Evolution of density-dependent wing polyphenism in insects

      Dispersal is one of the most universal traits in organisms. The density dependence of dispersal is favored example of conditional dispersal, and demonstrated by several empirical and theoretical studies. Wing polyphenism in insects are one of the most popular examples of density dependent dispersal. This polyphenism is represented as aphids or plant hoppers. These insects show distinctly separated two phenotypes from single genotype in response to change in environmental conditions. One is dispersal type (macropterous, winged, flight capable, etc.) that is flight capable, the other is reproductive type (brachypterous, wingless, flight incapable, etc.) that cannot flight but have higher reproductive ability than dispersal type. And several study show density mainly affect the wing determination. In general, if the density were high in sensitive period of individuals, they would be dispersal type. While individuals would be reproductive type if density were low. However, the effect of density for wing determination is different among local population. Therefore, in this study, we aim to reveal the relationship between density and wing determination in different evolutionary condition.