Examining the Biogeographic History and Evolution of Otters in the Americas to Identify Conservation Solutions

Abstract

Anthropogenic impacts affect nearly every living species. The habitats and ranges of many taxa are now so modified that modern distribution information alone is insufficient to determine what conditions they can persist in. As climate change and other anthropogenic impacts increase, clear information on species’ needs and tolerances simultaneously becomes even more critical for conservation and harder to obtain. Historic records and paleontological data can provide key insights into organisms’ past requirements, resilience, and adaptive capacity, which can be used to identify specific areas of vulnerability and to inform conservation policies and strategies. Here we review the evolutionary history and paleobiogeography of North and South American river otters to investigate how geography and environmental change have driven river otter evolution in the Americas, and shaped the ecology, threats, and conservation status of each of the extant species in these clades. Members of the two extant American otter genera, Lontra and Pteronura, overlap in geographic and ecological niche space, and their shared history provides an opportunity for an evolutionarily-grounded examination of relative rarity, specialization, and level of conservation concern. Integrated paleobiological, historical, and modern ecological data indicates that American otters are less habitat-specific than previously thought. We found that changes in waterway connectivity impacts speciation and population connectivity, and likely plays a role in population health and persistence in times of stress. All American river otters exhibit sensitivity to anthropogenic habitat modifications but can coexist with humans in urbanized environments with proper support. This deeper-time perspective suggests that otter conservation in regard to both habitat alteration and climate change may strongly benefit from supporting riverine ecosystem productivity and connectivity in both wild and urban settings.