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from the bird-brained-humans-did-them-in dept.
Four billion passenger pigeons vanished. Their large population may have been what did them in
Four billion passenger pigeons once darkened the skies of North America, but by the end of the 19th century, they were all gone. Now, a new study reveals that the birds' large numbers are ironically what did them in. The pigeons evolved quickly, but in such a way to make them more vulnerable to hunting and other threats.
[...] In 2014, Wen-San Huang, an evolutionary biologist at National Taiwan Normal University (NTNU) in Taipei, and colleagues turned to DNA in an attempt to solve the mystery. Genetic material from four 19th century museum specimens revealed that the species had relatively low genetic diversity—meaning that most individuals were remarkably similar to each other—and that its numbers had fluctuated 1000-fold for millions of years. Hunting and habitat loss came during a time when the species was already declining, the team concluded, which pushed the birds over the edge.
But the new study lays the lion's share of the blame back on people. Beth Shapiro, a paleogenomicist at the University of California, Santa Cruz, and colleagues sequenced the complete genomes of two passenger pigeons, and analyzed the mitochondrial genomes—which reside in structures that power cells—of 41 individuals. The specimens came from throughout the bird's range. In addition, they reanalyzed data from Hung's group, and, for comparison, sequenced the bird's closest living relative, the band-tailed pigeon.
[...] [The] passenger pigeon's huge population is what made it vulnerable [DOI: 10.1126/science.aao0960] [DX], Shapiro's team reports today in Science. The birds were able to adapt faster to their environment—and spread these changes quickly within their population—but this also caused all of them to be fairly genetically similar. And when a new threat—like human hunters and habitat loss—came around, they suddenly found their physiology and behavior were poorly suited for their declining numbers. Their population "went from being superbig to supersmall so fast they didn't have time to adapt," in part because they lacked the diversity to cope with this new way of living, Shapiro says.
According to Wikipedia:
The passenger pigeon or wild pigeon (Ectopistes migratorius) is an extinct species of pigeon that was endemic to North America. Its common name is derived from the French word passager, meaning "passing by", due to the migratory habits of the species. The scientific name also refers to its migratory characteristics.
(Score: 2) by Runaway1956 on Monday November 20 2017, @09:22PM
This article reminds me of the cheetah. Of course, like you, I think there is a hell of a lot of guesswork going on here. All of this guesswork based on three corpses, none of which was in a condition to provide it's full genome?
https://en.wikipedia.org/wiki/Cheetah#Taxonomy [wikipedia.org]
Although the cheetah is an African cat, molecular evidence indicates that the three species of the Puma lineage evolved in North America two to three million years ago, where they possibly had a common ancestor during the Miocene.[16] They possibly diverged from this ancestor 8.25 million years ago.[13] The cheetah diverged from the puma and the jaguarundi around 6.7 million years ago.[17] A genome study concluded that cheetahs experienced two genetic bottlenecks in their history, the first about 100,000 years ago and the second about 12,000 years ago, greatly lowering their genetic variability. These bottlenecks may have been associated with migrations across Asia and into Africa (with the current African population founded about 12,000 years ago), and/or with a depletion of prey species at the end of the Pleistocene.[18]
https://en.wikipedia.org/wiki/Population_bottleneck [wikipedia.org]