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Abstract Detail

Systematics Section/ASPT

Robertson, Aaron [1], Ballard, Harvey [2].

Do cryptic species partly explain extensive variation in eastern North American Viola subsinuata (Violaceae)?

The genus Viola (Violaceae) is a well-known temperate and tropical montane genus encompassing approximately 550-625 species and approximately two dozen infrageneric groups. One group, subsection Boreali-Americanae in Section Plagiostigma, also known as the acaulescent blue violets, is endemic to North America and contains 10-25 species, depending on the taxonomic treatment. The subsection is notorious for its extensive hybridization and introgression, and bewildering patterns of population and geographic variation in certain taxa. Several taxa have lobed to dissected leaf blades during some or all of the growing seasion. Taxa in the homophyllous group with such divided leaves produces lobed or divided leaf blades throughout the year and includes Viola pedatifida G. Don., Viola brittoniana Pollard (sometimes treated as a subspecies of the first one), Viola subsinuata (Greene) Greene (treated by some under the name Viola palmata L.), and an undescribed shale woodland violet in Virginia. Recent field and herbarium investigations have been initiated on plants assignable to the shallowly or deeply lobed-leaved Viola subsinuata. Focusing on extremes of lobing within populations in order to accommodate for putative hybridization with Viola sororia Willd. and other unlobed violets in the vicinity, we have detected four subtly distinct phenotypes with slightly overlapping ranges and somewhat different microhabitat tolerances, which may represent cryptic species with quite different evolutionary origins. A Great Lakes taxon with deeply biternately lobed leaf blades ranges from southeastern Michigan into western Ohio and near Lake Erie into New York, and may represent Pleistocene or post-Pleistocene hybridization of Viola pedatifida and Viola sororia followed by subsequent range contraction. A Western Alleghany Plateau/central Appalachian taxon with shallowly lobed leaf blades is distributed from eastern Ohio to Pennsylvania, south to Virginia, and potentially has a more ancient, non-hybrid origin. A Piedmont/Atlantic Coast phenotype is similar to Viola brittoniana, with simplified deeply lobed leaf blades, and may have a hybrid origin implicating the latter and Viola sororia. The fourth phenotype is a deeply lobed violet found from Virginia to southeastern Alabama, in different microhabitats from the shallowly lobed Appalachian phenotype. It produces the most consistently deeply divided and most densely villous leaf blades in the Viola subsinuata complex and likely has a more ancient, non-hybrid origin. Morphological studies and genetic characterization with microsatellites and chloroplast spacer sequences are underway to test hypotheses of cryptic species, clarify variation patterns, and illuminate the evolutionary bases of variation in this perplexingly polymorphic taxon.

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1 - Ohio University, Department of Environmental & Plant Biology, 315 Porter Hall, Athens, OH, 45701, USA
2 - Ohio University, ENVIR & PLANT BIOLOGY-PORTER H, 315 Porter Hall, Athens, OH, 45701-2979, USA

Viola subsinuata
Cryptic species.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PSY028
Abstract ID:575
Candidate for Awards:None

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