Data from: The maintenance of obligate sex in finite, structured populations subject to recurrent beneficial and deleterious mutation

<b>Abstract</b><br/>Although there is no known general explanation as to why sexual populations resist asexual invasion, previous work has shown that sexuals can outcompete asexuals in structured populations. However, it is currently unknown whether costly sex can be maintained with the weak structure that is commonly observed in nature. We investigate the conditions under which obligate sexuals resist asexual invasion in structured populations subject to recurrent mutation. We determine the level of population structure needed to disfavour asexuals, as calculated using the average Fst between all pairs of demes. We show that the critical Fst needed to maintain sex decreases as the population size increases, and approaches modest levels as observed in many natural populations. Sex is maintained with lower Fst if there are both advantageous and deleterious mutation, if mutation rates are sufficiently high, and if deleterious mutants have intermediate selective strengths, which maximises the effect of Muller's Ratchet. Additionally, the critical Fst needed to maintain sex is lower when there are a large number of subpopulations. Lower Fst values are needed to maintain sex when demes vary substantially in their pairwise distances (e.g., when arrayed along one dimension), although this effect is often modest, especially if some long-distance dispersal is present.

<b>摘要</b><br/>虽然目前尚无公认的普适性机制可以解释有性繁殖种群为何能够抵御无性类群的入侵，但已有研究表明，在结构化种群中，有性繁殖类群可在种间竞争中胜过无性繁殖类群。然而，当前尚不清楚在自然界普遍存在的弱结构化种群中，具备繁殖代价的有性繁殖能否得以维持。本研究探讨了在存在反复突变的结构化种群中，专性有性繁殖类群能够抵御无性类群入侵的条件。我们通过计算所有亚种群（deme）两两之间的平均遗传分化系数（Fst），确定了不利于无性类群所需的种群结构化程度阈值。研究发现，维持有性繁殖所需的临界Fst值会随种群规模增大而降低，并趋近于许多自然种群中观测到的适中水平。当种群同时存在有利突变和有害突变、突变率足够高，且有害突变具有中等选择强度时（此时可最大化穆勒氏棘轮（Muller's Ratchet）的作用效果），维持有性繁殖所需的Fst值会更低。此外，当亚种群数量较多时，维持有性繁殖所需的临界Fst值也会更低。当亚种群间的两两距离存在显著差异（例如沿一维排列时），则需要更低的Fst值才能维持有性繁殖，但该效应通常较为微弱，若存在一定程度的长距离扩散则尤其如此。