ARS | Publication request: Strategies to restore fragmented meta-populations of Fertile Crescent wheat landraces

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 29, 2007
Publication Date: November 29, 2007
Repository URL: http://growseed.org/ABSTRACTS.pdf
Citation: Jaradat, A.A. 2007. Strategies to restore fragmented meta-populations of Fertile Crescent wheat landraces [abstract]. Restoring Ancient Wheat. p. 6.

Technical Abstract: Historically, farmers in the Fertile Crescent (FC) planted diverse assemblages of genotypes (i.e., landraces, LRs) to lower the risk of failure and increase food security because they had limited capacity to control the spatially heterogeneous and temporally unpredictable environment of the FC with material inputs. This practice led to the development of LR meta-populations and the emergence of farmers’ seed systems through which they accessed and exchanged diverse genetic material. A meta-population structure, defined as a group of subpopulations interconnected by gene-flow and seed exchange among farmers, villages and eco-geographical regions favors a dynamic evolution of diversity. In the FC, traditional management of wheat LRs contributed more to the conservation of a general level of diversity than to the conservation of genetically stable and distinct populations. Therefore, a wheat LR is far from being a stable, distinct and uniform unit; its diversity is linked to the diversity of the material sown in its immediate geographical area and to the level of seed exchange. The introduction of high-yielding varieties (HYVs) into and the structural changes in farming systems of the FC led to the loss of genetic diversity and fragmentation of meta-population structures of its wheat LRs. These LRs embody not only diverse alleles and genotypes but also evolutionary processes such as gene flow between different populations and local knowledge systems such as folk taxonomies and information about selection for heterogeneous environments. For farmers to continue to grow, select and manage local LRs, and to reverse the fragmentation of their meta-populations and allow evolutionary processes that mould LR diversity to continue, the value of these LRs should be raised to approximate or exceed the social value of HYVs. Re-creating and structuring local seed systems to simulate a source-sink meta-population model is a first step towards restoring the fragmented meta-population structure of LRs. Such a model should identify the unit of analysis (e.g., the farmer as a decision maker and agent of conservation, the field or parcel representing a particular habitat, the landrace or a seed lot); incorporate variation among farmers in their practices, knowledge and gender; quantify patterns of seed exchange among farmers and their impact on LR population biology parameters; identify the limiting factors that determine distribution and range of a LR; and define the minimum area needed to create a dynamic equilibrium between "colonization" and "extinction" of a LR meta-population.