Evolutionary Biological Responses of Pikas (Lagomorpha, Mammalia) to Past Insular Ecosystems (Miocene-Holocene): A Key for the Management of Extant Species †

Abstract

The study of extinct biotas is fundamental to unraveling the evolutionary responses of organisms to insular habitats, which lack anthropogenic perturbations. Although paleobiological research has been historically biased towards species of large size, in the past few decades, small mammals studies have gained momentum. The present review discusses the general and specific eco-evolutionary adaptations to insular environments described in extinct species of pikas (Ochotonidae, Lagomorpha), given the last cutting-edge investigations. All lineages and species, known so far, occurred in Mediterranean Islands during Miocene-Holocene period. The review showed that, in a general trend, insular ochotonids experienced a body mass shift (towards larger morphotypes), as well as modifications in teeth features (hypselodonty, higher hypsodonty, more complex enamel patterns and increase of premolar and molar occlusal surface). The morphological design of some taxa was adapted to a non-cursorial locomotion with digging and leaping skills. Histological and paleopathological studies pointed to a slower life history than mainland forerunners, suggesting that they had a more K reproductive strategy. Such biological shifts response to the specific ecological pressures of insular habitats, characterized by resource limitation and low extrinsic mortality. At date, a single ochotonid species inhabits a true island, although some others occur in ecological ones. Furthermore, climate change will also strongly reduce ochotonid ranges, pushing them to very limited areas (e.g. top of mountains). For an effective management of endangered pikas, it is particularly relevant to know their evolutionary responses and ability to persist in certain environmental scenarios (e.g. isolation), by means of the study of their extinct relatives. The paleobiological data presented in the present research may be particularly useful in this field (e.g. identifying suitable candidates and locations for restoration and rewild programs).