Intraclutch Egg Size Variability in Hyla crucifer (Anura: Hylidae)

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Abstract
Egg size variability was documented in H. crucifer, a treefrog that breeds in temporary ponds. Range of egg diameter in 20 clutches from a single population was 1.08-1.48 mm. Coefficients of variation in egg size within clutches ranged from 2.06-5.41. Intraclutch variability in egg size (as measured by CV) was not significantly correlated with female body length, clutch size or mean egg size. Skewness and kurtosis statistics revealed that egg diameters of half of the clutches examined were distributed around the mean value in a non-normal fashion. Large and small eggs were raised in individual containers to examine effects of absolute egg size. Even though larger eggs resulted in significantly larger hatchlings, these individuals gained no benefit at metamorphosis: they did not experience increased survival, did not maintain their size advantage and did not metamorphose more quickly. Under ideal conditions (i.e., no predation or competition and persistence of the aquatic site) all egg sizes may be successful. But since natural conditions are rarely ideal (i.e., tadpoles do interact with predators and conspecifics and small ponds often dry up before larvae can metamorphose), larger hatchlings coming from larger eggs may sometimes have an advantage. Variable egg size may increase fitness of a female because by producing some small eggs she can increase her fecundity, an important consequence in the uncertain larval environment.