Abstract Detail

Systematics

Wettewa, Eranga [1], Bailey, Nicholas [2], Wallace, Lisa [3].

EPIC markers for understanding evolutionary diversification in Platanthera section Limnorchis (Orchidaceae).

Platanthera (Orchidaceae) is one of the largest genera of temperate orchids, with more than 200 species occurring in north temperate areas. Previous phylogenetic analyses in this genus have identified major radiations of species and tested sectional boundaries with respect to closely related genera, but we still lack a clear understanding of relationships among species within these major clades. Platanthera section Limnorchis has been identified as monophyletic in these previous analyses, and this group has long been recognized to be morphologically distinct from other Platanthera in North America. However, the recognition of several new species recently and morphological similarity of U.S. species with congenerics in Mexico and Asia have hindered a thorough understanding of species diversity and phylogenetic relationships in Limnorchis. In this project, we developed six novel exon-primed-intron-crossing (EPIC) markers (>4100 base pairs) to use in estimating the phylogeny of section Limnorchis. Preliminary phylogenetic results of sequence variation in these markers are presented to test two hypotheses: 1) Section Limnorchis is monophyletic relative to other Platanthera species, 2) Species diagnosed by morphological characters are genetically divergent and represent distinct evolutionary lineages. The EPIC markers support monophyly of section Limnorchis relative to the three outgroup species used in this analysis, P. orbiculata, P. leucophaea and P. clavellata. These markers suggest the green-flowered P. stricta is divergent from other green-flowered taxa that are clustered together as sister to the clade of white-flowered P. dilatata samples. Among the green-flowered taxa, species that are morphologically distinct are also genetically distinct. By contrast, the varieties of P. dilatata, which are also morphologically distinct, are not individually resolved as monophyletic in this data set. In comparison to previous analyses of P. dilatata based on ITS and cpDNA markers, there is greater polymorphism in the EPIC loci, which may facilitate a greater understanding of diversification in relation to geography for this species complex. The EPIC markers developed in this project are expected to amplify broadly within Platanthera and should be useful in resolving phylogenetic relationships in both closely and distantly related species as well as for intraspecific projects involving phylogeography, gene flow, and hybridization. These results will assist in revising the taxonomy of section Limnorchis, studying the evolution of flower morphology, and testing biogeographic hypotheses of diversification across North America.

1 - Mississippi State University, Biological Sciences, PO Box GY, Starkville, MS, 39762, USA
2 - Mississippi State University, PO Box GY, Starkville, MS, 39762, United States
3 - Mississippi State University, Biological Sciences, PO Box GY, Starkville, MS, 39762, United States

Keywords:
Platanthera
Limnorchis
EPIC markers.

Presentation Type: Poster
Session: P, Systematics Section/ASPT Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY017
Abstract ID:867
Candidate for Awards:None