Reflections on the transition from wind pollination to ambophily

In western and central Europe a limited number of anemophilous species has been observed to be regularly visited by anthophilous insects. Furthermore, it appears that the visitors may function as pollen vectors in a modest way. In open, wind-exposed environments, the typical habitat of anemophiles, biotic pollination is only of minor importance for their reproduction. On the basis of relevant indications two models are being suggested, visualising a change-over from anemophily to partial insect pollination (ambophily) at the population level. An extant relation of insects to an anemophilous population is regarded to be a necessary starting-point for a development towards ambophily. In addition, the occurrence within such a population of a genetic variant, characterised by a feature furthering biotic pollen transfer, is a prerequisite. Provided these conditions are being fulfilled, two different pathways may lead to ambophily. (1). In a population that is being subjected to conditions of decreased wind-intensity, only the variant is capable of surviving by availing itself of biotic pollen transfers, which may ultimately give rise to an ambophilous biotype. (2). In a population inhabiting an open environment, liable to a moderate action of wind, selective biotic pollination of the variant will cause the spreading of this type within the population, which may likewise lead to the formation of an ambophilous biotype. The significance of these concepts lies primarily in the possibility of their empirical testing in actual situations, which in some instances has already yielded interesting results.