eMonocot Cyperaceae

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Aneuploidal population differentiation in Carex sociata Boott (Cyperaceae) of the Ryukyu Islands, Japan

Publication Type:Journal Article
Year of Publication:2000
Authors:Ohkawa, T., Yokota, M., Hoshino T.
Journal:Botanical Journal of the Linnean Society
Volume:132
Pagination:337-358
Keywords:allozyme, allozyme variation, aneuploidy, complex cyperaceae, configurations, CRYPTOCARPAE, cytogeography, distance, diversity, genetic differentiation, genetic-relationships, hybridization, intraspecific aneuploids, NORTHEASTERN NORTH-AMERICA, spatial genetic structure
Abstract:

Chromosome numbers and configuration patterns were investigated at meiotic metaphase I in pollen mother cells of Carer sociata Boott collected from the Ryukyu Islands. Intraspecific aneuploidy composed of five consecutive chromosome numbers from 2n = 40 to 2n = 44 was found, and 2n=42 and 2n=44 aneuploids were both common. Almost all individuals examined showed stable chromosome associations at meiosis and almost all populations were characterized by a single chromosome number. These facts indicate the establishment of cytodemes in all localities, but the geographical distribution of each aneuploid type is widely overlapping. However, no obvious differences were found with respect to morphological, ecological, and genetic traits between the 2n = 42 and 2n = 44 aneuploids. Wright's inbreeding coefficients were highly positive, suggesting high levels of inbreeding of this species. The F-ST-values calculated among 11 populations were significantly positive at all examined loci, indicating the high levels of genetic differentiation among populations. Spatial autocorrelation analysis showed small-scale genetic structure in a population. These facts with respect to bleeding system and genetic structure indicate the extreme genetic differentiation and substructuring of C. sociata populations. We concluded that these reproductive traits such as restricted gene flow and inbreeding resulted in aneuploid differentiation among populations in C. sociata. (C) 2000 The Linnean Society of London.

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