Genetic Diversity, Population Size, and Conservation of the Critically Endangered Perrier’s Sifaka ( Propithecus perrieri )

Genetic data can be combined with ecological data to study the demographic history of a species, identify landscape features that influence migration patterns, and guide conservation efforts. Perrier’s sifaka ( Propithecus perrieri ) is a Critically Endangered, rare, and elusive social lemur living in a very restricted, fragmented landscape. To assess the effect of habitat loss and fragmentation on the genetic diversity of the Perrier’s sifaka population we examined 24 microsatellite markers genotyped for 67 samples corresponding to 42 individuals. Perrier’s sifaka shows a low current effective population size ( ca. 52–105) and a strong heterozygosity excess, suggesting a historically large but dwindling population. Moreover, we identified a pattern of isolation by distance, typical of continuous habitat, suggesting that sifakas were still able to cross the grasslands between forest fragments in the recent past. Our study calls for a unified conservation plan covering the two protected areas where the species is still present, if not the whole area of its past distribution. Further studies inferring the past demographic history of Perrier’s sifaka may confirm the population decline and shed light on its potential causes.