Changing expression of vertebrate immunity genes in
an anthropogenic environment: a controlled
experiment

Hablutzel, PI; Brown, M; Friberg, IM; Jackson, JA

Abstract

Background: The effect of anthropogenic environments on the function of the vertebrate immune system is a problem of general importance. For example, it relates to the increasing rates of immunologically-based disease in modern human populations and to the desirability of identifying optimal immune function in domesticated animals. Despite this importance, our present understanding is compromised by a deficit of experimental studies that make adequately matched comparisons between wild and captive vertebrates.

Results: We transferred post-larval fishes (three-spined sticklebacks), collected in the wild, to an anthropogenic (captive) environment. We then monitored, over 11 months, how the systemic expression of immunity genes changed in comparison to cohort-matched wild individuals in the
originator population (total n = 299). We found that a range of innate (lyz, defbl2, il1r-like, tbk1)and adaptive (cd8a, igmh) immunity genes were up-regulated in captivity, accompanied by an increase in expression of the antioxidant enzyme, gpx4a. For some genes previously known to show seasonality in the wild, this appeared to be reduced in captive fishes. Captive fishes tended to express immunity genes, including igzh, foxp3b, lyz, defbl2, and il1r-like, more variably. Furthermore, although gene co-expression patterns (analyzed through gene-by-gene correlations and mutual information theory based networks) shared common structure in wild and captive fishes, there was also significant divergence. For one gene in particular, defbl2,
high expression was associated with adverse health outcomes in captive fishes.

Conclusion: Taken together, these results demonstrate widespread regulatory changes in the immune system in captive populations, and that the expression of immunity genes is more constrained in the wild. An increase in constitutive systemic immune activity, such as we
observed here, may alter the risk of immunopathology and contribute to variance in health in vertebrate populations exposed to anthropogenic environments.

Citation

experiment. BMC Evolutionary Biology, 16(175), https://doi.org/10.1186/s12862-016-0751-8

• Journal Article Type: Article
• Acceptance Date: Aug 23, 2016
• Online Publication Date: Sep 1, 2016
• Publication Date: Sep 1, 2016
• Deposit Date: Sep 6, 2016
• Publicly Available Date: Sep 6, 2016
• Journal: BMC Evolutionary Biology
• Electronic ISSN: 1471-2148
• Publisher: Springer Verlag
• Volume: 16
• Issue: 175
• DOI: https://doi.org/10.1186/s12862-016-0751-8
• Publisher URL: http://dx.doi.org/10.1186/s12862-016-0751-8
• Related Public URLs: http://bmcevolbiol.biomedcentral.com/