Theory suggests that occasional or conditional sex involving facultative switching between sexual and asexual reproduction is the optimal reproductive strategy. Therefore, the true ‘paradox of sex’ is the prevalence of obligate sex. This points to the existence of powerful, general impediments to the invasion of obligately sexual populations by facultative mutants, and recent studies raise the intriguing possibility that a key impediment could be sexual conflict. Using Bateman gradients we show that facultative asexuality can amplify sexual conflict over mating, generating strong selection for both female resistance and male coercion. We hypothesize that invasions are most likely to succeed when mutants have negative Bateman gradients, can avoid mating, and achieve high fecundity through asexual reproduction – a combination unlikely to occur in natural populations.

理论表明，涉及有性和无性生殖之间兼职转换的偶发性或有条件的性行为是最佳的生殖策略。因此，真正的“性悖论”是专性性行为的普遍性。这表明存在着强大的，普遍的障碍，阻碍兼性突变体入侵专性人群，最近的研究提出了一个重要的可能性，即主要障碍可能是性冲突。使用贝特曼（Bateman）梯度，我们显示了兼性无性恋可以在交配过程中扩大性冲突，为女性抵抗力和男性胁迫产生强烈的选择。我们假设，当突变体的Bateman梯度为负时，入侵最有可能成功，可以避免交配，