ALLOMETRY OF REPRODUCTION IN 2 SPECIES OF GEKKONID LIZARDS (GEHYRA) -EFFECTS OF BODY-SIZE MINIATURIZATION ON CLUTCH AND EGG SIZES

In squamate reptiles there is an allometric pattern for small-bodied f emales to have smaller clutches and proportionally larger eggs than la rge-bodied females, and this pattern occurs both among and within spec ies. The allometric patterns in two species of the gecko Gehyra were s tudied to see how evolutionary reductions in adult body size affect fe cundity and offspring size among species, and how these changes affect allometric relationships within species. Gehyra dubia has two eggs pe r clutch (the typical clutch size for gekkonid lizards), whereas the s maller-bodied G. variegata has a single egg per clutch. Within both sp ecies, egg size increased with female body size. The data are consiste nt with at least two mechanistic hypotheses: (1) that the width of the pelvis constrains egg size; and (2) in species with invariant clutch sizes, larger females can only allocate additional energy towards egg size and not number. More direct tests of these hypotheses are warrant ed. Miniaturization of body sizes in Gehyra is correlated with a clutc h size reduction of 50% (from two to one), and a large (1.7-fold) comp ensatory increase in relative egg mass. However, the small-bodied G. v ariegata (one egg per clutch) had a lower relative clutch mass than di d G. dubia. These findings have implications for understanding the inf luence of evolutionary reductions in body size on reproductive traits, and for allometric trends in squamate reptiles in general.