Abstract Detail



Systematics

Murphy, Thomas H. [1], Estes, L. Dwayne [1].

Morphological Discontinuity in the Clematis reticulata Species Complex (Ranunculaceae: Subgenus Viorna) and its Taxonomic Implications.

Clematis subgenus Viorna consists of approximately 20 species in North America. While subgenus Viorna has been subjected to constant taxonomic scrutiny at the sectional and subsectional ranks, little attention has been directed towards variation at the intraspecific level. The past 40 years of Clematis subgenus Viorna taxonomy has shown that narrow endemism is common and species diversity is higher than originally thought. Clematis reticulata sensu lato is a member of subgenus Viorna that has escaped thorough taxonomic and systematic study. Past studies have attributed morphological variation to phenotypic plasticity and clinal variation, but this claim has never been supported with data. Recent observations of novel characters such as peduncle and pedicel length, bract position, bract size, and several vegetative characters appear to correspond to geographic disjunctions and habitat. Examination of herbarium specimens, extensive fieldwork, and observation of preliminary common garden experiments have led us to form eight hypothesized operational taxonomic units. To test these hypotheses, non-metric multidimensional scaling and cluster analyses were employed to detect distinct groups based on measurements of selected quantitative and qualitative morphological characters from herbarium specimens. Tukey HSD and nonparametric statistics were used to test the significance of all quantitative characters. This preliminary analysis further corroborates our hypothesis that C. reticulata sensu lato may consist of several potential new taxa. Future research will focus on increasing sample sizes of herbarium specimens used in multivariate analyses, incorporating a second data set from a common garden experiment to estimate phenotypic plasticity, and collecting data from micromorphological characters.


Related Links:
Blog by Dr. L. Dwayne Estes with Two Posts Pertaining to Clematis subgenus Viorna


1 - Austin Peay State University, Center of Excellence for Field Biology, SSC, D125, P.O. Box 4718, Clarksville, TN, 37040, USA

Keywords:
taxonomy
systematics
morphometrics
species delimitation
multivariate statistics
Clematis.

Presentation Type: Oral Paper
Number:
Abstract ID:757
Candidate for Awards:None


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