GENETIC-VARIABILITY IN THE 3 SUBSPECIES OF MARCHANTIA-POLYMORPHA (HEPATICAE) - ISOZYMES, RFLP AND RAPD MARKERS

Three subspecies of Marchantia polymorpha have been recently characterized by isozyme patterns, ecology and morphological characters. To confirm their taxonomic status and to better understand their relationships and genetic variability, a previous study on enzyme polymorphism was extended to additional colonies and enzymes. A parallel study was done with DNA markers derived from restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD). Results obtained with these different approaches (protein and DNA level) all support the taxonomic distinctness of the subspecies. Genetic similarity within subspecies was found to be high over wide geographic areas, and low among subspecies. The genetic divergence of the three subspecies may be taken to illustrate a case of speciation with adaptation to different ecological niches, and subsequent reproductive isolation. The hybrid origin of Marchantia polymorpha subsp. ruderalis, postulated in the past, is not supported by our data.