The maintenance of males and outcrossing is widespread, despite considerable costs of males. By enabling recombination between distinct genotypes, outcrossing may be advantageous during adaptation to novel environments and if so, it should be selected for under environmental challenge. However, a given environmental change may influence fitness of male, female, and hermaphrodite or asexual individuals differently, and hence the relationship between reproductive system and dynamics of adaptation to novel conditions may not be driven solely by the level of outcrossing and recombination. This has important implications for studies investigating the evolution of reproductive modes in the context of environmental changes, and for the extent to which their findings can be generalized. Here, we use Caenorhabditis elegans—a free-living nematode species in which hermaphrodites (capable of selfing but not cross-fertilizing each other) coexist with males (capable of fertilizing hermaphrodites)—to investigate the response of wild type as well as obligatorily outcrossing and obligatorily selfing lines to stressfully increased ambient temperature. We found that thermal stress affects fitness of outcrossers much more drastically than that of selfers. This shows that apart from the potential for recombination, the selective pressures imposed by the same environmental change can differ between populations expressing different reproductive systems and affect their adaptive potential.

中文翻译：

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热应激对秀丽隐杆线虫异型交配和自交群体的适应度影响不同。


尽管雄性的成本相当大，但雄性的维持和异型杂交仍然很普遍。通过实现不同基因型之间的重组，异型杂交在适应新环境过程中可能是有利的，如果是这样，则应在环境挑战下进行选择。然而，特定的环境变化可能会以不同的方式影响雄性、雌性、雌雄同体或无性个体的适应性，因此生殖系统和适应新条件的动态之间的关系可能不仅仅由异型杂交和重组的水平驱动。这对于调查环境变化背景下生殖模式进化的研究以及其研究结果的推广程度具有重要意义。在这里，我们使用秀丽隐杆线虫（一种自由生活的线虫物种，其中雌雄同体（能够自交但不能相互交叉受精）与雄性（能够雌雄同体受精）共存 - 来研究野生型以及强制异交的反应并强制自交系以应对环境温度的升高。我们发现热应激对异型杂交者的健康影响比自交者大得多。这表明，除了重组的潜力之外，相同的环境变化所施加的选择压力可能在表达不同生殖系统的种群之间有所不同，并影响它们的适应潜力。