Admixture mapping of quantitative traits in Populus hybrid zones: power and
limitations |
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Authors: | D Lindtke S C González-Martínez D Macaya-Sanz C Lexer |
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Institution: | 1.Unit of Ecology and Evolution, Department of
Biology, University of Fribourg, Fribourg, Switzerland;2.INIA, Forest Research Centre, Department of
Forest Ecology and Genetics, Madrid, Spain;3.Technical University of Madrid, ETS Forestry
Engineering, Department of Silviculture, Madrid, Spain;4.Jodrell Laboratory, Royal Botanic
Gardens, Kew, Richmond, Surrey, UK |
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Abstract: | Uncovering the genetic architecture of species differences is of central importance for
understanding the origin and maintenance of biological diversity. Admixture mapping can be
used to identify the number and effect sizes of genes that contribute to the divergence of
ecologically important traits, even in taxa that are not amenable to laboratory crosses
because of their long generation time or other limitations. Here, we apply admixture
mapping to naturally occurring hybrids between two ecologically divergent Populus
species. We map quantitative trait loci for eight leaf morphological traits using 77
mapped microsatellite markers from all 19 chromosomes of Populus. We apply
multivariate linear regression analysis allowing the modeling of additive and non-additive
gene action and identify several candidate genomic regions associated with leaf morphology
using an information-theoretic approach. We perform simulation studies to assess the power
and limitations of admixture mapping of quantitative traits in natural hybrid populations
for a variety of genetic architectures and modes of gene action. Our results indicate that
(1) admixture mapping has considerable power to identify the genetic architecture of
species differences if sample sizes and marker densities are sufficiently high, (2)
modeling of non-additive gene action can help to elucidate the discrepancy between
genotype and phenotype sometimes seen in interspecific hybrids, and (3) the genetic
architecture of leaf morphological traits in the studied Populus species involves
complementary and overdominant gene action, providing the basis for rapid adaptation of
these ecologically important forest trees. |
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Keywords: | model selection dominance overdominance Populus alba Populus tremula leaf morphology |
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