Parental Investment: Comparative Reproductive Energetics in Bisexual and Unisexual Lizards, Genus Cnemidophorus

Abstract

The reproductive energetics of 2 bisexual lizards (C. inornatus and C. tigris) and 2 unisexual lizards (C. uniparens and C. sonorae) was investigated with specific comparisons made between species, size groups and reproductive types. Clutch size was larger in unisexual species and in larger species within a reproductive type. Calories per milligram of eggs of these 4 spp. (.hivin.X = 6.58 cal/mg) were not correlated with either body size or reproductive type; differences in clutch volume between the species superceded differences in egg cal per milligram. Mean calories per egg were higher in large-bodied lizards and in bisexual lizards independent of size. The ratio of total clutch calories to total body calories (clutch/body) was significantly higher in unisexual species. Environmental constraints and genetic diversity among individuals are discussed as important factors in determining energy allocated to reproduction and among offspring in cnemidophorines.