Facultative sex and reproductive strategies in response to male availability in the spiny stick insect, Extatosoma tiaratum

Abstract

Facultative thelytoky, in which females can reproduce both sexually and asexually, offers a promising model system to understand the evolutionary significance of sex, by providing insights into whether the different reproductive modes reflect an adaptive life-history response to varying environmental conditions. Females of the spiny stick insect, Extatosoma tiaratum, can reproduce both sexually or asexually. We show that virgin females signal their reproductive state: males respond to signals produced by virgin females that have not commenced ovipositing, but fail to respond to ovipositing virgin females. Virgin females reared under different social environments varied their reproductive output: virgin females reared in the absence of males laid more eggs over a seven-day period than virgin females reared in the presence of males. The reproductive output of mated females over a seven-day period was higher than that of virgin females. These data suggest that female E. tiaratum adjust several life-history strategies in conjunction with facultative thelytoky.