The interaction of season length and development time alters size at maturity

An end-of-season penalty, with late-maturing individuals being smaller than early-maturing individuals, has been observed in a variety of univoltine t errestrial arthropods. The current study extends these observations, utiliz ing multiple populations of a single sexually dimorphic species to examine the ecological correlates and fitness consequences of late maturation at a small size. The orb-weaving spider, Nephila clavipes, inhabits a broad rang e of habitats that vary from mild to strong seasonality. Because males matu re several instars earlier than females, they can reach maturity much earli er in the growing season. Within a cohort, I found that female size at matu rity was negatively correlated with timing of maturation in strongly season al sites. At a less seasonal site, there was no correlation between female size and timing of maturation within a cohort. In most populations studied, male size was not correlated with the timing of maturation within a cohort . Within populations in strongly seasonal sites, late-maturing females had reduced fecundity. The probability of copulation, survivorship from maturit y to first clutch, clutch size relative to female size, and the number of p ossible clutches were all reduced with delayed maturation. The probability of prereproductive death for late-maturing females was strongly affected by stochasticity in the timing of the end of the growing season.