Genetic diversity and phylogeography in a Tasmanian rainforest conifer (Lagarostrobos franklinii (Hook F.) Quinn) Podocarpaceae

Genetic variation in Huon pine (Lagarostrobos franklinii), a Tasmanian rainforest conifer, was estimated using several marker systems and two spatial scales. Genealogy based methods were used to infer population history of eight Huon pine stands based on chloroplast DNA variation. Chloroplast nucleotide diversity (pi) was low (0.00093 +/- 0.00006) in a multilocus haplotype generated by three universal chloroplast primers (trnS- trnT, trnD-trnT, psbC- trnS). Five haplotypes were identified; two were widely distributed but the most frequently occurring haplotype was found only in trees in the western portion of the range. Genetic differentiation among populations was significant and showed a high degree of structure (GST = 0.26077 p ≤ 0.00001). Pairwise comparisons between populations revealed significant structure between the southeastern and northwestern watersheds and significant isolation by distance ( p ≤ 0.0220).; Nucleotide variation was also assessed in segments of three nuclear genes, 4Cl (4-coumarate: coenzyme A ligase), ITS2 (intergenic spacer region of ribosomal DNA) and G3pdh (glyceraldehyde 3-phosphate dehydrogenase). A total of 1,154 base pairs were sequenced from 79 individuals (158 alleles) representing seven geographic locations. Estimates of nucleotide diversity (pi = 0.00089 +/- 0.00007) and theta (theta) (0.00061 +/- 0.00031) were low for the combined loci and similar to chloroplast estimates. There was a higher level of variation at the 4Cl locus (pi = 0.00167 +/- 0.00014) associated with recombination. Nucleotide diversity for nuclear loci was highest in the subalpine Mt. Read population, previously described as a putative clonal stand. Population differentiation (FST =0.0130) was lower than estimated in chloroplast DNA, or in a previous allozyme investigation (FST = 0.095).; Multilocus genotypes based on RAPD markers (random amplified polymorphic DNA) were generated to further investigate genetic diversity in the Huon pine stand at Mt. Read. DNA was analyzed from 63 trees from Mt. Read and genetic diversity compared to 33 Huon pine samples from a wide geographic range. Twelve random decanucleotide primers amplified a total of 35 alleles. Only three of the alleles (8.6%) from the Mt. Read population were polymorphic in contrast to 18 (51.4%) polymorphic alleles in the reference population. (Abstract shortened by UMI.)...