Evolutionary correlations between escape behaviour and performance ability in eight species of snow skinks (Niveoscincus: Lygosominae) from Tasmania

Abstract

Three locomotor modes were examined (sprinting, jumping and climbing) in eight species of skinks: seven Niveoscincus spp. and Pseudemoia entrecasteauxii. These species formed four distinct ecological types: ground-dwelling, arboreal, heath/rock dwelling, and saxicolous. Significant behavioural preferences for particular escape modes in the field were found, which reflected the performance capabilities at an animal in the laboratory. This study used both non-phylogenetic and evolutionary based analyses to demonstrate that species occupying different microhabitats and using different escape tactics exhibit corresponding differences in performance abilities. Four Niveoscincus species are specialized in performance abilities and behavioural responses (N. greeni, N. ocellatus, N. pretiosus, N. orocryptus) by excelling in some performance abilities but having behavioural restrictions at attemping other locomotor modes. Only N. microlepidotus and N. orocryptus used escape tactics opportunistically; these species possess a suite of behavioural responses that may reflect the wide range of microhabitats they occupy. Ground-dwelling species N. metallicus, N. coventryi and Pseudemoia entrecasteauxii performed poorly at all performance abilities and seemed to have biomechanical limitations, rather than behavioural restrictions, on locomotor mode. Thus, when making interspecific comparisons, the behaviour of an animal needs to be considered before appropriate performance measures are selected. Phylogenetic analyses demonstrate that escape tactics and performance abilities have co-evolved in Niveoscincus, with an evolutionary trend towards behavioural and locomotor specialization.