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Exploring the assumptions underlying genetic variation in host nematode resistance (Open Access publication)

By Andrea Beate Doeschl-Wilson, Dimitrios Vagenas, Ilias Kyriazakis and Stephen Christopher Bishop

Abstract

The wide range of genetic parameter estimates for production traits and nematode resistance in sheep obtained from field studies gives rise to much speculation. Using a mathematical model describing host – parasite interactions in a genetically heterogeneous lamb population, we investigated the consequence of: (i) genetic relationships between underlying growth and immunological traits on estimated genetic parameters for performance and nematode resistance, and (ii) alterations in resource allocation on these parameter estimates. Altering genetic correlations between underlying growth and immunological traits had large impacts on estimated genetic parameters for production and resistance traits. Extreme parameter values observed from field studies could only be reproduced by assuming genetic relationships between the underlying input traits. Altering preferences in the resource allocation had less pronounced effects on the genetic parameters for the same traits. Effects were stronger when allocation shifted towards growth, in which case worm burden and faecal egg counts increased and genetic correlations between these resistance traits and body weight became stronger. Our study has implications for the biological interpretation of field data, and for the prediction of selection response from breeding for nematode resistance. It demonstrates the profound impact that moderate levels of pleiotropy and linkage may have on observed genetic parameters, and hence on outcomes of selection for nematode resistance

Topics: Research
Publisher: BioMed Central
OAI identifier: oai:pubmedcentral.nih.gov:2674900
Provided by: PubMed Central
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    Citations

    1. (2004). A resource allocation model describing the consequencesof artificial selection under metabolic stress,
    2. (1999). Anthelmintic resistance: past, presentand future,
    3. (1991). Breedingsheep in New Zealand for resistance to internal parasites: research results and commercial application, in:
    4. (2005). Cells, cytokines and other molecules associated with rejection to gastrointestinal nematode parasites,
    5. (1993). Correlationbetweenthe numberof scutellarand abdominalbristles in Drosophila melanogaster,
    6. (1985). Effect of experimental Ostertagia circumcincta infection on the performance of grazing lambs,
    7. (1992). Effect of selection for productivity traits on internal parasite resistance in sheep,
    8. (1994). Effective energy: a concept of energy utilization applied across species,
    9. (1999). Genetic andepidemiologicalrelationshipsbetween productivity and disease resistance: gastro-intestinal parasite infection in growing lambs,
    10. (1995). Genetic estimates for parasite resistance traits in sheep and their correlations with production traits,
    11. (1996). Genetic parameters for faecal egg count following mixed, natural, predominantly OstertagtiaExploring host nematode resistance 261 circumcincta infection and relationshipswith live weight in younglambs,
    12. (1996). Genetic relationships of lamb weight, maternal ability, and mature ewe weightin Swedish finewoolsheep,
    13. (2000). Genetics of Helminth Resistance, in: Axford
    14. (1992). Heritabilityofandgeneticcorrelationsamongfaecaleggcountsandproductivity traits in Romney sheep,
    15. (1996). Introduction to quantitative genetics, 4th edn.,
    16. (2006). Investigating genetic aspects of the variation in the host response to gastrointestinal parasites in sheep,
    17. KyriazakisI.,A modelto accountforthe consequences of host nutrition on the outcome of gastrointestinal parasitism in sheep: model evaluation,
    18. KyriazakisI.,A modelto accountforthe consequences of hostnutritionon theoutcomeofgastrointestinalparasitism in sheep:logicand concepts,
    19. KyriazakisI.,Explorationof the effects of host genotype and nutrition on the genetic parameters of lambs challenged with gastrointestinal parasites,
    20. (2003). Modeling of host genetics and resistance to infectious diseases: understanding and controlling nematode infections,
    21. (1997). Modelling responses to selection for gastro-intestinal parasites in sheep,
    22. (1977). Natural selection and animal breeding,
    23. (2005). nematode parasite infection levels in 6 month old lambs,
    24. (1997). Nematodeparasite controlof livestock in the tropics/ subtropics:the need for novel approaches,
    25. (2003). Reallocation of body resources in lactating mice highly selected for litter size,
    26. (1999). Selection for litter size and its consequencesfor the allocation of foodresources: a concept and its implications illustrated by mice selection experiments,
    27. (2000). The immunobiology of gastrointestinal nematode infections in ruminants,
    28. (1998). Towards a functional explanation for the occurrence of anorexia during parasitic infections,
    29. (1998). Undesirable side effects of selection for high productionefficiency in farm animals: a review,

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