Population-level immunologic variation in wild threespine stickleback (Gasterosteusaculeatus).

Area of Science:

• Ecology
• Immunology
• Genetics

Background:

• Wild organisms face diverse parasites, necessitating robust immune responses without causing self-damage.
• Current understanding of host-parasite interactions relies heavily on lab studies, overlooking natural genetic and environmental variations.
• Immune gene expression in wild populations is crucial for understanding natural immunoparasitology.

Purpose of the Study:

• To investigate immunologic variability in natural settings by comparing immune gene expression between two Alaskan stickleback populations.
• To determine if differing susceptibility to the cestode Schistocephalus solidus correlates with distinct immune gene expression patterns.
• To identify baseline immune differences in uninfected stickleback from populations with varying infection rates.

Main Methods:

• Examined immune gene expression in two Alaskan stickleback (Gasterosteus aculeatus) populations with known differences in susceptibility to Schistocephalus solidus.
• Compared gene expression profiles between infected and uninfected fish from both populations.
• Analyzed population-level differences in immune gene expression patterns.

Main Results:

• Distinct population-level immune gene expression patterns were observed in response to Schistocephalus solidus infection.
• Fish from the high-infection population showed signs suggestive of parasite-driven immune manipulation.
• Uninfected fish from the low-infection population displayed baseline inflammatory immune gene signatures, unlike those from the high-infection population.

Conclusions:

• Wild stickleback populations exhibit divergent immune responses to the same parasite, influenced by genetic and environmental factors.
• Parasite infection can trigger distinct immune gene expression patterns, potentially indicating host immune manipulation.
• Baseline immune profiles differ between populations, highlighting the importance of studying natural variation in host-parasite interactions.