Symbionts do not affect the mating incompatibility between the Brazilian-1 and Peruvian morphotypes of the Anastrepha fraterculus cryptic species complex

Francisco Devescovi,Elena I Cancio Martinez,Claudia A Conte,Diego F Segura,Kostas Bourtzis,Antonios Augustinos,Carlos Caceres,Silvia B Lanzavecchia

doi:10.1038/s41598-019-54704-y

Abstract

The South American fruit fly, Anastrepha fraterculus, is clearly undergoing a speciation process. Among others, two of their morphotypes, the Brazilian-1 and Peruvian, have accumulated differences in pre- and post-zygotic mechanisms resulting in a degree of reproductive isolation. Both harbor a different strain of Wolbachia, which is a widespread endosymbiotic bacterium among many invertebrates producing a range of reproductive effects. In this paper, we studied the role of this bacterium as one of the factors involved in such isolation process. Infected and cured laboratory colonies were used to test pre- and post-zygotic effects, with special emphasis in uni- and bi-directional cytoplasmic incompatibility (CI). We showed that Wolbachia is the only known reproductive symbiont present in these morphotypes. Wolbachia reduced the ability for embryonic development in crosses involving cured females and infected males within each morphotype (uni-directional CI). This inhibition showed to be more effective in the Peruvian morphotype. Bi-directional CI was not evidenced, suggesting the presence of compatible Wolbachia strains. We conclude that Wolbachia is not directly involved in the speciation process of these morphotypes. Other mechanisms rather than CI should be explored in order to explain the reduced mating compatibility between the Brazilian-1 and Peruvian morphotypes.

Highlights

The South American fruit fly, Anastrepha fraterculus, is clearly undergoing a speciation process
These bacteria are phylogenetically distributed in different supergroups within the order Rickettsiales, the majority of which participate in symbiotic relationships with different groups of arthropods[3,6,7]
Wolbachia affects the reproductive biology of its hosts in different ways, inducing reproductive alterations such as feminization of genetic males, parthenogenesis in haplodiploid species, the killing of male progeny deriving from infected females, and embryonic mortality due to cytoplasmic incompatibility (CI)[3,12,13]

Summary

Introduction

The South American fruit fly, Anastrepha fraterculus, is clearly undergoing a speciation process. Wolbachia reduced the ability for embryonic development in crosses involving cured females and infected males within each morphotype (uni-directional CI). This inhibition showed to be more effective in the Peruvian morphotype. Since CI acts as a post-zygotic isolation mechanism between populations with different infection status or harbouring incompatible Wolbachia strains, it was suggested that they could influence evolutionary processes of their hosts including speciation (e.g. Drosophila[20,22,23,24], Nasonia complex[18,24,25], Gryllus crickets[26])

Objectives

Methods

Results

Conclusion