Print this page

Examples and applied use

A CWR genetic reserve on The Lizard Peninsula in the United Kingdom

Wild chives, Allium schoenoprasum L., a wild relative of cultivated chives, flowering on The Lizard Peninsula, Cornwall, UK. (Photo: Hannah Fielder)

A recent study of CWR diversity across England demonstrated that The Lizard Peninsula, the most southerly point of mainland UK, is a hotspot of CWR taxon diversity (Fielder et al. 2015). The Lizard Peninsula is ecogeographically diverse in terms of its geology, soil types, topography and range of microclimates, which could give rise to a similarly diverse range of genetic diversity in the flora of the area. As a result, a genetic diversity study of eight CWR that occur on The Lizard was carried out to investigate whether it is also a hotspot of CWR genetic diversity and therefore a suitable site for the first genetic reserve with active management and monitoring of CWR in the UK.

AFLP molecular markers were used for this study, and populations of eight CWR were sampled from sites on The Lizard and also outside of The Lizard, in the southwest of the UK, to make a comparison. AFLPs measure genome-wide, neutral genetic diversity. Although the value of CWR lies in their adaptive diversity, methods to directly measure this diversity remain prohibitively expensive and time-consuming. However, by sampling diversity across the genome, the range of diversity conserved can be maximized and so too, the likelihood of conserving valuable adaptive traits.

Results showed that there was no significant difference between the amount of genetic diversity found in CWR populations on The Lizard compared to populations sampled from other parts of southwest UK, for any of the eight taxa studied. However, the diversity on The Lizard was found to be largely distinct from southwest populations for many of the study taxa.

It was concluded that, due to the diversity of CWR taxa and ecogeography on The Lizard and the differentiation of CWR populations at this site from other sites across the southwest, that it is a suitable location for the first UK CWR genetic reserve. A large area of the peninsula is already subject to formal and active conservation management and through discussion with local reserve managers, CWR have now been acknowledged in the management plan of The Lizard National Nature Reserve. It is hoped that this will help to establish long-term management of CWR in this area and that the genetic diversity data obtained through this study will provide a baseline for ongoing monitoring of CWR populations. In addition, it should be noted that although The Lizard is a suitable site for a genetic reserve, these results suggest that The Lizard is not, on its own, sufficient to conserve all of the genetic diversity for these CWR in the UK. Therefore, a recommendation is made that a network of complementary genetic reserves is established across the country.

Source: Fielder et al. (in prep)

Genetic diversity of Dianthus cintranus subsp. barbatus in Portugal

Dianthus cintranus Boiss. & Reut. subsp. barbatus R. Fern. & Franco, a wild relative of ornamental carnations (D. caryophyllus L.), endemic to Portugal, pictured here in Caramulo. (Photo: Joana Magos Brehm)
Site in Condeixa-a-Nova where a genetic reserve should be established for Dianthus cintranus Boiss. & Reut. subsp. barbatus R. Fern. & Franco, based on genetic, population size and threat data. (Photo: Joana Magos Brehm)

A genetic diversity study using AFLP molecular markers was undertaken for Dianthus cintranus Boiss. & Reut. subsp. barbatus R. Fern. & Franco―a priority CWR for conservation in Portugal. The AFLP analysis showed that D. cintranus subsp. barbatus has low but significant genetic differentiation among populations (FST=0.038). The AMOVA showed that the within population component of the genetic variance is extremely high (92%). The populations of the taxon are characterized by a high number of private alleles. Additionally, no significant pattern of isolation by distance was observed between the populations of D. cintranus subsp. barbatus (P=0.267), indicating no geographic restriction to gene flow. Given these results, a Bayesian clustering analysis was also performed, and the results obtained on population genetic structure complemented the analyses. Two genetic clusters were identified for D. cintranus subsp. barbatus.

Genetic (namely, expected heterozygosity, total number of polymorphic alleles, common and localized alleles, and inter‐population genetic distance), demographic (population size) and threat data were combined in order to prioritize populations of the studied species for in situ and ex situ conservation. Each of these criteria were standardized to “1”, giving the highest priority to species with the largest expected heterozygosity, number of polymorphic loci and to those whose populations had higher genetic differentiation as well as to those with the smallest populations and the highest number of threats. These standardized scores were then summed per population and transformed into percentages using the highest score as the reference value of 100%, as suggested by Delgado et al. (2008) based on the Vane-Wright et al. (1991) principles. The populations with higher percentages were prioritized for active conservation.

Source: Magos Brehm et al. (2012)

Islands as refugia of Trifolium repens genetic diversity

A genetic diversity study using AFLP molecular markers was carried out to compare mainland wild and landrace populations of Trifolium repens with wild populations collected from the islands surrounding the UK. Results showed that the population from the now uninhabited island of St Kilda (Outer Hebrides) is highly differentiated from UK mainland populations and genetically distinct from cultivated varieties, retaining genetic diversity through limited human influence, thus representing a unique conservation resource. In contrast, the mainland UK wild populations are relatively genetically similar to the cultivated forms, with geographic barriers preventing complete homogenization. It was concluded that islands, such as St Kilda, can act as refugia of genetic diversity and can, therefore, provide an opportunity to conserve populations from the threats that endanger their diversity and, at the same time, allow populations to diverge from their mainland counterparts.

Source: Hargreaves (2010) and Hargreaves et al. (2010)

Web Address of the page:

Links in this page