Bo. Jonsson et al., CLONAL DIVERSITY AND ALLOZYME VARIATION IN POPULATIONS OF THE ARCTIC SEDGE CAREX-BIGELOWII (CYPERACEAE), Journal of Ecology, 84(3), 1996, pp. 449-459
1 A study of allozyme variation in vegetatively propagating population
s of the rhizomatous sedge Carex bigelowii, revealed high levels of cl
onal diversity (genet diversity) within populations. The structure of
allelic variation within the populations suggests that sexual reproduc
tion has played a significant role in these C. bigelowii populations,
despite present lack of seedling recruitment. The study was carried ou
t in moss-heath communities on Icelandic lava-fields. Two adjacent pop
ulations were studied at one site, while a third population was studie
d at a second site, 35 km away from the first two populations. 2 The n
umber of genets detected in each population, among 85-88 analysed rame
ts, ranged from 41 to 55 (minimum estimate). Samples were taken every
4m along transects in the populations. Ramets with the same allozyme g
enotype were often spatially aggregated. No seedlings have been observ
ed in the populations during five years of demographic studies. 3 All
the populations studied showed a diploid expression of allozymes and h
igh levels of allelic variation, with on average 49% polymorphic loci
(P), 1.77 alleles per locus (A) and an allelic diversity (H-S) of 0.16
7, Similar levels of within-population variability are found in many w
ind-pollinated and outcrossing plant species. 4 The difference between
observed and expected heterozygosity was small in all populations, su
ggesting high levels of outbreeding. 5 Comparisons with other Carer ta
xa show that the levels of and structuring of allozyme diversity in C.
bigelowii is similar to that in other outbreeding species (usually rh
izomatous), and much higher than in inbreeding species (which are usua
lly caespitose). 6 Only 5% of the total allelic diversity was explaine
d by differences between the two study sites (G(ST) = 0.055), suggesti
ng extensive recent or historic gene-flow.