Whole-chloroplast analysis as an approach for fine-tuning the preservation of a highly charismatic but critically endangered species, Wollemia nobilis (Araucariaceae)

Abstract

The critically endangered Wollemia nobilis W.G. Jones, K.D. Hill & J.M. Allen is endemic to Wollemi National Park north of Sydney (Australia). All known wild individuals are restricted to four sites in a single canyon system. W. nobilis can reproduce sexually but at all sites individual clumps can be multi-stemmed from a common base. In the first genetic study of this species, no genetic variation was found across multiple genetic marker types representing hundreds of nuclear loci, indicating this species is characterised by very low genetic variation. In this study we searched for variation across the chloroplast using shotgun sequencing, bioinformatic extraction of chloroplast DNA and variant detection. Six chloroplast single nucleotide polymorphisms were detected, producing three chlorotypes. Chlorotype 1 is found in every individual surveyed at Sites 1 and 3, and in individuals from Sites 2 and 4. Chlorotype 2 – the most distinct chlorotype – was found in two individuals from Site 4. Chlorotype 3 consists of a single difference from Chlorotype 1 and may represent a somaclonal mutant. These findings will guide management and translocation of this critically endangered species. This study provides a practical template that is highly informative and easily applicable to other taxa in similar circumstances.

Ex Situ Conservation of Large and Small Plant Populations Illustrates Limitations of Common Conservation Metrics

“…A similar case is observed for the ancient relict Wollemi pine (Wollemia nobilis), a species with fewer than 100 extant wild trees. Until the recent discovery of three distinct chlorotypes (Greenfield et al 2017), no genetic diversity was detected in any extant W. nobilis plants (Peakall et al 2003). A single cutting could thereby represent 100% genetic capture of a wild population, and three cuttings could represent all known genetic diversity for the species.…”

Ecology and conservation of a living fossil: Australias Wollemi Pine (Wollemia nobilis)

“…However, following sequencing of the chloroplast genome (Yap et al, 2015), exceptionally low -yet detectable -genetic diversity was found in a whole-chloroplast analysis (Greenfield et al, 2016). More refined population genetic studies based on reduced representation genome sequencing approaches are ongoing but preliminary investigations 16 have identified low-level variation within and between subpopulations (Bragg et al, unpubl.).…”

Pine-ing for a Voice: Vegetal agencies, New Materialism and State Control through the Wollemi Pine

“…This lack of human contact is given as one of the reasons why specific trees within this enclave are estimated to be over 1000 years in age (Wong, 2019). Whilst this isolation has aided the species' survival, it has also limited the Wollemi in some ways: initial genetic studies of these ancient conifers originally revealed no genetic diversity in the small wild population that was spread across four close sites-an 'evolutionary bottleneck' (Greenfield, et al 2016;Peakall, et al 2003). More recent studies, however, demonstrate small genetic variations between specimens, but, given the Wollemi once covered a vast area of the Gondwanan supercontinent, these similarities in genetic material demonstrate that for extended periods the tree has existed in relative seclusion (Greenfield, et al 2016).…”

“…Whilst this isolation has aided the species' survival, it has also limited the Wollemi in some ways: initial genetic studies of these ancient conifers originally revealed no genetic diversity in the small wild population that was spread across four close sites-an 'evolutionary bottleneck' (Greenfield, et al 2016;Peakall, et al 2003). More recent studies, however, demonstrate small genetic variations between specimens, but, given the Wollemi once covered a vast area of the Gondwanan supercontinent, these similarities in genetic material demonstrate that for extended periods the tree has existed in relative seclusion (Greenfield, et al 2016). The continued survival of the Wollemi is phenomenal in a time when plant growth has been reduced by half from the beginning of human civilisation (Bar-On, Phillips and Milo, 2019).…”