Cryptic female choice predicated on wing dimorphism in decorated crickets

Abstract

Male decorated crickets, Gryllodes sigillatus, normally lack hind wings and are incapable of flight (short-winged males), but occasionally exhibit fully developed hind wings that make rudimentary flight possible (long-winged males). Long-winged males bear a cost of flight in the form of decreased insemination success, which arises as a consequence of two interrelated factors: (1) long-winged males exhibit a lower reproductive investment relative to short-winged males, as measured by the mass of a male's spermatophore and reproductive organs and (2) the postcopulatory behavior of females favors males that maximize their reproductive investment. Of particular importance to male mating success is the spermatophylax, a large gelatinous mass forming part of the spermatophore and consumed by the female after mating. Consumption of the spermatophylax keeps the female preoccupied while sperm are discharged from the remaining portion of the spermatophore (sperm ampulla) into her reproductive tract. The spermatophylax of long-winged males is significantly smaller than that of short-winged males and consequently requires less time to consume. As a result, the sperm ampulla of long-winged males is frequently removed before its complete evacuation and significantly sooner than that of short-winged males. Because the spermatophore-removal behavior of females mediates the relative insemination success of short-winged and long-winged males, it can be considered a form of cryptic female choice.