Unveiling biogeographic patterns in the worldwide distributed Ceratitis
capitata (medfly) using population genomics and microbiome composition
Abstract
Invasive species are among the most important, growing threats to food
security and agricultural systems. The Mediterranean fruit fly Ceratitis
capitata is one of the most damaging representatives of a group of
rapidly expanding species in the family Tephritidae due to their wide
host range and high invasiveness. Here, we used restriction
site-associated DNA sequencing (RADseq) to investigate population
genomic structure and phylogeographic history of medflies collected from
six sampling sites, including Africa (South Africa), the Mediterranean
(Spain, Greece), Latin America (Guatemala, Brazil) and Australia. A
total of 1,907 single nucleotide polymorphisms (SNPs) showed two genetic
clusters separating native and introduced ranges, consistent with
previous findings. In the introduced range, all individuals were
assigned to one genetic cluster except for those in Brazil, which showed
introgression of a genetic cluster that also appeared exclusively in
South Africa and could not be previously identified using microsatellite
markers. Moreover, the microbiome variations in medfly populations from
selected sampling sites was assessed by amplicon sequencing of the 16S
ribosomal RNA (V4 region). No strong patterns of microbiome variation
were detected across geographic regions or host plants, except for the
differentiation of the Brazilian specimens which showed increased
diversity and unique composition of its microbiome compared to other
sampling sites. The unique SNP patterns in the Brazilian specimens could
point to a direct migration route from Africa with subsequent adaptation
of the microbiota to the specific conditions present in Brazil. These
findings significantly improve our understanding of the evolutionary
history of global medfly invasions and adaptation to newly colonised
environments.