Maternal size determines clutch mass, whereas breeding timing influences clutch and egg sizes in the tropical lizard, Calotes versicolor (Agamidae)

Abstract

We studied the correlations between body size parameters (SVL and body condition) and clutch parameters (size and mass) as well as between clutch size and egg parameters (mass, volume, length, and width) in a population of Calotes versicolor, a multiclutched lizard that breeds from May to October in southern India. We also analyzed the relationships between early, mid, and late clutches among lizards of different SVL groups. Clutch size and SVL did not vary among years. Clutch size and clutch mass were positively correlated with body size. Egg mass and volume were negatively correlated with clutch size. Clutch size was larger in early and midbreeders than in late breeders. Interestingly, the eggs of late clutches were larger than those of early breeders. A trade-off between clutch size and egg volume was always obvious. The width of eggs did not vary with SVL or clutch timing, perhaps because the width of the pelvic aperture remained virtually constant after maturity. Thus, variation in egg volume in C. versicolor is because of variation in egg length. A wide range of variation in egg volume even among lizards with similar SVL suggests that there is no optimization of egg volume in this species. In contrast, the clutch mass of early, mid, and late clutches did not vary among lizards of comparable SVL. Apparently, SVL acts as a prime factor determining clutch mass in C. versicolor, and the latter is optimized by natural selection.