Thursday, August 14, 2014

Evolution in Action in Our Time

Evolutionarily speaking, coyotes diverged from gray wolves one million to two million years ago, and dogs from wolves roughly 15,000 years ago. Yet over the past century, as agriculture moved to the Midwest and California, farmland in the East reverted to woodlands. The rise of fossil fuels reduced the demand for firewood. Forests spread, and deer and other prey proliferated, while human intolerance for wolves kept a potential competitor at bay.

Thus did humans inadvertently create an ecological niche for a predator in one of the most densely populated regions of the country. In an exceedingly brief period, coyote, wolf and dog genes have been remixed into something new: a predator adapted to a landscape teeming with both prey and another apex predator, us. And this mongrel continues to evolve. Javier Monzon, an evolutionary biologist at Stony Brook University, has found that Eastern coyotes living in areas with the highest densities of deer also carry the greatest number of wolf genes. Another scholar of the Eastern coyote — Roland Kays, a zoologist at the North Carolina Museum of Natural Sciences in Raleigh — estimates that the Eastern coyote’s hybrid ancestry has allowed it to expand its range five times as fast as nonhybrid coyotes could have. In the urbanized Northeast, of all places, an abundance of large prey seems to have promoted a predator whose exceptional adaptability has derived, in large part, from the hodgepodge nature of its genome.
It seems that the Anthropocene is becoming an era of hybridization:
Humans are increasing the stresses on wildlife in myriad ways. Oil spills and agricultural runoff, each linked to fish hybridization, are not uncommon. Hunting and habitat alteration, of the sort that spurred coyote and wolf to mate in Canada, abound. Then, of course, there’s climate change. The list goes on, which leads to the following conclusion: One way we affect animals is by inadvertently enlarging their circles of sexual consideration, to the point that it even includes other species.
And, of course, biological thought has always been prey to ideological bias:
Then in the early- and mid-20th century, the concept of species hardened. Botanists could never ignore hybridization — it occurs between plants too frequently — but interbreeding among animals became the “grossest blunder in sexual preference which we can conceive of,” as one author wrote in 1930.

Looking back, Michael Arnold, a geneticist at the University of Georgia, and long a gadfly to the species orthodoxy, attributes this attitude to worries about miscegenation. Anxiety over racial “purity” perhaps affected how we thought about nature. If this is the case, biology is finally shedding the lingering influence of pseudoscience.

“Biodiversity has developed in a web of life rather than a tree of life,” Arnold told me. That interconnectedness lends strength. “It’s sort of cool that evolution is really messy.”

No comments:

Post a Comment