Experimental evolution

Experimental evolution is the use of laboratory experiments or controlled field manipulations to explore evolutionary dynamics.[1] Evolution may be observed in the laboratory as individuals/populations adapt to new environmental conditions by natural selection.

There are two different ways in which adaptation can arise in experimental evolution. One is via an individual organism gaining a novel beneficial mutation.[2] The other is from allele frequency change in standing genetic variation already present in a population of organisms.[2] Other evolutionary forces outside of mutation and natural selection can also play a role or be incorporated into experimental evolution studies, such as genetic drift and gene flow.[3]

The organism used is decided by the experimenter, based on the hypothesis to be tested. Many generations are required for adaptive mutation to occur, and experimental evolution via mutation is carried out in viruses or unicellular organisms with rapid generation times, such as bacteria and asexual clonal yeast.[1][4][5] Polymorphic populations of asexual or sexual yeast,[2] and multicellular eukaryotes like Drosophila, can adapt to new environments through allele frequency change in standing genetic variation.[3] Organisms with longer generations times, although costly, can be used in experimental evolution. Laboratory studies with foxes[6] and with rodents (see below) have shown that notable adaptations can occur within as few as 10–20 generations and experiments with wild guppies have observed adaptations within comparable numbers of generations.[7]

More recently, experimentally evolved individuals or populations are often analyzed using whole genome sequencing,[8][9] an approach known as Evolve and Resequence (E&R).[10] E&R can identify mutations that lead to adaptation in clonal individuals or identify alleles that changed in frequency in polymorphic populations, by comparing the sequences of individuals/populations before and after adaptation.[2] The sequence data makes it possible to pinpoint the site in a DNA sequence that a mutation/allele frequency change occurred to bring about adaptation.[10][9][2] The nature of the adaptation and functional follow up studies can shed insight into what effect the mutation/allele has on phenotype.

  1. ^ a b "Experimental Evolution". Nature.
  2. ^ a b c d e Long A, Liti G, Luptak A, Tenaillon O (October 2015). "Elucidating the molecular architecture of adaptation via evolve and resequence experiments". Nature Reviews. Genetics. 16 (10): 567–582. doi:10.1038/nrg3937. PMC 4733663. PMID 26347030.
  3. ^ a b Kawecki TJ, Lenski RE, Ebert D, Hollis B, Olivieri I, Whitlock MC (October 2012). "Experimental evolution" (PDF). Trends in Ecology & Evolution. 27 (10): 547–560. doi:10.1016/j.tree.2012.06.001. PMID 22819306.
  4. ^ Buckling A, Craig Maclean R, Brockhurst MA, Colegrave N (February 2009). "The Beagle in a bottle". Nature. 457 (7231): 824–829. Bibcode:2009Natur.457..824B. doi:10.1038/nature07892. PMID 19212400. S2CID 205216404.
  5. ^ Elena SF, Lenski RE (June 2003). "Evolution experiments with microorganisms: the dynamics and genetic bases of adaptation". Nature Reviews. Genetics. 4 (6): 457–469. doi:10.1038/nrg1088. PMID 12776215. S2CID 209727.
  6. ^ Trut LN (March 1999). "Early Canid Domestication: The Farm-Fox Experiment: Foxes bred for tamability in a 40-year experiment exhibit remarkable transformations that suggest an interplay between behavioral genetics and development". American Scientist. 87 (2): 160–169. doi:10.1511/1999.2.160. JSTOR 27857815.
  7. ^ Reznick DN, Shaw FH, Rodd FH, Shaw RG (March 1997). "Evaluation of the Rate of Evolution in Natural Populations of Guppies (Poecilia reticulata)". Science. 275 (5308): 1934–1937. doi:10.1126/science.275.5308.1934. PMID 9072971. S2CID 18480502.
  8. ^ Barrick JE, Lenski RE (December 2013). "Genome dynamics during experimental evolution". Nature Reviews. Genetics. 14 (12): 827–839. doi:10.1038/nrg3564. PMC 4239992. PMID 24166031.
  9. ^ a b Jha AR, Miles CM, Lippert NR, Brown CD, White KP, Kreitman M (October 2015). "Whole-Genome Resequencing of Experimental Populations Reveals Polygenic Basis of Egg-Size Variation in Drosophila melanogaster". Molecular Biology and Evolution. 32 (10): 2616–2632. doi:10.1093/molbev/msv136. PMC 4576704. PMID 26044351.
  10. ^ a b Turner TL, Stewart AD, Fields AT, Rice WR, Tarone AM (March 2011). "Population-based resequencing of experimentally evolved populations reveals the genetic basis of body size variation in Drosophila melanogaster". PLOS Genetics. 7 (3): e1001336. doi:10.1371/journal.pgen.1001336. PMC 3060078. PMID 21437274.

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