Context-dependent associations between heterozygosity and immune variation in a wild carnivore

Area of Science:

• Ecology
• Immunology
• Genetics

Background:

• Correlations between heterozygosity and fitness proxies in wild populations are known but lack a clear genetic basis.
• Wild Galapagos sea lions (Zalophus wollebaeki) provide a model for investigating the genetic underpinnings of immune variation.

Purpose of the Study:

• To test for associations between heterozygosity and immune variation in Galapagos sea lions.
• To examine these associations across different age classes and ecological contexts.

Main Methods:

• Longitudinal data collection from wild Galapagos sea lions.
• Analysis of correlations between homozygosity by locus and immune markers (immunoglobulin G, leukocyte concentration).
• Comparison of immune responses between different age groups and environmental conditions.

Main Results:

• Homozygosity by locus negatively correlated with serum immunoglobulin G in pups, indicating impaired early immune defense.
• Homozygosity by locus positively correlated with leukocyte concentration in juveniles in a high-stress environment, suggesting altered immune activity.
• Findings suggest reduced genetic diversity detrimentally impacts immune development and response.

Conclusions:

• Demonstrates the context-dependent expression of immune variation in the wild, supporting ecoimmunology principles.
• Suggests heterozygosity is vital for maintaining immune system heterogeneity and response to infection.
• Provides mechanistic insights into the link between heterozygosity and fitness.