Immune Investment and Tradeoffs in Butterflies
Animals are under constant threat from parasites, and in response, they have evolved elaborate immune defenses. While having robust immunity seems adaptive, there is often striking variation between individuals in their immune capacity. One reason is that immunity is costly and carries a risk of self-damage. I am interested in how individuals balance these tradeoffs when investing in parasite defenses and how this generates variation and impacts infection outcomes.
I am exploring these questions as a postdoc with Dr. Emilie Snell-Rood at the University of Minnesota where I am studying butterflies. Heavy metals are common pollutants, especially along roadsides, where much the remaining habitat for pollinators is located. Insects use melanin to sequester heavy metals, but melanin is also a central component of the insect immune response. I am testing how varying levels of heavy metal exposure change immune capacity. At low levels, it is possible that metal exposure leads to increased immunity as melanin pathways are up-regulated (hormesis), while at high levels, butterflies may face tradeoffs while trying to deal with both heavy metal toxicity and immune challenges. Testing these tradeoffs in butterflies will allow for a broader understanding of the plasticity of parasite defenses and how animals cope with multiple stressors and allocate resources towards immunity.
I am also collaborating with Emilie on a project involving road salts and Monarchs. Much of the habitat left for pollinators is along roadsides, yet plants in these areas are exposed to high levels of salt due to road management. At low levels, salt is a necessary nutrient, but at high levels it is stressful and even toxic. I am studying how sodium stress during development impacts immune capacity. This is particularly interesting in the context of migration, as migratory individuals are known to have increased investment in immunity. Learning how diet stress impacts immune capacity will have important implications for habitat restoration, and for how parasites may impact monarchs during different life history stages.
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