Copulatory behavior in a haplogine spider: males use differential genitalic movements for sperm removal and copulatory courtship

Abstract

Sexual selection may operate on pre-copulatory,copulatory, and post-copulatory traits. An example of a copulatorytarget of sexual selection is the genitalic movements amale performs during copulation. These movements mayfunction either to prevent sperm competition or to influencea female’s fertilization decision. Here we investigated howcopulation duration, pedipalp movements, and abdominalmovements that males of the pholcid spider Holocnemuspluchei produce during copulation influence sperm removaland/or patterns of successful sperm transfer. We comparedmating events with virgin and mated females for differencesin copulatory and post-copulatory behavior. We expectedlonger copulation duration, longer pedipalp movement duration,and more complex and frequent pedipalp and abdominalmovements when males mated with mated females comparedto virgin females. Except for abdominal movements, our resultscorroborated these predictions. Furthermore, when weinvestigated mating events with mated females, we observedsperm mass ejection from the female gonopore and physicalremoval of sperm by males’ procursi. Females withinterrupted second mating events showed a significant reductionof stored sperm masses compared to females with completedmating events. We suggest that males use alternatingpedipalp movements to remove most of the rival sperm storedby mated females prior to sperm transfer. Copulation durationand pedipalp movements can be further used to transfer spermand/or as a form of genitalic copulatory courtship.