A slightly different sort of genetic bottleneck can occur if a small group becomes reproductively separated from the main population. Population bottlenecks reduce the genetic variation and, therefore, the population's ability to adapt to new selective pressures, such as climatic change or shift in available resources.
Genetic drift can eliminate alleles that could have been positively selected on by the environment if they had not already drifted out of the population.
Most genes in the genome are inherited from either father or mother, thus can be traced back in time via either matrilinear or patrilinear ancestry.
Research on many (but not necessarily most) genes find different coalescence points from 2 million years ago to 60,000 years ago when different genes are considered, thus disproving of the existence of more recent extreme bottlenecks (i.e. But this is not inconsistent with the Toba catastrophe theory which suggests that a bottleneck of the human population occurred ca.
The cultures collected were then ran through electrophoresis and further studied using nuclear minisatellite variations and clones.
Via the male line, all humans can trace their ancestry back to a single male (Y-chromosomal Adam) at around 60,000 to 90,000 years ago.This species is a small member of the weasel family that formerly occupied plains and prairie habitat from Saskatchewan to Texas.The species was listed as threatened in the USA in 1967 and endangered in 1973.By studying mitochondrial DNA, which evolves 5-10 times faster than nuclear genes and which is also sensitive to demographic partitions, it was determined that the genetic bottleneck occurred between 6,000-20,000 years ago (Menotti-Raymond & O'Brien, 1993).The genetic mutations and variations were collected through blood and skin fibroblast cell cultures collected from the free-ranging subspecies of cheetahs.