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Abstract Detail

Systematics Section/ASPT

Almeda, Frank [1], Penneys, Darin S. [2], Reginato, Marcelo [3].

Patterns of chromosome number diversity and evolution in the Melastomataceae.

The number of species of Melastomataceae for which there is basic chromosome information has increased nearly 12-fold since 1970. Chromosome counts are now available for some 650 species in 76 genera. This constitutes 45% of the genera and 13% of the species worldwide. The diversity and derivation of chromosome numbers are evaluated in the context of what is known about other families in the Myrtales and a new forthcoming classification of the Melastomataceae based on a multi-gene phylogenetic analysis. Interpreting chromosome number evolution in the family presents some difficulties because of data gaps for some phylogenetically critical groups but sufficient data are now available to advance hypotheses about the original basic chromosome number for the family and to pose questions about a.) the direction of chromosome number change in clades, b.) the incidence of dysploidy and polypoidy, and c.) the relationships of high chromosome numbers to life history, variability, and geographic distribution. Forty haploid chromosome numbers (n) are known for the Melastomataceae, ranging from n=7 to n=90. Haploid numbers in the descending range from x=12 to x=9 are so common that they are considered the common basic numbers for the family. Five patterns of cytoevolution are proposed to account for the array of known chromosome numbers: 1. Stasis at the diploid level, 2. Interspecific polyploidy (euploidy), 3. Inter- and intra-specific polyploidy and dysploidy, 4. Constancy of paleopolyploid base numbers, and 5. Paleodysploidy followed by polyploidy. Polyploidy, preceded or followed by dysploidy, accounts for over 80% of all chromosome numbers reported for neotropical species.

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Related Links:
California Academy of Sciences, Department of Botany
Miconieae: Planetary Biodiversity Inventory website

1 - California Academy of Sciences, Department of Botany, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA, 94118, USA
2 - California Academy of Sciences, Department of Botany, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA, 94118, United States
3 - The New York Botanical Garden, 200th St. & Southern Blvd., Bronx, NY, 10458, USA

Chromosome numbers

Presentation Type: Oral Paper:Papers for Sections
Session: 39
Location: Elmwood/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 10:30 AM
Number: 39008
Abstract ID:278
Candidate for Awards:None

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