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Genome size and karyotype evolution in the slipper orchids (Cypripedioideae: Orchidaceae)
Author(s) -
Cox Antony V.,
Abdelnour Gregory J.,
Bennett Michael D.,
Leitch Ilia J.
Publication year - 1998
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2446538
Subject(s) - biology , genome size , karyotype , mitochondrial dna , evolutionary biology , orchidaceae , nuclear dna , genome , zoology , genetics , chromosome , botany , gene
Nuclear DNA contents (4C) were estimated by Feulgen microdensitometry in 27 species of slipper orchids. These data and recent information concerning the molecular systematics of Cypripedioideae allow an interesting re‐evaluation of karyotype and genome size variation among slipper orchids in a phylogenetic context. DNA amounts differed 5.7‐fold, from 24.4 pg in Phragmipedium longifolium to 138.1 pg in Paphiopedilum wardii . The most derived clades of the conduplicate‐leaved slipper orchids have undergone a radical process of genome fragmentation that is most parsimoniously explained by Robertsonian changes involving centric fission. This process seems to have occurred independently of genome size variation. However, it may reflect environmental or selective pressures favoring higher numbers of linkage groups in the karyotype.