Glaciers, neoteny and epigenesis

Abstract

Hypercarnivorous mammal species are among the most vulnerable to population losses and endangerment. Among species belonging to Family Canidae, hypercarnivores are frequently subject to intense conservation efforts including captive breeding and reintroduction attempts. However, hypercarnivorous species may be most vulnerable to morphological changes in captivity, potentially altering their cranial functionality and limiting their reintroduction success. Other canid species with varying dietary preferences are also maintained in captivity, although it is unknown if morphological changes are prevalent across all captive canid populations or if these changes are concentrated primarily within hypercarnivores. To examine whether canids display morphological changes in captivity regardless of dietary preference, we assessed cranial and mandibular shape of 1621 specimens representing 15 canid species using geometric morphometric techniques. All hypercarnivores (4 species) and many hypocarnivores (5 of 7 species) differed between captive and wild populations in at least one shape variable. None of the mesocarnivores (4 species) differed in any shape variable. Among the carnivory types, hypercarnivorous species had the most pronounced differences in shape, particularly associated with a widening and shortening of the cranium within captive populations. Changes in cranial shape may impact an animal's ability to successfully capture and consume prey, therefore differences in cranial shape in captive populations may represent an obstacle to future reintroduction success. By examining cranial and mandibular shape differences between captive and wild populations, we explore the long-term impacts of captivity in canids in an effort to mitigate these negative effects in the future and increase the potential for reintroduction success.