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Systematics Section / ASPT

Bailey, C. Donovan [2], Hughes, Colin E. [1], Robertson, Ashley [1], Harris, Stephen A [1].

Using multiple gene trees to investigate hybridization and polyploidy in Leucaena (Fabaceae)..

Leucaena comprises 22 species of mimosoid legumes whose overall distribution extends from the extreme southern US to South America. Leucaena includes two recognized allotetraploids along with three other tetraploid species whose origin through allo or autopolyploidy remains unclear. Four of the five tetraploids are among the six species of Leucaena whose fruits are commonly collected from the wild or brought into backyard cultivation for use as a food in south-central Mexico. The prevalence of tetraploidy in general, characterized allopolyploidy, and other characterized and putative hybrids within Leucaena suggests that hybridization and polyploidy have been important mechanisms in the evolution of the genus. Here we present results of a RAPD-based approach to develop sequence-characterized regions from the nuclear genome. Regions with higher levels of DNA sequence variation than conventional ITS and cpDNA loci, appropriate for resolving relationships within subclades of Leucaena (Fabaceae), were screened and specific primers developed for amplification and sequencing. The overall aim of this study is to develop independent data sets for Leucaena to generate robust hypotheses of the divergent relationships among the 17 diploid species and potentially reticulate relationships of the five tetraploid species. New preliminary data from A9 and 23L regions and a combined analysis of 23L, A9, ITS, and cpDNA for the diploid taxa are presented to discuss the effectiveness of the strategy in the context of the study goals.

1 - University of Oxford, Department of Plant Sciences, South Parks Road, Oxford, OX1 3RB, United Kingdom
2 - New Mexico State University, Department of Biology, P.O. Box 3001, Dept. 3AF, Las Cruces, New Mexico, 88003-8001, USA

molecular systematics.

Presentation Type: Paper
Session: 13-6
Location: Cottonwood C (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 12:15 PM
Abstract ID:681

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