ENZYME POLYMORPHISM IN PREISSIA-QUADRATA (HEPATICAE, MARCHANTIACEAE)

Citation
Mc. Boisselierdubayle et H. Bischler, ENZYME POLYMORPHISM IN PREISSIA-QUADRATA (HEPATICAE, MARCHANTIACEAE), Plant systematics and evolution, 205(1-2), 1997, pp. 73-84
Citations number
25
Categorie Soggetti
Plant Sciences
ISSN journal
03782697
Volume
205
Issue
1-2
Year of publication
1997
Pages
73 - 84
Database
ISI
SICI code
0378-2697(1997)205:1-2<73:EPIP(M>2.0.ZU;2-O
Abstract
Preissia quadrata has a high habitat specificity and a reproductive sy stem including frequent sexual reproduction and absence of specialized asexual propagules. Fertilization is aquatic. Colonies collected in E urope, Asia, eastern and western Canada show the species to be polymor phic at the eleven isozyme loci studied. Most often, thalli of the sam e colony appeared genetically identical. Partitioning of genetic varia tion was among rather than within colonies, suggesting a clonal struct ure of the colonies and a species structure consisting of a series of small populations reproductively isolated from each other. Little gene tic exchange between colonies growing nearby was present, but the spec ies does not appear to consist of regionally circumscribed genetically cohesive entities. Some European and Canadian colonies had identical electrophoretic patterns. The problem of understanding the phenomena h olding liverwort species together, both morphologically and geneticall y, remains an open question. The genetic structure of the species migh t be due to its past history. It might have had a continuous distribut ion in the northern part of the Northern Hemisphere. If so, little sub sequent genetic diversification, perhaps linked to its haploid-dominan t life cycle, must be supposed.