Copulatory cannibalism of male 'widow' spiders (genus Latrodectus) is a model example of the extreme effects of sexual selection, particularly in L. hasselti and L. geometricus where males typically facilitate cannibalism by females and mate only once. We show that these males can increase their reproductive success by copulating with final-instar, immature females after piercing the female's exoskeleton to access her newly developed sperm storage organs. Females retain sperm through their final moult and have similar fecundity to adultmated females. This is an adaptive male tactic because immature mating increases insemination success relative to adult mating (which predicts higher paternity) and moreover, rarely ends in cannibalism, so males can mate again. Although successful only during a brief period before the female's final moult, males may employ this tactic when they associate with final-instar females in nature. Consistent with this, one-third of L. hasselti females collected as immatures in nature were already mated. Immature mating alters sexual selection on these otherwise monogynous males, and may explain male traits allowing facultative polygyny in Latrodectus. Since male cohabitation with immature females is common among invertebrates, immature mating may be a widespread, previously unrecognized mating tactic, particularly when unmated females are of high reproductive value.
|State||Published - 1 Sep 2016|
Bibliographical noteFunding Information:
Israel Association for Canadian Studies to I.S., and NSERC Canada (discovery grants 229029-04 and 229029-12), Canada Research Chairs (950-228362), Canadian Foundation for Innovation and Research & Innovation Ontario (203764) to M.C.B.A.
© 2016 The Author(s) Published by the Royal Society. All rights reserved.
- Alternative male mating tactic
- Mating immature females
- Sexual selection
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Agricultural and Biological Sciences (all)