MATING SYSTEM AND MATING SUCCESS OF THE DESERT SOLDER AGELENOPSIS-APERTA

Field studies of the desert spider Agelenopsis aperta revealed a prima rily monogamous mating system. However polygyny, polyandry and polygyn andry were superimposed upon the primary system, with 9% of the marked males and 11% of the marked females in a field population mating more than once. In the laboratory males commonly mated multiply with ferti le offspring resulting, while females were less likely than males to m ate multiply. Monogamy under field conditions was enforced by two fact ors: (1) high travel costs to males, and (2) a significant decline in female receptivity after the first mating. Heavy males were more likel y to be accepted by females both in the field, and in female choice ex periments conducted in the laboratory. Finally, male weight determined the outcome of male-male agonistic interactions over females. One pos sible explanation for female choice in this system which lacks male pa rental investment is that females may be using male size as an indicat or of future success of their offspring.