In Nature this week, a team led by Colorado State University researchers published an evolutionary study of guppies, providing details about how organisms adapt to environmental change. The researchers transplanted wild Trinidadian guppy from a stream with predatory pike fish into two predator-free streams, then compared gene expression patterns in the brains of the original and transplanted populations after several generations. They also examined gene expression in fish from a naturally predator-free environment. The scientists found that when phenotypes changed within the transplanted fish in ways that are favored by natural selection, the genes that gave rise to those phenotypes tended not to evolve in response to selection pressures, suggesting that adaptive plasticity constrains evolution. Conversely, phenotypic changes that did not impart fitness to the fish in new environments were associated with rapid genetic changes.
And in Nature Genetics, a group of European researchers reported new data that suggest pig domestication may not have occurred as previously thought. While it is assumed that domestic pigs arose from a permanently isolated group of wild animals thousands of years ago, a review of genetic data from more than 600 domestic pigs and wild board in Europe and Asia indicates that domestic pigs originated from both Anatolian domestic pigs, as expected, as well as from European wild boars. Evolutionary modeling of the data suggests that domestic pigs interbred with wild boars over many generations, and thus modern-day domestic pigs share DNA with many wild populations, including potentially extinct ones. Selective breeding by humans may have helped overcome the effect of this interbreeding.