Dating the cheetah bottleneck
Few people will disagree: cheetahs are impressive creatures.These majestic cats are the bold sprinters of the Serengeti, propelling themselves at bursts of speed that are estimated to reach 75 mph, and accelerating from 0 to 60 mph as fast as a Ferrari 458 Italia or Porsche 911.Though being able to receive an organ donation from any individual in your species might sound appealing, being so excessively inbred can lead to an increase in the frequency of deleterious traits.This can lead to a decrease in fitness in the entire population, a phenomenon known as inbreeding depression.Siblings, third cousins twice removed, and even complete strangers on the other side of Africa could all probably donate a kidney to a fellow cheetah. O' Brien and his colleagues set out to precisely quantify the genetic similarity of cheetahs by sequencing the genomes of seven individuals: four from Namibia and three from Tanzania.The researchers studied several different measures of genetic variation and found that Cheetahs were dead last in almost every category among the species that the authors examined, emphasizing the depletion of variation in their genomes.
The prevailing hypothesis is that cheetahs experienced what is known as a genetic bottleneck.
Just as a bottle narrows from its base to its neck, a genetic bottleneck occurs when a gene pool is narrowed to a fraction of its former diversity.
This can happen via a natural disaster, such as a volcano wiping out all but a small portion of a population.
Survival of the fittest is not the only way evolution can happen.
Using sophisticated modeling of evolution, the authors estimated that a founder event for modern cheetahs took place over 100,000 years ago, leading to an initial reduction in genetic variation.