Evolution of sex-specific pace-of-life syndromes: genetic architecture and physiological mechanisms

Sex differences in life history, physiology, and behavior are nearly ubiquitous across taxa, owing to sex-specific selection that arises from different reproductive strategies of the sexes. The pace-of-life syndrome (POLS) hypothesis predicts that most variation in such traits among individuals, populations, and species falls along a slow-fast pace-of-life continuum. As a result of their different reproductive roles and environment, the sexes also commonly differ in pace-of-life, with important consequences for the evolution of POLS. Here, we outline mechanisms for how males and females can evolve differences in POLS traits and in how such traits can covary differently despite constraints resulting from a shared genome. We review the current knowledge of the genetic basis of POLS traits and suggest candidate genes and pathways for future studies. Pleiotropic effects may govern many of the genetic correlations, but little is still known about the mechanisms involved in trade-offs between current and future reproduction and their integration with behavioral variation. We highlight the importance of metabolic and hormonal pathways in mediating sex differences in POLS traits; however, there is still a shortage of studies that test for sex specificity in molecular effects and their evolutionary causes. Considering whether and how sexual dimorphism evolves in POLS traits provides a more holistic framework to understand how behavioral variation is integrated with life histories and physiology, and we call for studies that focus on examining the sex-specific genetic architecture of this integration

Sex chromosome complement regulates habit formation

Sex differences in brain function and behavior are regularly attributed to gonadal hormones. Some brain sexual dimorphisms, however, are direct actions of sex chromosome genes that are not mediated by gonadal hormones. We used mice in which sex chromosome complement (XX versus XY) and gonadal sex (ovaries versus testes) were independent, and found that XX mice showed faster food-reinforced instrumental habit formation than XY mice, regardless of gonadal phenotype. © 2007 Nature Publishing Group

Perception of microfinance debtors and loan officers on the importance of entrepreneurial and business skills for loan repayment rates

Entrepreneurial and business skills are widely recognized as important prerequisites for successful microbusiness entrepreneurship in developing countries and, therefore, loan repayment rates of microfinance institution (MFI) debtors. In the literature, it remains, however, unclear exactly what set of skills are most important. The present paper examines the extent to what microfinance debtors and loan officers agree on the relevance of various entrepreneurial and business skills for microbusiness performance and loan repayment. Results from two focus group discussions show that neither microfinance debtors nor loan officers agree on the ranking of skills. This suggests that microfinance debtors have specific needs for training and skills development, which, consequently, should be addressed on an individual basis. For loan officers to be effective in their duties of evaluating loan applications and supporting microfinance debtors, they need training to better understand the relevance of entrepreneurial and business skills for microfinance debtors’ loan repayment probabilities