Wednesday, February 29, 2012

Using genomics to test for a genetic bottleneck in Ring-tailed Lemurs

Increasing rates of deforestation, resource extraction, and bushmeat consumption have negatively impacted the endemic flora and fauna of Madagascar. This study sampled ring-tailed lemurs (L. catta) in two southwestern Madagascar sites to see if they had undergone a recent population bottleneck due to anthropogenic activities. They collected blood samples from 45 specimens, and tested for reductions in population size using an M-ratio test, and evaluated three mutation models for heterozygosity excess tests (stepwise, two-phase, and infinite allele). Analyses were conducted on samples containing both males and females, and then females only, as males are primarily the dispersing sex in L. catta.
Both populations showed reduction via the M-ratio test as well as significant heterozygosity excess via the infinite allele model, especially for one of the two populations, but the other analyses did not yield overall significant results.
The authors hold that their results are indicative of a recent genetic bottleneck in L. catta, and point to anthropogenic activities as the main cause of this genetic shift. They highlight the negative effects of a bottleneck, such as inbreeding depression and fixation of deleterious alleles, and conclude that accounting for human- and climate-founded perturbations are an important inclusion in genomics-based conservation assessments.

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