Diploid males support a two-step mechanism of endosymbiont-induced thelytoky in a parasitoid wasp.

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State: Serval
Version: Final published version
Serval ID
serval:BIB_290500FC0760
Type
Article: article from journal or magazin.
Collection
Publications
Title
Diploid males support a two-step mechanism of endosymbiont-induced thelytoky in a parasitoid wasp.
Journal
BMC Evolutionary Biology
Author(s)
Ma W.J., Pannebakker B.A., van de Zande L., Schwander T., Wertheim B., Beukeboom L.W.
ISSN
1471-2148 (Electronic)
ISSN-L
1471-2148
Publication state
Published
Issued date
2015
Volume
15
Number
1
Pages
84
Language
english
Abstract
BACKGROUND: Haplodiploidy, where females develop from diploid, fertilized eggs and males from haploid, unfertilized eggs, is abundant in some insect lineages. Some species in these lineages reproduce by thelytoky that is caused by infection with endosymbionts: infected females lay haploid eggs that undergo diploidization and develop into females, while males are very rare or absent. It is generally assumed that in thelytokous wasps, endosymbionts merely diploidize the unfertilized eggs, which would then trigger female development.
RESULTS: We found that females in the parasitoid wasp Asobara japonica infected with thelytoky-inducing Wolbachia produce 0.7-1.2 % male offspring. Seven to 39 % of these males are diploid, indicating that diploidization and female development can be uncoupled in A. japonica. Wolbachia titer in adults was correlated with their ploidy and sex: diploids carried much higher Wolbachia titers than haploids, and diploid females carried more Wolbachia than diploid males. Data from introgression lines indicated that the development of diploid individuals into males instead of females is not caused by malfunction-mutations in the host genome but that diploid males are most likely produced when the endosymbiont fails to activate the female sex determination pathway. Our data therefore support a two-step mechanism by which endosymbionts induce thelytoky in A. japonica: diploidization of the unfertilized egg is followed by feminization, whereby each step correlates with a threshold of endosymbiont titer during wasp development.
CONCLUSIONS: Our new model of endosymbiont-induced thelytoky overthrows the view that certain sex determination mechanisms constrain the evolution of endosymbiont-induced thelytoky in hymenopteran insects. Endosymbionts can cause parthenogenesis through feminization, even in groups in which endosymbiont-diploidized eggs would develop into males following the hosts' sex determination mechanism. In addition, our model broadens our understanding of the mechanisms by which endosymbionts induce thelytoky to enhance their transmission to the next generation. Importantly, it also provides a novel window to study the yet-poorly known haplodiploid sex determination mechanisms in haplodiploid insects.
Keywords
Diploid males, Diploidization, Endosymbiont, Feminization, Haplodiploidy, Sex determination, Thelytoky, Wolbachia titer
Pubmed
Web of science
Open Access
Yes
Create date
28/05/2015 10:19
Last modification date
08/05/2019 16:10
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