Mentesana Lucia, Andersson Martin N, Casagrande Stefania, Goymann Wolfgang, Isaksson Caroline, Hau Michaela
Max Planck Institute for Ornithology, Eberhard-Gwinner-Str., 82319, Seewiesen, Germany.
Department of Biology, Lund University, Sölvegatan 37, 223 62, Lund, Sweden.
Front Zool. 2021 Aug 5;18(1):38. doi: 10.1186/s12983-021-00422-z.
In egg-laying animals, mothers can influence the developmental environment and thus the phenotype of their offspring by secreting various substances into the egg yolk. In birds, recent studies have demonstrated that different yolk substances can interactively affect offspring phenotype, but the implications of such effects for offspring fitness and phenotype in natural populations have remained unclear. We measured natural variation in the content of 31 yolk components known to shape offspring phenotypes including steroid hormones, antioxidants and fatty acids in eggs of free-living great tits (Parus major) during two breeding seasons. We tested for relationships between yolk component groupings and offspring fitness and phenotypes.
Variation in hatchling and fledgling numbers was primarily explained by yolk fatty acids (including saturated, mono- and polyunsaturated fatty acids) - but not by androgen hormones and carotenoids, components previously considered to be major determinants of offspring phenotype. Fatty acids were also better predictors of variation in nestling oxidative status and size than androgens and carotenoids.
Our results suggest that fatty acids are important yolk substances that contribute to shaping offspring fitness and phenotype in free-living populations. Since polyunsaturated fatty acids cannot be produced de novo by the mother, but have to be obtained from the diet, these findings highlight potential mechanisms (e.g., weather, habitat quality, foraging ability) through which environmental variation may shape maternal effects and consequences for offspring. Our study represents an important first step towards unraveling interactive effects of multiple yolk substances on offspring fitness and phenotypes in free-living populations. It provides the basis for future experiments that will establish the pathways by which yolk components, singly and/or interactively, mediate maternal effects in natural populations.
在产卵动物中，母亲可以通过向蛋黄中分泌各种物质来影响发育环境，进而影响其后代的表型。在鸟类中，最近的研究表明，不同的蛋黄物质可以相互作用地影响后代的表型，但这种影响对自然种群中后代适应性和表型的意义仍不清楚。我们在两个繁殖季节测量了自由生活的大山雀（Parus major）卵中已知会影响后代表型的31种蛋黄成分的自然变异，这些成分包括类固醇激素、抗氧化剂和脂肪酸。我们测试了蛋黄成分分组与后代适应性和表型之间的关系。
孵化和雏鸟数量的变化主要由蛋黄脂肪酸（包括饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸）解释，而不是由雄激素激素和类胡萝卜素解释，这些成分以前被认为是后代表型的主要决定因素。脂肪酸也是雏鸟氧化状态和体型变化比雄激素和类胡萝卜素更好的预测指标。
我们的结果表明，脂肪酸是重要的蛋黄物质，有助于塑造自由生活种群中后代的适应性和表型。由于多不饱和脂肪酸不能由母亲从头合成，而必须从饮食中获取，这些发现突出了环境变异可能塑造母体效应及其对后代影响的潜在机制（例如，天气、栖息地质量、觅食能力）。我们的研究是朝着揭示多种蛋黄物质对自由生活种群中后代适应性和表型的相互作用效应迈出的重要第一步。它为未来的实验提供了基础，这些实验将确定蛋黄成分单独和/或相互作用地在自然种群中介导母体效应的途径。
