Bottleneck Effect
Published on Nov 18, 2015
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BOTTLENECK EFFECT
BY: ZOE BURCZYK
Bottleneck effect occurs when there is changes in gene frequency that result when numbers in a population are drastically reduced, and genetic variability is reduced as a result of the population being built up again from relatively few surviving individuals. (http://en.mimi.hu/biology/bottleneck.html)
Northern elephant seals have reduced genetic variation probably because of a population bottleneck humans inflicted on them in the 1890s. Hunting reduced their population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000—but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted. (http://evolution.berkeley.edu/evosite/evo101/IIID3Bottlenecks.shtml)
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About 12,000 years ago, a mass extinction event occurred that eliminated 75% of the world’s large mammal species. Fortunately, a handful of cheetahs managed to survive this extreme extinction event and were able to restore the world’s population of cheetahs.This event caused an extreme reduction of the cheetah’s genetic diversity, known as a population bottleneck, resulting in the physical homogeneity of today’s cheetahs. Focal palatine erosion, susceptibility to the same infectious diseases, and kinked tails characteristic of the majority of the world’s cheetahs are all ramifications of the low genetic diversity within the global cheetah population. (http://cheetah.org/about-the-cheetah/genetic-diversity/)
Photo by whl.travel
