The evolution of sex is tempered by costly hybridization in Boechera (rock cress)

Despite decades of research, the evolution of sex remains an enigma in evolutionary biology. Typically, research addresses the costs of sex and asexuality to characterize the circumstances favoring one reproductive mode. Surprisingly few studies address the influence of common traits that are, in many organisms, obligately correlated with asexuality, including hybridization and polyploidy. These traits have substantial impacts on traits under selection. In particular, the fitness consequences of hybridization (that is, reduced fitness due to interspecific reproductive isolation) will influence the evolution of sex. This may comprise a cost of either sex or asexuality, due to the link between hybridity and asexuality. We examined reproductive isolation in the formation of de novo hybrid lineages between two widespread species in the ecological model system Boechera. 17% of 664 crosses produced F1 fruits, and only 10% of these were viable, suggesting that postmating prezygotic and postzyg...

尽管进化生物学领域已有数十年的研究积累，但有性生殖的演化始终是一个未解之谜。通常而言，相关研究多围绕有性与无性生殖的代价展开，旨在明确偏向其中一种生殖模式的具体环境条件。令人意外的是，极少有研究探讨在多数生物中与无性生殖必然相关的常见性状的影响，这类性状包括杂交（hybridization）与多倍性（polyploidy）。这些性状对受选择的性状具有显著影响。具体而言，杂交的适合度后果（即由种间生殖隔离导致的适合度降低）会影响有性生殖的演化。由于杂交性与无性生殖之间存在关联，这类适合度后果可能构成有性或无性生殖的代价之一。本研究以生态模式系统弯蕊芥属（Boechera）的两个广布物种为研究对象，探究了全新杂交谱系形成过程中的生殖隔离情况。在664个杂交组合中，17%成功产生了F1代果实，其中仅10%具有活力，这表明交配后合子前（postmating prezygotic）与合子后（postzygotic）……