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Abstract Detail


Systematics Section

Adhikari, Binaya [1], Wallace, Lisa [1].

Geo-ecological patterns of distribution among the varieties of scentbottle orchids, Platantheradilatata, based on GIS.

Ecological analyses provide a complementary means of studying evolutionary responses to landscape changes. In this study, we examined environmental variation across populations of Platantheradilatata (Orchidaceae) identified from herbarium records and field collections using niche models based on numerous environmental variables to understand if divergence within this species is associated with ecological factors. Platanthera dilatata comprises three varieties, dilatata,albiflora and leucostachys, which are recognized based on differences in floral morphology and geographic range. Genetic studies have also indicated recent and active divergence in this species. If the varieties are geographically isolated,then allopatric divergence could be a leading cause of the genetic and morphological divergence we see in this species. Here, we test the hypothesis that the varieties are ecologically distinct in western North America. Niche models predicted similarly suitable areas for vars.dilatata and leucostachys in some areas, and models for vars. dilatata and leucostachys suggest similar environmental variables are responsible for the populations we examined in western North America. Relatively few populations of var. dilatata occur inthe coastal ranges of the Pacific Northwest,which suggests that the dry habitat between the Rocky Mountains and Pacific Coastal ranges could have limited westward colonization from the Rockies and fragmented coastal populations, thereby stimulating localized divergence of these varieties. Some of the variables predicted from niche models suggest different environmental variables are important to var. albiflora. This taxon is common in the southern Rockies, absent from coastal areas of the Pacific Northwest, and occurs in coastal areas of Canada and Alaska. Although it has been suggested that var. albiflora maybe limited to higher elevations than either of the other varieties, we did not find this variable to be of great importance in niche models for this taxon.These analyses will be helpful for identifying areas to target for population sampling to better understand genetic patterns of divergence and the underlying causes of evolutionary divergence in P.dilatata.

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1 - Mississippi State University, PO Box GY, Mississippi State, MS, 39762, USA

Keywords:
P. dilatata
western North America
niche models.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM
Number: PSY045
Abstract ID:390


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