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Genetic evidence for hybridization in red oaks ( Quercus sect. Lobatae , Fagaceae)
Author(s) -
Moran Emily V.,
Willis John,
Clark James S.
Publication year - 2012
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1100023
Subject(s) - biology , introgression , gene flow , hybrid , hybrid zone , taxon , evolutionary biology , genetic structure , gene pool , genetic admixture , fagaceae , genetic variation , local adaptation , genetic diversity , genetics , ecology , botany , gene , population , demography , sociology
• Premise of the study: Hybridization is pervasive in many plant taxa, with consequences for species taxonomy, local adaptation, and management. Oaks ( Quercus spp.) are thought to hybridize readily yet retain distinct traits, drawing into question the biological species concept for such taxa, but the true extent of gene flow is controversial. Genetic data are beginning to shed new light on this issue, but red oaks (section Lobatae ), an important component of North American forests, have largely been neglected. Moreover, gene flow estimates may be sensitive to the choice of life stage, marker type, or genetic structure statistic. • Methods: We coupled genetic structure data with parentage analyses for two mixed‐species stands in North Carolina. Genetic structure analyses of adults (including F ST , R ST , G’ ST , and structure) reflect long‐term patterns of gene flow, while the percentage of seedlings with parents of two different species reflect current levels of gene flow. • Key results: Genetic structure analyses revealed low differentiation in microsatellite allele frequencies between co‐occurring species, suggesting past gene flow. However, methods differed in their sensitivity to differentiation, indicating a need for caution when drawing conclusions from a single method. Parentage analyses identifed >20% of seedlings as potential hybrids. The species examined exhibit distinct morphologies, suggesting selection against intermediate phenotypes. • Conclusions: Our results suggest that hybridization between co‐occurring red oaks occurs, but that selection may limit introgression, especially at functional loci. However, by providing a source of genetic variation, hybridization could influence the response of oaks and other hybridizing taxa to environmental change.