Correlates of reproduction in females of the Western Whip snake, Hierophis viridiflavus: preliminary results.

In snakes, body size and reproductive output vary greatly among disjunct populations. Clutch size is notably influenced by food availability, thermal conditions and maternal body size. A comparison between three large-scale areas – north continental, south continental and island populations of European whip snakes – revealed significant variation in body size and reproductive output. More importantly, there was a geographical difference in the covariation between clutch size and maternal body size, two traits mechanistically linked as body size constrains clutch size. This suggests that clutch size can vary independently of maternal body size, a situation that provides opportunities to tease apart the contribution of phenotypic plasticity from local genetic adaptations in these two life-history traits.