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Abstract Detail

Systematics Section

Mayer, Michael [1], Rebman, Jon [2].

Is Cylindropuntia xfosbergii (Cactaceae) a hybrid?

Cylindropuntia xfosbergii (C. B. Wolf) Rebman, M. A. Baker, & Pinkava, the pink teddy-bear cholla, has long been assumed to be a hybrid. It is triploid, bears fruit with abortive seeds, and exhibits substantial morphological similarities to C. bigelovii (Engelm.) F. M. Knuth, one of its presumed parents. The putative hybrid is a rare endemic of the Anza Borrego Desert region of eastern San Diego County. The plant stands out as the tallest and pinkest cholla in the desert scrub of Vallecito and Mason Valleys. AFLP analysis of 27 exemplars of C. xfosbergii, C. bigelovii and exemplars of other parental candidates (C. californica var. parkeri, C. wolfii, and C. ganderi) generated 692 polymorphic loci. The results do not portray C. xfosbergii as a typical sterile hybrid: it possesses numbers of polymorphic and unique loci comparable to the other species in the study, including those that reproduce sexually. Cylindropuntia. xfosbergii shares more than 10 times the number of exclusive loci with C. bigelovii than with any other taxon. A neighbor-joining analysis also affirms the close relationship between C. xfosbergii and C. bigelovii, but reveals no other clear candidate for the second parent. We conclude that if C. xfosbergii is a hybrid, its other parent escaped our sampling or is extinct, or perhaps more likely, C. xfosbergii is not a hybrid, but the sister of C. bigelovii.

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1 - University of San Diego, Department of Biology, 5998 Alcala Park, San Diego, California, 92110-2492, USA
2 - San Diego Museum of Natural History, P.O. Box 121390, San Diego, California, 92112, USA


Presentation Type: Oral Paper:Papers for Sections
Session: 55
Location: 554/Convention Center
Date: Wednesday, August 4th, 2010
Time: 4:15 PM
Number: 55013
Abstract ID:250

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