Sea turtles and climate change
We are interested in how climate and weather patterns affect sea turtle behavior (e.g., nesting distributions, seasonal timing of nesting, nightly patterns of nesting, egg survival), and how climate change could affect the distribution and reproductive ecology of sea turtles worldwide. We are using species distribution modeling to predict the current and future geographic distribution of sea turtle nesting beaches to understand drivers of interspecific differences in the geographic distribution of nesting, and predict how offspring production may be affected. We are also interested in how stochastic disturbances, such as hurricanes, influence nesting beach quality.
Green-eyed treefrog, Litoria serrata
Amphibian populations are declining worldwide due to the fungal disease chytridiomycosis, a pathogen that grows best in cool, moist conditions. My current collaboration with Ross Alford, Lin Schwarzkopf, and Robert Puschendorf seeks to understand how the chytrid pathogen responds to temperature, and the implications of this in terms of disease susceptibility for individuals, populations, and species. To do this we am linking empirical data on frog behavior in the wild to the results of controlled laboratory experiments to understand how and why frog behavior influences pathogen fitness. We am focused on understanding (1) how different pathogen strains respond to temperature, (2) how the pathogen grows and reproduces under temperatures found in nature (an enormous gap in our current understanding), (3) how frogs can alter their thermoregulatory behavior to reduce susceptibility to disease, and (4) how sunlight penetration to the forest floor via canopy openings – such as those created by hurricanes – influences frog microhabitat use and the prevalence and severity of chytridiomycosis. Our work is funded by the Australian Research Council.
Conservation and wildlife management
We are experimentally manipulating canopy cover to understand the relationships between ectotherms and their environments. We removed overgrowing canopy cover (caused by fire suppression) to improve habitat quality for a rock-dwelling reptile assemblage (including endangered broad-headed snakes, Hoplocephalus bungaroides). Our work has shown that temperate reptile assemblages may limited by the availability of open forest canopies (and thus access to adequate thermal regimes), and that habitat quality can directly influence assemblage structure and individual fitness (growth rates, survival). We have now moved this project to the tropics, where we expect that high levels of canopy cover may be crucial to ectotherm persistence under climate change. Understanding how canopy cover varies spatially according to natural and anthropogenic disturbances will be necessary to mitigate increasingly warm and variable temperatures.
Reptile ecology and evolution
Broad-headed snake, Hoplocephalus bungaroides
We know surprisingly little about the ecology of most reptile and amphibian species, and we are interested in all aspects of the ecology, evolution, and behavior of these animals. Studying these traits is important for understanding how animals interact with their environments in nature, which can aid in protection from threats including habitat degradation and climate change. Our approach combines fieldwork and laboratory experiments to answer biological questions about how and why animals behave the way they do, and how behavior influences ecology and evolution. Our latest work focuses on (1) adaptive maternal manipulation of offspring phenotypes via nest-site selection, (2) the direct effects of contemporary climate change on fitness, (3) intraguild predation within reptile communities, and (4) behavior and movements of juvenile animals. Much of this work is in collaboration with Lin Schwarzkopf.
Evolution of parental care and trophic cascades
Parental care is extremely rare in reptiles, and over the past few years I have been working with Wen-San Huang in Taiwan to understand how and why maternal care has evolved in long-tailed skinks Eutropis longicaudata. In most species that provide parental care, some form of care is expressed throughout the entire geographic range; this species does not follow this general trend. Long-tailed skinks express maternal care only in a single population, but do not express maternal care throughout the rest of its geographic range. On Orchid Island, Taiwan long-tailed skinks nest within concrete retaining walls and remain with the eggs throughout incubation to actively deter egg-eating snakes (Oligodon formosanus) from entering the nest and consuming the eggs. Females nesting in the retaining walls gain a fitness advantage by exposing their eggs to high incubation temperatures, which decreases incubation duration and increases the proportion of eggs that hatch, offspring growth rates, and survival. We are using this model system to answer novel questions about how and why parental care evolves, and what the ecological costs and benefits are. On this island egg-eating snakes consume both lizard eggs and sea turtle eggs, and we are investigating apparent competition between sea turtles and lizards, mediated by an egg-eating snake predator.