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Linear and non-linear effects of yolk androgens on nestling development

Since the maternal origin of yolk androgens in avian eggs was discovered, many experimental studies have focused on studying its short- and long-term effects on offspring development. Most of these studies have tested the consequences of prenatal hormonal exposure by injecting physiological doses of androgens, into the egg yolk, subsequently monitoring its effects on nestling development. It is generally assumed a linear relationship between the injected hormone concentration and the affected trait. However, in this study where we used three androgen concentrations (low, intermediate and high), finding both linear and non-linear effects depending on the trait considered in spotless starling chicks (Sturnus unicolor). The fact that hormonal effect depends on the dose injected is useful to understand the different results between studies, and highlights the importance of considering dose-dependent effects when studying the balance of costs and benefits of maternal androgens.

The results of this study have just been published in The Journal of Experimental Biology, within an article signed by Jaime Muriel, Lorenzo Pérez-Rodríguez, Marisa Puerta and Diego Gil; entitled "Diverse dose-response effects of yolk androgens on embryo development and growth in a nestling passerine wild." The PDF is available on the left-side panel of this page.



  • Jaime Muriel injecting androgens in a starling egg (Photo: Lorenzo Pérez)
  • Gape of a spotless starling nestling (Photo: Lorenzo Pérez)
  • Intraclutch variability in nestling size (Photo: Lorenzo Pérez)