Current Biology
Volume 28, Issue 6, 19 March 2018, Pages 963-971.e8
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Rapid Global Spread of wRi-like Wolbachia across Multiple Drosophila

https://doi.org/10.1016/j.cub.2018.02.015Get rights and content
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Highlights

  • Closely related Wolbachia spread across eight diverse Drosophila

  • Spread was extremely rapid, over less than 30,000 years

  • mtDNA analyses indicate no horizontal transmission within these species

  • Only six of the eight Wolbachia strains cause detectable reproductive manipulation

Summary

Maternally transmitted Wolbachia, Spiroplasma, and Cardinium bacteria are common in insects [1], but their interspecific spread is poorly understood. Endosymbionts can spread rapidly within host species by manipulating host reproduction, as typified by the global spread of wRi Wolbachia observed in Drosophila simulans [2, 3]. However, because Wolbachia cannot survive outside host cells, spread between distantly related host species requires horizontal transfers that are presumably rare [4, 5, 6, 7]. Here, we document spread of wRi-like Wolbachia among eight highly diverged Drosophila hosts (10–50 million years) over only about 14,000 years (5,000–27,000). Comparing 110 wRi-like genomes, we find ≤0.02% divergence from the wRi variant that spread rapidly through California populations of D. simulans. The hosts include both globally invasive species (D. simulans, D. suzukii, and D. ananassae) and narrowly distributed Australian endemics (D. anomalata and D. pandora) [8]. Phylogenetic analyses that include mtDNA genomes indicate introgressive transfer of wRi-like Wolbachia between closely related species D. ananassae, D. anomalata, and D. pandora but no horizontal transmission within species. Our analyses suggest D. ananassae as the Wolbachia source for the recent wRi invasion of D. simulans and D. suzukii as the source of Wolbachia in its sister species D. subpulchrella. Although six of these wRi-like variants cause strong cytoplasmic incompatibility, two cause no detectable reproductive effects, indicating that pervasive mutualistic effects [9, 10] complement the reproductive manipulations for which Wolbachia are best known. “Super spreader” variants like wRi may be particularly useful for controlling insect pests and vector-borne diseases with Wolbachia transinfections [11].

Keywords

cytoplasmic incompatibility
horizontal transmission
introgression
mutualistic endosymbiont
mitochondrial variation
disease control

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