Post-copulatory Sexual Selection in Two Tropical Orb-weaving Leucauge Spiders

Abstract

This chapter focuses on descriptive and experimental studies of the sexual biology of two spider species, Leucauge mariana and Leucauge argyra. We examine general questions related to female effects on paternity by taking advantage of several unusual traits: direct female participation in forming copulatory plugs and physical clasping by the female rather than the male during copulation in both species; and derived traits in the genitalia of males and females and occasional female cannibalism of conspecific males by trapping the male's genitalia in adhesive copulatory plugs in L. argyra. These derived traits, combined with other aspects of sexual interactions that are typical of spiders in general, such as complete, easy female avoidance of unwanted sexual advances of males, copulatory courtship by males, and imperfect male ability to remove copulatory plugs from the female's genitalia, constitute a rich mixture from which clear lessons can be drawn. Post-copulatory sexual selection probably acts on male genitalia and their behavior in both species. Two derived male genitalic clasping and clamping devices L. argyra may be associated with the extremely aggressive female behavior. One genital structure in male L. mariana may have evolved under sexual selection by sperm competition to remove copulatory plugs from female genitalia. In contrast to expectations from theory based on male-female conflict, the female genitalia of L. argyra has a derived trait that selectively facilitates rather than impedes male genital clamping. In contrast to

Mating plugs and sexual cannibalism in the Colombian orb‐web spiderLeucauge mariana

“…However, male deposition of chemicals that form mating plugs is not the only trait that influences sperm competition. Females can also determine the efficacy of plug formation through the production or deposition of additional secretions (Aisenberg, Barrantes, & Eberhard, ; Uhl et al., ). In some spiders, the deposition of substances by females prior to mating plug formation alters the efficacy of plugs, but the propensity to do so depends on the quality of the males’ performance during courtship or mating (Aisenberg & Barrantes, ; Aisenberg & Eberhard, ; Kuntner, Gregorič, Zhang, Kralj‐Fišer, & Li, ; Uhl et al., ).…”

Demonstrating sexual selection by cryptic female choice on male genitalia: What is enough?

“…(Aisenberg et al. ) and Physocyclus globosus (Peretti et al. ), male genital behavior is correlated with sperm usage patterns, suggesting species‐specific stimulation of the female, but support is less convincing because several of the additional tests in Table are lacking.…”

Female wolf spiders exert cryptic control drastically reducing ejaculate size

“…Although very little is known, similar cryptic female mechanisms have been described in spider species. In the genus, Physocyclus females would eject males' sperm depending on their copulatory courtship performance (Peretti & Eberhard, ), or among the spider genera Lactrodectus , Leucage and Argiope it seems possible that females can bias fertilisation of their eggs by controlling the mating plug formation (Aisenberg, Barrantes, & Eberhard, ; Andrade & MacLeod, ; Schneider, Uhl, & Herberstein, ). Beyond the mechanisms, it has been also suggested that female spiders can selectively store sperm of courting males (Schneider & Lesmono, ), cannibalised males (Herberstein et al., ) and gift‐giving males (Albo, Bilde, & Uhl, ).…”