We found documentation that links the founding population
of beavers to the province of Manitoba in Canada.
(15) The Beringia model, or "Clovis first model," states that founding populations
from Siberia, following the big game animals, entered the New World approximately 11,000 YBP.
That pattern is consistent with a scenario in which moose populations worldwide trace back to recent population expansion combined with small sizes of founding populations
(Hundertmark et al.
Seeds of that diversity germinated from the founding populations
that moved across the Bering land bridge at the end of the Ice Age, so the ancestral population must have been a complex mix of people, Schurr says.
These observations can be explained by the postglacial colonization of East Lake by a single founding population
of Acadian origin characterized by the original haplotype 25 still found in the lake, followed by the local genesis of haplotype 106, the radiation of the two morphotypes through disruptive selection, and the development of their partial reproductive isolation.
A geneticist armed with computer simulations of prehistoric populations says that only about 200 to 300 people crossed the ice age land bridge from Asia to become the founding population
of North America.
Assuming that the selfing rate has been at about the levels measured in extant populations ([greater than or equal to] 98%) over this time, then it seems unlikely that linkage disequilibrium existed in the founding population
. If outcrossing rate is great enough to maintain linkage equilibrium in the source population(s), then adult worms must usually mate with other individuals rather than with themselves.
He estimates that it took just a few thousand years for a founding population
of 600 Stone Age people to travel from what's now India to southeastern Asia and then to Australia.--B.B.
In contrast, disruptive selection would be invoked if variation in differentiation of ecotypes among lakes reflects the local potential for adaptive diversification from a single founding population
. In the latter case, reproductive isolation may be achieved as a result of "niche-adapting" alleles that govern mate choice (Bush 1975; Rosenweig 1978; Rice 1984; Wilson 1989).
The analysis indicated that within 400 years of entering Europe, the founding population
split into at least three major groups: One stayed in the Balkan Mountains, another pressed north of the Danube River, and the third moved on to Western Europe.
Genetic revolution occurs after an extreme founder event and subsequent small population size has eroded virtually all genetic variability from the founding population
's gene pool.
Mexico harbored that founding population
, in Pope's view.