America bottleneck cheetah dating genetic
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In addition to the challenges posed by low genetic diversity, the cheetah also faces pressures from an increasingly fragmented habitat, and competition for food from both humans and other large cats. "Dating the Genetic Bottleneck of the African Cheetah." Proceedings of the National Academy of Sciences 90.8 (1993): 3172-176. The cheetah is unusual among fields in exhibiting near genetic uniformity at a variety of loci previously screened to measure population genetic diversity.
It has been hypothesized that a demographic crash or population bottleneck in the recent history of the species is causal to the observed monomorphic profiles for nuclear coding loci.
Natural selection acts on the genetic variation present in a population to remove those variants that fail to produce offspring in a particular situation and spread those variants that are particularly good at producing offspring.
A population with no genetic variation (in which every individual is genetically identical) cannot evolve in response to environmental or situational changes.
Females frequently mate with several different males while they are fertile and are then likely to bear a single litter of cubs fathered by multiple males making many of the cubs within a single litter only half-siblings.
This discovery has important implications for the conservation of these endangered animals.
Conservation biologists are interested in cheetah cheating because it impacts the cheetah population's level of genetic variation.
Loosely, genetic variation is a measure of the genetic differences within a population.
The timing of a bottleneck is difficult to assess, but certain aspects of the cheetah's natural history suggest it may have occurred near the end of the last ice age (late Pleistocene, approximately 10,000 years ago), when a remarkable extinction of large vertebrates occurred on several continents.
We demonstrate that these extant Iranian cheetahs are an autochthonous monophyletic population and the last representatives of the Asiatic subspecies We advocate that conservation strategies should consider the uncovered independent evolutionary histories of Asiatic and African cheetahs, as well as among some African subspecies.
Moderate levels of genetic diversity were observed for both of these indices in surveys of two cheetah subspecies, one from South Africa and one from East Africa.
Back calculation from the extent of accumulation of DNA diversity based on observed mutation rates for VNTR (variable number of tandem repeats) loci and mitochondrial DNA supports a hypothesis of an ancient Pleistocene bottleneck that rendered the cheetah depauperate in genetic variation for nuclear coding loci but would allow sufficient time for partial reconstitution of more rapidly evolving genomic DNA segments.
A population with low genetic variation is something of a sitting duck vulnerable to all sorts of environmental changes that a more variable population could persist through.