Steroid hormones play critical organizational and activational roles during vertebrate development, impacting everything from sexual differentiation to metabolic activity. For oviparous species such as birds, these hormones are transferred from female to egg during follicle maturation, and differences in relative and absolute concentrations of the steroid hormones may reflect differences in life history, developmental, and ecological conditions. Prior work on yolk steroid hormones has focused on a handful of candidate hormones (e.g. testosterone, androstenedione, and corticosterone), but we used high-performance liquid chromatography with tandem mass spectroscopy (LC-MS-MS) to quantify 27 yolk steroids from the eggs of seven shrubland bird species. In addition to comparing steroid profiles across species, we conducted exploratory analyses to determine how the hormones clustered using a principal component (PC) approach, and if PCs were correlated with aspects of egg resources (relative egg size, proportio...
Merrill, L., Chiavacci, S. J., Paitz, R. T., & Benson, T. J. (2019). Quantification of 27 yolk steroid hormones in seven shrubland bird species: interspecific patterns of hormone deposition, and links to life history, development, and predation risk. Canadian Journal of Zoology, 97(1), 1-12. https://doi.org/10.1139/cjz-2017-0351