Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations
Species boundaries in oaks are often not clear-cut, which is potentially a result of interspecific hybridization with trait introgression and phenotypic plasticity. Quercus rubra L. and Quercus ellipsoidalis E.J. Hill are two interfertile partially sympatric red oak species (section Lobatae) with di...
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‘Marin Drăcea’ National Research-Development Institute in Forestry
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doaj-9459ec2cad2e4e83bbe8f8d2d48616de2020-11-25T02:11:02Zeng‘Marin Drăcea’ National Research-Development Institute in ForestryAnnals of Forest Research1844-81352065-24452018-07-01611819410.15287/afr.2018.1020298Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populationsOliver Gailing0Sarah Kostick1Oliver Caré2Sudhir Khodwekar3School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, 49931-1295, USA & Forest Genetics and Forest Tree Breeding, Faculty of Forest Sciences, University of Göttingen, 37077 Göttingen, GermanyBiological Sciences Department, Michigan Technological University, Houghton, MI, 49931-1295, USA & Washington State University, Department of Horticulture, Pullman, WAForest Genetics and Forest Tree Breeding, Faculty of Forest Sciences, University of Göttingen, 37077 Göttingen, GermanySchool of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, 49931-1295, USA & University of Mumbai, Mumbai, IndiaSpecies boundaries in oaks are often not clear-cut, which is potentially a result of interspecific hybridization with trait introgression and phenotypic plasticity. Quercus rubra L. and Quercus ellipsoidalis E.J. Hill are two interfertile partially sympatric red oak species (section Lobatae) with different adaptations to drought. Quercus ellipsoidalis is the most drought tolerant of the North American red oak species and is characterized by deep tap roots, a shrubby growth and by deeply dissected leaves. Genetic differentiation between species is low for most molecular markers. However, one genic microsatellite in a CONSTANS-like (COL) gene, FIR013, was previously identified as outlier locus under strong divergent selection between species. In this study, we analyzed leaf morphometric traits in neighboring (parapatric) Q. rubra/Q. ellipsoidalis populations and in one sympatric population from the same region along an environmental gradient. Using multivariate statistics of leaf traits both species showed distinct bimodal frequency distributions for the first canonical discriminant function with some overlap in the phenotypic extremes, especially in the sympatric population. Leaf dissection traits showed strong and consistent differentiation between species in sympatric and parapatric populations, while differentiation for leaf size was lower in the sympatric population under more similar environmental conditions. Leaf phenotypes in F1 hybrids and introgressive forms suggested maternal effects and introgression of leaf traits between species. The association of outlier gene copy number at FIR013 with species-discriminating leaf traits in Quercus rubra can be a reflection of population differences since outlier gene copy number and population membership show significant collinearity. Similar environmental selection pressures on outlier alleles and leaf shape could also have resulted in this association. In future studies, segregating full-sib families could be used to test whether outlier alleles and associated genomic regions are indeed associated with leaf traits or other species-discriminating characters.https://www.afrjournal.org/index.php/afr/article/view/1020traits, est-ssrs, oaks, hybridization |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Oliver Gailing Sarah Kostick Oliver Caré Sudhir Khodwekar |
spellingShingle |
Oliver Gailing Sarah Kostick Oliver Caré Sudhir Khodwekar Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations Annals of Forest Research traits, est-ssrs, oaks, hybridization |
author_facet |
Oliver Gailing Sarah Kostick Oliver Caré Sudhir Khodwekar |
author_sort |
Oliver Gailing |
title |
Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations |
title_short |
Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations |
title_full |
Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations |
title_fullStr |
Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations |
title_full_unstemmed |
Leaf morphological and genetic variation between Quercus rubra and Quercus ellipsoidalis: comparison of sympatric and parapatric populations |
title_sort |
leaf morphological and genetic variation between quercus rubra and quercus ellipsoidalis: comparison of sympatric and parapatric populations |
publisher |
‘Marin Drăcea’ National Research-Development Institute in Forestry |
series |
Annals of Forest Research |
issn |
1844-8135 2065-2445 |
publishDate |
2018-07-01 |
description |
Species boundaries in oaks are often not clear-cut, which is potentially a result of interspecific hybridization with trait introgression and phenotypic plasticity. Quercus rubra L. and Quercus ellipsoidalis E.J. Hill are two interfertile partially sympatric red oak species (section Lobatae) with different adaptations to drought. Quercus ellipsoidalis is the most drought tolerant of the North American red oak species and is characterized by deep tap roots, a shrubby growth and by deeply dissected leaves. Genetic differentiation between species is low for most molecular markers. However, one genic microsatellite in a CONSTANS-like (COL) gene, FIR013, was previously identified as outlier locus under strong divergent selection between species. In this study, we analyzed leaf morphometric traits in neighboring (parapatric) Q. rubra/Q. ellipsoidalis populations and in one sympatric population from the same region along an environmental gradient. Using multivariate statistics of leaf traits both species showed distinct bimodal frequency distributions for the first canonical discriminant function with some overlap in the phenotypic extremes, especially in the sympatric population. Leaf dissection traits showed strong and consistent differentiation between species in sympatric and parapatric populations, while differentiation for leaf size was lower in the sympatric population under more similar environmental conditions. Leaf phenotypes in F1 hybrids and introgressive forms suggested maternal effects and introgression of leaf traits between species. The association of outlier gene copy number at FIR013 with species-discriminating leaf traits in Quercus rubra can be a reflection of population differences since outlier gene copy number and population membership show significant collinearity. Similar environmental selection pressures on outlier alleles and leaf shape could also have resulted in this association. In future studies, segregating full-sib families could be used to test whether outlier alleles and associated genomic regions are indeed associated with leaf traits or other species-discriminating characters. |
topic |
traits, est-ssrs, oaks, hybridization |
url |
https://www.afrjournal.org/index.php/afr/article/view/1020 |
work_keys_str_mv |
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