C. Lannerherrera et al., DIVERSITY IN NATURAL-POPULATIONS OF WILD BRASSICA-OLERACEA AS ESTIMATED BY ISOZYME AND RAPD ANALYSIS, Genetic resources and crop evolution, 43(1), 1996, pp. 13-23
Naturally occurring populations of wild Brassica oleracea were collect
ed in Spain, France, and Great Britain. Allele frequencies at four iso
zyme loci were determined for 18 populations, while five populations w
ere screened using five random primers to generate RAPDs. Levels of ho
mozygosity and gene diversity, H, were computed for each population us
ing isozyme data and RAPD data when applicable. Homozygosity levels te
nded to be higher in smaller populations, which could also be observed
as increased numbers of homozygous loci in smaller populations. Gene
diversity values based on isozymes indicated considerable within popul
ation variation regardless of population size. The RAPID based gene di
versities were significantly higher and the two exceptional population
s displayed diversity levels more in keeping with the rest. The coeffi
cient of gene differentiation, G(ST), for populations in each region s
howed that the Spanish populations were more homogeneous than the Fren
ch or British. When the G(ST) for all populations was calculated using
isozymes vs. RAPD data, the RAPD data gave a significantly lower valu
e, a plausible result of the higher within population variation detect
ed using RAPDs. Genetic distances between populations from different r
egions were also calculated from both data sets and used to produce ph
enograms. Clustering according to geographic region was not evident us
ing either isozyme or RAPD data.