Crop gene pool methodology
Step 4: Selection of target sites
Once the target taxon distribution has been identified and mapped, and ecogeographic diversity analysis undertaken (Step 3), protected area (PA) overlays are used to ascertain whether the target taxon populations occur within the boundaries of an existing PA. CWR, like any other group of wild plant species, are located both within and outside existing PAs; however, the most efficient approach in the first instance (to avoid purchase of sites to establish genetic reserves) is to establish CWR genetic reserves within existing PAs (Maxted et al., 2007). Therefore, the most appropriate PAs (e.g., national parks and heritage sites) within which to locate genetic reserves should be identified.
GIS analysis using PA shape files provides an indication of which PAs contain populations of the target taxa. In addition, this method can be used to predict which PAs contain high concentrations of CWR diversity. To be certain that the populations do exist within the PA(s), it is necessary to confirm their presence before genetic reserve establishment is recommended. This information is not always easy to obtain; however, it may be possible to contact the agency responsible for the management of the PA to see if they have an inventory of taxa available at the site or whether it is possible for site staff to confirm the presence of the taxon. If possible, ground truthing by visiting the site(s) personally should be undertaken. This is of course subject to available time and resources.
Where target taxon populations are found to already occur within existing PAs, these populations should be prioritized for inclusion in the CWR genetic reserve network on the basis that they have already been afforded some degree of protection, even if only by default. However, it is important to stress that even though a target taxon population may occur within the boundaries of a PA, this does not automatically mean that the population is actively conserved. On the contrary, few PAs are established to conserve specific target taxa, and those that have tend to focus on animal conservation. To conserve the range of genetic diversity inherent in CWR populations, active site management and monitoring is needed—many PAs do not even have management plans, and those that do, are often limited by financial resources and lack of capacity to put the plan into practice.
In cases where a few to several PAs are found to contain populations of a target taxon, results of the ecogeographic diversity analysis can be used to select sites that best represent the ecogeographic diversity within the target taxon. A further consideration for the selection of PAs is the option for multiple-taxon genetic reserves. Analysis of all target taxa within the crop gene pool (and preferably across several crop gene pools) may reveal that some PAs contain populations of more than one taxon. In terms of expediency of resource use, multi-taxon reserves have obvious advantages over those that only contain a population of one taxon.
Where target taxon populations do not already occur within existing PAs, these populations should also be prioritized for inclusion in the CWR genetic reserve network on the basis that they have not already been afforded any degree of protection; especially for rare or threatened species. Obviously, justifying the need for and actually establishing new PAs will involve a significant initial injection of time and resources. Nomination of genetic reserves at the target locations may of course be hindered by a range of socio-political factors, such as legal issues, land use conflicts, issues of land ownership, or lack of local support. Therefore, if possible a range of alternative sites should be recommended and ranked according to their suitability based on ecogeographic considerations.
Step 4 actions – select and prioritize target sites
This is the final stage in the process, leading to the identification of CWR genetic reserves, which should ideally be assigned a priority ranking so that if for some reason a genetic reserve cannot be established at the best site (e.g., due to land use conflict or legal complications), the next best site is promoted, and so on.
- Ascertain whether one or more populations of the target taxa occur within the boundaries of existing PAs. To achieve this, overlay target taxon distribution data with protected area shape files. A GIS program such as ArcGIS or DIVA GIS can be used for this purpose. PA data are available free of charge for use for scientific research, which are imported into the GIS program, along with the coordinate data collated under Step 3.
- If one or more populations of a target taxon appear to fall within the boundaries of one or more existing PAs, follow up the analysis by verifying the presence of the taxon at the site. This is not always easy or possible, but it is important to try. If it is not possible to visit the site personally, contact the agency responsible for the management of the PA and ask if they have a recent taxon inventory available. If no recent inventory is available, ask if site staff are available to verify the presence of the taxon. If verification is undertaken by a third party it will be necessary to arrange for voucher specimens or at least photographs of the plants to be sent to ensure the correct identification has been made.
- Select sites for the establishment of CWR genetic reserves. At this stage, there are a number of different variables to take into consideration, depending on the range of the target taxon and other factors:
Prioritize the selected sites. The main criterion for allocating priorities to sites is the conservation of the maximum genetic diversity possible. When assigning priorities for a particular target taxon, the ecogeographic analysis will form the basis of the priority ranking of sites. When the aim is to conserve multiple taxa within the same sites, a balance has to be met between prioritizing those sites that contain the greatest taxonomic diversity and those that contain less taxonomic diversity, but more genetic diversity specific to particular target taxa. Other factors to take into account when assigning priority ranking to selected sites include: land use, potential development pressures (e.g., sites closer to towns and cities may be less secure), presence of invasive species (particularly on islands), level and quality of site management, legal status, potential conflict with existing site management aims and social unrest. A thorough assessment of all factors, both scientific and socio-political, must be made and considered when selecting the ideal sites.
- For taxa that occur in only one location, it is obvious that this location must be recommended for genetic reserve establishment, regardless of whether the population exists within or outside an existing PA.
- For taxa that occur in more than one location, the results of the ecogeographic diversity analysis carried out under Step 3 need to be added into the equation. There is no one fixed way of decision-making at this stage, but first and foremost, since the aim is to conserve the maximum genetic diversity within and between populations of the target taxa as possible, then sites that are most likely to represent that diversity should be selected. For advice on site selection based on ecogeographic diversity analysis, see Maxted et al. (2004, 2008) and Iriondo et al. (2008).
- For taxa that occur both within and outside PAs, existing PAs should ideally be selected for inclusion in the CWR genetic reserve network. However, a balance will have to be met between ecogeographic suitability of sites and feasibility. In other words, if very little intra-taxon genetic diversity is likely to be conserved by enacting active conservation of populations within existing PAs, it may also be necessary to recommend that new genetic reserves are established for other genetically distinct populations.
- When possible, a range of taxa should be assessed all together to try to ascertain whether it is feasible to establish multi-taxon reserves. When focusing on a crop gene pool conservation strategy, this may not always be possible, depending on whether the target taxa are found at the same locations. The identification of multi-taxon reserves is most likely to be achieved through the development of national CWR strategies which target a country's entire CWR flora. Therefore, during the development of a crop gene pool in situ conservation strategy, collaboration with organizations responsible for developing national CWR conservation strategies is advised in countries where the target crop gene pool taxa are to be conserved.
- The potential effects of climate change on populations of the target taxa also need to be taken into account. Considerations include: the particular vulnerablity of populations in coastal and high altitude areas; whether there is sufficient intra-population genetic diversity and reproductive success in populations to allow adaptation to new conditions; and whether small, fragmented populations with little migration will be able to colonize new sites (Veteläinen et al., 2007). In the absence of detailed studies on individual target taxa, it will not be possible to predict exactly where sites need to be established because a) we will not know whether populations of a taxon will have the ability to adapt to new conditions at current sites, b) whether populations will have the ability to migrate to new sites, and c) if migration occurs, how quickly it will take place and in what direction. However, greater emphasis on habitat protection to prevent and reduce habitat fragmentation and the establishment of corridors between habitat patches to facilitate range shifts of mobile species is likely to be important for many CWR taxa (Jarvis et al., 2008).
Crop gene pool methodology introduction > Step 1 > Step 2 > Step 3 > Step 4