Basically, autochthony is judged by the time over which the ancestry of the collection has existed as a population at this location.
In practice, this means that at a given level of SSB, an evolved population was sparser (i.e. existed at a lower density) than a nonevolved population.
Because of the nature of food webs within ecosystems, organisms at higher trophic levels exist at a lower population density and are often quite sensitive to changes in food availability.
However, pathogenic variants may exist at a low frequency in populations of ostensibly healthy controls, as these may be in a pre-clinical disease phase, or phenotyped using methods with incomplete sensitivity.
However, one would expect that recurrently variant SNPs in our data set would often exist at a higher frequency in the general population, and would thus be more likely to have been previously discovered.
Inherited bacteria exist at a variety of prevalence levels in natural populations, from 1% to 100% of individuals.
In TCR transgenic mice, these cells are dependent on the premature expression of the transgenic TCRαβ in DN thymocytes and hence represent an artificially exaggerated population of cells that exists at a very low frequency in normal mice [24].
We assume that the cofactor, Schistosoma haematobium, exists at a stable endemic level in many sub-Saharan African populations.
The industrial, economically depressed environs of Port Talbot (population 35,000) exist at an extreme remove from Hollywood, where he has been appearing in the "Twilight" vampire screen saga.
Here, we examine whether such variation also exists at the population level.
