The sex ratio of a population is a major determinant of the population's survival and the reproductive success of individuals within the population. The ability of an individual to adjust the sex ratios of the offspring they produce, or to change their sex at the adult level such that the number of males and females at the population level are influenced, is a powerful concept and one that has been discussed in an evolutionary context for decades. Although for some systems, such as reptiles and some fishes, the mechanisms by which sex can be altered through environmental cues have been addressed in detail, in other systems, such as birds and mammals, surprisingly little is known about the mechanisms of sex ratio adjustment. This symposium will bring together researchers studying hormonal mechanisms of sex adjustment in birds, reptiles, fishes, humans, and non-human mammals in an effort to stimulate new research avenues in the study of sex ratio adjustment. By demonstrating novel approaches in their own vertebrate systems used to address similar questions about sex ratio adjustment, we will encourage cross-fertilization of ideas among speakers and introduce the SICB audience to potential research avenues to which their current research in their respective systems could prove applicable. The symposium will include presentations by nine speakers, including one assistant professor, two associate professors, five professors, and one senior lecturer. Three of the nine speakers are women and three are foreign nationals. Efforts were made to include those with the highest level of expertise in the field of hormone-mediated sex ratio adjustment, while stimulating (1) interactions between foreign and US researchers, (2) interactions between young scientists and established scientists, and (3) incorporation of underrepresented groups at the nexus of hormone-mediated sex ratio adjustment in multiple vertebrate systems.
Using the funds supplied, I organized a symposium that took place at the annual meeting of the Society for Integrative and Comparative Biology, in San Francisco, CA in January 2013. This symposium also resulted in seven published journal articles. The idea of sex adjustment lies at the intersection of several scientific fields, including maternal/fetal programming (which, itself, has implications ranging from ecological to medical), environmental toxicology, and evolutionary biology. This symposium offered new insights into how maternal exposure to stress and other environmental and social cues can influence offspring phenotype in a variety of vertebrate species. In addition, those working on endocrine disruptors may gain some insight into how exposure to hormone mimics may influence the physiology and behavior of offspring at a variety of developmental levels. Combining information among classes may lead to new insights into potential conserved mechanisms of hormone action. An understanding of these mechanisms can then be used in agricultural industry and medicine where knowledge of sex ratio control would be lucrative, in the field of conservation where preventative or even therapeutic practices involving sex ratio control could be useful, and finally towards a full understanding of the adaptive significance associated with the powerful maternal effect of offspring sex ratio adjustment in the wild. The symposium allowed for the building of contacts between potential students and mentors and will also provide opportunities for education of students and postdocs within and outside of SICB through the publications that are now published in Integrative and Comparative Biology.
