distinguish homozygotes and heterozygotes and allow rapid identifications of gene fragments using different DNA sequences (Lowe et al., 2004).

Molecular techniques are contributing to different approaches of surveying and assessing genetic variation for management and conservation purposes.

Assessments of population genetic structure using molecular techniques (Table 3-2) have involved the following approaches: (1) surveys of a species to identify genetic hot spots (e.g., Lowe et al., 2000), genetic discontinuities (Moritz, 1994), genetically isolated and unique populations (Cavers et al., 2003) or populations under different geopolitical management that need to be uniformly managed for the conservation of the species (Karl and Bowen, 1999; Cavers et al., 2003); (2) identification of the genetic history of domesticated species to construct a history of introduction and likely sources of origin (Zerega et al., 2004, 2005), and weed invasions including the search for biological control agents from a relevant source region (McCauley et al., 2003); (3) examination of remnant populations of an exploited or depleted species to assess future population viability and develop appropriate management actions and determine processes and ecological factors affecting gene flow dynamics, and (4) development of genetic resource management strategies for plants in the early stages of domestication by comparisons of exploited and nonexploited populations or between domesticated and natural populations.

Domestication can lead to reduced genetic diversity.

The loss of genetic diversity can arise from processes associated with domestication: (1) competition for land resources resulting from the widespread planting of domesticated varieties may lead to the elimination of natural populations, (2) pollen or seed flow from cultivars in production areas can overwhelm those of remnant wild populations, causing genetic erosion of the natural populations, (3) a genetic bottleneck is formed when selective breeding of one or a few superior lines (e.g., Inga edulis-Hollingsworth et al., 2005; Dawson et al., 2008) results in increased inbreeding or increased genetic differentiation relative to source populations. Consequently domesticated lines often contain only a subset of the genetic variation of natural populations. Conversely, however, the breeding process can also be used to fix extreme traits or introduce additional variation in selected phenotypic characters. Agricultural diversity depends on wild sources of genes from neglected and underutilized species in order to maintain the productivity and adaptability of domesticated species. The optimization of livelihood benefits during environment change requires a stronger integration between initiatives to conserve agricultural biodiversity and wild biodiversity (Thompson et al., 2007).

Domesticated populations can have conservation value.

Recent studies using molecular techniques have found that when domestication occurs in ways that do not lead to the loss of wild populations, genetic erosion or genetic bottlenecks, the domesticated population can itself provide a valuable contribution to genetic resource management and conservation. In Latin America, Inga edulis, which has been utilized by local people for several thousands of years (Dawson et al., 2008), has remained genetically diverse in five sites in the Peruvian Amazon relative to natural stands (Hollingsworth et al., 2005). In this example, genetic differentiation estimates indicated that the domesticated stands were introduced from remote sources rather than from proximate natural stands (Dawson et al., 2008). Despite maintaining high levels of diversity, this suggests that domesticated stands can also have negative impacts on long term performance through source mixing.

Village-level domestication strategies have conservation advantages in the context of global genetic resource management.

Village-level domestication has been promoted for the development of new tree crops in developing countries (Weber et al., 2001; Leakey et al., 2003), rather than the centralized distribution of a single line or a few selected genotypes. This practice involves individual communities or villages developing superior lines of new crops from local populations or landraces that are specific to the participating communities, using established domestication practices. This strategy has the inherent advantage of harnessing adaptive variation for a range of local environmental factors, while sourcing from multiple villages ensures that a broad range of genetic variation is preserved across the species range. This strategy provides long-term benefit for genetic diversity conservation where native habitats are increasingly being lost to development. The success of this strategy lies partly in developing an appreciation for a diversity of forms within the new crop, such as has occurred in the wine industry, where customers have been educated to appreciate the diversity of flavors offered by different grape varieties.

Biodiversity and genetic diversity have been "protected" by international policies.

The Convention on Biological Diversity (CBD, 1992) was ratified in 1993 to address the broad issues of biodiversity conservation, sustainable use of its components and the equitable sharing of the benefits arising from the use of biodiversity. Its Global Strategy of Plant Conservation (GSPC) included global targets for 2010, such as "70% of the genetic diversity of crops and other major socioeconomically valuable plant species conserved." The International Treaty