The influence of invasive mongoose on the genetic structure of the endangered Amami rabbit populations.
Invasive carnivores often cause heavy damage to native species on small islands. Endangered Amami rabbit (Pentalagus furnessi) populations have been fragmented into a north-isolated population (NI) and a south-large population (SL) caused by predation pressure from the invasive small Indian mongoose (Herpestes auropunctatus) on Amami Oshima Island in southern Japan. We investigated the genetic structure of these rabbit populations to determine the effects of fragmentation. We collected rabbit feces from most of the Amami Oshima Island habitat and sequenced the mitochondrial DNA (mtDNA) control region along with its 5′-flanking region (312 bp) and genotyped eight microsatellite DNA loci. Genetic diversity was lower in the NI than that in the SL population, and FST values between the two populations were significantly higher than zero in both the mtDNA and microsatellite DNA. Bayesian clustering analyses suggested four ancestral clusters of Amami rabbit, but clear genetic structure was not observed. A partial Mantel test supported isolation-by-distance but not habitat fragmentation. These results suggest that the low genetic diversity in the NI population was caused by the small population size after fragmentation; however, the difference in genetic structure between the two populations was caused by isolation-by-distance and the structure has been maintained.