EFFECTS OF EGG SIZE AND DENSITY ON METAMORPHIC TRAITS IN TADPOLES OF THE NATTERJACK TOAD (BUFO-CALAMITA)

We examined whether intrapopulational variation in egg size was correlated with developmental rates and metamorphic traits of natterjack toads (Bufo calamita) grown at different experimental densities. Mean egg size of siblings was positively correlated with both mean size of hatchlings at the initiation of feeding and mean developmental rates to the feeding stage. However, size at and survival to metamorphosis were not related to ovum or hatchling size. At high densities tadpoles had slower growth rates, longer larval periods, and lower survival, and were smaller at metamorphosis. Length of larval period was inversely related to early tadpole growth rate for all densities. Mass at metamorphosis was positively correlated to tadpole growth rate, except at high densities. Size at metamorphosis was inversely related to length of larval period at low densities, but relationships were inconsistent at higher densities.