eMonocot Cyperaceae

an authoritative resource for Cyperaceae data worldwide, integrating global and regional perspectives

Changes in chromosome number associated with speciation in sedges: A phylogenetic study in Carex section Ovales (Cyperaceae) using AFLP data

Publication Type:Journal Article
Year of Publication:2007
Authors:Hipp, A. L., Rothrock, P. E., Reznicek, A. A., Berry P. E.
Date Published:2007
Keywords:AFLP phylogeny, agmatoploidy, amplified fragment length polymorphisms (AFLP), Carex, chromosomal evolution, maximum likelihood, minimum evolution, speciation

Phylogenetic analysis of amplified fragment length polymorphisms (AFLP) was used to infer patterns of morphologic and chromosomal evolution in an eastern North American group of sedges (ENA Clade I of Carex section Ovales). Distance analyses of AFLP data recover a tree that is topologically congruent with previous phylogenetic estimates based on nrDNA sequences and provide support for four species groups within ENA Clade I. A maximum likelihood method designed for analysis of restriction site data is used to evaluate the strength of support for alternative topologies. While there is little support for the precise placement of the root, likelihood of topologies in which any of the four clades identified within ENA Clade I is forced to be paraphyletic is much lower than likelihood of the optimal tree. Chromosome counts for a sampling of species from throughout section Ovales are mapped onto the tree as well as counts for all species in ENA Clade I. Parsimony reconstruction of ancestral character states suggest that (1) Heilborn’s hypothesis that more highly derived species in Carex have higher chromosome counts does not apply within section Ovales, (2) the migration to Eastern North America involved a decrease in average chromosome count within section Ovales, and (3) intermediate chromosome counts are ancestral within ENA Clade I. A more precise understanding of chromosomal evolution in Carex should be possible using likelihood analyses that take into account the intraspecific polymorphism and wide range of chromosome counts that characterize the genus.

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