Reproductive Behaviors Of Two Congeneric, Sympatric Jumping Spiders: Gene Flow Barriers And Polyandry

Abstract

This two part study compares aspects of jumping spider reproductive behavior and their implications 1) as gene flow barriers during the process of speciation and 2) in the occurrence of polyandry. Courtship behaviors of Phidippus audax and P. carolinensis were observed. P. carolinensis displays simple courtship behavior when compared to the visually complex behavior of P. audax. P. carolinensis males appear to be incorporating a vibratory element into their courtship display, and a possible stridulatory organ, located on the male pedipalp, is described. Large differences in courtship display, complexity of courtship badges, and phenologies between the species most likely prevent gene flow between them and may play a role in speciation within the genus. Three prominent hypotheses on the forces driving the occurrence of polyandry (renewal of sperm supply, prolonged female choice, and fitness benefits) were tested in P. audax. Monogamously mated females were compared to polyandrously mated females in degree of multiple mating, clutch viability, and offspring size. Female spiders become choosier as their number of male encounters increase, and polyandrous females were more likely to mate multiply. There was a trend towards higher hatching success in polyandrous clutches, whereas degree of polyandry did not affect offspring size. Prolonged female choice is likely to be a strong driving force for polyandry in this species, and its possible mechanisms are discussed.