Acceptance threshold theory can explain occurrence of homosexual behaviour

Same-sex sexual behaviour (SSB) has been documented in a wide range of animals, but its evolutionary causes are not well understood. Here, we investigated SSB in the light of Reeve's acceptance threshold theory. When recognition is not error-proof, the acceptance threshold used by males to recognize potential mating partners should be flexibly adjusted to maximize the fitness pay-off between the costs of erroneously accepting males and the benefits of accepting females. By manipulating male burying beetles' search time for females and their reproductive potential, we influenced their perceived costs of making an acceptance or rejection error. As predicted, when the costs of rejecting females increased, males exhibited more permissive discrimination decisions and showed high levels of SSB; when the costs of accepting males increased, males were more restrictive and showed low levels of SSB. Our results support the idea that in animal species, in which the recognition cues of females and ...

同性性行为（same-sex sexual behaviour, SSB）已在众多动物类群中被报道，但其演化成因仍未得到充分阐明。本研究基于里夫接受阈值理论（Reeve's acceptance threshold theory），针对同性性行为展开探究。当识别过程无法实现完全无差错时，雄性用以识别潜在交配对象的接受阈值需被灵活调控，以在错误接受雄性个体的成本与接纳雌性个体的收益之间，最大化自身的适合度收益。通过实验操控雄性埋葬甲（burying beetles）搜寻雌性的时长与繁殖潜力，我们改变了其对接受或拒绝失误所感知到的成本。正如研究所预期，当拒绝雌性的成本上升时，雄性会采取更为宽松的识别决策，展现出更高水平的同性性行为；而当接受雄性的成本升高时，雄性则更为保守，仅表现出较低水平的同性性行为。本研究结果支持这一假说：在雌性与雄性的识别线索存在……的动物类群中，