Data from: Multiple independent origins of intermediate species between Sorbus aucuparia and S. hybrida (Rosaceae) in the Baltic region

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Populations intermediate between the diploid and sexual Sorbus aucuparia and the tetraploid and facultative apomictic Sorbus hybrida are scattered in coastal regions of southern Scandinavia. Our aims were to investigate whether these populations were of local and independent origins, whether they were morphologically and molecularly distinct from each other and whether they could give rise to constant offspring by apomixis. Six intermediate populations from the Baltic Sea basin were studied for variation at nuclear and plastid microsatellite loci, for morphological differentiation patterns, and for ploidy level by flow cytometry. Seeds were sown to check for constancy with the mother plants. Three populations from Gotland and possibly the small population from Uppland were in each case fixed for a unique combination of genetic markers, had restricted variation in leaf shape and were morphologically divergent from each other. Flow cytometry analysis showed that the four genetically monomorphic populations were consistently triploid. Cultivation showed that offspring from trees within two of the monomorphic populations had leaf shapes closely similar to the mother individuals. In contrast, a population from Gotland and a population from Åland were variable at molecular marker loci and were variable in leaf shape. The three monomorphic Gotland populations and possibly also the Uppland population propagate asexually by apomixis, and they have independent origins. The two variable populations are apparently composed of hybrids that have been formed repeatedly and independently between individuals of the two parental species growing at the same sites. One of the Gotland apomicts has already been described as Sorbus teodori. Sorbus faohraei Hedrén & J.Levin and Sorbus atrata Hedrén & J.Levin are described as new apomictic species from Gotland.,Molecular base data SorbusMolecular data obtained from analysis of Sorbus meinichii s.l. and its parental taxa in the Baltic Sea region. CH01H10, MSS16, MSS1, and MSS3 are nuclear microsatellite loci; rps16pm2 and trnT-Lpm4 are plastid microsatellite loci. “1” indicates the presence of an allele at a locus. Uncertain presence of an allele is indicated by “?”. Samples without any recorded alleles have missing information for that particular locus. The combination of fragments at plastid loci is summarized as haplotypes. Ploidy level is given for samples analyzed by flow cytometry.,

Notes

External Organisations
Lund University; Royal Botanic Gardens Victoria

Associated Persons
Joel Levin (Creator); Jaume Pellicer (Creator); Mikael Hedrén (Creator)