Meeting Abstract
Hormones regulate phenotypic development in response to genetic and environmental variation. These molecular signals thus represent the underlying targets of phenotypic selection. Our understanding of the genetic basis of these signals, as well as their functional roles, is constantly improving. But how do molecular signals evolve in concert with the phenotypes they regulate? Our knowledge here is rudimentary. For example, although we know that hormonal pleiotropy generates correlations among phenotypic traits and plays an important role in phenotypic integration, we don’t fully understand the role of pleiotropy in evolution. We set out here to test the hypothesis that phenotypic responses of life-history traits to hormone variation evolve in a conservative fashion. We predict that variation in these responses results from tissue-specific expression of the same downstream effectors, even across large taxonomic groups. We measured variation in life-history traits and trade-offs responding to the same hormone manipulation in different butterfly species. We then used gene expression data in different tissues to better understand the molecular basis of the developmental mechanisms underlying the measured phenotypic variation in these species. Our results suggest in part that juvenile hormone affects some traits similarly in nearly every species we measured, but the strength and even direction of effect on other traits vary among species. We will connect these and other results from our experiments on life-history variation to our gene expression data on multiple species and tissues. In addition to identifying the molecular developmental basis of the effects of juvenile hormone on life-history variation among butterflies, we will test our hypothesis by investigating the consistency of evolutionary responses in specific downstream molecular signals.
