In polygynous species, males typically mate with more than one female, and male investment in any one mating should decrease if securing that mating reduces future mating opportunities. In contrast, monogynous males mate only once, so they should invest maximally in that single mating. In two monogynous, sexually cannibalistic Latrodectus spider species (L. geometricus, L. hasselti), males can mate and fertilize immature females. This recently described tactic is time-consuming because males must wait days for females to be capable of mating. It is also risky since immature females approached too early may kill males outright. However, if males typically find only one female in their lifetime, increasing the opportunity to mate may be worth these costs. We investigated whether this tactic is also practiced by a polygynous congener, L. hesperus, in which males typically mate more than once and may avoid time-consuming, risky encounters. In laboratory trials, we showed that males copulate with immature females. Moreover, males mounted immatures more rapidly, copulated for longer, and fathered more offspring than males that mated adults females. We concluded that monogyny is not a necessary condition for immature mating to be favored as an alternative reproductive tactic and suggest that it may be common in other spider taxa.

中文翻译：

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不成熟的交配作为多性雄性西方寡妇蜘蛛的策略

在一夫多妻种中，雄性通常与多于一个雌性交配，如果确保这种交配减少了未来的交配机会，则在任何一种交配中的雄性投资都应减少。相反，雌雄同体的雄性只交配一次，因此他们应该在这种单亲交配上投入最大的钱。在两个单性，食人性的Latrodectus蜘蛛物种（L. geometricus，L. hasselti）中，雄性可以交配并给未成熟的雌性受精。这种最近描述的策略非常耗时，因为雄性必须等待几天才能让雌性交配。这也是有风险的，因为未成熟的女性过早到达可能会彻底杀死男性。但是，如果男性一生中通常只找到一名女性，那么增加交配的机会可能是值得的。我们调查了该策略是否也由多妇同种异种L. hesperus实施，其中雄性通常交配不止一次，并且可以避免耗时，危险的相遇。在实验室试验中，我们表明雄性与未成熟的雌性交配。而且，与交配成年雌性的雄性相比，雄性的不成熟更快，交配的时间更长，并且后代繁殖更多。我们得出的结论是，单性生殖不是将不成熟交配作为替代生殖策略的必要条件，并暗示在其他蜘蛛类群中可能很常见。