Comparative genetic study confirms exceptionally low genetic variation in the ancient and endangered relictual conifer, Wollemia nobilis (Araucariaceae)

Abstract

The Wollemi pine, Wollemia nobilis (Araucariaceae), was discovered in 1994 as the only extant member of the genus, previously known only from the fossil record. With fewer than 100 trees known from an inaccessible canyon in southeastern Australia, it is one of the most endangered tree species in the world. We conducted a comparative population genetic survey at allozyme, amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) loci in W. nobilis, Araucaria cunninghamii and Agathis robusta - representatives of the two sister genera. No polymorphism was detected at 13 allozyme loci, more than 800 AFLP loci or the 20 SSR loci screened in W. nobilis. In Ag. robusta only one of 12 allozyme loci, five of 800 AFLP loci and none of the 15 SSR loci were variable. For A. cunninghamii, 10 of > 800 AFLP loci and five of 20 SSR loci were variable. Thus low genetic diversity characterizes all three species. While not ruling out the existence of genetic variation, we conclude that genetic diversity is exceptionally low in the Wollemi pine. To our knowledge this is the most extreme case known in plants. We conclude that the combination of small population effects, clonality and below-average genetic variation in the family are probable contributing factors to the low diversity. The exceptionally low genetic diversity of the Wollemi pine, combined with its known susceptibility to exotic fungal pathogens, reinforces current management policies of strict control of access to the pines and secrecy of the pine locations.

High genetic diversity and significant population structure in Cedrus brevifolia Henry, a narrow endemic Mediterranean tree from Cyprus

“…Such high levels of diversity may have resulted from the species not having been strongly affected by genetic drift and/or inbreeding processes, because their population sizes may never have been reduced below a certain threshold. Similarly, narrowly distributed species do not necessarily demonstrate high differentiation among populations (Gitzendanner and Soltis 2000;Peakall et al 2003). Life history traits (i.e.…”

Population size, center–periphery, and seed dispersers’ effects on the genetic diversity and population structure of the Mediterranean relict shrub Cneorum tricoccon

“…However, experimental evidence has not always supported this generalization (see Peakall, Ebert, Scott, Meagher, & Offord, 2003; Vanden‐Broeck et al., 2011). Low rates of evolution, genetic stability, and habitat reliability have been proposed as some of the factors that may influence the genetic patterns of relict species (Hampe & Petit, 2007).…”

Cross transferability of SSRs to five species of Araucariaceae: a useful tool for population genetic studies in Araucaria araucana

“…C. Moreno et al / Forest Systems (2011) 20(2), 303-314 et al, (from Scott et al, 2003 nomic homology is likely to translate into greater conservation of SSR flanking regions and, as a result, in higher transferability of primer pairs (Rossetto, 2001). Studies within the Araucariaceae family showed a very low genetic variability among and within species (Peakall et al, 2003;Scott et al, 2005). Moreover, after sequencing, similar structure of the microsatellite stretches and a high sequence conservation of the flanking regions was observed among several species of Araucariaceae .…”