Data from: Effects of individual-based preferences for colour-banded mates on sex allocation in zebra finches

Sex allocation theory predicts that females mated to attractive males produce more sons than females mated to unattractive males. However, previous tests of this hypothesis have obtained mixed results. We suggest that females differ in the traits they find attractive. To test this proposition, we assessed female zebra finches’ preferences for males banded with red or green plastic leg bands and then tested the sex allocation pattern of females paired with preferred and non-preferred males. Although most females preferred red-banded males, 34% of females consistently preferred green-banded males. The sex ratio at laying and hatching was not influenced by paternal preferred status. However, the fledging sex ratios differed between females paired with preferred and non-preferred males due to sex-biased chick mortality; sons of females paired with preferred males were born heavier and were more likely to survive than daughters. Our results indicate that female zebra finches show individual variation in their preferences for colour banded males, although females do not seem to adjust the offspring sex ratio in response to their mate’s band colour. However, the differential post-hatch mortality suggests females may differentially allocate resources into male and female eggs according to their individual mate preferences.

性分配理论（Sex allocation theory）预测，与具有吸引力的雄性交配的雌性所产的雄性后代比例，高于与无吸引力雄性交配的雌性。然而，此前对该假说的验证得到了混杂不一的结果。我们提出，雌性对雄性吸引力的评判特质存在个体差异。为验证这一命题，我们先评估了雌性斑胸草雀（zebra finches）对佩戴红色或绿色塑料腿环的雄性的偏好，随后对与偏好雄性、非偏好雄性配对的雌性的性分配模式进行了测试。尽管多数雌性更偏好佩戴红色腿环的雄性，但仍有34%的雌性始终青睐佩戴绿色腿环的雄性。产卵及孵化阶段的性比并未受父本偏好性的影响。然而，由于存在性别偏向的雏鸟死亡率，与偏好雄性配对的雌性所育的出飞幼鸟性比在两组间存在显著差异：与偏好雄性配对的雌性所产的雄性雏鸟出生体重更高，且存活率高于雌性雏鸟。我们的研究结果表明，雌性斑胸草雀对佩戴彩色腿环的雄性的偏好存在个体差异，尽管雌性似乎并未根据配偶的腿环颜色调整后代性比。但孵化后死亡率的差异提示，雌性或许会根据自身对配偶的个体偏好，对雄性和雌性卵进行差异化的资源分配。