Portal de Periódicos da CAPES

Reverse Evolution of Armor Plates in the Threespine Stickleback

2008; Elsevier BV; Volume: 18; Issue: 10 Linguagem: Inglês

10.1016/j.cub.2008.04.027

1879-0445

Jun Kitano, Daniel I. Bolnick, David A. Beauchamp, Michael M. Mazur, Seiichi Mori, Takanori Nakano, Catherine L. Peichel,

Ecology and Vegetation Dynamics Studies

Faced with sudden environmental changes, animals must either adapt to novel environments or go extinct. Thus, study of the mechanisms underlying rapid adaptation is crucial not only for the understanding of natural evolutionary processes but also for the understanding of human-induced evolutionary change, which is an increasingly important problem [1Palumbi S.R. The Evolution Explosion: How Humans Cause Rapid Evolutionary Change. W.W. Norton & Company, New York2001Google Scholar, 2Smith T.B. Bernatchez L. Evolutionary change in human-altered environments.Mol. Ecol. 2008; 17: 1-8Crossref PubMed Scopus (100) Google Scholar, 3Carroll S.P. Hendry A.P. Reznick D.N. Fox C.W. Evolution on ecological time-scales.Funct. Ecol. 2007; 21: 387-393Crossref Scopus (436) Google Scholar, 4Hendry A.P. Ferrugia T.J. Kinnison M.T. Human influences on rates of phenotypic change in wild animal populations.Mol. Ecol. 2008; 17: 20-29Crossref PubMed Scopus (490) Google Scholar, 5Majerus M. Melanism: Evolution in Action. Oxford University Press, Oxford1998Google Scholar, 6Reznick D.N. Ghalambor C.K. Crooks K. Experimental studies of evolution in guppies: a model for understanding the evolutionary consequences of predator removal in natural communities.Mol. Ecol. 2008; 17: 97-107Crossref PubMed Scopus (54) Google Scholar, 7Stockwell C.A. Hendry A.P. Kinnison M.T. Contemporary evolution meets conservation biology.Trends Ecol. Evol. 2003; 18: 94-101Abstract Full Text Full Text PDF Scopus (758) Google Scholar, 8Gienapp P. Teplitsky C. Alho J.S. Mills J.A. Merila J. Climate change and evolution: disentangling environmental and genetic responses.Mol. Ecol. 2008; 17: 167-178Crossref PubMed Scopus (757) Google Scholar]. In the present study, we demonstrate that the frequency of completely plated threespine stickleback fish (Gasterosteus aculeatus) has increased in an urban freshwater lake (Lake Washington, Seattle, Washington) within the last 40 years. This is a dramatic example of “reverse evolution,” [9Teotónio H. Rose M.R. Perspective: reverse evolution.Evolution Int. J. Org. Evolution. 2001; 55: 653-660Crossref PubMed Google Scholar] because the general evolutionary trajectory is toward armor-plate reduction in freshwater sticklebacks [10Bell M.A. Foster S.A. The Evolutionary Biology of the Threespine Stickleback. Oxford University Press, Oxford1994Google Scholar]. On the basis of our genetic studies and simulations, we propose that the most likely cause of reverse evolution is increased selection for the completely plated morph, which we suggest could result from higher levels of trout predation after a sudden increase in water transparency during the early 1970s. Rapid evolution was facilitated by the existence of standing allelic variation in Ectodysplasin (Eda), the gene that underlies the major plate-morph locus [11Colosimo P.F. Hosemann K.E. Balabhadra S. Villarreal G. Dickson M. Grimwood J. Schmutz J. Myers R.M. Schluter D. Kingsley D.M. Widespread parallel evolution in sticklebacks by repeated fixation of Ectodysplasin alleles.Science. 2005; 307: 1928-1933Crossref PubMed Scopus (1005) Google Scholar]. The Lake Washington stickleback thus provides a novel example of reverse evolution, which is probably caused by a change in allele frequency at the major plate locus in response to a changing predation regime.