Saving seeds for planting and sharing.

Abstract Most seed saving is relatively easy, and many gardeners already know how to do it. But the key to getting the most out of saving and sharing garden seeds is understanding how these affect diversity and adaptation, and what that means to people and the communities. This chapter focuses on concepts that can make your seed saving and sharing more effective and consistent with your goals and values, and on practical suggestions for using those concepts. The four processes that shape the genetic diversity in garden crops, and all living organisms are discussed. Being aware of these processes gives you a new way to see and manage what's going on in the garden and seed stocks, to keep varieties healthy and vigorous, and retain important characteristics. Two of these processes (mutation and gene flow) usually increase diversity in the garden by adding new alleles; the other two (selection and genetic drift) typically decrease diversity by removing alleles. These processes result in microevolutionary changes in garden crops, that is, changes in frequencies of alleles and of genotypes over time.