Comparison of genetic diversity of the invasive weed Rubus alceifolius Poir. (Rosaceae) in its native range and in areas of introduction, using amplified fragment length polymorphism (AFLP) markers
L. Amsellem et al., Comparison of genetic diversity of the invasive weed Rubus alceifolius Poir. (Rosaceae) in its native range and in areas of introduction, using amplified fragment length polymorphism (AFLP) markers, MOL ECOL, 9(4), 2000, pp. 443-455
Theory predicts that colonization of new areas will be associated with popu
lation bottlenecks that reduce within-population genetic diversity and incr
ease genetic differentiation among populations. This should be especially t
rue for weedy plant species, which are often characterized by self-compatib
le breeding systems and vegetative propagation. To test this prediction, an
d to evaluate alternative scenarios for the history of introduction, the ge
netic diversity of Rubus alceifolius was studied with amplified fragment le
ngth polymorphism (AFLP) markers in its native range in southeast Asia and
in several areas where this plant has been introduced and is now a serious
weed (Indian Ocean islands, Australia). In its native range, R. alceifolius
showed great genetic variability within populations and among geographical
ly close populations (populations sampled ranging from northern Vietnam to
Java). In Madagascar, genetic variability was somewhat lower than in its na
tive range, but still considerable. Each population sampled in the other In
dian Ocean islands (Mayotte, La Reunion, Mauritius) was characterized by a
single different genotype of R. alceifolius for the markers studied, and cl
osely related to individuals from Madagascar. Queensland populations also i
ncluded only a single genotype, identical to that found in Mauritius. These
results suggest that R. alceifolius was first introduced into Madagascar,
perhaps on multiple occasions, and that Madagascan individuals were the imm
ediate source of plants that colonized other areas of introduction. Success
ive nested founder events appear to have resulted in cumulative reduction i
n genetic diversity. Possible explanations for the monoclonality of R. alce
ifolius in many areas of introduction are discussed.