Data from: Brood parasitism is linked to egg pattern diversity within and among species of Australian passerines

Bird eggs show striking diversity in color and pattern. One explanation for this is that interactions between avian brood parasites and their hosts drive egg phenotype evolution. Brood parasites lay their eggs in the nests of other species, their hosts. Many hosts defend their nests against parasitism by rejecting foreign eggs, which selects for parasite eggs that mimic those of the host. In theory, this may in turn select for changes in host egg phenotypes over time to facilitate discrimination of parasite eggs. Here, we test for the first time whether parasitism by brood parasites has led to increased divergence in egg phenotype among host species. Using Australian host and nonhost species and objective measures of egg color and pattern, we show that (i) hosts of brood parasites have higher within-species variation in egg pattern than nonhosts, supporting previous findings in other systems, and (ii) host species have diverged more in their egg patterns than nonhost species after controlling for divergence time. Overall, our results suggest that brood parasitism has played a significant role in the evolution of egg diversity and that these effects are evident, not only within species, but also among species.鸟类卵在颜色与花纹上展现出显著的多样性。对此的一种解释是，鸟类育雏寄生者（avian brood parasites）与其宿主之间的协同互作驱动了卵表型（egg phenotype）的演化。育雏寄生者会将卵产于其他物种——即其宿主——的巢内。诸多宿主会通过排斥外来卵来抵御寄生行为，这一选择压力促使寄生者的卵演化出与宿主卵相似的形态。从理论上来说，这一过程反过来又会推动宿主卵表型随时间发生改变，以提升对寄生卵的识别效率。本研究首次检验了育雏寄生者的寄生行为是否导致宿主物种间的卵表型分化加剧。本研究以澳大利亚的宿主与非宿主鸟类为研究对象，通过客观量化卵的颜色与花纹特征，得到以下结果：（1）育雏寄生者的宿主在卵花纹的种内变异程度上高于非宿主物种，这一发现验证了其他研究体系中的既往结论；（2）在控制物种分化时间（divergence time）的影响后，宿主物种的卵花纹分化程度显著高于非宿主物种。综上，本研究结果表明，育雏寄生在鸟类卵多样性的演化过程中发挥了重要作用，且这一效应不仅存在于物种内部，也体现在不同物种之间。