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Abstract Detail


Agoglossakis, Kalliopi M. [1], Olfelt, Joel [2].

Leaf Shape, Morphometrics, and Taxonomic Boundaries Within the Arctic-Alpine Succulent Rhodiola integrifolia (Crassulaceae).

Knowledge of patterns of morphological variation across a taxon’s range, coupled with molecular phylogenetic data, can provide the power to describe both the taxon’s evolutionary history, and its current taxonomic subgroups in ways that are useful to systematists, field botanists, and plant conservation biologists. We are studying patterns of variability within Rhodiola integrifolia, which ranges from arctic-alpine habitats of eastern Russia, northern Siberia, and Alaska, along the highest altitudes of the western mountains of North America, down to the sky islands of New Mexico and Arizona. Disjunct populations, far from the main range, occur in South Dakota, Minnesota, and New York (subspecies leedyi). These populations are protected under state and federal endangered species acts. Another distinct subspecies occurs on Sierra Blanca, New Mexico (subspecies neomexicana). The current nomenclature for R. integrifolia is based on early morphological studies using plants from a limited portion of the range. This nomenclature does not correspond well with current phylogenetic analyses of the taxon, which were constructed using samples from across the range, and suggest the taxon contains at least two lineages that should be described as distinct species (north and south lineages, respectively). To test the correspondence of morphological variation across the range of R. integrifolia with the current phylogeny, and potentially to develop corresponding taxonomic keys, we are analyzing R. integrifolia herbarium specimens. We described twelve groups across the range of R. integrifolia based on biogeography and taxonomy and obtained 904 specimens from ten herbaria in the US, Canada, and Russia. Of these, we selected 287 specimens with well-preserved leaves and digitized them (300dpi). We identified seven leaf landmarks (i.e., features along the leaf margin and prominent venation) for shape analysis using geometric morphometric methods, and eight traditional morphological features (e.g. leaf length/width ratio) for standard measurements. Our preliminary landmark analysis of 178 plants from nine of the groups suggests shape variability is greatest in Alaska and that four groups have shapes unique to the regions. Our preliminary analyses of the traditional morphological data do not identify diagnostic features that would be useful in a taxonomic key, but preliminary Principal Components Analysis of the geometric morphometric shape coordinates suggests that the morphological differentiation broadly corresponds with the molecular phylogeny. The patterns of morphological variation may result from plant responses to local environments and may make the development of taxonomic keys problematic for this taxon.

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1 - Northeastern Illinois University, Biology, 5500 North St. Louis, Chicago, IL, 60625, United States
2 - Northeastern Illinois University, 5500 North St. Louis Avenue, Chicago, IL, 60625, USA

Geometric morphometrics
leaf morphology
subspecies delimitation
species boundaries
cryptic species
relictual species.

Presentation Type: Oral Paper
Session: 3, Ecology Section - Community Processes and Delineation
Location: Sundance 5/Omni Hotel
Date: Monday, June 26th, 2017
Time: 9:30 AM
Number: 3006
Abstract ID:486
Candidate for Awards:None

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