Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Nat Ecol Evol. 2021 Jan;5(1):135-141. doi: 10.1038/s41559-020-01331-w. Epub 2020 Nov 9.
The widespread presence of same-sex sexual behaviour (SSB) has long been thought to pose an evolutionary conundrum, as participants in SSB suffer the cost of failing to reproduce after expending the time and energy to find a mate. The potential for SSB to occur as part of an optimal strategy has received less attention, although indiscriminate sexual behaviour may be the ancestral mode of sexual reproduction. Here, we build a simple model of sexual reproduction and create a theoretical framework for the evolution of indiscriminate sexual behaviour. We provide strong support for the hypothesis that SSB can be maintained by selection for indiscriminate sexual behaviour, by showing that indiscriminate mating is the optimal strategy under a wide range of conditions. Further, our model suggests that the conditions that most strongly favour indiscriminate mating were probably present at the origin of sexual behaviour. These findings have implications not only for the evolutionary origins of SSB, but also for the evolution of discriminate sexual behaviour across the animal kingdom.
同性性行为（SSB）的广泛存在长期以来一直被认为是一个进化难题，因为参与 SSB 的个体在花费时间和精力寻找伴侣后，无法繁殖，从而付出了代价。SSB 作为一种最佳策略的一部分发生的可能性受到的关注较少，尽管滥交可能是性繁殖的原始模式。在这里，我们建立了一个简单的性繁殖模型，并为滥交行为的进化创造了一个理论框架。我们通过表明滥交是在广泛的条件下的最佳策略，为 SSB 可以通过选择滥交来维持的假设提供了强有力的支持。此外，我们的模型表明，最有利于滥交的条件可能在性行为起源时就存在。这些发现不仅对 SSB 的进化起源有影响，而且对整个动物王国中区分性行为的进化也有影响。
