The Anatolian Diagonal and Paleoclimatic Changes Shaped the Phylogeography of Cynips quercus (Hymenoptera, Cynipidae)

Population genetics and phylogeography of Tabanus bromius (Diptera: Tabanidae)

Background

Tabanus bromius (Diptera: Tabanidae) is one of the most notable Tabanidae species of veterinary and medical importance distributed throughout the Palearctic region. In this study, we investigate the genetic diversity and the phylogeographic structure of T. bromius sampled from Turkey, Croatia, and Iran.

Methods

For this purpose, a 686-base-pair (bp) fragment of mitochondrial DNA cytochrome oxidase I gene (COI) and 1339 bp of the nuclear DNA internal transcribed spacer (ITS) were sequenced from 247 individuals representing 15 populations.

Results

The sequences generated 169 COI haplotypes and 90 ITS alleles. A higher haplotype/allele diversity (h = 0.9909 for the COI gene and Ad = 0.8193 for the ITS region) compared to a low nucleotide diversity (π = 0.020605 for COI gene and π = 0.013667 for the ITS region), present for a high number of singleton and private haplotypes/alleles imply population expansion in the past. The results of phylogenetic analysis led to the uncovering of geographically significant groupings of lineages with regard to the entrance of the species into Anatolia and the location of major geographic barriers. According to current data, the species appears to have entered Turkey from Caucasia and Iran. A molecular clock applied to the COI data suggests that T. bromius diverged from the outgroup species nearly 8.83 million years ago, around the end of the Miocene era.

Conclusions

The results of this study indicate remarkable genetic diversity across the studied range of the species. High haplotype/allele versus low nucleotide diversity and demographic analyses implied that the T. bromius populations have undergone a series of expansions and retreats in the past. Our current findings suggest that T. bromius split from outgroups around the Late Miocene. Subsequent diversification events during the climatic and environmental fluctuation times of the Late Pliocene and Early Pleistocene periods also significantly influenced the species, resulting in the formation of some major genetic lineages. The phylogenetic analyses indicate that T. bromius most likely entered Turkey from the Caucasus region and Iran.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04970-5.

Ecology and Evolution of Gall-Inducing Arthropods: The Pattern From the Terrestrial Fossil Record

Insect and mite galls on land plants have a spotty but periodically rich and abundant fossil record of damage types (DTs), ichnotaxa, and informally described gall morphotypes. The earliest gall is on a liverwort of the Middle Devonian Period at 385 million years ago (Ma). A 70-million-year-long absence of documented gall activity ensues. Gall activity resumes during the Pennsylvanian Period (315 Ma) on vegetative and reproductive axial organs of horsetails, ferns, and probably conifers, followed by extensive diversification of small, early hemipteroid galler lineages on seed-plant foliage during the Permian Period. The end-Permian (P-Tr) evolutionary and ecological crisis extinguished most gall lineages; survivors diversified whose herbivore component communities surpassed pre-P-Tr levels within 10 million years in the mid-to late Triassic (242 Ma). During the late Triassic and Jurassic Period, new groups of galling insects colonized Ginkgoales, Bennettitales, Pinales, Gnetales, and other gymnosperms, but data are sparse. Diversifying mid-Cretaceous (125–90 Ma) angiosperms hosted a major expansion of 24 gall DTs organized as herbivore component communities, each in overlapping Venn-diagram fashion on early lineages of Austrobaileyales, Laurales, Chloranthales, and Eurosidae for the Dakota Fm (103 Ma). Gall diversification continued into the Ora Fm (92 Ma) of Israel with another 25 gall morphotypes, but as ichnospecies on a different spectrum of plant hosts alongside the earliest occurrence of parasitoid attack. The End-Cretaceous (K-Pg) extinction event (66 Ma) almost extinguished host–specialist DTs; surviving gall lineages expanded to a pre-K-Pg level 10 million years later at the Paleocene-Eocene Thermal Maximum (PETM) (56 Ma), at which time a dramatic increase of land surface temperatures and multiplying of atmospheric pCO2 levels induced a significant level of increased herbivory, although gall diversity increased only after the PETM excursion and during the Early Eocene Climatic Optimum (EECO). After the EECO, modern (or structurally convergent) gall morphotypes originate in the mid-Paleogene (49–40 Ma), evidenced by the Republic, Messel, and Eckfeld floras on hosts different from their modern analogs. During subsequent global aridification, the early Neogene (20 Ma) Most flora of the Czech Republic records several modern associations with gallers and plant hosts congeneric with their modern analogs. Except for 21 gall DTs in New Zealand flora, the gall record decreases in richness, although an early Pleistocene (3 Ma) study in France documents the same plant surviving as an endemic northern Iran but with decreasing associational, including gall, host specificity.