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Abstract Detail


Dignan, Audrey [1], Bruederle, Leo [2].

Historical Biogeography of Physocarpus opulifolius s.l. (Rosaceae): Implications for the Flora of Colorado and the Southwestern US.

Modern distributional patterns are largely shaped by historical climatic conditions. Glacial-interglacial fluctuations throughout the Pleistocene resulted in widespread re-organizations of vegetation communities and complex biogeographic histories of many North American plants, including Physocarpus (Cambess.) Raf. (Rosaceae), an Arcto-Tertiary relict. Further, these geographic responses have resulted in broad disjunctions within distributions as well as sympatry among taxa with disparate biogeographic histories. Here, we investigate the historical biogeography of the taxonomically challenging Physocarpus opulifolius (L.) Maxim. sensu lato (Rosaceae), a species complex with cryptic morphological variation. To reduce taxonomic uncertainty and ensure precise identification, we assessed variation for follicle pubescence — a diagnostic character for the complex — following The Flora of North America, North of Mexico (FNA). Using occurrence data from 280 georeferenced herbarium accessions collected across the range of the complex, we constructed climatic niche models and hindcast to the Last Glacial Maximum (ca. 21,000 yr BP) and mid-Holocene (ca. 6,000 yr BP). Physocarpus opulifolius s.l. can be differentiated into two primary forms, which display key differences in geographic range since the LGM. Physocarpus opulifolius sensu stricto appears to have occupied an Atlantic Coastal Plain refugium during the LGM, while the second taxon in the complex, P. intermedius (Rydb.) Schneid., survived the LGM in suitable habitats as far southwest as the Sierra Madre Oriental in Mexico. Further, the disjunction in the modern distribution of P. intermedius — which has core range in eastern temperate woodlands and prairies, and isolated populations along the North American Cordillera from the Black Hills to the Sierra Madres — appears to have arisen during post-glacial expansion. The biogeographical and morphological differences between these two taxa support taxonomic recognition of the P. opulifolius s.l. complex. These findings shed light on the biogeographic origins of the flora of the southwestern US and documented the importance of precise taxonomic identification.

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1 - 2801 S Roslyn St, Denver, CO, 80231, United States
2 - University Of Colorado Denver, Integrative Biology, CB171, P.o. 173364, Denver, CO, 80217, United States

Historical Biogeography
climatic niche modeling
eastern woodland-prairie

Presentation Type: Oral Paper
Session: BIOG1, Biogeography I
Location: Tucson E/Starr Pass
Date: Monday, July 29th, 2019
Time: 11:30 AM
Number: BIOG1013
Abstract ID:643
Candidate for Awards:None

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