318 In Situ, Ex Situ Conservation across the region, but it may involve sampling every 1–50 km The population samples and data collected during this mission can then be used to formulate further conservation priorities and to develop an appropriate strategy, thus providing the same result as the ecogeographic survey for groups that are better biologically understood Conservation Objectives The products of the ecogeographic survey, gap analysis, or survey mission provide a basis for the conservationist to formulate future conservation priorities and strategies for the target taxon Within the target area, zones of particular interest may be identified, for example, areas with high concentrations of diverse taxa, low or very high rainfall, or high frequency of saline soils or extremes of altitude or exposure In general, areas with very distinctive characteristics are likely to contain plants with distinct genes or genotypes If a taxon is found throughout a particular region, then the researcher can use the ecogeographic data to positively select a series of diverse habitats to designate as reserves If a taxon has been found at one location but not at another with similar ecogeographic conditions, then the conservationist may suggest that these similar locations should be searched Within the target taxon, specific variants may be identified that warrant conservation priority, for example, species that have previously unrecognized utilization potential, populations that are particularly in danger of genetic erosion, or those that had not previously been conserved The conservationist must set out a clear, concise statement of the proposed conservation strategy for the target taxon and, if appropriate, prioritize actions These may have been established in the project commission, but if not the conservationist should undertake the task This should answer questions such as: Which populations require conservation? Can local farmers play a part in conservation activities? Do population levels require close monitoring? Should a national or international collecting team be directed to collect the priority target taxa? What conservation strategy or strategies are appropriate? What combination of conservation techniques is appropriate or is a more detailed study required before any of these questions can be answered? Field Exploration Once the conservation objectives have been clarified, whichever conservation strategy is to be applied, the ecogeographic information is used to locate and identify the general locality of the animal or plant populations that are to be conserved The ecogeographic data will rarely be sufficiently comprehensive to precisely locate actual populations Therefore, the preparatory element of conservation activities will be followed by field exploration, during which actual populations are located Ideally, populations of the target taxon that contain the maximum amount of genetic diversity in the minimum number of populations will be identified, but how is this goal to be achieved? Commonly there will be too much diversity in both crops and wild species to conserve all their alleles, even if these were known then or at some future time Thus the conservationist must attempt to conserve the range of diversity that best reflects the total genetic diversity of the species How many animals or plants must be sampled, which specimens and what pattern of sampling is appropriate? To answer these specific questions the conservationist should know the amount of genetic variation within and between populations, local population structure, the breeding system, taxonomy and ecogeographic requirements of the target taxon, and many other biological details Some of this information will be supplied following the ecogeographic survey, but some will remain unavailable Therefore, the practice of field exploration will be modified depending on the biological information on the target taxon and target area that is available For a botanical project, the field botanist should select populations if they are found on the periphery of the target taxon’s distribution or those that contain morphological or ecological variants Atypical populations or those growing under atypical conditions may possess genes or alleles that are unknown or extremely rare in the target taxon’s center of diversity, and this material possibly contains genetic variation that is of special use to breeders (e.g., disease or pest resistance or adaptation to soil or climate that is unknown in the crop itself) Conservation Strategies There are two basic conservation strategies, each composed of various techniques, that the conservationist can adopt to conserve genetic diversity once it has been located The two strategies are ex situ and in situ conservation Article of the CBD (1992) provides the following definition of these categories: In situ conservation means the conservation of ecosystems and natural habitats and the maintenance and recovery of viable populations of species in their natural surroundings and, in the case of domesticates or cultivated species, in the surroundings where they have developed their distinctive properties Ex situ conservation means the conservation of components of biological diversity outside their natural habitats There is an obvious fundamental difference between these two strategies: in situ conservation involves the location, designation, management, and monitoring of target taxa where they are encountered, whereas ex situ conservation involves the location, sampling, transfer, and storage of target taxa from the target area Because of this fundamental difference, there is little overlap between the two strategies However, the two techniques should not be seen as alternative, they are complementary and should be applied in tandem to ensure maximum maintenance of diversity The two basic conservation strategies may be further subdivided into the following specific techniques, which are discussed in sections Ex Situ Techniques and In Situ Techniques: Ex Situ Seed/embryo storage In vitro storage Semen/ovule/ pollen/deoxyribonucleic acid (DNA) storage Field gene bank/ livestock parks Botanic/zoological garden, and In Situ Genetic reserve On-farm Ex Situ Techniques In ex situ conservation, genetic variation is maintained away from its original location and samples of a species, subspecies,