Female Perspectives on Breeding Phenology in Eastern Ontario Gray Treefrogs

Abstract

Studies of the forces that shape local adaptation contribute to our understanding of origins of range-wide variation, speciation, and potential responses to changing environments. Phenology is an important component of such local adaptation. Phenological research is central to studies of geographical range limits and species distributions, migration, speciation, response to climate change and ex situ conservation and re-introduction programs. Despite over 22,000 phenological studies published thus far, there is a lack of phenological information on reproductive patterns of temperate anurans, particularly for females. My thesis therefore focuses on gaining insights into temperate frog phenology primarily of females, and patterns of female choice. I focus on Hyla versicolor (Gray Treefrogs), an Eastern North American temperate frog. My data come from perimeter transect surveys done at two wetlands at the Queen’s University Biological Station over the entire 2014 breeding season. I compared male and female peak abundance using an N-mixture model. Both males and females peaked on Julian Day 154 (June 3rd 2014). Females arrived three days after males in my focal wetlands, and left three days before. Timing of arrival is most likely based on a combination of females responding to male advertisement calls, and both sexes responding to abiotic factors (e.g. temperature, precipitation) across the season. Additionally, I looked at trends in male size over the season and found a weak positive relationship between male size and Julian day. However, females showed no preference for larger males, implying that female choice may focus on other things like genetic quality. I did find evidence of positive assortative mating, perhaps because of biophysical limitations of small females carrying larger males during oviposition. A fuller knowledge of female phenology enhances our understanding of local adaptation, and potentially provides insights into speciation and responses to climate change.