RAPD variation among and within small and large populations of the rare clonal plantRanunculus reptans(Ranunculaceae)

Abstract

In the pre-alpine region of Europe numbers and sizes of populations of the clonal lake shore plant Ranunculus reptans have declined because of the regulation of lake water levels. We investigated genetic variation among and within 17 populations of different size (cover 1-10 000 m) in R. reptans with RAPD (random amplified polymorphic DNA) profiles. We sampled 127 rosettes in 14 populations at Lake Constance and three populations at or near Lake Como. There was significant genetic variation between plants from the two lake regions (5.9%, analysis of molecular variance [AMOVA], P < 0.001), among populations within lake regions (20.4%, P < 0.001), and within populations (73.7%, P < 0.001). Under the assumptions of Wright's island model the variation among populations corresponds to a gene flow of N(e)m = 0.70. Within the 14 Lake Constance populations we detected significant genetic variation among subpopulations separated by only a few metres (4.0% of the within-population variation; P < 0.05). Molecular variance was 24% smaller in small populations covering <100 m area than in larger ones (P < 0.03), indicating that samples from large populations were genetically more variable than samples representing comparable areas of smaller populations. We conclude that gene flow among populations is very limited and that genetic drift has caused reduced genetic variability of smaller populations. Conservation of genetic variability in R. reptans requires persistence of large and also of small populations (because of population differentiation), and it could be enhanced by increasing the size of small populations (to counter genetic drift).

Genetic rescue in interconnected populations of small and large size of the self-incompatible Ranunculus reptans

“…Second, populations often have genetic substructure, with close relatives living close together and, consequently, frequent inbreeding (Waller, 1993). In fact, populations of R. reptans are known to be genetically substructured (Fischer et al, 2000b). A third reason is that interpopulation outbreeding leads to a decreased likelihood of incompatible crosses.…”

“…The 'far' population came from a different lake basin or a different region. In the two cases, the 'near' population came from a separate lake basin, but RAPD-based F ST and allozyme-based F ST were both low (o 0.04; Fischer et al, 2000b;Y Willi, unpublished data). Populations were used as partners once or twice, with the exception of the Lago Maggiore population, which was used three times.…”

“…Plants of each target population were crossed with plants of two other populations following a near-far design. The 'near' partner population came from the same basin of Lake Constance, and these shared relatively high genetic similarity (Fischer et al, 2000b). The 'far' population came from a different lake basin or a different region.…”

On the evolution of clonal plant life histories

“…However, empirical evidence of differentiation in neutral genetic variation among populations appears as large for clonal as for non-clonal plants, which suggests that genetic drift is as pronounced in clonal as in non-clonal plants (Fischer et al, 2000;Stehlik and Holderegger, 2000;Wolf et al, 2000) .…”

Genetic diversity and population structure of ginseng in China based on RAPD analysis

“…Randomly amplified polymorphic DNA (RAPD) analysis is a quick and effective way to detected genetic variations among numerous plant populations [7][8][9].…”