Clonal Diversity and Allozyme Variation in Populations of the Arctic Sedge Carex Bigelowii (Cyperaceae)

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Ecology.Summary 1 A study of allozyme variation in vegetatively propagating populations of the rhizomatous sedge Carex bigelowii, revealed high levels of clonal diversity (genet diversity) within populations. The structure of allelic variation within the populations suggests that sexual reprodugtion has played a significant role in these C. bigelowii populations, despite present lack of seedling recruitment. The study was carried out in moss-heath communities on Icelandic lava-fields. Two adjacent populations were studied at one site, while a third population was studied at a second site, 35 km away from the first two populations. 2 The number of genets detected in each population, among 85-88 analysed ramets, ranged from 41 to 55 (minimum estimate). Samples were taken every 4 m along transects in the populations. Ramets with the same allozyme genotype were often spatially aggregated. No seedlings have been observed in the populations during five years of demographic studies. 3 All the populations studied showed a diploid expression of allozymes and high levels of allelic variation, with on average 49% polymorphic loci (P), 1.77 alleles per locus (A) and an allelic diversity (Hs) of 0.167. Similar levels of within-population variability are found in many wind-pollinated and outcrossing plant species. 4 The difference between observed and expected heterozygosity was small in all populations, suggesting high levels of outbreeding. 5 Comparisons with other Carex taxa show that the levels of and structuring of allozyme diversity in C. bigelowii is similar to that in other outbreeding species (usually rhizomatous), and much higher than in inbreeding species (which are usually caespitose). 6 Only 5% of the total allelic diversity was explained by differences between the two study sites (GST = 0.055), suggesting extensive recent or historic gene-flow.

Genetic structure and gene flow in an endangered perennial grass, Arctophila fulva var. pendulina

“…Jonsson et al 1996;Auge et al 2001;Lundqvist and Andersson 2001;Persson and Gustavsson 2001;Hangelbroek et al 2002). For example, in Carex bigelowii no seed-derived plantlets have been observed in natural stands, even though the species is genotypically highly variable (Jonsson et al 1996).…”

Allozyme diversity and geographic variation in the widespread coastal sedge, Carex arenaria

“…Two rare Idh-1 alleles (alleles 2 and 3) were each found in one site. For the enzyme system MDH, comparisons with other Carex species which have two to three polymorphic MDH loci (Jonsson et al , 1996;B.O. Jonsson & H.C. Prentice, in prep.…”

“…Despite having high chromosome numbers, Carex species usually show diploid patterns of variation at allozyme loci (e.g. Waterway, 1990;Ford et al , 1991;Hedrén & Prentice, 1996;Jonsson et al , 1996) and crossing experiments need to be carried out to investigate the genetic background of the Pgm-1 dosage effect. In the calculations of allelic variation, the 'dosage heterozygote' was treated as a 1 : 1 heterozygote (with one copy of each allele).…”

“…The majority of these species are characteristic of wetlands or tundra habitats (e.g. Ford et al, 1991;McClintock & Waterway, 1993;Jonsson et al, 1996) and are likely to have been relatively abundant in areas south of the ice-sheets during the glacial periods.…”

Genetic Variation and Clonal Diversity of the Two Divergent Types of Clonal Populations of Leymus chinensis Tzvel on the Song Liao Steppe in the West of Northeastern China

“…According to reports of plant ecologists (Jonsson et al 1996;Stehlik and Holderegger 2000), ramets having an identical genotype at all loci studied were considered to belong to the same clone. Expected and observed heterozygosities (H exp and H obs ) and Wright's fixation index (F; Wright 1965) were calculated for all populations using BIOSYS-1 (Swofford and Selander 1981).…”