Investigating the effects of topography and clonality on genetic structuring within a large Norwegian population of Arabidopsis lyrata.
OBJECTIVE
The gene flow through pollen or seeds governs the extent of spatial genetic structure in plant populations. Another factor that can contribute to this pattern is clonal growth. The perennial species Arabidopsis lyrata ssp. petraea (Brassicaceae) is a self-incompatible, clonal species found in disjunctive populations in central and northern Europe.


METHODS
Fourteen microsatellite markers were employed to study the level of kinship and clonality in a high-altitude mountain valley at Spiterstulen, Norway. The population has a continuous distribution along the banks of the River Visa for about 1.5 km. A total of 17 (10 m x 10 m) squares were laid out in a north-south transect following the river on both sides.


RESULTS
It is shown that clonal growth is far more common than previously shown in this species, although the overall size of the genets is small (mean diameter = 6.4 cm). Across the whole population there is no indication of isolation by distance, and spatial genetic structure is only visible on fine spatial scales. In addition, no effect of the river on the spatial distribution of genotypes was found.


CONCLUSIONS
Unexpectedly, the data show that populations of small perennials like A. lyrata can behave like panmictic units across relatively large areas at local sites, as opposed to earlier findings in central Europe.
Department of Biology, Norwegian University of Science and Technology, Trondheim. lundemo@bio.ntnu.no
Sverre
S
Lundemo
Hans K
HK
Stenøien
Outi
O
Savolainen
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D001947:Breeding; D051456:Gene Flow / Q000235:genetics; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D018895:Microsatellite Repeats / Q000235:genetics; D009664:Norway