An Overview of the Evolution of the Genus Astragalus (Fabaceae) in the Old World‎

Abstract

In the present study, the trend of divergence and fragmentation of different sections of Astragalus in the Old World has been investigated. Based on previous studies, Astragalus species are divided into three groups: primitive, intermediate, and advanced. The distribution maps of each of these groups in the Old World were presented in the study. The primitive group consists mainly of herbaceous sections with simple hairs and an old drought-tolerant section with woody stems and bifurcating hairs that are densely distributed in Asia and Africa and scattered in Europe. The intermediate group, with thorny cushion shapes, is often scattered in the Zagros and Alborz mountains, mountainous regions of Turkey, Lebanon, and Jordan, and extend from the east to Afghanistan, the Hindu Kush, and the southern parts of the Himalayas. The results of the study show that the distribution pattern of the advanced group is very heterogeneous and its pattern is consistent with the primitive group. The simple hair sections are often scattered below 35 degrees north latitude and the bifurcated hairs sections are more frequently distributed above 35 degrees north latitude. Annual Astragalus species are heterogeneously distributed in all three main groups. In all three groups, parallel evolution has taken place at the level of sections and species. At each point of distribution, their number has a limited distribution. In addition, some species have achieved non-genetic diversity by functional or regulatory genetic, hereditary or structural mechanisms and created distinct species that have adapted in nature to the ecological conditions of the same areas and continue to regenerate with even more distributions.

Keywords

• plant evolution
• astragalus
• section
• primitive
• intermediate
• advanced