Sex-specific maternal effect on egg mass, laying order, and sibling competition in the Bengalese finch (Lonchura striata var. domestica)
Sex-specific maternal effect on egg mass, laying order, and sibling competition in the Bengalese finch (Lonchura striata var. domestica)
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DOI：
10.1007/s00265-007-0400-8
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发表时间：
2007-05
影响因子：
2.3
通讯作者：
M. Soma;D. Saito;T. Hasegawa;K. Okanoya
中科院分区：
文献类型：
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作者：
M. Soma;D. Saito;T. Hasegawa;K. Okanoya
母性效应，如对卵子的投资，对后代的适应性有深远的影响。由于不同步孵化导致的性别特异性脆弱性和年龄等级，当一窝卵内发生不平等的兄弟姐妹竞争时，母亲预计会根据产卵顺序和性别来扭曲自己的投资。孟加拉雀的孵化是不同步的，并显示出适度的雌雄大小的二态性。然而，与普遍接受的体型依赖脆弱性的假设相反，体型较小的性别（男性）更容易受到兄弟姐妹竞争造成的发展压力的影响。我们研究了母性投资是否会受到产蛋顺序和蛋性别的影响，并通过观察在实验条件下饲养的雏鸡，探讨了不同性别、产蛋顺序和年龄等级的生长模式可能存在的差异。在实验条件下，雏鸡的组成受到控制，年龄等级比自然条件下更强。我们发现，总体而言，母体投资模式偏向于兄弟姐妹竞争的不利部分，即晚产的蛋和儿子，而不是早产的蛋和女儿。我们还研究了产卵顺序对成虫体型和生长模式性别差异的影响。在次等年龄层饲养时，雌性可以通过延长成熟时间来弥补生长速度下降的缺陷，而雄性则不能。我们认为，这种性别特异性的生长模式可能是早期发育压力易感性的性别差异的原因。
Maternal effects, such as investment in eggs, have profound effects on offspring fitness. Mothers are expected to skew their investment depending on the laying order and sex when unequal sibling competition occurs within a brood because of sex-specific vulnerability and age hierarchy caused by asynchronous hatching. The Bengalese finch hatches asynchronously and shows a moderate reversed sexual size dimorphism. However, contrary to commonly accepted assumptions of size-dependent vulnerability, the smaller sex (male) is more vulnerable to developmental stress caused by sibling competition. We investigated whether maternal investment would be biased by the position in laying order and the sex of eggs, and also explored the possible differences in growth patterns depending on sex, laying order, and age hierarchy by observing chicks fostered to experimentally manipulated broods where brood composition was controlled and age hierarchy was more enhanced than in natural breeding conditions. We found that overall patterns of maternal investment favored the disadvantageous sectors of sibling competition, i.e., eggs of later laying order and sons over those of early laying order and daughters. We also examined the effect of laying order on adult body size and sex differences in growth patterns. When reared in the subordinate age hierarchy, females could compensate for the deficit of decreased growth rate by taking longer to mature, whereas males could not. We suggest that this sex-specific growth pattern could be the cause of sex differences in vulnerability to early developmental stress.