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- Ekblom, Robert, 1976-
(författare)
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Immunoecology of the Great Snipe (Gallinago media) : Mate Choice, MHC Variation, and Humoral Immunocompetence in a Lekking Bird
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- At the centre of the vertebrate immune system is a group of proteins called MHC (major histocompatibility complex) molecules. These function in self – non self recognition and activation of the immune defence against intruding parasites and pathogens. In this thesis I have investigated individual variation in MHC class II genes and antibody producing ability in relation to ecology and behaviour in the great snipe (Gallinago media), a lekking bird, breeding in northern Europe. There was much variation in the MHC genes of the great snipe and the sequence data show that balancing selection has been acting on these genes. I found genetic differentiation in the MHC between two separate geographic regions of the great snipe distribution. Furthermore, this structure was more pronounced than that previously found in neutral genetic markers, suggesting that different selection pressures (possibly resulting from variation in parasitic fauna) are acting in these different regions. The birds produced specific antibodies following injection with two novel antigens. Males that were chosen as mates, had higher antibody titers than their neighbouring males, suggesting that this ability may be important in female mate choice. Such choice could give the offspring an enhanced immune system or could favour females directly by avoidance of sexually transmitted diseases. Females choosing to mate with a male having a different set of MHC genes than their own could give the offspring immune system the ability to react to a wide range of parasites. No such mate choice could, however, be found in the great snipe. Instead, females preferred males with certain MHC alleles, irrespective of their own MHC type. If those alleles confer resistance to parasites currently prevailing in the population, such resistance would be inherited by the offspring, thereby enhancing their fitness.
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| 2. |
- Nilsson, Robert, 1981-
(författare)
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Competitive performance prediction of elite alpine skiers
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The overall aim of this doctoral thesis was to identify physiological and anthropometric variables valid for prediction of competitive performance in alpine skiing (indicated by FIS points).Method: Paper I-III in this doctoral thesis followed an experimental, hypothesis-generating design which included both junior and senior elite alpine skiers. In all papers, physiological and anthropometric test results (X-variables) were correlated with FIS points (Y-variables) in order to investigate the predictive power of physiological and anthropometric variables for competitive performance in alpine skiing. The significance of the included test results was examined using bivariate and multivariate data analysis.Results: The results of Paper I show that included aerobic test results, neither alone nor in combination with anthropometric variables, could predict competitive performance of junior elite alpine skiers. Principal component analysis shows that male and female junior alpine skiers could be separated based on test results but that none of the included tests were important for sport-specific performance. The best multivariate models reached R2 = 0.51 to 0.86 and Q2 = -0.73 to 0.18. While several significant regression models could be observed, none of these met the criteria for valid models. The lack of predictive power of observed prediction models was confirmed by cross-validation. The results of Paper II show that included physiological test results from the test battery Fysprofilen could not predict competitive performance of senior elite female alpine skiers. Principal component analysis shows that there is a high correlation between individual physiological test results and their corresponding Fysprofilen score points, indicating that they can be used interchangeably. The Mann-Whitney U test was not significant neither for SL nor for GS. This suggests that Fysprofilen score points (summarized as Fysprofilen Index) and competitive performance (indicated by FIS points) are independent. The best multivariate models for SL and GS reached R2 = 0.27 to 0.43 and Q2 = - 0.8 to - 0.17, indicating low predictive power for competitive performance (as confirmed by cross-validation). The results of Paper III show that included physiological test results from a novel test battery could not predict competitive performance of senior elite female alpine skiers on a group level. When data were analyzed on a group level, the best models for SL and GS reached R2 = 0.39 to 0.40, Q2 = 0.15 to 0.21, indicating low predictive power. In contrast, when data were analyzed on an individual level, valid models with high predictive power (R2 = 0.88 to 0.99 and Q2 = 0.64 to 0.96) were generated. A comparative analysis between individual multivariate models shows that the relative importance of different physiological qualities for athletic performance varies between skiers.Conclusion: When applying tests on alpine skiers, a holistic approach should be considered. This because competitive performance in alpine skiing is the result of a number of interacting dimensions. Before applying physiological tests, the validity and reliability of the test protocols must also be determined. Administering tests that do not meet these criteria will probably waste not only important resources for clubs and ski federations but also risk misleading coaches and athletes when planning and implementing preparatory training.
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