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I.7 An observational approach to the immunocompetence handicap hypothesis
The Scientific and Social Program of the VI~ ISDC1 Congress
1.7 AN OBSERVATIONAL HYPOTHESIS
APPROACH TO THE IMMUNOCOMPETENCE
S 147
HANDICAP
Frode Skarstein, lvar Folstad Department of Ecology/Zoology, IBG, University of Tromso, 9037 Tromso, Norway Development and maintenance of carotenoid based secondary sexual traits may have costs to immunity. Consequently, as envisioned in the Immunocompetence handicap hypothesis, such traits may be used in mate choice for heritable parasite resistance, as envisioned in the lmmunocompetence handicap hypothesis. Here, we show that the carotenoid based coloration of the salmonid Arctic charr is negatively related to lymphocyte counts. Additionally, there is a positive relationship between levels of circulating lymphocytes and intensities of the pathogenic parasite C. truncatus. This suggests that only individuals with low intensities of this parasite are able to pay the immunological costs of ornamentation, thus signalling their resistance towards the parasite. Moreover, two low pathogenic parasites show positive correlations to coloration. Are these positive correlations resulting from allocation of limited amounts of carotenoids between ornamental and immunological functions?
1.7 AN OBSERVATIONAL HYPOTHESIS
APPROACH TO THE IMMUNOCOMPETENCE
S 147
HANDICAP
Frode Skarstein, lvar Folstad Department of Ecology/Zoology, IBG, University of Tromso, 9037 Tromso, Norway Development and maintenance of carotenoid based secondary sexual traits may have costs to immunity. Consequently, as envisioned in the Immunocompetence handicap hypothesis, such traits may be used in mate choice for heritable parasite resistance, as envisioned in the lmmunocompetence handicap hypothesis. Here, we show that the carotenoid based coloration of the salmonid Arctic charr is negatively related to lymphocyte counts. Additionally, there is a positive relationship between levels of circulating lymphocytes and intensities of the pathogenic parasite C. truncatus. This suggests that only individuals with low intensities of this parasite are able to pay the immunological costs of ornamentation, thus signalling their resistance towards the parasite. Moreover, two low pathogenic parasites show positive correlations to coloration. Are these positive correlations resulting from allocation of limited amounts of carotenoids between ornamental and immunological functions?