HCS Spring 2016 Seminar Series
“The beard tongues: rapid diversification in a changing environment.”
Abstract: Penstemon (Plantaginaceae), commonly known as the beardtongues, is the largest genus endemic to North America, and it is hypothesized to represent multiple and parallel adaptive radiations. Its 280 species comprise six subgenera, 12 sections and 23 subsections. Most species occur in the western cordillera, but species range from Guatemala to Alaska and coast-to-coast. The Intermountain Region, bounded by the Rocky Mountains in the east and the Cascade-Sierra Nevada system in the west, represents the center of diversity for Penstemon. Penstemon exhibits considerable morphological diversity. Species may be woody, suffrutescent, or herbaceous. Some species form dense mats, some are long-lived shrubs, and others are short-lived perennials. Variable characters in leaves, inflorescence architecture, vestiture, and floral structures distinguish species of Penstemon. Flowers of most penstemons attract a wide variety of insect pollinators including bees and wasps, lepidopterans, or bee flies, whereas ca. 40 species have floral syndromes typical of hummingbird pollination. Using a previously sequenced data set consisting of the nuclear ITS region and two chloroplast genes (trnCD and trnTL), we conducted a preliminary analysis of speciation rates associated with major morphological groups across the Penstemon phylogeny. Morphological features were coded as either binary or multistate characters and analyzed using the BiSSE and MuSSE models from the R package DIVERSITREE. Diversification analyses were also completed using the program BAMM to look for changes in the rate of diversification. Results of this study are discussed in the context of global change since the Last Glacial Maximum.
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