Abstract
We investigated the phylogeographic patterns of Merodon species (Diptera, Syrphidae) in the Eastern Mediterranean. Ten species were sampled on five different islands and mainland sites as a minimum. All samples were screened for their mtDNA COI barcode haplotype diversity, and for some samples, we additionally generated genomic fingerprints. The recently established zoogeographic distribution categories classify these species as having (1) Balkan distribution; (2) Anatolian distribution; (3) continental areas and large islands distribution; and (4) with wide distribution. The ancestral haplotypes and their geographical localities were estimated with statistical parsimony (TCS). TCS networks identified as the ancestral haplotype samples that originated from localities situated within the distributional category of the species in question. Strong geographical haplotype structuring was detected for many Merodon species. We were particularly interested to test the relative importance of current (Aegean Sea) and past Mid‐Aegean Trench) barriers to dispersal for Merodon flies in the Aegean. We employed phylogenetic β‐diversity (Pβ total) and its partition in replacement (Pβ repl) and richness difference (Pβ rich) to test the importance of each explanatory variable (interisland distance, MAT, and island area) in interisland differences using partial Mantel tests and hierarchical partitioning of variation. β‐Analyses confirmed the importance of both current and past barriers to dispersal on the evolution of group. Current interisland distance was particularly important to explain the replacement of haplotypes, while the MAT was driving differences in richness of haplotypes, revealing the MAT as a strong past barrier whose effects are still visible today in the phylogenetic history of the clade in the Aegean. These results support the hypothesis of a highly restricted dispersal and gene flow among Merodon populations between islands since late Pleistocene. Additionally, patterns of phylogeographic structure deduced from haplotype connections and ISSR genome fingerprinting data revealed a few putative cases of human‐mediated transfers of Merodon spp.
Highlights
Hoverflies (Diptera, Syrphidae) constitute an important pollinator group standing in importance only to bees (Hymenoptera, Apoidea)
The best-fit model for the ML analysis was the General Time Reversible (GTR) model + gamma-distributed rates, while the Kimura 2-parameter (K2P; Kimura 1980) nucleotide substitution model was used for the NJ analyses
Our results identified that interisland distance is partly responsible for the observed haplotype distributional patterns, namely the replacement of haplotypes, and the MidAegean Trench (MAT) as a strong past barrier, the effects of which are still visible today in the phylogenetic history of the clade in the Aegean
Summary
Hoverflies (Diptera, Syrphidae) constitute an important pollinator group standing in importance only to bees (Hymenoptera, Apoidea).
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