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Abstract Detail

Systematics Section

Ocampo, Gilberto [1].

Evolution of chromosome numbers in Portulaca (Portulacaceae).

Portulaca L. (Portulacaceae) comprises ca. 100 species distributed around the world. There are records in the literature on chromosome numbers for ca. 20% of species in the genus, and the base chromosome number has been proposed at x = 4 or 9. The most common haploid number is 9, but the range varies from n=4 in P. suffrutescens, to n=27 in certain subspecies of P. oleracea, although there is a report of n=57 for a putative hybrid found in Hawaii. A preliminary study to estimate ancestral chromosome numbers in Portulaca is presented here. A phylogeny for 18 taxa (13 species, 6 subspecies, and one cultivar) was obtained using a combined data matrix of nuclear (ITS) and chloroplast (ndhF, psbD-trnT spacer, and ndhA intron) DNA sequences. This hypothesis of relationships and the data on chromosome numbers obtained from the literature were used to reconstruct the evolution of chromosome numbers in a likelihood framework, by comparing the eight models available in the program chromEvol (Mayrose et al., 2010). The base chromosome number for the genus and variations in chromosome numbers along the phylogeny are discussed.

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1 - California Academy of Sciences, Department of Botany, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA, 94118, USA

chromosome number

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PSY029
Abstract ID:352

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