Data from: The colour of paternity: extra-pair paternity in the wild Gouldian finch does not appear to be driven by genetic incompatibility between morphs

In socially monogamous species, individuals can use extra-pair paternity and offspring sex allocation as adaptive strategies to ameliorate costs of genetic incompatibility with their partner. Previous studies on domesticated Gouldian finches (Erythrura gouldiae) demonstrated a genetic incompatibility between head colour morphs, the effects of which are more severe in female offspring. Domesticated females use differential sex allocation, and extra-pair paternity with males of compatible head colour, to reduce fitness costs associated with incompatibility in mixed-morph pairings. However, laboratory studies are an oversimplification of the complex ecological factors experienced in the wild, and may only reflect the biology of a domesticated species. This study aimed to examine the patterns of parentage and sex-ratio bias with respect to colour pairing combinations in a wild population of the Gouldian finch. We utilized a novel PCR assay that allowed us to genotype the morph of offspring before the morph phenotype develops, and to explore bias in morph paternity and selection at the nest. Contrary to previous findings in the laboratory, we found no effect of pairing combinations on patterns of extra-pair paternity, offspring sex ratio, or selection on morphs in nestlings. In the wild, the effect of morph incompatibility is likely much smaller, or absent, than was observed in the domesticated birds. Furthermore, the previously studied domesticated population is genetically differentiated from the wild population, consistent with the effects of domestication. It is possible that the domestication process fostered the emergence (or enhancement) of incompatibility between colour morphs previously demonstrated in the laboratory.

在社会一夫一妻制物种中，个体可借助配对外父权（extra-pair paternity）与后代性分配作为适应性策略，以缓解与配偶间遗传不相容性带来的适应性代价。此前针对驯养七彩文鸟（Gouldian finch，学名Erythrura gouldiae）的研究证实，其头部色型间存在遗传不相容性，且该不相容性对雌性后代的影响更为严重。驯养雌性个体可通过差异性性分配，以及与头部色型相容的雄性进行配对外父权交配，来降低异色型配对中不相容性带来的适合度代价。然而，实验室研究过度简化了野生种群所经历的复杂生态因子，且仅能反映驯养物种的生物学特性。本研究旨在探究野生七彩文鸟种群中，基于配对色型组合的父权模式与性比偏倚特征。本研究采用了一种新型聚合酶链式反应（Polymerase Chain Reaction，PCR）检测方法，可在后代色型表型显现前对其色型进行基因分型，并借此探索巢内的色型父权偏倚与选择现象。与此前实验室研究结果相悖，本研究未发现配对组合对巢幼鸟的配对外父权模式、后代性比或色型选择存在影响。在野生种群中，色型不相容性的影响相较于驯养种群中观测到的结果，可能显著更弱，甚至完全不存在。此外，此前研究所用的驯养种群与野生种群存在遗传分化，这与驯养过程带来的影响相符。推测驯养过程可能促成了此前实验室中观测到的头部色型间不相容性的出现（或增强）。