Wolbachiaas agents of extensive mtDNA lineage sharing between species through multiple infection

Abstract

ABSTRACTWolbachiacan manipulate arthropod host reproduction, triggering the homogenisation of mtDNA variation within species and introgression between hybridising species through indirect selection. While fixation within species of mtDNA variants linked toWolbachiainfections has been documented, a broader understanding of the potential consequences ofWolbachiainfection through hybridisation is limited. Here we evaluateWolbachiatransmission through hybridisation as a mechanistic explanation for extensive mtDNA paraphyly between two species of iron-clad beetle (Zopheridae). Our analyses reveal a complex pattern of mitochondrial variation, supporting the introgression of at least five mtDNA lineages fromTarphius canariensisintoT. simplex, in a background of a sharedWolbachiainfection across both species. Genetic clustering and demographic simulations reveal a clear pattern of nuclear differentiation between species, a limited signature of historical gene flow, and the eastwards range expansion ofT. simplexacross the existing distribution ofT. canariensis.These results are consistent with hybridisation during early stages of secondary contact, during whichWolbachiainfection facilitated recurrent mtDNA introgression events. These results highlight the complex restructuring of mitochondrial differentiation across invertebrate species that can result from bacterial endosymbiotic infections, a phenomena with potentially profound impacts for the disciplines of phylogeography and species delimitation.