The central argument of both of these papers is that farmers manage crop variability in distinctive ways.

The first paper discusses how formal plant breeders can potentially contribute a great deal in a collaboration with farmers to improve crop varieties for local use. Yet to do so, plant breeders and other outside researchers must have some understanding of local selection practices and their impact on crop populations, in terms of the concepts central to the genetic theory underlying plant breeding. In this research we integrated methods from both social and biological sciences to better understand selection and its consequences from farmers’ perspectives, but in terms of the concepts used by plant breeders. Among the households we worked with, farmers’ selection practices were not always effective – yet they understood quite clearly the reason for this and had no expectations of responses to selection in some traits given the methods available to them. A role for plant breeder collaboration with farmers was indicated by farmers’ statements, practices and genetic perceptions regarding selection as well as the genetic response of their maize populations to selection.

In the second paper, Catherine Longley discusses how farmers from two ethno-linguistic groups in Sierra Leone have contrasting perceptions of the semi-weed rice, salli foreh. The ways in which these perceptions relate to local cultural beliefs, knowledge systems and agricultural practices are analysed. Salli foreh is thought to exist as a hybrid that acts as a bridge for gene exchange. Farmers’ different perceptions of salli foreh may affect the potential for natural out-crossing and creation of new biological variability. The paper illustrates how different farming communities manage variability in distinctive ways and highlight the need for detailed ethnographic characterisation in understanding farmer influences on processes of micro-evolutionary change.