MULTIPLE PATERNITY AND 1ST MATE SPERM PRECEDENCE IN THE SIERRA DOME SPIDER, LINYPHIA-LITIGIOSA KEYSERLING (LINYPHIIDAE)

Field observations of individually marked female sierra dome spiders, followed by electrophoretic paternity analyses, indicated that 60-70% of all eggs were fertilized by first mates. In this spider, first mates are determined via combat between males incited by females. They are larger than later mates, because the latter seldom fight other males prior to mating. However, a field experiment in which females mated first with a small male and the 1-2 days later with a large male (where neither male fought prior to mating), showed that first mate sperm precedence persits regardless of the physical qualities of first mates. Thus phenotypic attributes per se of first mates do not promote first mate advantage and females rely 'blindly' on the intrasexual process to determine their major sire. Consideration of five mating circumstances and associated patterns of paternity suggests that females control differential sperm use. For example, among secondary mates the duration of preinsemination phase copulation, when males might try to displace sperm, was negatively correlated with fertilization success. The copulatory behaviour of different secondary mates of individual females refuted the hypothesis that first mate sperm precedence is maintained by mating plugs. Male size was not correlated with quantity of sperm transferred or length of the intromittant organ, eliminating additional modes of sperm competition as explanations for first mate advantage. © 1991 The Association for the Study of Animal Behaviour.