Nunney L, Luck R F
Department of Biology, University of California, Riverside 92521.
Theor Popul Biol. 1988 Feb;33(1):1-30. doi: 10.1016/0040-5809(88)90002-0.
W. D. Hamilton (1967, Science 156, 477-488) calculated the optimum sex-ratio strategy for a population subdivided into local mating groups. He made three important assumptions: that the females founding each group responded precisely to the number of them initiating the group; that ail broods within a group matured synchronously; and that males were incapable of dispersing between groups. We have examined the effects of relaxing each of these assumptions and obtained the following results: (1) When broods mature asynchronously the optimum sex ratio is considerably more female biased than the Hamiltonian prediction. (2) Increasing male dispersal always decreases the optimum female bias to the sex ratio, but it is of particular interest that when moderate levels of dispersal are coupled with asynchrony of brood maturation then the optimum strategy is relatively insensitive to changes in foundress number. (3) When females cannot precisely determine the number of other foundresses initiating the group then the optimum strategy is almost exactly the strategy appropriate to a group of average size. These effects can be most easily understood in terms of local parental control (LPC) of the sex ratio. Through LPC a founding female can alter the mating success of her sons by altering the sex ratio of her brood. Asynchrony in the maturation of broods within a group increases the control that a founding female has over the mating success of her sons, whereas male dispersal reduces it. We have shown that the role of LPC and the role of inbreeding, which favors a female-biased sex ratio in haploidiploid species, are independent and that their effects can be combined into a single general formula r = (1-(r2/z2) E(alpha z/alpha r]/(1 + I). The concept of LPC can also be used to interpret two factors which have been proposed to select for the Hamiltonian sex ratios: local mate competition is LPC acting through sons; and sib mating is LPC acting through daughters.
W. D. 汉密尔顿（1967年，《科学》156卷，477 - 488页）计算了一个细分为本地交配群体的种群的最优性别比例策略。他做出了三个重要假设：每个群体的奠基雌性对发起该群体的雌性数量做出精确反应；一个群体内的所有窝同步成熟；以及雄性无法在群体间扩散。我们研究了放宽这些假设中的每一个所产生的影响，并得到了以下结果：（1）当窝异步成熟时，最优性别比例比汉密尔顿的预测更偏向雌性。（2）增加雄性扩散总是会降低最优性别比例中的雌性偏向，但特别有趣的是，当中等程度的扩散与窝成熟的异步性相结合时，最优策略对奠基雌性数量的变化相对不敏感。（3）当雌性不能精确确定发起群体的其他奠基雌性数量时，最优策略几乎恰好是适合平均规模群体的策略。这些影响从性别比例的本地亲代控制（LPC）角度最容易理解。通过LPC，一个奠基雌性可以通过改变其窝的性别比例来改变其儿子的交配成功率。群体内窝成熟的异步性增加了奠基雌性对其儿子交配成功率的控制，而雄性扩散则降低了这种控制。我们已经表明，LPC的作用和近亲繁殖的作用（在单双倍体物种中有利于偏向雌性的性别比例）是相互独立的，并且它们的影响可以合并为一个单一的通用公式r = (1 - (r2/z2) E(αz/αr])/(1 + I)。LPC的概念还可用于解释被认为选择汉密尔顿性别比例的两个因素：本地配偶竞争是通过儿子起作用的LPC；同胞交配是通过女儿起作用的LPC。
