Genetic variation in rimu — an investigation using isozyme analysis

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Abstract
The amount and partitioning of genetic variation in five South Island populations of rimu (Dacrydiun cupressinum Lamb.) was investigated through isozyme analysis. The megagametophyte of rimu seed was used as enzyme source material for starch gel electrophoresis. Fourteen enzyme systems, represented by 25 individual gene loci, were studied. Results indicate that rimu has low levels of genetic variation compared with most northern hemisphere conifers. Only 18% of the 25 loci investigated were polymorphic, and the effective number of alleles per locus averaged 1.07. It is suggested that variability may have been lost through genetic drift in restricted populations during the repeated cold periods of the glacial/in terglacial cycles of the last two million years, or through stabilising selection in the comparatively uniform climates of New Zealand.