Genetic structure of hepatic species

Abstract

The main reasons for extremely limited information about liverwort genetics, particularly population genetics, are: (a) the continuing practice of phenetic species definition, which initiates a chain of confusion, and (b) a concentration on observational studies rather than experimentation. Useful genetical and cytological markers are known, and ways of harnessing them to obtain a detailed and precise insight into the genetic structure of liverwort species are discussed. Once the genetical bases for enzyme polymorphisms in liverworts have been identified, isoenzymes can be expected to assume the major role in population genetics. Certain chromosome markers, especially Giemsa C-bands, however, hold similar promise. Detailed information concerning each of the following should now be forthcoming: (a) the relationship between inter- and intra-populational genetic variation; (b) the genetic structure of populations; (c) the extent of gene flow; (d) the degree of self-fertilization; (e) the degree of outcrossing; (f) the possibility of unidirectional gene flow between haploids and diploids, and (g) the possibility of hybridization.