![]() ![]() It is conceivable that the process of natural selection acting on one particular gene resulted in a loss of diversity amongst other nearby genes, or amongst those genes that are somehow linked to the selected gene. But there is another possible explanation for their unusual level of genetic diversity: natural selection. (doi:10.1126/science.aao0960) doi:10.1126/science.aao0960Īs I mentioned, it was fairly widely-accepted that the passenger pigeon’s population underwent huge periodic fluctuations that, in turn, reduced their overall genetic diversity from expected levels. The structure of the phylogeny does not correlate with geography, which is consistent with an absence of geographic population structure. Colors in the inset to (Figure 1A) match the phylogeny in (Figure 1B). Inferred Ne (blue shading indicates the 95% HPD interval) and mitochondrial phylogeny from a Bayesian coalescent analysis. Passenger pigeon effective population size (Ne) estimate from mitochondrial genomes. Sleek and slender, this species was built for speed, and they wandered freely over vast distances (Figure 1A).įig. The passenger pigeon, Ectopistes migratorius, were handsome medium-sized birds who raised their families in huge, social colonies throughout the eastern United States. Instead, the passenger pigeon mitochondrial genome indicated that their population had been stable for the past 20,000 years - a time period that included dramatic climatic changes, such as the end of the last ice age in North America, which is precisely when you’d expect to see population fluctuations. The researchers reasoned that, if the passenger pigeon’s population had been fluctuating by a thousand-fold for long periods of time, then genetic diversity in all regions of the genome should be affected equally.įurther, they discovered that the genetic diversity in the mitochondrial genome did not correspond with the genomic data. The authors of that study suggested that passenger pigeons were not always super-abundant ( ref read more).īut when the researchers examined the entire genome closely, they found that genetic diversity varied: some regions of the genome had very low diversity, whilst others did not. Despite their huge population, the 2014 study indicated that passenger pigeons had much less genetic diversity than expected. ![]() In a study published in 2014, researchers sought to understand how such an abundant species could possibly be driven extinct, particularly since many scientists have estimated that passenger pigeons were, arguably, the most populous bird species on the planet, ever. But how could these birds decline so rapidly? Surely, people did not murder every last one of them, did they? Shouldn’t mind-bogglingly huge and wide-spread populations protect a species from extinction? Why didn’t some pigeons survive in remote areas? As extinctions go, the extinction of the passenger pigeon is truly a stupendous human achievement, unparalleled in recorded history: thanks to our penchant for relentless killing combined with large-scale habitat destruction, these iconic birds’ population crashed from billions to zero in just fifty years. ![]()
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