Abstract Detail


Wettewa, Eranga [1], Wallace, Lisa [2].

Insights on the biogeographic origin and the floral trait evolution of Platanthera subgenus Limnorchis (Orchidaceae), using target enrichment approaches.

Platanthera is one of the largest genera of temperate orchids and exemplifies a lineage that has adaptively radiated into diverse habitats within North America, Asia, Europe, North Africa, Borneo, and Sarawak. Major centers of diversity in this genus are western North America and eastern Asia. The diversity in floral morphological traits such as the floral color, shape and the length of nectar spur has led to numerous pollination syndromes in the flowers, making Platanthera an ideal system to study the evolution of floral traits and pollination biology.  Despite its diversity, a thorough phylogenetic hypothesis for the genus is lacking because no studies have yet sampled taxa exhaustively or developed a robust molecular toolkit. Nevertheless, in past phylogenetic studies, some intrageneric groups of species appear to be monophyletic. While there is strong evidence that suggests monophyly of subgenus Limnorchis, the majority of taxa in this group have not been included in a phylogenetic analysis. In this study, I developed a new toolkit for Platanthera consisting of genomic information from 617 low-copy nuclear loci. Using a targeted enrichment approach, I collected high-throughput sequence data from these loci in 23 accessions, including nine diploid species of subgenus Limnorchis. A maximum likelihood analysis resolved a strongly supported monophyletic clade for subgenus Limnorchis. Ancestral biogeographic reconstruction indicated that subgenus Limnorchis originated in western North America ca. 3 – 4.5 Mya from an ancestor that was widespread in western North America and eastern Asia and subsequently diversified in western North America, followed by dispersal of some species to eastern North America. Ancestral character reconstruction suggests convergent evolution of spur length, shape and viscidium shape, in response to similar pollinators. Understanding the biogeographic history and morphological diversification of subgenus Limnorchis within a phylogenetic context will contribute to an updated taxonomy for the subgenus.

1 - Mississippi State University, Department of Biological Sciences, 219 Harned Hall, 295 Lee Blvd, Mississippi State,, Starkville, MS, 39762, United States
2 - Old Dominion University, Biological Sciences, Mills Godwin Building Rm. 110, Norfolk, VA, 23529, United States

target capture
Target Enrichment

Presentation Type: Oral Paper
Session: SYS3, Systematics III: Cooley Award presentations
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 12:15 PM
Number: SYS3010
Abstract ID:469
Candidate for Awards:George R. Cooley Award

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