THE PATTERNS OF GENETIC DIVERSITY IN CARPENTARIA-ACUMINATA (ARECACEAE), AND RAIN-FOREST HISTORY IN NORTHERN AUSTRALIA

Carpentaria acuminata occurs in monsoon rainforest and is endemic to t he Northern Territory, Australia. The genetic diversity of C. acuminat a populations was surveyed across the geographical range of the specie s using isozyme analysis. Genetic diversity within C. acuminata popula tions (H-E = 0.143) Was typical of rainforest species and woody angios perms generally. Genetic diversity was not correlated with rainforest patch size. However, there was significant heterogeneity among populat ions (F-ST = 0.379), with infrequent effective gene flow among populat ions (Nm = 0.39). Genetic diversity was negatively correlated with inc reasing distance between neighbouring C. acuminata populations, but ge ographical distance was not a good predictor of genetic similarity. C. acuminata is a favoured food of mobile frugivores such as Torres Stra it pigeons and flying foxes. The decreased diversity with decreasing d ensity of populations indicated that seed dispersal by frugivores has been important for the maintenance of diversity in this species. Popul ations known to have originated on relatively young, Holocene landform s were not necessarily genetically depauperate. Gene flow by pollen is apparently limited because C. acuminata populations are significantly inbred regardless of genetic diversity (F = 0.641). The distribution and diversity of rare alleles, i.e. those occurring in few populations , is consistent with the theory of rainforest contraction during the P leistocene.