Does stress mess with rodents’ heads? Influence of habitat availability and genetic factors in mandible fluctuating asymmetry (FA) in South American water rats (Nectomys squamipes, Sigmodontinae) from Brazilian Atlantic rainforest remnants

Loss of developmental stability can lead to deviations from bilateral symmetry (i.e. Fluctuating Asymmetry -FA), and is thought to be caused by environmental and genetic factors associated with habitat loss and stress. Therefore, levels of FA might be a valuable tool to monitor wild populations if FA serves an indicator of exposure to stress due to impacts of habitat loss and fragmentation. In studies examining FA and habitat fragmentation, FA levels are often explained by loss of genetic variation, though few studies have addressed FA’s use as indicator of environmental impact. Here we investigated whether habitat loss, genetic variation and/or inbreeding affect the developmental instability in Brazilian Atlantic rainforest populations of a Neotropical water rat (Nectomys squamipes). We sampled individuals from eight forest remnants with different amounts of available habitat and assessed FA levels with geometric morphometric techniques using adult mandibles. We used observed heterozyg...