MODELS OF POLYGENIC SEX DETERMINATION AND SEX-RATIO CONTROL
MODELS OF POLYGENIC SEX DETERMINATION AND SEX-RATIO CONTROL
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DOI：
10.1111/j.1558-5646.1982.tb05005.x
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发表时间：
1982-01-01
期刊：
影响因子：
3.3
通讯作者：
BULL, JJ
中科院分区：
文献类型：
--
作者：
BULMER, MG;BULL, JJ
在随机交配群体中，性别比是多基因的，即由许多基因控制而影响很小，提出了性别比进化的数学模型。这些模型涉及性别决定机制、雌性异种配型、单倍-二倍体、环境和多基因性别决定的各种例子，并考虑性别比例均值和方差的演变。在平衡状态下，预测的平均性别比通常与单位点理论预测的相同（例如，在最简单的情况下为1/2）。当不处于平衡状态时，性别比P以与遗传力乘以(1/2-P)/P（1-P）成比例的每代比率向平衡方向发展，或者当必须考虑适应性时，可以考虑一个类似的因素。性别比变异的进化取决于同一性别内的适合度差异。如果一个性别内的适合度是恒定的，那么当性别比趋于平衡时，方差会增加，但当性别比处于平衡时，方差不会改变（突变和连锁不平衡的变化除外）。在平衡状态下，雄性和雌性之间存在负相关（- 0.64），这在一定程度上掩盖了总加性遗传方差。相反，如果作为雄性（雌性）的适应度与受精卵之间的环境参数相关，那么在性别比例平衡中，当（且仅当）雄性在相对有利于雄性的环境中过度繁殖时，加性遗传变异就会减少，雌性也是如此。环境性别决定（一种雄性在一组环境中发育，雌性在另一组环境中发育，但成年动物混合在一起的系统）只有在雄性和雌性的适合度与性别决定的环境变量之间的相关性不同时才会进化稳定。这些结果特别讨论了爬行动物的性别是由卵的孵化温度决定的。
Mathematical models are presented for sex ratio evolution in random mating populations where the sex ratio is polygenic, i.e., controlled by many genes with small effects. The models address various examples of sex determining mechanisms, female heterogamety, haplo-diploidy, environmental and polygenic sex determination and consider the evolution of sex ratio mean and variance. At equilibrium, the mean sex ratio predicted is usually the same as predicted from single locus theory (e.g., 1/2 in the simplest case). When not at equilibrium, the sex ratio, P, evolves towards it at a per-generation rate proportional to the heritability times (1/2-P)/P(1-P) or a comparable factor when fitnesses must be considered. The evolution of the sex ratio variance depends upon fitness differences within a sex. If fitness within a sex is constant, the variance increases as the sex ratio moves toward equilibrium, but does not change when the sex ratio is at equilibrium (except for mutation and changes in linkage disequilibrium). There is a negative correlation (-.64) between males and females at equilibrium, which partly obscures the total additive genetic variance. If instead fitness as a male (female) correlates with an environmental parameter among zygotes, at the sex ratio equilibrium the additive genetic variance decreases if (and only if) males are overproduced in the parts of the environment relatively beneficial to males, and similarly for females. Environmental sex determination (a system in which males develop in 1 set of environmental circumstances, females in others, but adults mix) is evolutionarily stable only if the correlation between fitness and the environmental variable of sex determination differs for males and females. These results are discussed particularly in reference to reptiles in which sex is determined by the incubation temperature of the egg.