背景:获得配对交配(EPC)是一个复杂的行为过程。男性和女性之间的相互作用以获得EPC可能参与大脑功能进化并导致更大的大脑。因此,我们假设可以通过鸟类的相对大脑大小来预测配对亲子关系(EPP)率。过去的工作暗示EPP率与大脑大小有关,但是经验证据很少。
方法:我们整理了有关215种鸟类EPP水平和大脑大小的已发表参考文献的数据,以使用系统发育广义最小二乘(PGLS)模型和系统发育路径分析来研究EPP速率的进化是否可以通过大脑大小来预测。
结果:我们发现EPP率(EP后代的百分比和具有EP后代的育卵百分比)与相对脑大小呈负相关。我们应用系统发育路径分析来测试相对脑大小和EPP率之间的因果关系。最佳支持模型(ΔCICc<2)表明大大脑导致EPP率降低,这未能支持高EPP率导致更大大脑进化的假设。
结论:这项研究表明,追求EPC可能是鸟类的一种自然本能,男性和女性之间的相互作用可能会导致大脑变大,这反过来可能会限制它们在鸟类中两性的EPC水平。
BACKGROUND: Gaining extrapair copulations (EPCs) is a complicated behavior process. The interaction between males and females to procure EPCs may be involved in brain function evolution and lead to a larger brain. Thus, we hypothesized that extrapair paternity (EPP) rate can be predicted by relative brain size in birds. Past work has implied that the EPP rate is associated with brain size, but empirical evidence is rare.
METHODS: We collated data from published references on EPP levels and brain size of 215 bird species to examine whether the evolution of EPP rate can be predicted by brain size using phylogenetically generalized least square (PGLS) models and phylogenetic path analyses.
RESULTS: We found that EPP rates (both the percentage EP offspring and percentage of broods with EP offspring) are negatively associated with relative brain size. We applied phylogenetic path analysis to test the causal relationship between relative brain size and EPP rate. Best-supported models (ΔCICc < 2) suggested that large brain lead to reduced EPP rate, which failed to support the hypothesis that high rates of EPP cause the evolution of larger brains.
CONCLUSIONS: This study indicates that pursuing EPCs may be a natural instinct in birds and the interaction between males and females for EPCs may lead to large brains, which in turn may restrict their EPC level for both sexes across bird species.