Data from: Admixture mapping of quantitative traits in Populus hybrid zones: power and limitations

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 due to
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 (QTL) 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.