Population genetics of the long-lived Huon pine Lagarostrobos franklinii: An endemic Tasmanian temperate rainforest tree Original Research Article

Genetic diversity, within and among natural populations at 32 sites, of the long-lived temperate rainforest Huon pine tree Lagarostrobos franklinii was assessed using isozymes. Overall, genetic diversity, based on six enzyme loci, was low (A = 1·6, P = 46%), both within and among populations (Fst = 0·095). The most isolated sites (Yellow Creek, Spero River, Newall Creek, Mt Read) deviated significantly from expected allelic frequencies and/or had the greatest genetic distances from other sites. Most of these isolated sites are currently unprotected. Genotype frequencies within most sites (20 out of 32) deviated significantly from Hardy-Weinberg equilibrium expectations (p < 0·0015) and had high fixation indexes indicative of effective inbreeding. The high levels of inbreeding observed by these measures at some sites did not reflect isolation from gene flow. The most similar pairs of populations were located in the headwaters of the three major habitat catchments, which originate within close geographic proximity of one another. Over 90% of individuals at Mt Read, the highest altitude site known, were genetically identical. This, combined with other evidence, suggests that the population at this site is principally vegetatively derived and may be exceptionally old. Inbreeding and low diversity does not appear to have affected the speciesʹ ability to persist for long periods.