Dr. Dan Warner
For more information, please visit the Warner Lab Website
My research interests broadly center around physiological, behavioral, and evolutionary ecology. I am interested in how environmental factors (e.g., temperature and moisture) encountered by developing embryos affect offspring phenotypes and their subsequent fitness consequences. Additionally, much of my work evaluates how environmental factors affect maternal reproductive physiology, behaviors and allocation strategies, as well as their impacts on offspring phenotypes and fitness. My integrative approach combines laboratory and field studies to provide insights into the adaptive significance (or lack thereof) of organismal responses to the environment. I focus on reptiles (primarily lizards and turtles) because these organisms have a variety of characteristics that make them excellent models for empirical tests of adaptive evolution. My current work focuses on the two related topics below.
Developmental Plasticity and Parental Effects
Decades of research demonstrate that embryo physiology is sensitive to surrounding environments, which can influence developmental patterns and offspring phenotypes in ways that could impact fitness. In addition, the phenotype or environment of parents (typically the mother) can influence offspring phenotypes independent of, or interacting with, inherited genes. These parental effects are a form of developmental plasticity that spans generations, and can influence evolutionary processes. My research on this topic involves a series of on-going laboratory experiments (using the brown anole lizard) designed to elucidate the role of the parental and embryonic environments in shaping phenotypic variation in reptiles. A critical component of this research involves field work (on islands in Florida’s Intracoastal Waterway) aimed to quantify how natural selection operates on environmentally-induced phenotypic variation under natural conditions. This combination of lab and field studies provides robust assessments of how natural selection has shaped organismal responses to developmental environments.
Ecology and evolution of temperature-dependent sex determination.
Numerous organisms, including many reptiles, have temperature-dependent sex determination (TSD), whereby temperature during embryonic development determines offspring sex. My Ph.D. research focused on the adaptive value of this atypical sex-determining mechanism a short-lived Australian lizard. Although, I demonstrated that TSD enables each sex to develop at their own optimal temperature (thereby enhancing parental and offspring fitness), we still have a relatively poor understanding of the adaptive significance of TSD in longer-lived reptiles. To address this, I am currently involved in a long-term study to evaluate the sex-specific effects of egg incubation temperature on reproductive success in the painted turtle. My research on this topic also aims to understand physiological mechanisms underlying TSD and the impacts of climatic variation on sex ratios under TSD.
Warner DA, MA Moody, RS Telemeco, JJ Kolbe. 2012. Egg environments strongly impact embryonic development, but have minimal consequences for hatchling phenotypes in an invasive lizard. Biological Journal of the Linnean Society 105:25-41.
Warner DA, MA Moody, RS Telemeco. 2011. Is water uptake by reptilian eggs regulated by physiological processes of embryos or a passive hydraulic response to developmental environments? Comparative Biochemistry and Physiology A 160:421-425.
Warner DA, R Shine. 2011. Interactions among thermal parameters determine offspring sex under temperature-dependent sex determination. Proceedings of the Royal Society of London B 278:256-265.
Warner DA, MN Chapman. 2011. Does solitary egg incubation enhance water uptake and offspring quality in a lizard that lays single-egg clutches? Journal of Experimental Zoology 315:149-155.
Warner DA, CF Jorgensen, FJ Janzen. 2010. Maternal and abiotic effects on egg mortality and offspring size of turtles: temporal variation in selection over seven years. Functional Ecology 24:857-866.
Du, WG, DA Warner, T Langkilde, T Robbins, R Shine. 2010. The physiological basis of geographic variation in rates of embryonic development within a widespread lizard species. American Naturalist 176:522-528.
Warner DA, RS Radder, R Shine. 2009. Corticosterone exposure during embryonic development affects offspring growth and sex ratios in opposing directions in two lizard species with environmental sex determination. Physiological and Biochemical Zoology 82:363-371.
Janzen FJ, DA Warner. 2009. Parent-offspring conflict and selection on egg size in turtles. Journal of Evolutionary Biology 22:2222-2230.
Warner DA, X Bonnet, KA Hobson, R Shine. 2008. Lizards combine stored energy and recently acquired nutrients flexibly to fuel reproduction. Journal of Animal Ecology 77:1242-1249.
Warner DA, R Shine. 2008. The adaptive significance of temperature-dependent sex determination in a reptile. Nature 451:566-568.