Condition-dependent sexual reproduction is driven by benefits, not costs of sex

Facultative sexual organisms must allocate resources to both asexual and sexual reproduction. Optimal patterns of investment in sex depend on the relative costs and benefits of each reproductive mode, and may consequently be context- and condition-dependent. Two proposed explanations for the observed variation in investment in sex among facultative sexual lineages invoke alternative condition-dependent scenarios. Under the ‘fitness-associated sex’ hypothesis, sex is predicted when individuals are in poor condition or experience stressful environments. Under the ‘resource-demanding sex’ hypothesis, sex is only affordable to individuals in good condition experiencing favourable environments. Direct tests of these contrasting hypotheses are rare; moreover, investment in different components of sexual reproduction responds differently to cues promoting sex, and may be subject to different energetic constraints. Using genotypes of facultative sexual Daphnia carinata that differ in their leve...

兼性有性生殖生物需同时将资源分配至无性生殖与有性生殖过程。有性生殖的最优投入模式，取决于两种生殖模式各自的相对成本与收益，因此可能随环境背景与个体状态而异。针对兼性有性生殖类群间有性生殖投入的观测差异，学界已提出两种基于不同个体状态的解释假说。在「适合度关联有性生殖（fitness-associated sex）」假说框架下，当个体状态不佳或处于胁迫环境时，理论上会倾向于进行有性生殖。而在「资源依赖型有性生殖（resource-demanding sex）」假说中，仅当个体状态良好且处于适宜环境时，才能够承担有性生殖的成本。目前针对这两种截然对立的假说的直接检验极为匮乏；此外，有性生殖不同组分的投入，对促有性生殖信号的响应模式存在差异，且可能受不同的能量约束机制调控。本研究使用在[原文未完整表述内容]方面存在差异的兼性有性生殖隆线溞（Daphnia carinata）基因型