Genetic Convergent Evolution: Stunning Gene Similarities Among Diverse Animals 164
Toe, The writes "It has long been understood that completely different animals can end up with very similar traits (convergent evolution), and even that genes can converge. But a new study shows an unbelievable level of convergence among entire groups of genes. The study shows that animals as diverse as bats and dolphins, which independently developed echolocation, converge in nearly 200 different genomic regions concentrated in several 'hearing genes.' The implications are rather deep, if you think about it, delving into interesting limitations on diversity or insights into the potential of DNA. And perhaps more importantly, this finding goes a long way toward explaining why almost aliens in the universe look surprisingly identical to humans (though still doesn't explain why they all speak English)."
Re:What I've said all along (Score:5, Informative)
/sigh [wikipedia.org]
Re:What I've said all along (Score:2, Informative)
Underlying genetic evolution is the notion that genes pick up random mutations over time. Most of these have no effect on function, so you can estimate how long ago two species diverged by counting how many differences are in the genome. These guys had the clever idea of taking species that we think diverged a long time ago, but that have a similar trait (ie, echolocation), with the hypothesis that the genes controlling that might be more similar, even in these very different animals, than the genes for dissimilar traits.
Imagine a software project that forks and is maintained by separate groups. Over time, the two projects look more and more different. Now imagine that both of these forks end up with a new feature in common that didn't exist in the pre-fork code. The study hypothesis is essentially that code related to the new feature will be similar between the two projects, where code associated with other features that aren't the same between projects, will be more different
Genetically, this might happen either because the random mutations in hearing genes that facilitate echolocation facilitate echolocation in any environment, provide a survival advantage, and become conserved in multiple environments. As dolphins and echolocating bats diverged, acute hearing was favored in both species, so their hearing genes are more similar than those of echolocating and non-echolocating bats, even though the genes for "wings" are more similar between bats than dolphins. Because it seems unlikely that the large number of differences that separate bats as a group from dolphins might have come up separately, the study proposes that the first bat-ears were as different from dolphin-ears as bat wings are different from dolphin flippers, and that the specialization into echolocating bats brought those hearing genes closer together, following a convergent path.
This is a much more subtle form of convergent evolution that, say, wings. "Wings" as a feature provide a definite advantage, and wing structures have evolved multiple times in multiple forms. The genes that define insect wings are completely different from those that define bat wings. It's a dramatic demonstration of nature using multiple solutions to the same problem. The current study suggests that nature is also capable of finding the same solution from multiple starting points.