I completely missed an interesting blog post by Prof. Andy Lowe of the University of Adelaide when it came out a couple of years ago. “Local is not always best” updates a paper in a previous article ((Lowe AJ (2010) Composite provenancing of seed for restoration: progressing the ‘local is best’ paradigm for seed sourcing. In: The State of Australia’s Birds 2009: Restoring Woodland Habitats for Birds. (Eds David Paton and James O’Conner). Supplement to Wingspan 20(1) pp 16-17.)) on where you should get your seeds from for habitat restoration projects. In summary, the answer is: not all from one, nearby place.
To simulate the natural mixing of genes during a restoration programme, it would be necessary to restore populations using a mixture of material sampled at different distances from the focal site, a practise defined as composite provenancing. This ‘composite provenance’ would be predominantly composed of locally sourced material, taken from genetically healthy stock, but would also incorporate local and ecogeographically matched sources. In addition, a smaller proportion of material, depending on the natural gene flow dynamics of the focal species (but usually somewhere between 10 and 30%), should be comprised of material from much further a field.
Though Prof. Lowe deals with wild species in his paper and blog post, I think “composite provenancing” is also be relevant for crops. Sometimes, too much is made of “genetic integrity” and localism.