Climatic niche partitioning following successive invasions by fruit flies in La Réunion

1. Biological invasions have profound effects on community structure. The community composition following invasions can be influenced by the habitat diversity and the species' responses to abiotic factors. 2. We evaluated the tolerance to climatic factors and analysed the field distribution of four polyphagous fruit flies (Diptera: Tephritidae) of La Réunion Island (three exotic species that successively invaded the island and the endemic species Ceratitis catoirii) in order to evaluate the opportunities of coexistence by niche differentiation. 3. Atmospheric humidity and immersion in water in the laboratory greatly influence the survival of fruit fly pupae. While C. catoirii and C. rosa are very sensitive to desiccation, C. capitata and especially Bactrocera zonata are relatively tolerant. B. zonata also tolerated immersion in water much longer than did C. rosa and C. catoirii, that in turn were more resistant than C. capitata. Overall, field distributions agree with the predictions based on this study of humidity combined with previous data on the effects of temperature. 4. Climatic niche partitioning promotes coexistence between some but not all pairs of invasive species. Thus, C. rosa can coexist with both C. capitata and B. zonata at the regional scale, while climatic niches are not different enough to promote coexistence of the latter two species. The endemic species has no private climatic niche either and this now very rare species could be in the process of extinction. 5. By promoting coexistence or not, climatic diversity in invaded areas can directly affect the community composition following invasions.