Immunity, life history and conservation in the Galapagos sea lion

Infectious disease threatens health and biodiversity across the globe, and disease emergence may become more common as humans further encroach on habitats and modify environments. To assess the risks of disease emergence in natural populations accurately, we require an understanding of the workings of immunity in the wild. This thesis is about immunity in the context of life history in the endangered Galapagos sea lion, and aims to contribute to understanding of immune dynamics in wild populations, and to evidence-based conservation management.

The introduction reviews the development of the discipline of ecological immunology, and discusses the application of its methodological tools to little-known species such as the Galapagos sea lion. The first data chapter uses these tools to describe the ontogeny of Galapagos sea lion immunity in two contrasting ecological contexts. The second data chapter contextualises the immune variation described in the first by assessing the relationship between immune activity and condition. The third data chapter introduces a genetic dimension through the analysis of inbreeding estimates with immune measures. The fourth and final data chapter uses epidemiological models to assess the risk of Galapagos sea lion exposure to canine distemper virus under different management and environmental scenarios. The discussion brings together the results of the data chapters and evaluates emergent themes and limitations in the context of suggestions for future work.

The results show that the study of immune variation in species such as the Galapagos sea lion can provide useful insight into the dynamics of immunity in the wild, and information that can have practical application to conservation. They also lay a foundation for integrated epidemiological analyses of disease risk that incorporate physiological and immunological variation, and that have potential for constructive development beyond the Galapagos sea lion.