Data from: Assessing the contributions of reduced immigrant viability and fecundity to reproductive isolation

Reduced fitness of immigrants from alternative environments is thought to be an important reproductive isolating barrier. Most studies evaluating the importance of the relative fitness of immigrants to speciation have focused on reduced survival of immigrants (i.e., immigrant inviability). However, variation in fecundity appears to have a greater impact on variation in fitness than does variation in viability, suggesting that reduced fecundity of immigrants could act as an important yet largely overlooked reproductive isolating barrier. Using a model and a survey of studies of local adaptation, we evaluate the relative strength of reduced immigrant viability and fecundity as potential causes of reproductive isolation. We found that reduced fecundity as compared to reduced viability as a reproductive isolating barrier should increase in importance as the relative costs of reproduction increase. Consistent with the elevated demands of reproduction reported in the literature, we found that reproductive isolation from reduced immigrant fecundity was of similar magnitude or greater than that from reduced immigrant viability, particularly in the early stages of speciation. These results suggest that the important role of differential fecundity in local adaptation extends to speciation.

来自异质环境的迁入者适合度降低，被认为是一类重要的生殖隔离障碍（reproductive isolating barrier）。绝大多数评估迁入者相对适合度对物种形成（speciation）重要性的研究，均聚焦于迁入者存活劣势（immigrant inviability）。然而，繁殖力（fecundity）的变异对适合度变异的影响程度显著高于存活能力变异，这提示迁入者繁殖力降低或许是一类重要却长期被忽视的生殖隔离障碍。本研究通过构建理论模型并梳理局部适应（local adaptation）相关研究文献，评估了迁入者存活劣势与繁殖力降低作为生殖隔离潜在诱因的相对强度。研究发现，随着繁殖相对成本（relative costs of reproduction）升高，相较于迁入者存活劣势，繁殖力降低作为生殖隔离障碍的重要性将显著提升。与文献中报道的繁殖需求升高现象一致，本研究结果显示，由迁入者繁殖力降低所引发的生殖隔离，其强度与迁入者存活劣势引发的生殖隔离相当甚至更高，尤其在物种形成的早期阶段更为突出。上述结果表明，繁殖力差异在局部适应中的关键作用，同样可延伸至物种形成过程中。