The evolution of mating preferences and of the male displays favored by these preferences can occur if display traits are correlated with genetic quality: offspring of males with attractive displays should then inherit "good genes," resulting in the benefit of high quality offspring for preferring females. Implicit in this scenario is the requirement of ample genetic variation in the display trait and a genetic correlation between the display and components of offspring fitness. How is this genetic variation maintained, and how does the environmental variation that is experienced by most natural populations affect the genetic relationships between female preferences, male traits, and the quality of their offspring? Using gray tree frogs as a model system, this study will investigate the relationship between an attractive male display trait - call duration - and offspring fitness in different environments. In particular, the study will determine how the genetic quality of the father, assayed in terms of call duration, and the quality of the environment together affect several components of offspring fitness, including condition, expression of the display trait, and allocation of resources to reproduction. This study will also examine the genetic relationship between condition and call duration in offspring; because condition may reflect many genes, and these genes may have different effects in different environments, the relationship between condition and display traits may help explain the persistence of genetic variation in male displays. Thus, a central goal of this study is to understand how environmental variation affects the genetic relationships between display traits and offspring fitness and, ultimately, how genetic variation in sexually-selected traits is maintained.
