Ontogeny of Immune Function

Abstract

Abstract Upon hatching, birds enter a world abundant with viruses, bacteria, mycoplasma, rickettsia, chlamydia, fungi, protozoa, cestodes, trematodes, nematodes, acanthocephalans, acarines, and insects with parasitic life-styles. In this chapter, parasites are defined as organisms that increase their fitness at the expense of the host’s fitness, and the words parasites, pathogen and infectious agent are used interchangeably. The diversity and complexity of the ecological interactions between birds and their infectious agents have been overlooked, in part because the avian immune system has been so successful at mitigating these threats. Traditionally, the investigation of parasite resistance has been the province of medical institutions. Although immunity is critical for the survival and reproductive success of the individual, ornithologists have made little effort to apply what is known about how the immune system controls infectious disease to problems in avian ecology and evolution. The increasing interest in avian host-parasite interactions (Loye and Zuk 1990; Clayton and Moore 1996), suggests that this situation may soon change.