Relationship between mass and length in Australian elapid snakes

Least squares regression analysis of log mass on both log snout-vent and log total length for individuals of each sex of 14 populations of ten species of Australian elapid snakes indicates that in the 37 most robust data sets isometry occurs in 21 cases, negative allometry in ten cases and positive allometry in six. Isometry seems to be the most common kind of allometry in 'colubroid'-shaped snakes. There are no cases of different kinds of allometry between the sexes in any one species. However, in Austrelaps ramsayi both measures of length indicate that mass is relatively greater in males than in females over the middle and large end of the size range. The population of regression lines for log mass on log length for large diurnal, surface-active elapids are bounded by Austrelaps ramsayi on the heavy side and by Pseudonaja textilis on the light side. These extreme morphological differences may be related to the species' extreme ecological differences. The former species is a frog eating, live-bearing inhabitant of a cool environment with a short growing season, whereas the latter is a lizard, bird and mammal eating, egg-laying inhabitant of a warm environment with a longer growing season.