Bb. Kinloch et al., GENETICS OF CRONARTIUM-RIBICOLA - IV - POPULATION-STRUCTURE IN WESTERN NORTH-AMERICA, Canadian journal of botany, 76(1), 1998, pp. 91-98
Population genetic parameters were estimated for six populations of Cr
onartium ribicola in western North America from British Columbia to th
e southern Sierra Nevada, and two outgroups from eastern North America
, using isozyme, random amplified polymorphic DNA (RAPD) and restricti
on fragment length polymorphism (RFLP) markers on cultured haploid clo
nes. Diversity was low, with only 8% polymorphism in the 212 markers i
dentified. Each polymorphic locus had only two alleles, except for an
RFLP marker in the ribosomal DNA complex with multiple alleles, that r
esulted from variable numbers of tandem repeats. Expected heterozygosi
ty within populations, estimated from diploid teliospores, was only 0.
025. The three types of markers were highly consistent with each other
for these parameters. Yet, populations were highly differentiated; th
e proportion of the total variation attributable to differences among
populations was 0.205. Multivariate statistical analysis as well as di
fferent clustering algorithms based on contrasting evolutionary assump
tions (drift, mutation) all showed similar relationships and differenc
es among populations. Genetic distances were not associated with geogr
aphic distances; western populations within a few kilometres of each o
ther were often more distant from each other genetically than they wer
e from eastern populations across the continent. The lack of pattern o
ver the landscape of this metapopulation is consistent with aspects of
the life cycle and epidemiological behavior of the pathogen, in which
genetic drift appears to play a major role.