Gap analysis: a tool for complementary genetic conservation assessment

Aim Gap analysis is a well-established conservation technique that identifies areas in which selected elements of biodiversity are represented and through comparison with existing in situ protected area networks identifies habitats or ecosystems that need additional protection. We aim to demonstrate that gap analysis may be extended to encompass both in situ and ex situ genetic diversity conservation strategies. Location Global, with exemplar case study from sub-Saharan Africa. Methods An extended methodology of gap analysis is proposed that involves the following steps: (1) circumscription of target taxon and target area; (2) assessment of natural diversity through a review of intrinsic taxonomic, genetic and ecogeographical diversity combined with threat assessment; (3) assessment of current complementary in situ and ex situ conservation strategies; and (4) reformulation of the conservation strategy through analysis of the differences between the pattern of natural, intrinsic diversity and the elements of that diversity already effectively represented by existing in situ and ex situ conservation actions. Results To illustrate the gap analysis approach proposed, the methodology was applied to the conservation of African Vigna species (cowpea Vigna unguiculata (L.) Walp. and its wild relatives) and indicated: (1) genetic reserves should be established at the southern tip of Lake Tanganyika, the coastal area of Sierra Leone and between Lake Victoria and the other Great Lakes, and (2) 14 taxa and several countries should be targeted for further seed collection. Main conclusions The robust nature of the extended methodology for gap analysis has been demonstrated and indicates that its scope as an effective conservation tool may be expanded to fully address the need for a more comprehensive and complementary conservation strategy that encompasses both in situ and ex situ applications. However, it should be stressed that the methodology is applicable for any form of biodiversity (wild or cultivated), where the conservation of genetic diversity is the prime goal.