Genetic variation and clonal diversity in introduced populations of Mimulus guttatus assessed by genotyping at 62 single nucleotide polymorphism loci

Background: Single nucleotide polymorphisms (SNPs) are increasingly being used to study non-native populations. SNPs are relatively information poor on a per locus basis, but allow genotyping more loci than others markers (e.g., microsatellites) and have the advantage of consistent allele calls between studies.  Aims: We investigated the utility of a newly developed set of SNP markers, suitable for high throughput genotyping to characterise genotypic variation and population structure in non-native populations of the facultative clonal herb Mimulus guttatus in the United Kingdom (UK).  Methods: We analysed 62 SNP markers and using a high throughput platform genotyped 383 individuals from 10 populations from the native range in North America and 14 populations in the UK.  Results: We found wide variation in genotypic diversity within UK populations, indicating reproductive strategies that vary from mostly clonal to mostly sexual. All but one UK population were, on average, more closely related to each other than to North American populations, and the exceptional UK population showed strong affinity to native Alaskan plants.  Conclusions: A small number of SNPs can detect patterns of clonality and broad-scale relationships between native and introduced populations. However, elucidating population structure at a finer scale will require genotyping individuals at greater depth