By the 1970s, most "experimental psychology" courses were taught methodologically without significant presupposition of a content area.
As the century ends, an experimental methods course is among the few required courses in most psychology curricula and its range of methods would surprise experimental psychologists from the beginning of the century.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m