Landscape genetics and wing morphometrics show a lack of structuring across island and coastal populations of the drone fly in theMediterranean

Abstract

AbstractTheMediterranean basin is a region of species richness, rarity and endemism, and is thus an area of significant conservation importance. Conservation of insect biodiversity benefits pollination services in the fragmentedMediterranean landscape. However, the question of the distribution patterns of an important long‐distance pollen disperser, the hoverflyEristalis tenax(Diptera,Syrphidae), remains open. Therefore, we explored the spatial distribution of genetic and phenotypic diversity of this species across theCentral‐EasternMediterranean. Connectivity between continental and island populations ofE. tenaxwas studied by integrating molecular (allozyme loci and mitochondrialDNAsequences of the cytochromecoxidase subunit I gene) and phenotypic data (wing geometric morphometrics). Allozyme (FSTvalues,STRUCTUREanalysis, analysis of molecular variance) and phenotypic data (wing shape) and landscape genetics (Alleles in Space analysis) suggest thatE. tenaxpopulations within theMediterranean are largely connected, and that there is an absence of large‐scale geographic structuring. Intraspecific variability was only 1.54% among samples, and theMediterranean populations showed an almost complete lack ofCOI mtDNAhaplotype diversity. Thus, our results suggest thatE. tenaxpopulations are well mixed, and that a considerable amount of gene flow takes place, even among populations that are a great distance apart. AsE. tenax's ecological amplitude is wide, and the species is therefore widespread in both natural and man‐made landscapes, it probably maintains a high level of population similarity by its large population sizes (as revealed by theθparameter) and constant intermixing among populations. From an applied point of view, large‐scale species intermixing enables pollen spread across distant island plant populations, especially those threatened by extinction.