Geographic isolation affects inter- and intra-specific seed variability in the Astragalus tragacantha complex, as assessed by morpho-colorimetric analysis

The effect of geographical isolation on the inter- and intra-specific seed variability of the Astragalus tragacantha complex was investigated by using a computer-aided imaging system. In particular, seed morphometric and colorimetric features of Astragalus balearicus, A. tegulensis, A. terraccianoi, A. thermensis and A. tragacantha were measured and the data used to discriminate among regions of provenance, taxa and populations. Discriminant analysis of the data supports the accepted taxonomy of the group and the hypothesis that inter-specific differentiation resulted from geographical isolation. The results also showed a positive correlation between the wideness of the species’ distribution and the levels of seed intra-specific variability