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Abstract Detail

Systematics Section/ASPT

Challangundla, Lavanya [1], Wallace, Lisa [2].

Morphological and genetic analyses do not indicate differences among the varieties of Xanthisma spinulosum (Asteraceae) in Arizona.

Xanthisma spinulosum encompasses five varieties, three of which occur in Arizona. Despite this recognition of varieties, there is considerable variation within and across populations, which makes identification of these taxa difficult in the field. This suggests that recognition of varieties may not be warranted. In this study, we quantified morphological and genetic variation on herbarium collections of the three varieties occurring in Arizona, chihuahuanum, goodingii, and spinulosum, to evaluate their distinctiveness. Morphological traits were measured on stems, leaves, inflorescences and flowers and genetic variation was estimated using Amplified Fragment Length Polymorphism (AFLP). Neither K-means analysis nor principal components analysis of the morphological dataset indicated the presence of distinct groups, and no diagnostic characters separating the three taxa could be identified. Genetic analysis based on AFLP’s for 50 specimens also indicated little evidence of genetic structuring consistent with varietal designation (ÏST = 0.024, p< 0.05). A neighbor-joining analysis based on the matrix of AFLP bands also suggests lack of three distinct varieties, which is consistent with the morphological dataset. These results support the presence of a highly variable species, Xanthisma spinulosum without discernible intraspecific ranks.

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1 - Mississippi State University, Biological Sciences, PO Box GY, O-160, Mississippi State, MS, 39762, USA
2 - Mississippi State University, PO Box GY, Mississippi State, MS, 39762, USA

Xanthisma spinulosum
Intraspecific variation
Intraspecific ranks
herbarium specimens.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PSY054
Abstract ID:870
Candidate for Awards:None

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