Research in the Warner Lab examines interactions between organisms and their environments across multiple life-history stages (from embryos to adults). By quantifying relationships between phenotypes and fitness, we aim to understand how natural selection has shaped phenotypic variation, including the behavioral or plastic responses of organisms to the environment. We use a variety of techniques (e.g., genotyping, radio-immunoassays, respirometry, mark-recapture experiments) and combine field and lab studies to gain a comprehensive understanding of adaptive evolution and other ecological processes. Our research focuses on reptiles because we are particularly fascinated with these animals, and perhaps more importantly, many reptiles have characteristics that make them excellent models for addressing fundamental questions in evolutionary ecology.
|
Developmental plasticity and egg physiological ecology
Plastic responses of embryos to developmental conditions are nearly ubiquitous throughout life. Decades of research demonstrate that embryonic environments influence developmental patterns and offspring phenotypes in ways that impact fitness. Our research on this topic integrates lab studies of egg physiological ecology with release-recapture experiments in the field to understand how selection has shaped patterns of developmental plasticity. For example, we have shown that temperature and moisture conditions during egg incubation affect offspring body size via their influence on developmental rate or yolk metabolism. These phenotypic effects, in turn, influence individual survival and/or reproductive success later in life. We have studied the fitness consequences of developmental conditions in several species (jacky dragons, fence lizards, painted turtles, sliders), but most of our current work is on the brown anole lizard. We are currently investigating how multiple environmental factors during egg incubation (e.g., temperature, moisture, substrate, salinity) and during post-hatch life stages (e.g., competition, predation, nutrition) affect phenotypic development and fitness in these lizards. |
Hatchling brown anole
|
Marking nest sites of brown anoles
Female skink brooding her eggs
|
Evolutionary ecology of parental effects Parental effects occur when the phenotype or environment of the parents (typically the mother) influence offspring phenotypes independent of, or interacting with, inherited genes. In other words, parental effects are a form of developmental plasticity that spans generations. Our research addresses how maternal environments (e.g., nutrition, social conditions, age) influence patterns of reproductive investment, and in turn, how investment impacts offspring phenotypes and fitness. We also evaluate the fitness consequences of maternal nest-site choice, which is a behavioral maternal effect that influences the environment that embryos experience during development. Research on this topic also incorporates aspects of sex allocation biology (i.e., the differential investment towards sons versus daughters) and parent offspring conflict (i.e., evolutionary conflict arising from parent/offspring differences in optimal investment). Much of our work on these topics focus on the brown anole lizard – their reproductive biology makes them an interesting model as they lay a single egg about once per week, which enables females to differentially invest into each offspring that they produce. Also, we recently started research on the five-lined skink – their egg brooding behaviors allow us to investigate interesting questions about maternal effects and the evolution of parental care. |
|
Ecology of tropical reptiles and amphibians
We have recently initiated work in lowland rainforest at La Selva Biological Station in Costa Rica. One of our future aims is to understand how developmental conditions during egg incubation might influence offspring survival under environments with different competitive and predatory pressures. To address this, we have initiated studies of developmental plasticity in several of the Anolis species that inhabit the forests of La Selva, but our work on this topic is still at very early stages. In addition, we have recently started (in 2025) conducting surveys of the leaf litter herpetofauna in several different forest plots at different successional stages to quantify the spatial and temporal patterns of reptile and amphibian abundance and diversity. This work will be important in documenting how human disturbances have impacted the leaf litter communities over time, which will be useful for conservation efforts. |
Collecting data in the rainforest
|
One of our experimental islands
|
Phenotypic selection in the wild
The potential for traits to evolve in response to natural selection depends largely on the strength, form and consistency of selection in nature. To quantify phenotypic selection in the wild, we conducted a large-scale cross-generational study on several populations of brown anole lizards located on islands in Florida's Intracoastal Waterway. These islands provide an outstanding opportunity to assess spatial variation in selection and to assess the temporal consistency of phenotypic selection across generations. To complement our lab-based studies, we have used these islands for release-recapture studies to address how selection operates on incubation-induced phenotypes and embryo reaction norms for different traits. |
|
Urban adaptation and invasion biology Urbanization and biological invasion are two major components of global change, and have strong impacts on local populations. Our work with brown anole lizards (as well as other anoles) has addressed important questions about 1) how demographic factors affect establishment of invasive populations, 2) how natural selection operates on newly-established populations, and 3) how human structures might contribute to the establishment and extinction of invasive populations. We have also examined how the urban heat-island effect influences nesting behavior and the thermal conditions in nests, and their consequences on developing embryos. Our work has provided novel insights into the causes of biological invasion and how organisms acclimate and/or adapt to human-disturbed habitat. |
A Puerto Rican Crested Anole in Miami
|
Jacky dragon from Australia
|
Evolutionary ecology of temperature-dependent sex determination In many organisms, the temperature that embryos experience during development determines offspring sex. This temperature-dependent sex determination (TSD) is a form of developmental plasticity and the numerous independent origins of TSD raise many questions about its adaptive significance. Our past work has focused on understanding the fitness consequence of TSD. We have shown that egg incubation temperature affects sex-specific fitness in the jacky dragon (a short-lived lizard species from Australia), and we have similar evidence for this pattern from our work on the African rock agama. Our work on turtles has also evaluated the physiological and behavioral mechanisms that enable sex ratios to adjust to climatic variation, and how regional climate and habitat change will impact nest temperatures and primary sex ratios. |
