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Abstract Detail



Systematics Section/ASPT

Cardinal-McTeague, Warren [1], Gillespie, Lynn [1].

Evolution of pollen morphology in tribe Plukenetieae (Euphorbiaceae).

Tribe Plukenetieae (Euphorbiaceae, Acalyphoideae) is a diverse pantropical lineage of c. 17 genera and c. 350 species notable in the family for their twining habit, stinging hair defenses, diverse floral and pollen morphology, and specialized pollination syndromes. Plukenetieae pollen is extremely variable, especially in exine morphology and aperture condition. Of the three subtribes, Dalechampiinae is differentiated by tricolporate pollen with an endocingulate endopore, while Plukenetiinae have tricolpate pollen with uneven aperture margins. Tragiinae pollen can be tricolpate with uneven aperture margins, weakly tricolpate or triporate, irregularly aperturate, or inaperturate, and is predicted to have experienced multiple transitions to poorly defined apertures and inaperturate pollen, which are uncommon conditions in eudicot pollen. Using a molecular phylogeny obtained with nrITS and plastid psbA-trnH, 3’ partial ndhF, and matK sequence data, and ancestral state reconstructions, we elucidate the evolutionary history of pollen morphology in Plukenetieae. Exine morphology was variable throughout the phylogeny and ancestral states were found to be equivocal. Endopores were most likely lost once in the ancestor of Plukenetiinae + Tragiinae, followed by multiple independent shifts to less defined apertures and inaperturate pollen in subtribe Tragiinae. Our results strongly suggest that pollen morphology is useful for defining generic and subgeneric boundaries, and that Plukenetieae may be an important study group to help explore the selective pressures for reduced pollen apertures in eudicots.


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1 - Canadian Museum of Nature, Research & Collections, PO Box 3443, Station D, Ottawa, ON, K1P 6P4, Canada

Keywords:
Euphorbiaceae
pollen
SEM
ancestral character reconstruction
Phylogenetics
Evolution
taxonomy.

Presentation Type: Oral Paper:Papers for Sections
Session: 5
Location: Salon 9/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 11:45 AM
Number: 5015
Abstract ID:275
Candidate for Awards:Cinq Mars Award


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