Genetic Consequences of a Severe Population Bottleneck in the Guadalupe Fur Seal (Arctocephalus townsendi)

Abstract

Population bottlenecks may lead to diminished genetic variability and correlative effects on fitness. The Guadalupe fur seal was nearly exterminated by commercial sealers during the late 18th and early 19th centuries. To determine the genetic consequences of this population bottleneck, we compared the variation at a 181 bp section of the mitochondrial DNA (mtDNA) control region from the bones of 26 prebottleneck fur seals versus variation in the extant population. We found 25 different mtDNA genotypes in the prebottleneck fur seals and only 7 genotypes among 32 extant fur seals, including only one of the ancient genotypes. These data demonstrate a substantial loss of genetic variability correlating with the recent population bottleneck. We also found from several genetic measures that the prehistoric population of Guadalupe fur seals was robust and that it had been increasing at some time during the late prehistoric period. Continued recovery of this species may, however, owe more to more immediate nongenetic factors, such as poaching and local availability of food resources during the breeding season and consequent effects on pup survival, than on the reduced genetic variability.

Genetic erosion in the snailLittoraria subvittata(Reid, 1986) due to mangrove deforestation

“…Habitat alteration or destruction has a potential impact on populations through the substantial reduction of effective population size and genetic variability (Weber, 2004). The loss of genes in these populations can increase the effect of genetic drift, leading to genetic differentiation from unaffected populations (Vandergast et al, 2006;Dibattista, 2008).…”

Extremely low genetic diversity and weak population differentiation in the endangered Colombian river turtle Podocnemis lewyana (Testudines: Podocnemididae)

“…Pairwise mismatch distribution graphs were produced in DNASP 5.0. These methods are expected to either identify past demographic events such as population expansion or to detect when demographic historical information has disappeared due to the influence of recent population bottlenecks (Weber et al 2004;Johnson et al 2007). …”

“…S2). By contrast, bottlenecks are expected to show multimodality in mismatch distributions (Rogers and Harpending 1992;Weber et al 2004;Johnson et al 2007). Thus, the results of the mismatch distribution analysis suggest a signature of population expansion, and this is further supported by our observation of negative Tajima's D and Fu's F S values and the star-like haplotype network topology ( Fig.…”

Creation Nerves of the Lumbar and Sacral Plexus in California Sea Lions (Zalophus Californianus) and Northern Elephant Seals (Mirounga Angustirostris)/Formiranje Nerava Iz Lumbalnog I Sakralnog Pleksusa Kod Kalifornijskog Morskog Lava (Zalophus Californianus) I Severnomorskog Slona (Mirounga Angustirostris)

“…In addition they also report a different number of lumbar and sacral vertebrae. It is commonly known that there are some discrepancies in the origin of the lumbosacral plexus even amongst individual specimens of the same species in terrestrial mammals [23,[31][32][33][34][35][36][37]. Therefore, it can be assumed that the same differences in the origination of the lumbosacral plexus would exist in pinnipedia.…”