Bolund Elisabeth, Schielzeth Holger, Forstmeier Wolfgang
Max Planck Institute for Ornithology, 82 319 Seewiesen, Germany.
Proc Biol Sci. 2009 Feb 22;276(1657):707-15. doi: 10.1098/rspb.2008.1251.
The classical version of the differential allocation hypothesis states that, when females reproduce over their lifetime with partners that differ in their genetic quality, they should invest more in reproduction with high-quality males. However, in species with lifetime monogamy, such as the zebra finch, partner quality will typically remain the same. In this case, the compensatory investment (CI) hypothesis predicts higher investment for low-quality males, because low genetic quality offspring are more dependent on maternal resources. Here, we show that female zebra finches invested more resources, both in terms of egg volume and yolk carotenoid content, when paired to a low genetic quality male, as judged from his previous ability to obtain extra-pair paternity in aviary colonies. We also found that females deposited slightly larger amounts of testosterone into eggs when paired to a low parental quality male, as judging from his previous success in rearing offspring. This is, to our knowledge, the first experimental support for the CI hypothesis in a species with lifetime monogamy. We stress that in more promiscuous species, the benefits of classical differential allocation may partly be neutralized by the supposed benefits of CI.
差异分配假说的经典版本指出，当雌性在其一生中与基因质量不同的伴侣繁殖时，它们应该在与高质量雄性的繁殖中投入更多。然而，在终身实行一夫一妻制的物种中，比如斑胸草雀，伴侣质量通常会保持不变。在这种情况下，补偿性投资（CI）假说预测，对低质量雄性的投资会更高，因为低基因质量的后代更依赖母体资源。在此，我们表明，从雄性之前在鸟舍群体中获得婚外父权的能力判断，当雌性斑胸草雀与低基因质量的雄性配对时，它们在卵体积和卵黄类胡萝卜素含量方面都会投入更多资源。我们还发现，从雄性之前养育后代的成功情况判断，当雌性与低亲代质量的雄性配对时，它们会在卵中注入略多的睾酮。据我们所知，这是对终身实行一夫一妻制物种中CI假说的首个实验支持。我们强调，在滥交程度更高的物种中，经典差异分配的益处可能会部分被CI假定的益处抵消。
