Life history traits as predictors for biological invaders ?

Fruit flies (Diptera: Tephritidae) of Réunion Island constitute a good model to test the hypothesis that invasions might be predicted by life history traits. Indeed a series of four successive invasions by species belonging to the same family has been reported in the past. The endemic Ceratitis catoirii has been first displaced by the invasion of Ceratitis capitata in the 1940's. These two species have later been displaced again by Ceratitis rosa, introduced in 1955 and finally, Bactrocera zonata has been detected in 1991. We tested whether the ability of a species to displace another was dependent on life-history characteristics. Fecundity and mortality parameters as well as body size indicate that the different species can be placed on an r/K trade-off except for the endemic species, which is outperformed by the other three species for all traits. Among the three introduced species, the invasion rank was not correlated to a high intrinsic rate of increase. On the contrary, B. zonata, which was able to displace all other species, has a low rate of increase, large adult size, long prereproductive period, low fecundity and delayed senescence, which suggests that the K lifestyle favors invasion in the presence of competitors. (Texte intégral