Systematics and phylogeography of the Dactylorhiza maculata complex (Orchidaceae) in Scandinavia: insights from cytological, morphological and molecular data

David Ståhlberg, Mikael Hedrén

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    Abstract

    Flow cytometry, morphometry and molecular markers [plastid DNA and internal transcribed spacers(ITS) of nuclear ribosomal DNA] were used to determine taxonomic and phylogeographic patterns in Dactylorhiza maculata s.l. from Scandinavia. A total of 238 individuals from 27 populations from throughout all of Scandinavia, including the adjacent Kola Peninsula of Russia, were analyzed. Diploid D. maculata ssp. fuchsii and autotetraploid D. maculata ssp. maculata are morphologically differentiated. Fragment size variants from 10 plastid DNA loci (seven microsatellite loci and three loci with indel variation) were combined to give 43 haplotypes. Three major groups of haplotypes were found. Group I haplotypes were prevalent in the north and the northeast, whereas Group II haplotypes were prevalent in the south and the southwest. Group III was represented by only a single haplotype and appeared to be the result of introgression from D. incarnata s.l. Group I and Group II
    haplotypes did not correspond with cytologically and
    morphologically defined D. maculata ssp. fuchsii or
    D. maculata ssp. maculata. Past introgressive gene flow
    rather than recent hybridization is envisaged. Intermediate
    Group I haplotypes between Group II and the rest of Group
    I were detected in a zone of contact in central Sweden,
    which may suggest plastid DNA recombination. The six
    ITS alleles scored showed strong positive correlation with
    taxonomy. All data sets obtained for ssp. maculata were
    significantly correlated with geography. Three different
    autotetraploid lineages are hypothesized. One lineage may
    represent postglacial immigration from the south and the
    other two lineages may represent eastern immigration
    routes. Morphology and ITS data suggested that subarctic
    populations of ssp. maculata should be recognized as var.
    kolaensis.
    Original languageEnglish
    Pages (from-to)107-132
    JournalPlant Systematics and Evolution
    Volume273
    Issue number1-2
    DOIs
    Publication statusPublished - 2008

    Subject classification (UKÄ)

    • Ecology

    Free keywords

    • Introgression
    • Flow cytometry
    • Dactylorhiza
    • Polyploidy
    • Plastid DNA
    • Morphometry
    • ITS

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