Quantitative genetics of zebrafish ontogeny under changing environmental conditions

Quantitative genetics has provided a proximate tool for making evolutionary predictions based on genetic and environmental sources of variation. Unfortunately, quantitative models have failed to address the evolutionary consequences of development in complex, changeable environments. This type of knowledge can only be achieved by tracking unique genotypes across all possible combinations of changing environmental factors.;The first part of my research focuses on the consequences of changing environmental oxygen on zebrafish cardiovascular development. I found that cardiac output at the 48th hour of development in a given oxygen environment was conditional upon oxygen conditions during the first 24 hours of development. These conditional responses varied across genotypes, resulting in interactions between genotype, early, and later environments (G xExE).;The second part of my research focused on the consequences of changing oxygen on zebrafish morphology. I found that body shape in zebrafish in a given oxygen environment for days 6--90 was conditional upon oxygen conditions for days 0--6. These conditional responses also varied across genotypes.;The third part of my research focused on the consequences of changing oxygen on zebrafish behavior, size, and physiology. I found that size and behavior in zebrafish was dictated by oxygen conditions for days 0--30. Physiology, however, was influenced most by oxygen conditions for days 30--90.;The fourth part of my research focused on the consequences of changing food rations of zebrafish size and swimming ability. I found that fish raised under all possible combinations of high and low food treatments achieved the same body size at 60 days. Swimming performance, however, was conditional on interactions between feeding treatments. I also detected significant family-level variation for these responses, indicating at least some heritable variation.;These studies comprise some of the first quantitative genetic studies to track developmental outcomes across more than one instance of environmental change. My work has shed light on the evolutionary potential in complex, changeable environments as well as provided a tractable tool for partitioning the proximate sources of development across discrete ontogenetic periods.