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Carnegie Museum of Natural History
4400 Forbes Ave, Pittsburgh, Pennsylvania 15213
Join us for science seminars at Carnegie Museum of Natural History. Hear Carnegie scientists and invited researchers discuss their latest findings on a wide variety of topics.
Earth Theater, first floor rear
Admission to the seminar is free. Check in at the front desk.
“Integrative Systematic Approaches Drive a Taxonomic Revolution in the Violet Family”
Harvey Ballard, PhD
Over the last 25 years, increasingly integrative systematic studies of the violet family, Violaceae, have led us to an ever greater appreciation of biological diversity and evolutionary processes in violets. Phylogenies based on nuclear and/or chloroplast gene regions have provided us a guide to examine patterns of morphological, anatomical, and cytogenetic differentiation at all levels in the Violaceae and have urged remodeling of genera and infrageneric groups. At the family level, we have been involved with describing or recircumscribing nearly a dozen new genera as distinct evolutionary lineages and have extensively revised the classification of genera. In the primarily herbaceous and cosmopolitan genus Viola, by far the largest with approximately 600 species, collaborative studies have revealed one of the most complex stories of allopolyploid evolution in the angiosperms, as well as numerous fascinating biogeographic patterns and disjunctions. In fact, only three of the primary evolutionary lineages of 16, two in South America, are diploid, whereas the remainder around the world are allopolyploid with two to 14 genomes. Our investigations into North American violets were rejuvenated five years ago, with a focus on Appalachian representatives of the dastardly «acaulescent blue» violets. This high-allopolyploid lineage embraces five genomes from three dramatically divergent violet lineages and displays bewildering variation patterns and extensive hybridization. Using a more integrative taxonomic approach involving intensive local field studies, common garden observations of flowering and fruiting morphology, examinations of petal trichomes and seeds, reproductive behavior and seed output, microsatellite data, and ecological niche inference, we have unexpectedly found much greater levels of diversity than previously known. Using the Unified Species Concept as an objective filter, we are interpreting species as evolutionary products and delineating them more narrowly. Our efforts are making taxonomic sense of highly polymorphic «species» that previously befuddled specialists and lay taxonomists, usually resulting in a number of regional or even local endemics with highly uniform morphologies and unique ecological niches. This exciting «taxonomic revolution» is leading us (hopefully) into an era where evolutionary principles guide us to detect and delineate species as products of evolution as much as possible, rather than the unfortunate fruits of taxonomic opinion.