Abstract Detail

Chromosome and Karyotype Evolution in Plants

Poindexter, Derick [1], Windham, Michael [2].

Chromosomal Variation in Carex Section Acrocystis: An Exploration of Phylogeographic Patterns and Morphological Correlates.

With more than 2,000 recognized species, Carex (Cyperaceae) is the 5^th most speciose genus of plants and a keystone taxon in a diversity of habitats. The first comparative chromosome studies of Carex were published just over a century ago by O. Heilborn, and it was clear from the start that the group would be a challenging subject for cytogenetic research. First, the genus proved to have unusually high chromosome base numbers (averaging ca. 2n = 60), making the precise determination of chromosome numbers difficult. Second, carices experience two unusual post-meiotic mitoses that tend to be more prominent than, and easily confused with, meiosis. And finally, members of the genus have holocentric chromosomes, meaning that chromosomal fission and fusion episodes occur with tremendous regularity, resulting in the proliferation of fertile dysploid populations within a given species. Due to these challenges, most members of the genus remain poorly known cytogenetically, and our understanding of the systematic utility of karyotypic variation has thus been limited. Here we present a case study focused on the largely North American clade of Carex section Acrocystis. Our cytogenetic analyses of this group resulted in 160+ chromosome counts representing 38 species and 7 natural hybrids. These data are presented within the context of an extensive morphological reassessment, biogeographic analysis, and improved phylogenetic resolution using NGS methods. This work provides a much-needed foundation for further investigations of chromosomal evolution within the genus Carex as a whole.

1 - University of North Carolina Chapel Hill, Biology, North Carolina Botanical Garden, NCU Herbarium, 401 Coker Hall, 120 South Rd., Chapel Hill, NC, 27599, USA
2 - Duke University, Biology, Campus Box 90338, Durham, NC, 27708, USA

Keywords:
Carex
Holocentric
Cyperaceae
Acrocystis.

Presentation Type: Colloquium Presentations
Session: C11, Chromosome and Karyotype Evolution in Plants
Location: /
Date: Friday, July 23rd, 2021
Time: 1:00 PM(EDT)
Number: C11012
Abstract ID:489
Candidate for Awards:None