Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
Nat Commun. 2013;4:1603. doi: 10.1038/ncomms2634.
Sex allocation theory explains why most species produce equal numbers of sons and daughters, and highlights situations that select for deviation from this norm. Past research has, however, heavily focused on situations with discrete generations. When temporally varying generational overlap affects future mate availability, models predict cyclical shifts in sex allocation, but these predictions have not yet been appropriately tested. Here we provide evidence that mosquitofish (Gambusia holbrooki) populations possess a suitable life history: some autumn-born females bred alongside their own offspring, while such overlap was rare or absent for spring-born females and for all males. Our analytic model of sex allocation for these populations produced a perfect rank-order correlation between observed birth sex ratio biases and theoretical predictions, with stronger biases observed as the extent of female generational overlap increased. This is the first robust evidence that sex allocation theory accounts for cases when mating opportunities vary predictably over time.
性分配理论解释了为什么大多数物种产生的儿子和女儿数量相等，并强调了选择偏离这一规范的情况。然而，过去的研究主要集中在具有离散世代的情况下。当随时间变化的世代重叠影响未来配偶的可获得性时，模型预测性分配会出现周期性变化，但这些预测尚未得到适当的检验。在这里，我们提供了证据表明食蚊鱼（Gambusia holbrooki）种群具有合适的生活史：一些秋季出生的雌性与自己的后代一起繁殖，而这种重叠在春季出生的雌性和所有雄性中很少或不存在。我们对这些种群的性分配分析模型产生了一个完美的等级相关关系，即观察到的出生性别比偏差与理论预测之间的关系，随着雌性世代重叠程度的增加，观察到的偏差更强。这是第一个强有力的证据，证明性分配理论可以解释交配机会随时间变化而可预测地变化的情况。
