Nutritional geometry provides insight into the dual roles of natural and sexual selection in insect cuticular hydrocarbon evolution

Abstract Interactions between natural and sexual selection have been integral to the development of sexual selection theory, yet the role of natural selection in sexual trait evolution has received far less empirical attention than the role of sexual selection, and the extent to which natural and sexual selection are aligned remains an important empirical question. Insect cuticular hydrocarbons (CHCs) provide a good model for exploring interactions between natural and sexual selection because of their dual roles in sexual signalling and desiccation resistance. We used the geometric framework for nutrition to explore the potential for, and magnitude of trade‐offs between male attractiveness, desiccation resistance and the abundance and blend of CHCs in the cricket Teleogryllus oceanicus . Attractiveness and desiccation resistance were both maximized on a diet that was rich in carbohydrate relative to protein. Although maximum expressions occurred at significantly different locations in nutritional space, the difference in angles between maximum attractiveness and desiccation resistance were small. Attractiveness and desiccation resistance were both associated with CHCs of moderate, rather than maximum, abundance and with a blend that was rich in two shorter chained alkenes relative to a single longer chained alkane. Partial correlations between fitness traits suggested that CHCs contribute indirectly to male attractiveness via their role in desiccation resistance. Our findings are consistent with the idea that natural and sexual selection on CHCs can be broadly aligned, facilitating rapid adaptation to ecological conditions and promoting speciation. Read the free Plain Language Summary for this article on the Journal blog.