The outcome of natural selection depends on the demographic processes of birth, death, and development. Here, we derive conditions for protected polymorphism in a population characterized by age- or stage-dependent demography with two sexes. We do so using a novel two-sex matrix population model including basic Mendelian genetics (one locus, two alleles, random mating). Selection may operate on survival, growth, or fertility, any or all of which may differ between the sexes. The model can therefore incorporate genes with arbitrary pleiotropic and sex-specific effects. Conditions for protected polymorphism are expressed in terms of the eigenvalues of the linearization of the model at the homozygote boundary equilibria. We show that in the absence of sexual dimorphism, polymorphism requires heterozygote superiority in the genotypic population growth rate. In the presence of sexual dimorphism, however, heterozygote superiority is not required; an inferior heterozygote may invade, reducing the population growth rate and even leading to extinction (so-called evolutionary suicide). Our model makes no assumptions about separation of time scales between ecological and evolutionary processes, and can thus be used to project sex×stage×genotype dynamics of eco-evolutionary processes. Empirical evidence that sexual dimorphism affects extinction risk is growing, yet sex differences are often ignored in evolutionary demography and in eco-evolutionary models. Our analysis highlights the importance of sexual dimorphism and suggests mechanisms by which an allele can be favored by selection, yet drive a population to extinction, as a result of the structure and interdependence of sex- and stage-specific processes.

中文翻译：

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在两性阶段结构的人群中进行的选择：遗传学，人口统计学和多态性。

自然选择的结果取决于出生，死亡和发育的人口统计过程。在这里，我们推导出以具有性别特征的年龄或阶段依赖性人口统计学为特征的人群中受保护的多态性的条件。我们使用包括基本孟德尔遗传学（一个基因座，两个等位基因，随机交配）在内的新型两性矩阵种群模型进行此操作。选择可能取决于生存，生长或生育，其中任何或全部可能在性别之间有所不同。因此，该模型可以整合具有任意多效性和性别特异性效应的基因。受保护的多态性的条件以纯合子边界平衡时模型线性化的特征值表示。我们表明，在没有性二元性的情况下，多态性要求杂合子在基因型群体增长率上具有优势。但是，在存在性二态性的情况下，不需要杂合子优势。劣质的杂合子可能会入侵，从而降低种群的增长速度，甚至导致灭绝（所谓的进化自杀）。我们的模型没有假设生态过程和进化过程之间的时间尺度分离，因此可以用来预测生态进化过程的性别×阶段×基因型动态。性二态性影响灭绝风险的经验证据正在增长，但是性别差异在进化人口学和生态进化模型中常常被忽略。我们的分析突出了性二态性的重要性，并提出了通过选择有利于等位基因的机制，