Résumé
Reconstructing and characterizing introduction routes is a key step
towards understanding the ecological and evolutionary factors underlying
successful invasions and disease emergence. Here, we aimed to decipher
scenarios of introduction and stochastic demographic events associated
with the global spread of an emerging disease of bananas caused by the
destructive fungal pathogen Mycosphaerella fijiensis. We analysed the
worldwide population structure of this fungus using 21 microsatellites and
8 sequence-based markers on 735 individuals from 37 countries. Our
analyses designated South-East Asia as the source of the global invasion,
and supported the location of the centre of origin of M. Fijiensis within
this area. We confirmed the occurrence of bottlenecks upon introduction
into other continents followed by widespread founder events within
continents. Furthermore, this study suggested contrasting introduction
scenarios of the pathogen between the African and American continents.
While potential signatures of admixture resulting from multiple
introductions were detected in America, all the African samples examined
seem to descend from a single successful founder event. In combination
with historical information, our study reveals an original and
unprecedented global scenario of invasion for this recently emerging
disease caused by a wind-dispersed pathogen.