CLADE-SPECIFIC RELATIONSHIPS BETWEEN FOSSORIAL BEHAVIOR AND EXTINCTION RISK ACROSS MAMMALIA

As anthropogenic climate change and habitat destruction proceed, it is increasingly important to understand extinction risk dynamics and identify at-risk groups. Many fossorial taxa are at risk or endangered, but whether fossoriality facilitates elevated or reduced extinction risk is unclear. Burrowing and denning may help reduce extinction risk by shielding individuals from climatic changes and predation, whereas extreme fossorial specialization may promote endemism and hinder dispersal abilities. Similarly, extinction risk dynamics in “exploitative fossorial” taxa (e.g., many pikas), which take advantage of existing crevices or other animals’ burrows, are poorly understood. True and exploitative fossoriality have evolved many times across Mammalia, mammals exhibit various degrees of fossorial specialization, and mammalian phylogeny is well-understood. Thus, mammals are an optimal system for investigating relationships between fossoriality and extinction risk. Here, I conduct a survey of extinction risk (proxies: IUCN Red List status for extant taxa, stratigraphic duration and abundance for fossil taxa, geographic range area) and fossorial tendencies across Mammalia. Data include body size, life habit (including engagement in true and/or exploitative fossoriality), engagement in social or solitary behavior, and extinction risk proxies for 3393 extant terrestrial mammal and 35 fossil mammal species. Geographic range size was calculated using GBIF occurrence data to generate convex hulls for each taxon, and calculating the area of each convex hull. Preliminary results suggest that the relationships between fossoriality, exploitative fossoriality, and extinction risk are largely clade-specific. Extant rodents, carnivorans, and eulipotyphlans demonstrate decreased extinction risk among both true and exploitative fossors, whereas afrotherians, xenarthrans, and marsupials show increased extinction risk among these functional groups. Therefore, a “one size fits all” approach for investigating extinction risk of certain functional groups is likely not appropriate, and phylogenetic context is needed to best predict and conserve at-risk taxa.