Males of a sexually cannibalistic spider chemically assess relative female quality
Males of a sexually cannibalistic spider chemically assess relative female quality
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DOI：
10.1186/s12862-020-01657-w
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发表时间：
2020-07-23
影响因子：
3.4
通讯作者：
Schneider, Jutta M.
中科院分区：
文献类型：
--
作者：
Cory, Anna-Lena;Schneider, Jutta M.
背景 择偶是一种分类学上广泛存在的现象，尽管雄性也有择偶行为，但主要由雌性进行。虽然选择的成本和收益已得到充分研究，但其潜在机制在很大程度上尚不清楚。存在不同的模型，即基于顺序或同时采样的最佳 n 或阈值规则，其所需的认知需求不同。我们采用实验方法来揭示性食人蜘蛛 Argiope bruennichi 中雄性择偶的潜在机制。雄性仅限于两次交配并优先垄断体型较大的雌性，而它们可能会在一次交配后离开较小的雌性并重新开始寻找配偶。在这里，我们利用了北方和南方种群雌性之间显着的体型差异，并向雄性提供了三只不同体型的雌性，这些雌性与起源相匹配：所有三只雌性要么来自与雄性相同的北欧种群，要么来自南方种群，其中最小的雌性与最大的北方雌性体型大致相同。这使得可以检验雄性将其交配策略基于固定的局部尺寸阈值的假设。我们预测北方男性会在北方女性中挑剔，但会接受所有南方女性，因为她们都高于这个阈值。结果雄性与它们遇到的第一只雌性交配，这与她的体型无关。无论雌性的起源如何，雄性都会选择一夫一妻制的策略，与三只中最大的雌性一起，而在一次交配后，它们会留下最小的雌性。同样的模式也适用于南方雌性，尽管三人组中最小的雌性与垄断的北方雌性大小相似。由于雄性视力较差，并且不会主动对所有雌性进行采样，因此它们可能仅根据挥发性化学线索获得了有关雌性之间相对体型差异的信息。结论我们的研究结果表明maleA.布鲁尼奇可以评估交配质量的相对差异，并根据当时的条件（北方与南方）调整其交配策略。我们拒绝存在适合当地的固定阈值，并认为我们的结果最好通过在南方条件下提高的可调整阈值来解释。
Background Mate choice is a taxonomically wide-spread phenomenon, mostly exerted by females although male mate choice occurs as well. While costs and benefits of choosiness have been well studied, the underlying mechanisms are largely unclear. Different models exist, namely best-of-n or threshold rules, based on sequential or simultaneous sampling, which differ in the required cognitive demands. We applied an experimental approach to shed light on the underlying mechanisms of male mate choice in the sexually cannibalistic spiderArgiope bruennichi.Males are limited to two copulations and preferentially monopolise large females, while they may leave smaller females after a single copulation and resume mate search. Here, we utilised significant size-differences between females from Northern and Southern populations and presented males with three different-sized females that were matched for origin: all three females originated either from the same Northern European population as the males or from Southern populations where the smallest female was about the same size as the largest Northern female. This allowed testing the hypothesis that males base their mating tactic on a fixed local size threshold. We predicted Northern males to be choosy among Northern females, but to accept all Southern females since they would all be above that threshold. Results Males copulated with the first female they encountered, which was independent of her body size. Regardless of the females' origins, males chose a monogynous tactic with the largest female in the trio, while they left the smallest female after one copulation. The same pattern applied to Southern females even though the smallest females in the trio were of a similar size as monopolised Northern females. Since males have poor eyesight and did not actively sample all females, they likely have gained information about relative size differences between females based on volatile chemical cues only. Conclusions Our findings suggest that maleA. bruennichican assess relative differences in mate quality and adjust their mating tactic to the prevailing conditions (Northern vs. Southern). We reject the presence of a locally-adapted fixed threshold and argue that our results are best explained by an adjustable threshold that was raised under Southern conditions.