Fenstemaker, Sean , Ballard Jr, Harvey .
Testing a hybrid origin for the enigmatic Atlantic Coast violet, Viola pectinata E.P.Bicknell.
The stemless blue violets (Viola subsection Borealiamericanae) have been considered a taxonomic nightmare throughout their history, reportedly involving substantial phenotypic variation, fertile interspecific hybrids and introgression, and odd mutational forms. Certain violets have received remarkably divergent treatment by various specialists, depending on interpretations of their evolutionary status and origin, and emphasis on particular traits. One such enigmatic violet is Viola pectinata E.P.Bicknell, known from few populations along the eastern Atlantic Coast. It resides on edges of salt marshes and sandy meadows. It has unlobed leaves with coarsely and sharply toothed margins. The flowers, fruits and seeds of Viola pectinata are similar to those of V. brittoniana. The latter has deeply lobed leaves and is more broadly distributed in similar salt marsh and meadow habitats along the eastern coast. Both species are typically found together, and they often grow near Viola cucullata, a marsh violet with unlobed small-toothed leaves and subtly different flowers and fruit. Occasional hybrids of Viola brittoniana and Viola cucullata with shallowly lobed leaves have been reported. Violet specialists have treated Viola pectinata as a distinct species, a variety, a form, or an anomalous phenotype without recognition under V. brittoniana. We have proposed the hypothesis that Viola pectinata is a spontaneous hybrid recombinant of V. brittoniana x V. cucullata. To test this hybrid derivative hypothesis, we generated DNA sequences of the trnL intron and adjacent trnL-trnF spacer for representatives of several Viola groups related to the stemless blues and several violet species within the latter group, including the V. brittoniana complex. The V. brittoniana complex consisted of individuals from one population each of Viola brittoniana and V. cucullata, two populations of V. pectinata, and individuals of V. brittoniana X cucullata. Sequence divergence was low among the stemless blue violets, but all individuals of V. brittoniana and V.brittoniana x cucullata shared a unique 6bp indel that was absent in V. cucullata, V. pectinata and other stemless blue violets. This divergence in haplotype supports a closer relationship between V. pectinata and V. cucullata than between V. pectinata and V. brittoniana. Furthermore, if a hybrid origin for V. pectinata is correct, then V. cucullata is the egg parent and V. brittoniana is the pollen parent for both V. pectinata populations. More variable chloroplast spacers and the nuclear LEAFY gene are currently being investigated for additional genetic insights into the taxonomic and evolutionary status of Viola pectinata.
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1 - Ohio University, Environmental & Plant Biology, 315 Porter Hall, Athens, OH, 45701, USA
2 - Ohio University, Environmental & Plant Biology, and Molecular & Cellular Biology Program, 315 Porter Hall, Athens, OH, 45701, USA
Viola subsect. Borealiamericanae
Presentation Type: Poster:Posters for Sections
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM