Introduction to ecoimmunology: An integrative approach

The immune system is critical for protecting animals from a litany of diseases, including established pathogens and parasites (e.g., influenza, malaria), as well as newly emerging infectious diseases such as Zika Virus. Although researchers have long recognized the importance of immunity within ecological research, only recently with the establishment of the field of ecological immunology (ecoimmunology), has it received formal empirical attention. To say it has been a challenge to study the immune system in groups of non-model organisms would be an understatement. This challenge is due, in no small part, to the fact that, unlike many other regulatory systems that show some degree of conservation across groups, a hallmark of the immune system is its diversity. This diversity is important for responding to both previously encountered and novel pathogens, but it also allows for specialization of immune responses within the broader contact of environmental, life history, and evolutionary forces an animal has experienced. While classic, model organisms have provided an important base of information on the organization of the immune system and its more specific mechanistic actions, efforts to understand the immune system inmore natural contexts including its inherent variability have catalyzed the field of ecological immunology, which has grown tremendously in the past decade.Unlike traditional immunology, ecoimmunology is focused on understanding how the immune system responds in an environmentally relevant context. Often times, ecoimmunology studies are conducted in the field where animals are exposed to a myriad of ecologically relevant challenges that may affect their immune response. However, a number of critical studies also rely onmore controlled, laboratory experiments that allow formore direct examination of immune function in response to interactive challenges, but always with ecological relevancy inmind. In conversations with other ecoimmunologists over the years, we have found that there is tremendous excitement for the field (as evidenced by the increasing number of publications in the field and the recently established Division of Ecoimmunology and Disease Ecology at the Society for Integrative and Comparative Biology). Despite the substantial increase in research with an ecoimmunological focus, it remains challenging to find an appropriate venue to publish one's findings. There is a gap among ecological journals, immunology or physiology journals, and the more taxonomically focused venues that are home to many non-model organism publications. This special issue on ecoimmunology was conceived, in part, to illustrate the breadth of research questions being addressed by ecoimmunologists, and to highlight recent advances in methods that may be of use to those in the field or interested in pursuing related questions. An additional, equally important goal is to introduce the Journal of Experimental Zoology Part A: Ecological and Integrative Physiology as a venue that is welcoming to ecoimmunology research. Consistent with this mission, the journal was recently renamed Ecological and Integrative Physiology, replacing its former subtitle, Ecological Genetics and Physiology, to reflect its focus onemerging areas of integrative research including ecoimmunology. Contributions for this special issue were solicited from established leaders in the field as well as from newer laboratories that are adding to the rich diversity and integrative nature that characterizes ecoimmunology.