The Relationship Between Wing Coloration, Developmental Stress, and Immune Capacity in Monarch Butterflies
Monarch butterflies utilize melanin for a variety of functions, including in their immune systems to trap foreign objects, but also to create the black coloration in the veins and spots on their wings. These features are thought to play a structural role by producing stronger wings and may be used as signals during mate choice, yet little is known about how differences in their immune system affects the melanin and coloration of the monarch’s wings. We asked whether the coloration of monarch wings is influenced by investment in immune function and from exposure to environmental stressors during development, such as to road salt or parasites. To look into these relationships, monarchs were raised with exposure to low, high and a control amount of salt in their diet, then released for migration. Wing photos of each were taken, along with a scale imprint of the abdomen to screen for presence of the OE parasite. Additionally, a select group was tested for immune capacities. The individual wing photos were then analyzed to quantify different aspects of color. Results will help to determine if the coloration in monarch wings is used to signal information about immune capacity or developmental history, as wing coloration can be sexually selected by females. Furthermore, this research will improve our understanding more broadly of how investments in immunity can lead to tradeoffs in the evolution of traits in species, and the overall impacts of developmental stress on both traits and immunity.