Data from: Incomplete offspring sex bias in Australian populations of the butterfly Eurema hecabe

Theory predicts unified sex ratios for most organisms, yet biases may be engendered by selfish genetic elements such as endosymbionts that kill or feminize individuals with male genotypes. Although rare, feminization is established for Wolbachia-infected Eurema butterflies. This paradigm is presently confined to islands in the southern Japanese archipelago, where feminized phenotypes produce viable all-daughter broods. Here, we characterize sex bias for E. hecabe in continental Australia. Starting with 186 wild-caught females, we reared >6000 F1–F3 progeny in pedigree designs that incorporated selective antibiotic treatments. F1 generations expressed a consistent bias across 2 years and populations that was driven by an ~5% incidence of broods comprising greater than or equal to80% daughters. Females from biased lineages continued to overproduce daughters over two generations of outcrossing to wild males. Treatment with antibiotics of differential strength influenced sex ratio only in biased lineages by inducing an equivalent incomplete degree of son overproduction. Brood sex ratios were nevertheless highly variable within lineages and across generations. Intriguingly, the cytogenetic signature of female karyotype was uniformly absent, even among phenotypic females in unbiased lineages. Molecular evidence supported the existence of a single Wolbachia strain at high prevalence, yet this was not clearly linked to brood sex bias. In sum, we establish an inherited, experimentally reversible tendency for incomplete offspring bias. Key features of our findings clearly depart from the Japanese feminization paradigm and highlight the potential for more subtle degrees of sex distortion in arthropods.

Usage Notes
F1 Brood dataFamily-wise offspring sex ratio data for female Eurema hecabe sampled in North Queensland (2008 and 2009).

理论预测大多数生物体的性别比例趋于统一，然而自私遗传元素，如共生体，可能会引发偏差，导致具有雄性基因型的个体被淘汰或雌性化。尽管这种现象较为罕见，但感染了沃尔巴西亚（Wolbachia）的欧莱玛（Eurema）蝴蝶已出现雌性化的实例。这一模式目前仅限于日本列岛南部的岛屿上，雌性表型个体在此产生可育的全女儿后代。在此，我们描述了澳大利亚大陆上欧莱玛（E. hecabe）的性别偏差。我们从186只野生捕获的雌性个体开始，通过谱系设计，并融入选择性抗生素治疗，培育了超过6000只F1至F3代后代。F1代在两年内以及不同种群中表现出一致的偏差，这一偏差由大于或等于80%女儿的后代组成，其发生率为约5%。具有偏差谱系的雌性后代在连续两代与野生雄性杂交后，仍然过度产生女儿。不同强度的抗生素处理仅影响具有偏差谱系的性别比例，通过引发儿子过度生产的同等不完全程度。然而，后代性别比例在谱系和代际之间仍然高度可变。令人好奇的是，即使在不具有偏差谱系的表型雌性中，雌性核型的细胞遗传学特征也普遍缺失。分子证据支持存在单一高流行率的沃尔巴西亚菌株，但这一现象并未明确与后代性别偏差联系起来。总之，我们确立了一种可遗传、实验可逆的后代性别偏差倾向。我们研究发现的显著特征与日本的雌性化模式明显不同，并突出了节肢动物中性别扭曲的更微妙程度。

使用说明
F1代后代数据
来自北昆士兰州（2008年和2009年）女性欧莱玛（Eurema hecabe）的家族后代性别比例数据。