Mitochondrial DNA genetic variation of the Robber Fly Diogmites angustipennis (Diptera: Asilidae)

Abstract

Diogmites angustipennis Loew (Diptera: Asilidae) is a widespread predatory robber fly inhabiting grassland and woodland ecosystems across the Southeastern, Central, and Western United States, yet its population genetics have remained entirely uncharacterized. To evaluate genetic variation across the species' range, we analyzed a 406 bp fragment of the mitochondrial 16S rRNA gene from 33 individuals collected in 14 U.S. states. Fourteen haplotypes were observed, with 17 variable nucleotide sites, and high overall haplotype diversity (Hd = 0.922). Several haplotypes, including H2 and H11, were geographically widespread, whereas others were regionally restricted singletons. A statistical parsimony network identified haplotype H2 as a central, ancestral lineage, while H15 was the most divergent. Neutrality tests (Tajima's D, Fu and Li's D+, Fu's Fs) were negative overall. Negative but nonsignificant neutrality statistics are consistent with population expansion, but alternative explanations (e.g., purifying selection) cannot be ruled out. Genetic differentiation among regions was generally low, and gene flow was highest between the Southwest and Southeast (FST = 0.004; Nm = 62.25), indicating substantial connectivity. These findings demonstrate high mitochondrial diversity in D. angustipennis and reveal population structure consistent with historical expansion and regionally variable gene exchange. The study establishes a baseline for North American robber fly species genetic variation and highlights the utility of mtDNA markers for future phylogeographic work in Diogmites and other asilid taxa.