Changes in a single color-vision gene demonstrate convergent evolutionary adaptations in widely separated species and across vastly different time scales, according to a study publishing on April 11 in the open access journal PLOS Biology by David Marques of the University of Victoria, British Columbia, and colleagues. The study, which combined genetic analysis with a 19-year-long selection experiment, supports the idea that the mechanisms of adaptive evolution may be more predictable than previously suspected.
“These data support the emerging view in evolutionary biology that mechanisms underlying adaptive evolution are often highly repeatable and thus may be predictable,” said Marques. “They show that evolutionary ‘tinkering’ with a limited set of tools can lead to convergent ‘solutions’ to common problems both within species and between widely separated groups.” Paper. (public access) – David A. Marques, John S. Taylor, Felicity C. Jones, Federica Di Palma, David M. Kingsley, Thomas E. Reimchen. Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments. PLOS Biology, 2017; 15 (4): e2001627 DOI: 10.1371/journal.pbio.2001627More.
Them’s fightin’ words. Was there not a law laid down by Stephen Jay Gould in Wonderful Life that there is no pattern, that if the tape were rewound, things would all be different? For example:
Run the tape again, and let the tiny twig of Homo sapiens expire in Africa. Other hominids may have stood on the threshold of what we know as human possibilities, but many sensible scenarios would never generate our level of mentality. Run the tape again, and this time Neanderthal perishes in Europe and Homo erectus in Asia (as they did in our world). The sole surviving human stock, Homo erectus in Africa, stumbles along for a while, even prospers, but does not speciate and therefore remains stable. A mutated virus then wipes Homo erectus out, or a change in climate reconverts Africa into inhospitable forest. One little twig on the mammalian branch, a lineage with interesting possibilities that were never realized, joins the vast majority of species in extinction. So what? Most possibilities are never realized, and who will ever know the difference? Arguments of this form lead me to the conclusion that biology’s most profound insight into human nature, status, and potential lies in the simple phrase, the embodiment of contingency: Homo sapiens is an entity, not a tendency.
See also: Convergent evolution of crocodile and dolphin skull shapes
Evolution appears to converge on goals—but in Darwinian terms, is that possible?
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