Genetic variationGenetic variation

Genetic variation

The Wollemi Pine’s exceptionally low genetic diversity (Peakall et al. 2003), reported in the previous recovery plan (NSW DEC 2006a), was confirmed by Greenfield et al. (2016). The Wollemi Pine chloroplast genome has also since been sequenced (Yap et al. 2015). More refined population genetic studies based on reduced representation genome sequencing approaches are currently in progress. Preliminary analyses have detected low-level variation within and between stands (Bragg et al. unpubl. data) and the genome of the Wollemi Pine has recently been mapped (Stevenson et al. 2023 preprint). Analysis of the Wollemi Pine genome indicates that its population expanded rapidly 8-6 million years BP, before shrinking to approximately 20% of its size 7-3 million years BP (Stevenson et al. 2023 preprint). Wollemi Pine has existed as a relictual population since 120,000 years BP (Australia’s last major glacial/drying period). Population genomic analysis revealed high levels of inbreeding and clonal propagation with extremely low heterozygosity, even for a gymnosperm genome (Stevenson et al. 2023 preprint). This low genetic diversity may contribute to low rates of seed viability in the Wollemi Pine. Implications for the Wollemi Pine’s ability to adapt to changing conditions are the subject of ongoing research; this is also likely to have implications for the adaptability, or lack thereof, of the species to respond to invasive pathogens and pests.