Sex-specific growth rates in zebra finch nestlings: a possible mechanism for sex ratio adjustment
Sex-specific growth rates in zebra finch nestlings: a possible mechanism for sex ratio adjustment
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DOI：
10.1093/beheco/arg094
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发表时间：
2004-01-01
影响因子：
2.4
通讯作者：
Martins, TLF
中科院分区：
文献类型：
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作者：
Martins, TLF
野生和圈养的斑胸草雀（Taenopygia guttata），像其他几个物种一样，在食物稀缺的情况下，在羽翼未丰时产生雄性偏向的性别比例。这是由于主要的性别比例调整和女性偏见的雏鸟死亡率。鉴于幼鸟在低体重时的繁殖力较低，在限制食物的条件下生产雌性后代对父母的回报较低，这被认为是一种功能性解释（Trivers和Willard的适应性投资假设; 1973）。然而，另一种机械的假设是，在限制条件下，雌性小鸡的生产成本更高。因此，在这些条件下，父母的回报率较低会发生在雌性后代的早期而不是晚期。为了验证这一假设，我在食物梯度上人工饲养小鸡。在没有父母-后代和同胞-同胞相互作用的情况下，在限制食物的条件下，雌性的最终体重和生长率较低。对于雄性动物，最终体重和生长速率与食物条件无差异。在食物限制条件下，雌性生长率低可能是导致鸟类雌性偏向死亡的一个潜在机制。更重要的是，这一结果是最有力的证据，女性后代经历更高的边际健身效益，从额外的食物比男性，它的影响，小学和中学的性别比例调整。此外，由于这种机制已被证明在父母与后代的互动的情况下，现在可以提出重大的问题，父母和后代的行为如何相互作用，在他们的影响次要性别比例的调整。
Wild and captive zebra finches (Taenopygia guttata), like several other species, produce a male-biased sex ratio at fledging when food is scarce. This is due to primary sex-ratio adjustment and female-biased nestling mortality. Given that young females fledging at low body masses have been shown to have low fecundity as adults, lower returns to parents from producing female offspring in conditions of restricted food has been raised as a functional explanation (Trivers and Willard's hypothesis of adaptive sexual investment; 1973). However, an alternative, mechanistic hypothesis is that under restricted conditions female chicks are more costly to produce. In consequence, lower returns to parents under these conditions would happen earlier in the life of female offspring rather than later. To test this hypothesis, I hand-reared chicks on a food gradient. In the absence of parent-offspring and sib-sib interactions, final body mass and growth rates for females were lower in conditions of restricted food. For males, final body mass and growth rates did not differ with food condition. Low female growth rates in food-restricted conditions might be one potential mechanism causing female-biased mortality in birds. More importantly, this result is the strongest evidence yet of female offspring experiencing higher marginal fitness benefits from additional food than males and it has implications for primary and secondary sex-ratio adjustment. Also, as this mechanism has been shown in the absence of parent-offspring interactions, significant questions can now be raised as to how parental and offspring behavior interact in their effects on secondary sex-ratio adjustment.