Chapter 3 - Secondary Sexual Traits, Immune Response, Parasites, and Pathogens: The Importance of Studying Neotropical Insects

Abstract

Thirty years ago, Hamilton and Zuk proposed that parasites are a central tenet in understanding the relationship between elaboration of secondary sexual traits and female choice, and how the parasites' selective pressure favors the host genetic variation. However, here we provide evidence that, at least in insects, this hypothesis has not been properly tested. The main reason is that studies have not taken into account the natural parasites confronted by males, and hence how those parasites affect the development of secondary sexual traits. In addition, to understand this relationship it is essential to recognize not only how immune response fights each parasite species, but also how immune response, secondary sexual traits, and parasites are related (the mechanism). In this chapter we propose that neotropical insects could be a good model system to test Hamilton and Zuk's theory. On the one hand, a widely distributed insect species could provide a natural experiment because they are confronted with different habitats and parasites or pathogens, and this may reveal how sexual traits and immune response vary among populations according to their local adaptations. On the other hand, the comparison of different species in the same habitat will reveal the contribution of parasites or pathogens vs abiotic factors to the relationship between immune response, sexual traits, and natural parasites or pathogens. Neotropic heterogeneity presents the possibility of studying sexual selection from an integrated point of view: from molecules to populations and species.