Adaptations for Dispersal
Dispersal is an important stage in the life history of many organisms with numerous benefits, but it is not without risk. Thus, there is the potential for strong selection on dispersal-enhancing traits depending on the ecological context of the system. Invasive and range-expanding species have been a major focus of research into selection for the evolution of dispersal phenotypes, as individuals with a high dispersal propensity are often favoured during colonization. Through my empirical research on invasive cane toads (Rhinella marina) in Australia, I have shown that rapid shifts in morphology can occur with invasion, that these changes are heritable, they can influence locomotion, and hence dispersal capabilities. My research explores the ways that invasion dynamics are influenced by evolutionary processes.
Nutritional Constraints
Species expanding into new habitats often encounter novel selection pressures that drive rapid local adaptation. I am particularly interested in the nutritional adaptations of colonizing species because the essential compounds required for consumer growth and survival are often heterogeneously distributed in nature, and this leads to potential mismatches between dietary supply and consumer demand. My research examines fatty acid phenotypes of threespine stickleback populations to understand the balance between metabolic adaptations and evolution in foraging traits in the transition from marine to freshwater ecosystems. To understand the evolutionary changes that occur in the transition from nutrient-rich to nutrient-poor environments, it is important to study the role of key metabolic adaptations, for example the increased expression, or duplication of genes responsible for metabolic processes.
Evolution Along Environmental Gradients
Adaptations evolve in response to environmental conditions, but these are rarely discrete, and species distributions typically span a range of habitats and ecosystems. Species do not exist in isolation however, and evolve within communities and coevolve in pairs. An example of this can be seen from my current work on coevolution between the endosymbiont bacteria, Hamiltonella defensa, and its host, the black bean aphid (Aphis fabae). Aphids are a common agricultural pest, and often invasive, thus there is strong interest in developing biocontrol methods as an alternative to pesticides. Targeted release of parasitoid wasps (Lysiphlebus fabarum), which deposit their eggs inside aphid bodies, eventually killing them, is one such method; however, the naturally occurring endosymbiont bacteria H. defensa is known to protect aphids as it is lethal to wasp larvae. Understanding the interactions between these three species is critical if we are to design effective biocontrols. The abundances and distributions of these species will be impacted by climate change, and coevolutionary relationships will be affected as well. My research takes advantage of environmental gradients to explore coevolution, and explain contemporary patterns of biodiversity.
Amphibian Conservation
Amphibians represent one of the most vulnerable vertebrate groups on the planet. Climate change, habitat destruction, and the introduction of exotic pathogens are likely to result in population declines in the coming decades. Unless we take action, many species are at risk of extinction. Amphibians are frequently characterized by poor dispersal capabilities, thus habitat fragmentation due to urbanization and agriculture restricts gene flow, resulting in genetically depauperate populations. Such populations are particularly vulnerable to pathogens or environmental change, thus it is critical that we understand their genetic population structure if we are to protect and conserve at risk species. I plan to focus on the movement ecology and population genetics of at risk amphibian species to unite my background in dispersal ecology and molecular genetics with conservation biology.