Wolbachia have made it twice: Hybrid introgression between two sister species of Eurema butterflies

• Published in: Ecology and evolution Vol. 10; no. 15; pp. 8323 - 8330
• Main Authors: N. Miyata, Mai, Nomura, Masashi, Kageyama, Daisuke
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.08.2020; John Wiley and Sons Inc; Wiley
• Subjects: Arthropods; Butterflies & moths; Chromosomes; Cytochrome; cytoplasmic incompatibility; Deoxyribonucleic acid; DNA; Endosymbionts; Eurema hecabe; Eurema mandarina; Females; feminization; Genes; Genetic engineering; Haplotypes; hybrid introgression; Infections; Males; meiotic drive; Mitochondria; Mitochondrial DNA; Offspring; Original Research; Phylogenetics; Phylogeny; Sex ratio; Sibling species; Software; Wolbachia; Japan; Okinawa; Eurema mandarina; Eurema hecabe; feminization; Wolbachia; mitochondrial DNA; meiotic drive; hybrid introgression; cytoplasmic incompatibility
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6539

Wolbachia, cytoplasmically inherited endosymbionts of arthropods, are known to hijack their host reproduction in various ways to increase their own vertical transmission. This may lead to the selective sweep of associated mitochondria, which can have a large impact on the evolution of mitochondrial lineages. In Japan, two different Wolbacahia strains (wCI and wFem) are found in two sister species of pierid butterflies, Eurema mandarina and Eurema hecabe. In both species, females infected with wCI (C females) produce offspring with a nearly 1:1 sex ratio, while females infected with both wCI and wFem (CF females) produce all‐female offspring. Previous studies have suggested the historical occurrence of hybrid introgression in C individuals between the two species. Furthermore, hybrid introgression in CF individuals is suggested by the distinct mitochondrial lineages between C females and CF females of E. mandarina. In this study, we performed phylogenetic analyses based on nuclear DNA and mitochondrial DNA markers of E. hecabe with previously published data on E. mandarina. We found that the nuclear DNA of this species significantly diverged from that of E. mandarina. By contrast, mitochondrial DNA haplotypes comprised two clades, mostly reflecting Wolbachia infection status rather than the individual species. Collectively, our results support the previously suggested occurrence of two independent historical events wherein the cytoplasms of CF females and C females moved between E. hecabe and E. mandarina through hybrid introgression. Two sister species of butterflies, Eurema mandarina and E. hecabe, are distinct by nuclear gene sequences. The comparison of mitochondrial gene sequence variations revealed two independent occurrences of Wolbachia‐associated hybrid introgression.