Circum-Antarctic continental distribution patterns in pteridophyte species

Parris. B. S. (Fern Research Foundation, 21 James Kemp Place, Kerikeri, Bay of Islands. New Zealand). Circum-Antarctic continental distribution patter ns in pteridophyte species. Brittonia 53: 270-283. 2001.-Four major austral continental distribution patterns are evident in pteridophytes. Twenty-two species are completely circum-Antarctic. Another 39 species are partially circum-Antarctic, occurring in Australasia (Australia and New Zealand) and Africa (including Madagascar) but not South America, while 29 are in Africa and South America but not Australasia, and 13 are in South America and Aus tralasia but not Africa. Two hypotheses are considered as explanations for the patterns: continental drift following the breakup of Gondwana and long- distance dispersal. Fossil evidence indicates that the majority of pteridop hyte families involved appeared after the southern continents had drifted a part, so long-distance dispersal is likely to explain the distribution of s pecies in these families on now widely separated continents. For those fami lies extant before the break-up, there is no indication in the fossil recor d that the species involved were present in Gondwana. Aspects of the ecolog y of the species that are partly or completely circum-Antarctic indicate th at long-distance dispersal, rather than continental drift. is a likely expl anation for the patterns.