The role of parasites and pathogens in the evolution of life history traits is of increasing interest to both ecologists and evolutionary biologists. Immunology, which was once studied almost exclusively by immunologists, has become an important area of proximate investigation to animal physiologists as a means for understanding changes in disease susceptibility and the neural and neuroendocrine mechanisms that mediate these changes. The coalescence of these different perspectives has given rise to the field of ecological immunology, an interdisciplinary research field that examines...