Data from: Past and present dynamics of sorghum and pearl millet diversity in Mount Kenya region

Crop populations in smallholder farming systems are shaped by the interaction of biological, ecological and social processes, occurring on different spatiotemporal scales. Understanding these dynamics is fundamental for the conservation of crop genetic resources. In this paper we investigated the processes involved in sorghum and pearl millet diversity dynamics on Mount Kenya. Surveys were conducted in ten sites distributed along two elevation transects and occupied by six ethnolinguistic groups. Varieties of both species grown in each site were inventoried and characterized using SSR markers. Genetic diversity was analyzed using both individual and population based approaches. Surveys of seed lot sources allowed characterizing seed-mediated gene flow. Past sorghum diffusion dynamics were explored by comparing Mount Kenya sorghum diversity with that of the African continent. The absence of structure in pearl millet genetic diversity indicated common ancestry and/or important pollen and seed-mediated gene flow. On the contrary, sorghum varietal and genetic diversity showed geographic patterns, pointing to different ancestry of varieties, limited pollen-mediated gene flow, and geographic patterns in seed-mediated gene flow. Social and ecological processes involved in shaping seed-mediated gene flow are further discussed.小农种植系统中的作物种群由生物、生态与社会过程的交互作用所塑造，这些过程发生于不同的时空尺度之中。明晰此类动态变化，对于作物遗传资源（crop genetic resources）的保护具有基础性意义。本文针对肯尼亚山地区高粱与珍珠粟的多样性动态相关过程开展了调查研究。调研沿两条海拔样带布设了10个采样点，涉及6个民族语言群体的定居区域。研究人员对每个采样点种植的上述两个物种的品种进行了清点，并采用简单序列重复（Simple Sequence Repeat，SSR）标记开展品种特征鉴定。遗传多样性分析同时采用了基于个体与基于种群的两类分析方法。通过对种子批来源的调查，得以解析种子介导的基因流特征。此外，通过将肯尼亚山地区的高粱多样性与非洲大陆的高粱多样性进行比对，探究了历史上高粱的扩散动态。珍珠粟的遗传多样性未呈现种群结构，这一结果表明其拥有共同的祖先，或存在大量由花粉与种子介导的基因流。与之形成对照的是，高粱的品种与遗传多样性呈现出显著的地理分布模式，这指向品种的不同起源、有限的花粉介导基因流，以及种子介导基因流的地理分布特征。本文还进一步讨论了塑造种子介导基因流的社会与生态过程。