Egg size has a crucial impact on the reproductive success of a mother and the performance of her offspring. It is therefore reasonable to employ egg size as a proxy for egg content when studying variation in offspring performance. Here, we tested species differences in allometries of several egg content parameters with egg area. We measured individual eggs in five species of annual killifish (Cyprinodontiformes), a group of fish where egg banks permit population survival over dry season. Apart from comparing allometric scaling exponents, amounts and compositions of egg components across the different species, we assessed the explanatory power of egg area for egg wet and dry weight and for hatchling size. We found notable species-specific allometries between egg area and the other egg parameters (egg dry weight and water content, elemental composition and triglyceride content). Across species, egg area predicted egg wet weight with highest power. Within species, coefficients of determination were largest in A. elongatus, a large piscivorous species with large eggs. Our study shows that systematically using egg area as a proxy of egg content between different species can ignore relevant species-specific differences and mask within-species variability in egg content.

卵的大小对母亲的生殖成功及其后代的表现具有至关重要的影响。因此，在研究后代性能变化时，采用蛋的大小作为蛋含量的替代指标是合理的。在这里，我们测试了几种蛋含量参数与蛋面积的异构关系中的物种差异。我们对五种一年生的致死鱼类（Cyprinodontiformes）中的单个卵进行了测量，这是一组鱼类，卵库可以使它们在旱季生存。除了比较不同物种的异形缩放指数，卵成分的数量和组成外，我们还评估了卵面积对卵干重和孵化量的解释能力。我们发现了鸡蛋面积与其他鸡蛋参数（例如蛋干重和水分，元素组成和甘油三酸酯含量）。在整个物种中，卵子面积预测出的卵湿重最大。在物种内，确定系数在A. elongatus，一种带大卵的大型食肉种类。我们的研究表明，系统地使用卵面积作为不同物种之间卵含量的代理可以忽略相关物种特异性差异并掩盖卵含量的种内变异性。