Phylogeographic patterns of Merodon hoverflies in the Eastern Mediterranean region: revealing connections and barriers

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.

Moderate fire severity is best for the diversity of most of the pollinator guilds in Mediterranean pine forests

“…, Ståhls et al. ), and perhaps these resources are affected even at moderate fire severities. Furthermore, their lower abundance may also be associated with increased drought following moderate and higher fire severity (Ponisio et al.…”

“…Among hoverflies, the immature stages of the abundant Eumerus spp. group and Merodon avidus species are associated with belowground storage organs of plants (Grkovi c et al 2015, St ahls et al 2016, and perhaps these resources are affected even at moderate fire severities. Furthermore, their lower abundance may also be associated with increased drought following moderate and higher fire severity (Ponisio et al 2016).…”

Cryptic speciation in theMerodon luteomaculatuscomplex (Diptera: Syrphidae) from the eastern Mediterranean

“…The nuclear 28S rRNA gene is also used as an additional source of information to resolve taxonomic uncertainties (Mengual et al., ), although it is usually applied at the genus level. Inter‐simple sequence repeats (ISSR) have been used to discern closely related insect species (Kehlmaier & Assmann, ) and for assessments of population‐level genetic polymorphism (Ståhls et al., ). In addition to molecular data, geometric morphometry has been successfully used in cryptic species delimitation due to its considerable discriminatory and statistical power in revealing minor but stable morphological variation, often undetectable to the naked eye (Nedeljković et al., , ; Šašić et al., ; Vujić, Ståhls, et al., ).…”

“…Ståhls et al. () recently studied the phylogeographical patterns of selected Merodon species in the eastern Mediterranean. They concluded that both current and past geographical barriers have influences on the dispersal and evolution of Merodon .…”

Optimal inventorying and monitoring of taxonomic, phylogenetic and functional diversity

“…PD has mostly been measured based on phylogenetic trees or cladograms (Faith 1992). This notion can be extended to intra-specific variability, in which case individuals or populations of one or more species are studied under the same framework (Ståhls et al 2016). Yet, in lieu of precise phylogenetic information on the member taxa of a community, taxonomic diversity (LD) may be used as a surrogate for PD, being calculated from an ultrametric tree (i.e.…”