Athletic anurans: the impact of morphology, ecology and evolution on climbing ability in invasive cane toads

Although primarily terrestrial, cane toads (Rhinella marina) sometimes climb near-vertical surfaces (tree-trunks, cliffs, fences) during foraging or dispersal activities. We scored climbing ability (in laboratory trials) of 288 cane toads from four regions in Australia, plus two sites on the island of Hawai'i. We found strong divergence in climbing ability associated not only with sex and relative limb length, but also population of origin. Within each population, longer-limbed individuals (and hence, males rather than females) were better climbers, although the geographical divergence in climbing ability remained significant even when sex and limb length were included in multivariate regression models. The geographical difference in climbing ability (but not morphology) disappeared when the progeny were raised in captivity under identical conditions, without climbing opportunities. Although influenced by morphology, climbing ability in wild-caught cane toads appears to be driven primarily by local environmental conditions that facilitate and/or reward arboreal activity.