2003 Volume 8 Issue 7 Pages 203-213
Variations in morphology, chromosome numbers and genetic features of the Dumortiera hirsuta complex in Taiwan were studied. Among the five populations examined, three (TPD, TNP, and THT) included only monoploid plants, while mono- and diploids were mixed in the others (THS and TTW). Diploid plants were considered to be allopolyploids on the basis of fixed heterozygosity found in allozyme banding patterns. Although some alleles of the diploids could not be found among the co-existing monoploids and the mono- and diploids had different DNA sequences in the atpB-rbcL intercoding region, both the mono- and diploid plants of THS and TTW and monoploids of THT shared a unique feature, that is, they had upright, short hairs scattered on the dorsal surface of thalli. The hairs were regarded to be homologous with short rhizoids found at the thallus margins which sometimes also occur on the surface of carpocephala. Two different monoploids intermingled in the population TNP; they not only differed in morphological features (color and texture of thalli in wet condition and density of hairs at the thallus margins), but also were proved to be distantly related from each other using allozyme estimations (Nei's genetic distance=1.25). The Dumortiera hirsuta complex in Taiwan includes a wide range of morphological and genetic variation and also it is apparent that 1) monoploids can grow on non-calcareous substrata, 2) plants with different levels of ploidy coexist in the same population, 3) diploids show fixed heterozygosity, and 4) there exist at least four monoploid "species" in Taiwan. Fixed heterozygosity found among diploid plants suggests that diploids of Dumortiera hirsuta in Taiwan have been derived by ancient hybridization events between the different types of monoploid "species", although the putative "parents" could not be identified.
