Is sex advantageous in adverse environments? A test of the abandon-ship hypothesis

Understanding the evolution and maintenance of sexual reproduction remains a long-standing challenge in evolutionary biology. Stress often induces sexual reproduction in facultatively sexual species (those species capable of both sexual and asexual reproduction). The abandon-ship hypothesis predicts higher allocation to sex under stress to allow low-fitness individuals to recombine their genotype, potentially increasing offspring fitness. However, effective tests of the abandon-ship hypothesis, particularly in multicellular organisms, are lacking. Here we test the abandon-ship hypothesis, using cyanogenic and acyanogenic defense phenotypes of the short-lived perennial herb Trifolium repens. Cyanogenesis provides an effective defense against herbivores and is under relatively simple genetic control (plants dominant for cyanogenesis at two alleles express the defended phenotype). Thus, maladapted individuals can acquire adaptive defense alleles for their offspring in a single episode of s...

解析有性生殖的演化与维持机制，始终是进化生物学领域长期存在的核心挑战。胁迫往往会诱导兼性有性生殖物种——即可同时进行有性与无性生殖的物种——产生有性生殖。弃船假说（abandon-ship hypothesis）预测，在胁迫环境下，生物会将更多资源分配给有性生殖，以使低适合度个体能够重组自身基因型，从而潜在提升后代适合度。然而，目前针对该假说的有效检验仍较为匮乏，针对多细胞生物的相关检验尤为不足。本研究以短命多年生草本白车轴草（Trifolium repens）的产氰与非产氰防御表型为研究对象，对弃船假说进行检验。产氰作用可有效抵御草食动物的取食，且其遗传调控机制相对简单：在两个与产氰相关的等位基因上呈显性的植株，会表现出防御表型。因此，适应不良的个体可通过单次有性生殖事件，为后代获取适应性防御等位基因……