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Abstract Detail

Systematics Section/ASPT

Johnson, Erin [1], Ochoterena, Helga [2], Flores Olvera, Hilda [3], Douglas, Norman [1], Moore, Michael J. [1].

Exploring the phylogenetic position of a bizarre, poorly known gypsum endemic plant: Hedyotis teretifolia (Rubiaceae).

Hedyotis (Rubiaceae) is a taxonomically difficult genus that includes a number of arid-adapted species in North America. Most North American Hedyotis species are small, herbaceous plants with narrow leaves and do not display a preference for one soil type. However, the northern Mexican species Hedyotis teretifolia is restricted to gypsum soils in southwestern Coahuila and is characterized by several morphological features that are bizarre for the family, including strong succulence, petals that persist on the flowers during fruit development, and an unusual ovary position. It appears that Hedyotis teretifolia diverged from the other major lineages in the Houstonia Clade early on in the history of the clade, and the unusual morphology and soil preferences of H. teretifolia may mean that this taxon became adapted to gypsum soon after it split from the rest of the Houstonia Clade, perhaps several million years ago. This divergence suggests this species may be a relatively ancient lineage and perhaps distinct enough from the other species in the Houstonia Clade to warrant treatment as a new genus. To test these hypotheses, we generated DNA sequence data for H. teretifolia and several other North American taxa in the genus, including three chloroplast loci (trnL/F spacer atpB/rbcL spacer, and the rps16 intron) and one nuclear locus (ITS). Phylogenetic analyses based on these sequences and all other Spermacoceae sequences on GenBank suggest that H. teretifolia diverged early on in the evolutionary history of North American Hedyotis, but do not clearly resolve whether H. teretifolia should be treated as a new genus.

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Related Links:
Phylogeny and Phylogeography of Gypsum Endemism

1 - Oberlin College, Department of Biology, 119 Woodland St., Oberlin, OH, 44074, USA
2 - Instituto De Biologia, UNAM, Depto Botánica-Apdo.Postal 70-367, Coyoacan, Mexico DF, N/A, 04510, Mexico
3 - Instituto De Biologia, UNAM, Depto Botánica, Apdo.Postal 70-367, Coyoacan, Mexico, DF, 04510, Mexico

gypsum endemism
North America.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PSY031
Abstract ID:507
Candidate for Awards:None

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