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Evidence for the hybrid origin ofpotamogeton ×cooperi (Potamogetonaceae): Traditional morphology-based taxonomy and molecular techniques in concert

Research paper by Zdeněk Kaplan, Judith Fehrer

Indexed on: 01 Dec '04Published on: 01 Dec '04Published in: Folia Geobotanica



Abstract

The identity of plants morphologically intermediate betweenPotamogeton crispus andP. perfoliatus from two recently discovered sites, one in Moravia, Czech Republic and another in Wales, United Kingdom, was investigated with molecular markers. Evidence from restriction fragment length polymorphism analysis of the nuclear internal transcribed spacer region of ribosomal DNA and of thetrnK-trnQ chloroplast DNA intergenic spacer confirmed the morphology-based determination of two putative hybrid samples asP. ×cooperi. The hybrids showed the ITS variants of both parental taxa, consistent with the expected biparental inheritance of nuclear DNA. The chloroplast DNA markers indicateP. crispus as the female parent in both hybridization events. The hybrid origin of another dubious sample was excluded by the molecular data, in accordance with previous detailed morphological examination. This plant represented an extreme, narrow-leaved form ofP. perfoliatus, imitatingP. ×cooperi in some characters. The results of the molecular analyses are discussed in relation to the morphology of the plants. They underline that somePotamogeton hybrids could indeed be identified by careful and detailed morphological examination and also that these identifications were reliable and confirmed by molecular markers. This study exemplifies that long-term taxonomic expertise usually generates very well-founded specific questions suitable for straightforward treatment by appropriate molecular methods. The process and ecological implications of hybrid formation are also discussed