REPRODUCTIVE STRATEGIES AND POPULATION STRUCTURE IN THE ENDANGERED PTERIDOPHYTE TRICHOMANES SPECIOSUM (HYMENOPHYLLACEAE: PTERIDOPHYTA)

摘要

Trichomanes speciosum Willd. Hymenophyllaceae is unique amongst European ferns in that the gametophyte generation can survive indefinitely in the absence of the sporophyte; propagate vegetatively and disperse locally. Reproductive success; both in terms of spore production and sporophytic recruitment currently vary widely across the species' broad; disjunct range; declining from south to north and west to east. Reproductive success would appear to be controlled largely by climatic factors; althoughgenetic components also must be considered. Detailed study of populations throughout the species' range; over a 15 year period; have led to a greater understanding of growth rates; powers of dispersal and the reproductive strategies currently operating.Using this knowledge; the extent and pattern of genetic variation regionally and locally; i.e within sites; can be used to infer the routes and mechanisms of colonisation and subsequent reproductive history.Many sites for this species have been considered as glacial refugia; i.e.; supporting relictual populations through cycles of glaciation throughout the Tertiary. The validity of these claims is tested using molecular and other data.