Causal explanations for the evolution of ‘low gear’ locomotion in insular ruminants

作者：Roberto Rozzi, Sara Varela, Pere Rosselló Bover, Jeff M. Martin · 发表于：Journal of Biogeography · 年份：2020 · DOI：10.1111/jbi.13942 · 被引用次数：33 · 研究领域：Evolution and Paleontology Studies、Animal Ecology and Behavior Studies、Wildlife Ecology and Conservation

Abstract Aim Mammals on islands often undergo remarkable evolutionary changes. The acquisition of ‘low gear’ locomotion, namely short and robust limb elements, has been typically associated with the island syndrome in large mammals and, especially, ruminants. Here we provide an investigative framework to examine biotic and abiotic selective factors hypothesized to influence evolution of this peculiar type of gait. Location Islands worldwide. Taxon Bovidae. Methods We calculated response variables associated with ‘low gear’ locomotion in 21 extinct and extant insular bovids. We assembled data on the physiography of 11 islands and on life history and ecological traits of the focal taxa. We estimated 10 predictors (island area and four topographic indices, body mass, body size divergence, number of predators and competitors, large mammal richness) and used multiple regressions, regression trees, and random forests to assess their contextual importance. Results The acquisition of ‘low gear’ locomotion generally happens on islands with a small number of competitors. However, the roughness of the island terrain appears to be also important, without being a main driver. Finally, although the most extreme cases of ‘low gear’ locomotion occurred on islands with no mammalian predators, our models show a non‐significant relationship with this factor. Main conclusions The evolution of ‘low gear’ locomotion in insular ruminants does not simply result from phyletic dwarfing and predatory r...