Meeting Abstract

S5-1.1  Saturday, Jan. 5  Targets for hormone-mediated sex ratio adjustment in vertebrates CREWS, D; University of Texas at Austin crews@mail.utexas.edu

When considering sex ratios, we have to first define the nature of the question. Are we speaking of the gonads, secondary and accessory sex structures, physiology, brain, behavior, or all of the above elements. If these elements are not concordant, the exceptions can prove illustrative of underlying processes at both the proximate and ultimate levels. At each of these levels ‘sex’ is the binary outcome resulting from the modulation of conserved networks of genes, proteins, cells, organs and, in the case of the brain, discrete nuclei. These networks operate at multiple, and sequential levels that usually are linear during the lifespan, but in some instances reversals are possible. For example, the gonads arise from a single anlagen and, in most instances ovaries or testes result, although ovotestes are the norm in some species and gonadal reversal a property of other species. Other sexually dimorphic structures differentiate from multiple anlaga by reciprocal and sex-specific atrophy/hypertrophy typically in an exaggerated manner, although the capacity to develop structures characteristic of the opposite gonadal sex remains inherent and intact. A perspective that integrates these different properties will be presented.