Environmental and population dependency of genetic variability-fitness correlations in Rana temporaria

Authors

  • DAVID LESBARRÈRES,

    Corresponding author
    1. Ecological Genetics Research Unit, Department of Biological and Environmental Sciences, PO BOX 65, FI-00014 University of Helsinki, Finland,
    2. Present Address: Department of Biology, Laurentian University, Sudbury, Ontario P3E 266, Canada,
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  • CRAIG R. PRIMMER,

    1. Department of Biological and Environmental Sciences, PO BOX 65, FI-00014 University of Helsinki, Finland,
    2. Present Address: Department of Biology, 20014, University of Turku, Finland,
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    • Present Address: Department of Biology, 20014, University of Turku, Finland

  • ANSSI LAURILA,

    1. Department of Population Biology, Evolutionary Biology Centre, Uppsala University, SE-752 36 Uppsala, Sweden
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  • JUHA MERILÄ

    1. Ecological Genetics Research Unit, Department of Biological and Environmental Sciences, PO BOX 65, FI-00014 University of Helsinki, Finland,
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David Lesbarrères, §Present Address: Department of Biology, Laurentian University, Sudbury, Ontario PZE 266, Canada, Fax: + 358-9-191 57694; E-mail: dlesbarreres@lourention.ca

Abstract

Considerable effort has been invested in studying the relationship between fitness and genetic variability. While evidence exists both for and against positive genetic variability–fitness correlations (GFC), the possible environment and population-dependency of GFCs has seldom been tested. We investigated GFCs in common frog (Rana temporaria) tadpoles reared under different temperatures and feeding regimes in four replicate populations. Genetic variability in eight microsatellite loci in 238 parents was used to estimate heterozygosity (H) and mean expected d2 in 158-sibships (4515 offspring). Generalized linear mixed model analyses of offspring fitness traits (survival to metamorphosis, developmental and growth rate) revealed that offspring survival probability was positively correlated with H, and that relationships were similar in all four populations tested. However, significant interaction between other genetic variability measures (d2, relatedness) and treatment conditions indicated that GFCs were detectable in some, but not in all environments. Interestingly, GFCs between survival and both heterozygosity and relatedness were most pronounced in stressful environments (i.e. limited food). Developmental and growth rates were significantly associated with d2 but less with H and relatedness. Furthermore, many of these GFCs were population-specific. These results suggest — in line with the contention that expression of inbreeding depression can be environment dependent — that GFCs can also be highly sensitive to the environmental conditions under which they are measured. The results further suggest that the observed positive correlation between H and survival probability is likely to be explainable by the ‘general’, rather than by the ‘local’ or ‘direct’ effect hypotheses.

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