■ Abstract Evolutionary ecology see

■ Abstract Evolutionary ecology seeks to understand the selective reasons for the
design features of the immune defense, especially with respect to parasitism. The
molecular processes thereby set limitations, such as the failure to recognize an antigen,
response specificity, the cost of defense, and the risk of autoimmunity. Sex, resource
availability, and interference by parasites also affect a response. In turn, the defense
repertoire consists of different kinds of immune responses—constitutive or induced,
general or specific—and involves memory and lasting protection. Because the situation
often defies intuition, mathematical analysis is typically required to identify the costs
and benefits of variation in design, but such studies are few. In all, insect immune
defense is much more similar to that of vertebrates than previously thought. In addition,
the field is now rapidly becoming revolutionized by molecular data and methods that
allow unprecedented access to study evolution in action.