PROTANDRY AND MOLTING TO MATURITY IN THE SPIDER PITHYOHYPHANTES-OPHRYGIANUS

In SW Sweden, these overwintering subadult sheetweb spiders moult to maturity in late spring, males on average maturing before females. Spiders did not moult when starving or at a low temperature. There was no threshold due to photoperiod since the spiders completed moulting in darkness. However, accelerated photoperiod caused faster moulting. In males, high food level caused a significant decrease in time to moulting, but not so in females. In natural photoperiod and high food level, the initial mass was negatively correlated with time to moulting in males. Protandry occurred under all environmental conditions investigated. Since males were larger than females, protandry is selected for and not an incidental effect of males having a shorter development time associated with smaller body size. Phenotypic plasticity in growth rate in response to available food seems to be considerable in both sexes. -from Authors