Recent literature and popular news stories reveal strong scientific and popular interest in the reproductive behavior of humans and other animals, including the myriad environmental influences on reproductive development. An overriding objective of this training program is to enhance understanding of the genesis and relevance of sex and gender.
History has shown that important insights into the basic mechanisms of reproduction and development can be gained by study of non-human model systems, as well as evolutionarily diverse non-model systems. The Program’s title, “Common Themes in Reproductive Diversity” is intended to focus attention on the universal challenge all animals must meet, to reproduce and provide for offspring, while also addressing the myriad ways in which animals accomplish these ends. Training focuses on three areas:
- Developmental contributions to reproductive behavior
- Origins and expression of differences among the sexes
- Interactions between sex, health, and disease
Developmental contributions to reproductive behavior
This theme encompasses the ways in which genetic and non-genetic factors, including parental and environmental factors, shape the development of offspring and reproductively relevant social behavior. Because of the diversity of parental effects and their mechanisms, from cellular and molecular to frequency-dependent population effects, a deep understanding of parental effects requires concerted study in a settling that intentionally synthesizes the essential contributions of a wide range of disciplines.
Several program faculty are devoted to research on these effects:
- Alberts dissects the impact of the maternal environment on the behavior of rat pups.
- Hahn is a bioinformatics researcher who studies the evolution and function of sex chromosomes and the role of gene networks in sexual differentiation in the genomes of several model systems, including humans.
- Heiman studies neuroendocrine changes postpartum and the role of oxytocin in post-partum depression in humans.
- Hurley studies the effects of early-life social isolation on the regulation of reproductive vocal communication.
- Ketterson studies effects of steroid hormones and immunoglobulins deposited by mothers in egg yolk on the growth, disease resistance, and offspring sex ratio in songbirds, as well as the impact of male parental behavior on offspring begging and growth.
- Moczek explores the molecular, genetic, and ecological determinants of sex-specific horn formation by young dung beetles.
- Moyle studies the genetic mechanisms of reproductive isolation and how reproduction goes awry.
- Rosvall’s group researches interactions between behavior, physiology, and reproductive performance, with one primary focus on female-female competition
- Sanders studies the effects of drug exposure on the in utero hormonal milieu and the subsequent development of adult sexual and non-sexual behaviors in humans.
- Sengelaub focuses on the role of maternal licking in neural development and sexual behavior in the rat.
- From an evolutionary perspective, Wade has developed a theory integrating how direct (genetic) and indirect (parental) effects on offspring traits influence the evolutionary process (e.g., how the evolution of a female turtle’s preference for a nest site is affected by temperature-dependent influences on the sex ratio of her offspring).
- Todd and Garcia examine how environment and experience affect mate choice, reproductive strategies, and sexual behavior in humans.
Origins and expression of differences among the sexes
This theme addresses the physiological mechanisms and evolutionary forces contributing to the development and maintenance of sex differences in physiology, morphology, and behavior. Across species, including humans, many of the behaviors, morphologies, and physiological processes that are essential for reproduction are sexually dimorphic. Studies of model and non-traditional organisms provide important insights into the shared mechanisms by which hormones guide sexual differentiation and/or influence adult reproductive physiology and behavior.
Expertise among program faculty runs from the molecular to the evolutionary:
- Hahn, Moczek and Rosvall study the molecular genetics and genomics of hormone actions during development.
- Demas, Foley, Smith, Sengelaub, Hurley, Wellman and Rosvall address how hormonal effects on cellular physiology and anatomy induce sexually dimorphic physiology and behavior at the organismal level.
- Demas, Heiman, Ketterson, Sanders, Sengelaub, and Smith study the roles of hormones in mediating developmental and adult plasticity in fertility and reproductive behavior, including that of humans.
- Ketterson, Moczek, Smith, and Wade employ a comparative approach to the evolution of hormone-mediated sexual dimorphism.
Interactions between sex, health, and disease
Sexual physiology and behavior are linked in a wide variety of intriguing ways with the transmission of diseases and parasites and an organism’s ability to cope with disease and illness. Sexual behavior is a major mode of disease transmission in humans as well as other animals, and sexually and non-sexually transmitted diseases and parasites play a critical role in the evolution and maintenance of sexual reproduction in natural populations.
The program’s faculty includes leading experts in the relationships among disease, parasitism, immunity, and sexual reproduction:
- Lively studies the role of disease and parasitism in the evolution and maintenance of sexual reproduction and how the co-evolution of sexually reproducing animals and their parasites influences the evolution of disease resistance.
- Demas and Ketterson study tradeoffs between the immune system’s ability to fight disease and reproductive physiology.
- Wade studies how disease resistance evolves in structured populations.
- Sanders and Heiman study the reciprocal interactions between diverse human sexual behaviors and the epidemiology of sexually transmitted diseases, as well as changes in specific immune parameters across the reproductive cycle.