Earth's environmental role: entering a new one (Evolution)

by David Turell , Friday, June 02, 2017, 14:44 (2729 days ago) @ dhw

Work with stickleback fish indicate being dumped into a new unfamiliar stream isn't all bad:

https://www.sciencedaily.com/releases/2017/05/170531133328.htm

"It's hard being a misfit: say, a Yankees fan in a room full of Red Sox fans or a vegetarian at a barbecue joint. Evolutionary biologists have long assumed that's pretty much how things work in nature too. Animals that wander into alien environments, surrounded by better-adapted locals, will struggle. But a team of researchers from The University of Texas at Austin was surprised to find that sometimes, misfits can thrive among their much more numerous native cousins.

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"Yet when the researchers did a series of experiments placing varying numbers of fish from one habitat into the other habitat with local fish, they found the transplants fared surprisingly well. Monitoring the fish in underwater cages over time, the researchers observed that survival had less to do with where a fish was from, and more to do with whether they were the common or rare type within their cage. In either habitat, when stream fish were in the minority, they survived better than when they were in the majority, for instance.

"The scientists found that immigrants could fly under the radar in the face of some threats, which helped them beat the odds.

"You come in and you eat something nobody else around you eats, so you aren't competing for food," Bolnick says. "The local parasites don't know what to do with you because you have an unfamiliar immune system. So you're better off than the residents."

"Bolnick notes that being less adapted to the environment also has some negative effects on immigrants, just as theory predicts, but their study shows that in some instances the benefits of rarity can outweigh the drawbacks of being in an unfamiliar environment.

"'We found newcomers in the population pass on their genes more often than residents, and they contribute more to the next generation," Bolnick says.

"The team found that this effect gives migrants an outsized impact on the genetics of their adopted population. This slows the pace of evolutionary divergence -- the rate at which each of the two populations might pick up new traits that make it differ more from the other.

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"'Just because the streams look similar to us, on the surface, doesn't mean that they are interchangeable," says Bolnick. "Every stream is ecologically unique. And so every stream population's adaptations must be similarly unique.'" (my bold)

Comment: Note my bold. Eco-niches are unique, and we are still learning about environmental effects on species. Remember Reznick's guppies. And we have no research on human genetic responses in prospective ways because that cannot be done. Translating animal studies to humans is all we have.