The Mediterranean weedy vegetation and its origin

Abstract

An overview on the origin and evolutionary trends in the Mediterranean weedy vegetation is presented, with reference to the phytosociological units to which they are ascribed: Stellarietea mediae, Papaveretea rhoeadis, Oryzetea sativae. It is postulated that the “Neolithic revolution” was more likely a “Neolithic evolution”, i.e. the result of a process of selection and demographic growth that lasted for at least 10000 yrs, before leading to the domestication of plants and animals. During this very long time, wild crop relatives were simply growing together with the wild weed relatives, in their original milieu. At the beginning of agriculture, fields were obtained to the detriment of oak-woods and maquis-vegetation; the deforestation had probably a patchy pattern, resulting from the burn-beating practice, and the annual plants from the vegetation around the fields were probably quite abundant also within the fields, at least those having the most prolific seed set, the most durable seeds and the most effective dispersal strategies, together with a diachronic, life-long, flowering and seed-dispersal. These features, apparently in contrast with the achievement of a within-population- organizational hierarchy, are in reality an extreme expression of the attitude of weedy plant species in "amplifying adaptation", or, in other words, of its "adaptation to adapt", which is the cornerstone of the opportunistic life strategy. The Mediterranean weedy vegetation is therefore a flexible system, able to cope with changes and disturbances: species frequency and composition may undergo great variations, but the functional role of any weedy community keeps.