Developmental plasticity of immune defence in two life-history ecotypes of the garter snake, Thamnophis elegans – a common-environment experiment.

PALACIOS, M. G.; SPARKMAN, A. M.; BRONIKOWSKI, A. M.

JOURNAL OF ANIMAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 80 p. 431 - 437

0021-8790

1. Ecoimmunological theory predicts a link between life-history and immune defence strategies such that fast-living organisms should rely more on constitutive innate defences compared to slow-living organisms. An untested assumption of this hypothesis is that the variation in immune defence associated with variation in life-history has a genetic basis. 2. Replicate populations of two life-history ecotypes of the garter snake Thamnophis elegans provide an ideal system in which to test this assumption. Free-ranging snakes of the fast-living ecotype, which reside in lakeshore habitats, show higher levels of three measures of constitutive innate immunity than those of the slow-living ecotype, which inhabit meadows around the lake. Although this pattern is consistent with the ecoimmunological pace-of-life hypothesis, environmental differences between the lakeshore and meadow habitats could also explain the observed differences in immune defence. 3. We performed a common-environment experiment to distinguish between these alternatives. Snakes born and raised in common-environment conditions reflected the immune phenotype of their native habitats when sampled at 4 months of age (i.e., fast-living lakeshore snakes showed higher levels of natural antibodies, complement activity, and bactericidal competence than slow-living meadow snakes), but no longer showed differences when 19 months old. 4. This suggests that the differences in innate immunity observed between the two ecotypes have an important—and likely age-specific—environmental influence, with these immune components showing developmental plasticity. A genetic effect in early life may also be present, but further research is needed to confirm this possibility, and therefore provide a more definitive test of the ecoimmunological pace-of-life hypothesis in this system.