Genetic Evidence that Lomatia tasmanica (Proteaceae) is an Ancient Clone

Abstract

Lomatia tasmanica W.M.Curtis is an endangered species with only one population. The population occurs over a distance of 1.2 km and consists of several hundred stems. Although it flowers occasionally, fruit production has never been observed, and it propagates vegetatively. The genetic diversity in L. tasmanica, and its relationship with the other species of this genus in Tasmania was investigated using allozyme analysis and chromosome counts. Sixteen isozyme loci were scored on 78 L. tasmanica plants collected from throughout the range of the species. No genetic diversity was found in L. tasmanica. Lomatia tinctoria possessed 22 (2n = 22) chromosomes, like other Lomatia species previously counted, while L. tasmanica had 33 to 29 chromosomes, which makes it an unstable triploid. The triploid nature of L. tasmanica would explain its lack of genetic diversity and its apparent sterility. This suggests that the entire species may be one genet, one of the largest plant clone ever found. Fossilised leaves identified as L. tasmanica by Jordan et al. (1991) and dated as at least 43 600 years old may indicate the minimum age of this genet. This clone maybe one the worldÕs oldest known living plant individual. IntroductionLomatia tasmanica W.M.Curtis is an endangered shrub species, restricted in distribution to south-western Tasmania. It was first collected by D. King in May 1934. However, this population appears to have since become extinct. A flowering specimen from a second population was later collected by D. King in 1965. This specimen was sent to J. H. Willis for identification and the plant was described by W. M. Curtis in 1967. Only one population is currently known. The species is found along creek gullies in rainforest in south-western Tasmania.Interestingly, the species has never been observed to form mature fruit and seeds. It has been observed to flower but not annually. Regeneration appears to be vegetative by rhizome (Brown and Gray 1985). W. M. Curtis suggested that the species may be of hybrid origin (A. M. Gray, pers. comm., to Brown and Gray 1985). Brown and Gray (1985) further speculated that L. polymorpha may be a parent, since it grows in the vicinity. Lomatia tinctoria was considered a less likely parent because it does not presently grow in the vicinity of L. tasmanica. The objectives of this study were firstly to estimate the level of genetic diversity within L. tasmanica using allozyme analysis and, secondly, to determine the genetic distinctiveness of L. tasmanica from the other Tasmanian Lomatia species, L. tinctoria and L. polymorpha, using allozyme analysis and chromosome counts.

Divergent levels of genetic variation and ploidy among populations of the rare shrub, Grevillea repens (Proteaceae)

“…One of these plants at the PR site was identified as a triploid, raising the possibility of a number of such ploidy variants within the populations. Ploidy variation within genera appears to be very rare within the Proteaceae (Ramsay 1963;Stace et al 1998) and triploidy has been reported in only one other member of this large, ancient family (Lynch et al 1998). In G. repens, the PR and Captains Creek populations contained both triploid and diploid individuals.…”

No sex at all? Extremely low genetic diversity in Gagea spathacea (Liliaceae) across Europe

“…A number of taxa does so in parts of their ranges, like invasive species with only one sex introduced (only male Elodea canadensis Michx. introduced in Europe), at the limits of their ranges (Bauert et al, 1998) or within small and/or relict populations (Lynch and Balmer, 2004;Lynch et al, 1998;Peakall et al, 2003;Villarreal et al, 2010). For the few autochthonous sexually sterile plant species which occupy a more than local range, inherent sexual sterility often results from severe problems in meiosis.…”

Perennial Roots to Immortality ,

“…Clonal propagation is the only means for propagation, because it is a sterile ancient clone. When a branch falls, that branch produces new roots, establishing a new plant that is genetically identical to its parent (Lynch et al, 1998). Here, the production of new roots becomes essential for achieving potential immortality.…”

“…Stolons can be produced aboveground or underground (in the latter case, forming rhizomes). Van Dijk (2009) elegantly reviewed the direct and indirect methods currently used to estimate plant age in clonal and nonclonal plants, showing several examples of plant species using clonal propagation with maximum lifespans of thousands of years, with the most notable example, King's Lomatia (Lomatia tasmanica), being dated at 43,600 years (Lynch et al, 1998). Only one wild-living clone of this species is known.…”