Neglected mechanisms of adaptation to a changing world: pre-establishment selection on biological invaders

It is silently assumed that invasive propagules that are introduced into a novel distribution range are a random subset of the native population of origin, basically because there is virtually no data on what happens when propagules are taken up and transported across the globe, and introduced. Nonetheless, there are good reasons to think that these steps in the invasion process may be selective with respect to individual variation. For example, curious individuals are more likely to be caught in traps, and healthier individuals (incl. larvae, seeds iedtc.) are more likely to survive extended periods in transport. We have tested for signals of such selective filtering during the black box of the pre-establishment steps of the invasion pathway by following the fate of a pool of extensively phenotyped individuals from a native population: who gets caught and who does not, who survives the entry to captivity, who survives the transport, etc. In this project funded by the Spanish Minstry for Science, we studied this in two weaver species which have been introduced from Senegal and which have established several non-native populations on the Iberian Peninsula. We compared morphology, condition, infection with avian malaria, behaviour and endocrinology among successful and less successful individuals. First results in this very nice paper in Molecular Ecology, and further results in this paper in Evolutionary Applications.