Morphometric diversity and geographic differentiation in six dogrose taxa (Rosa Sect. Caninae, Rosaceae) from the Nordic countries
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The dogroses (Rosa Sect. Caninae) are characterized by a unique meiosis - the canina meiosis - that results in restricted recombination. In the present study, we investigate population differentiation and morphometric diversity within six taxa, of Nordic dogroses, with the help of automated image analysis of leaflet shape and manually-measured reproductive characters. The total morphometric diversity in each character type was partitioned into its hierarchical components. The within-taxon structure of diversity in leaflet shape is similar (in both rank and magnitude) to the within-taxon structure of reproductive character diversity in all the taxa, with the between-population component of diversity accounting for the majority of the total diversity. The within-taxon structuring of diversity in the dogroses is comparable to that found in selfers and in species characterized by restricted recombination (such as permanent translocation heterozygotes). The relatively high within- and between-family components of diversity in R. dumalis subsp. dumalis may be a reflection of a heterogeneous genome and/or of a higher degree of outcrossing than in the other dogrose taxa. Rosa rubiginosa is characterized by low overall levels of intraspecific variation. There is weak geographic differentiation between populations of R. dumalis subsp. dumalis (in leaflet shape) and R. rubiginosa (in reproductive characters). The study provides no support for the division of R. dumalis into subsp. dumalis and subsp. coriifolia but, in contrast, shows a clear separation between varieties umbelliflora and venusta within R. sherardii.