Loss of mitochondrial diversity in invasive populations of Asian honey bees, Apis cerana (Hymenoptera: Apidae), in the austral-Pacific.
Introduced species are a significant global concern because they can disrupt native ecosystems and cause economic damage to agricultural systems and infrastructure. The mitochondrial DNA (mtDNA) diversity of invasive populations can help to identify the source and number of incursions and reveal whether these populations have maintained standing genetic variation that might allow mitochondrial genomes to adapt to new environments. We investigated mitochondrial diversity in native and invasive populations of the Asian honey bee (Apis cerana). We generated 144 sequences of mitochondrial cytochrome c oxidase subunit I (COI) from samples spanning three invasive populations (Australia, New Guinea and Solomon Islands) and three native-range Indonesian populations (Java, Sulawesi and Flores). We then analysed these sequences together with published COI sequences to evaluate changes in mtDNA diversity associated with the recent spread of A. cerana across the Austral-Pacific region. Mitochondrial COI diversity was consistent with invasive A. cerana populations having endured severe founder event bottlenecks during colonisation of New Guinea from Java, and then again during colonisation of Australia and the Solomon Islands from New Guinea. Mitochondrial diversity of native-range Indonesian populations was high (26 COI haplotypes detected), particularly on Java (20 haplotypes), while all samples from invasive populations carried the same COI haplotype. Indeed, the single COI haplotype of invasive A. cerana populations is consistent with invasive populations being founded by just one, or very few, queens, as previously suggested from nuclear markers. Further investigation is needed to understand the fitness effects, if any, of mitochondrial diversity loss in invasive A. cerana populations of the Austral-Pacific.