Natural selection is being run, more or less, by the gentleman hunter we have up top there with the classy antique deer rifle. He does not believe in evolution, yet he and his ilk are currently sort of in charge of it because they are the ones culling the herds of bighorn sheep, clearing the hills of ginseng and emptying the rivers of salmon. The findings of this horrific new study — “Human predators outpace other agents of trait change in the wild” — more or less clarify that traditional conservation efforts and hunting/fishing regulations encourage the killing of the largest, healthiest adults, leaving the weakest members of the community to breed. This, of course, fucks things up on an evolutionary scale. From the New York Times:
The new findings are more sweeping. Based on an analysis of earlier studies of 29 species — mostly fish, but also a few animals and plants like bighorn sheep and ginseng — researchers from several Canadian and American universities found that rates of evolutionary change were three times higher in species subject to “harvest selection” than in other species. Writing in The Proceedings of the National Academy of Sciences, the researchers say the data they analyzed suggested that size at reproductive maturity in the species under pressure had shrunk in 30 years or so by 20 percent, and that organisms were reaching reproductive age about 25 percent sooner.
In Alberta, Canada, for example, where regulations limit hunters of bighorn sheep to large animals, average horn length and body mass have dropped, said Paul Paquet, a biologist at the University of Calgary who participated in the research. And as people collect ginseng in the wild, “the robustness and size of the plant is declining,” he said.
The researchers said that reproducing at a younger age and smaller size allowed organisms to leave offspring before they were caught or killed. But some evidence suggests that they may not reproduce as well, said Chris Darimont, a postdoctoral fellow in environmental studies at the University of California, Santa Cruz, who led the work. The fish they studied that are reproducing earlier “on average have far, far, far fewer eggs than those who wait an additional year and grow a few more centimeters,” he said in an interview.
Dr. Darimont said it was unknown whether traits would change back if harvesting were reduced, or how long that might take.
The researchers also noted that the pattern of loss to human predation like hunting or harvesting is opposite to what occurs in nature or even in agriculture.
Predators typically take “the newly born or the nearly dead,” Dr. Darimont said. For predators, targeting healthy adults can be dangerous, and some predator fish cannot even open their mouths wide enough to eat adult prey. Animals raised as livestock are typically slaughtered relatively young, he said, and farmers and breeders retain the most robust and fertile adults to grow their herds or flocks.
“Targeting large, reproducing adults and taking so many of them in a population in a given year — that creates this ideal recipe for rapid trait change,” Dr. Darimont said.
Some fisheries scientists have said their studies of fish stock had not shown a correlation between fishing intensity and growth rates. And some wildlife conservationists question the idea that hunting can have harmful effects on species.
Dr. Paquet said that although he had confidence in the new findings, he knew there would be questions about the analytical methods he and his fellow researchers used. “That’s expected,” he said. “That’s how science proceeds.”
He said he had anticipated that the work would be “contentious” among trophy hunters. “Essentially, we are saying, ‘You should not do this because it is having effects even you might not like,’ ” he said.