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The New England Botanical Club is holding monthly meetings in a virtual format using Zoom. Meetings will be the first Saturday of the month at 7pm (except January on second Saturday). Non-members may register for the meeting access link here.
Dr. Eric T. Doucette
Dept of Biology
Massachusetts College of Liberal Arts
North Adams, MA
"A Species-Complex Approach to Taxon Delimitation in Amelanchier (shadbush)"
Mark your calendar for the next NEBC Meeting on Saturday, May 1, 2021 at 7pm via Zoom.
Abstract: Amelanchier (shadbushes or serviceberries) are shrubs and small trees related to apples and hawthorns and are most conspicuous in the spring for their white flowers. Shadbushes grow throughout North America, often in abundance, and less frequently in southern Europe, northern Africa, western Asia, and eastern Asia. They are most common in early successional habitats, their fruits are eaten by many species of wildlife, and some species are sold horticulturally. Identification of Amelanchier to the species level has a deserved reputation for difficulty owing to well-documented characteristics that create morphological complexity: interspecific gene flow, multiple ploidy levels generated by hybridization, and near-obligate apomixis (asexual seed production) in polyploids. These processes create entities that fill the phenotypic space between both diploids and other polyploids, and they weaken taxon cohesion. Many of these polyploids are geographically restricted, yet morphologically distinguishable "microspecies," while others become widespread, successful polyploid species. Recognizing all "microspecies" as species may burden Amelanchier taxonomy and nomenclature and mischaracterize the temporal position of the speciation processes in these taxa. Conversely, including all of this diversity into the conventional, currently circumscribed species greatly widens their morphological breadth and obscures real morphological, ecological, and phenological differences between them. A species-complex approach to taxon delimitation recognizes diploids and distinct widespread polyploids, but places hybrid-derived "microspecies" in diploid-centered species complexes as opposed to naming them as distinct species. This species-complex approach serves the goals of recognizing taxa and the mechanisms that form them, minimizes the identification error rate prevalent in the field and herbaria, acknowledges the frequent inter-complex hybridization, and does not burden the formal taxonomy.
