Article

The evolution and speciati on within secl. Brassica can be eharae terized as allopatrie with weakly developed crossing barri ers. Crossing experimenls show Ihat the ehromosomal pairing in spee ies hybrids is high, indiealing that ali the speeies of the cytodcme have basicall y the same C genome. The relali ve ly wide intraspecifie geneli cal and morphological variati on is probably a result of local and regional differentiation. In most regions of the distribution area the specics consisl of spati ally well isolated populations and local adaptation has often given rise lo morphologica ll y dislinet populations as in, for instance, B. Cretica , B. rupestris, and B. villosa. Most populations are small, the reproductive capacity may fluctuate from one year to another and 'bottle-neck' situations may occur frequently. Results of crossing experiments and molecular in vesti galions lead to the eonelusion thal a li culti vatcd forms together with wild west European material belong to the same biological species, B. oleracea. Prospects for in situ conservation of wild populations are discussed.