Estimating inbreeding depression in natural plant populations using quantitative and molecular data
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Inbreeding and inbreeding depression are important issues in the biology and conservation of natural plant and animal populations, primarily when subpopulation sizes are reduced due to habitat fragmentation. In this study, we propose a method for estimating inbreeding depression in progenies of natural plant populations, combining the estimation of the fixation index by codominant markers with the experimental evaluation of quantitative traits. Our technique estimates apparent inbreeding depression in structured natural populations using the linear regression of phenotypic means on the inbreeding coefficients estimated with codominant markers. This method was applied to data from 112 maternal progenies of 10 natural subpopulations of Eugenia dysenterica DC, a fruiting tree species from the Brazilian savanna (Cerrado). The results show that the proposed method was efficient at detecting the presence of inbreeding depression for seedling emergence and initial growth traits in the species. This corroborates the importance of maintaining high levels of heterozygosity for in situ conservation or genetic restoration of natural populations.
KeywordsInbreeding depression Eugenia dysenterica Endogamy Heterozygosity-fitness correlation Brazilian Cerrado Fixation index
We are grateful to RV Naves for helping in field collection and to JAF Diniz-Filho and two anonymous reviewers for helpful comments and suggestions on the manuscript. This work was supported by a senior postdoctoral grant to LJ Chaves and research fellowships to LJ Chaves, R Vencovsky, MPC Telles and ASG Coelho, from the Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq—Brazil.
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