F. Batista et al., Allozyme diversity in three endemic species of Cistus (Cistaceae) from theCanary Islands: Intraspecific and interspecific comparisons and implications for genetic conservation, AM J BOTANY, 88(9), 2001, pp. 1582-1592
Patterns of variation at 13 isozyme loci were examined in 11 populations in
three Cistus species strictly endemic to the Canary Islands. Cistus osbaec
kiaefolius and C. chinamadensis display low levels of isozyme variation ass
ociated with moderate to high interpopulation differentiation, which probab
ly arose through historical bottlenecks in a landscape of habitat fragmenta
tion, grazing, and human influence. By contrast, C. symphytifolius ranks am
ong the subset of narrow endemics with high levels of isozyme variation and
features different degrees of genetic structuring that are closely associa
ted with taxonomic ascription. Low interpopulation differentiation in var.
leucophyllus is possibly a reflection of its recent origin or of moderate l
evels of gene flow between its populations. High interpopulation differenti
ation in var. symphytifolius probably arose due to slight ecological differ
ences between populations coupled with low levels of gene flow. Interpretat
ion of neighbor-joining trees in the light of geological data substantiates
the hypothesis that C. symphytifolius (or a very close relative) might be
the ancestor of the other stands of Cistus in the islands. Conservation imp
lications of our survey are the identification of the two populations of C.
chinamadensis with the highest allele and genotype richness for preservati
on on genetic grounds and advice to prevent artificial gene flow in this ta
xon test it might disrupt locally adapted gene combinations. All population
s of C. osbaeckiaefolius should be given conservation priority on ecologica
l grounds despite their genetic depauperation.