Gene flow between sexual and asexual strains of parasitic wasps: a possible case of sympatric speciation caused by a parthenogenesis-inducing bacterium

Pairs of obligate social parasites and their hosts, where some of the parasites have recently diverged from their host through intraspecific social parasitism, provide intriguing systems for studying the modes and processes of speciation. Such speciation, probably in sympatry, has also been propounded in the ant Myrmica rubra and its intraspecific social parasite. In this species, parasitism is associated with queen size dimorphism, and the small microgyne has become a social parasite of the large macrogyne. Here, we investigated the genetic divergence of the host and the parasite queen morphs in 11 localities in southern Finland, using nuclear and mitochondrial markers of queens and workers. We formulated and tested four speciation-related hypotheses that differed in the degree of genetic divergence between the morphs. The queen morphs were genetically distinct from each other with little hybridization. In the nuclear data, when localities were nested within queen morphs in the hierarchical amova, 39% of the genetic variation was explained by the queen morph (standardized F'CT = 0.63, uncorrected FCT = 0.39), whereas 18% was explained by the locality (F'SC = 0.39, FSC = 0.29). This result corroborated the hypothesis of advanced sympatric speciation. In contrast, the mitochondrial DNA could not settle between the hierarchical levels of locality and queen morph, thus substantiating equally the hypotheses of incipient and advanced sympatric speciation. Together, our results support the view that the microgynous parasite has genetically diverged from its macrogynous host to the level of a nascent species.

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“…Essentially, thelytoky may contribute to sympatric speciation by promoting barriers to gene flow (Adachi‐Hagimori et al . ; Neumann et al . ).…”

Section: Discussionmentioning

confidence: 99%

Genetic divergence between the sympatric queen morphs of the antMyrmica rubra

et al. 2015

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“…Speciation caused by PI bacteria in nature had never been reported. But recently, Adachi‐Hagimori et al. (2011) have documented a possible case of sympatric speciation caused by a PI‐ Rickettsia in the eulophid wasp Neochrysocharis formosa (Westwood), with the thelytokous strain possibly originated in sympatry from the infection of an individual of the arrhenotokous strain.…”

Section: Discussionmentioning

confidence: 99%

Integration of molecular, ecological, morphological and endosymbiont data for species delimitation within thePnigalio soemiuscomplex (Hymenoptera: Eulophidae)

Gebiola

Gómez‐Zurita

Monti³

et al. 2012

Molecular Ecology

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Integrative taxonomy is a recently developed approach that uses multiple lines of evidence such as molecular, morphological, ecological and geographical data to test species limits, and it stands as one of the most promising approaches to species delimitation in taxonomically difficult groups. The Pnigalio soemius complex (Hymenoptera: Eulophidae) represents an interesting taxonomical and ecological study case, as it is characterized by a lack of informative morphological characters, deep mitochondrial divergence, and is susceptible to infection by parthenogenesis-inducing Rickettsia. We tested the effectiveness of an integrative taxonomy approach in delimiting species within the P. soemius complex. We analysed two molecular markers (COI and ITS2) using different methods, performed multivariate analysis on morphometric data and exploited ecological data such as host-plant system associations, geographical separation, and the prevalence, type and effects of endosymbiont infection. The challenge of resolving different levels of resolution in the data was met by setting up a formal procedure of data integration within and between conflicting independent lines of evidence. An iterative corroboration process of multiple sources of data eventually indicated the existence of several cryptic species that can be treated as stable taxonomic hypotheses. Furthermore, the integrative approach confirmed a trend towards host specificity within the presumed polyphagous P. soemius and suggested that Rickettsia could have played a major role in the reproductive isolation and genetic diversification of at least two species.

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“…2), and the scape is apically brown in Closterocerus chamaeleon but uniformly brownish in Closterocerus ruforum . Part of the 28S D2 rDNA of Closterocerus chamaeleon has already been sequenced (Adachi-Hagimori et al 2011), and we are also in the process of sequencing another section of its 28S rDNA and the DNA barcoding region of its mtDNA, which will be uploaded to GenBank to facilitate identification of this species.…”

Section: Resultsmentioning

confidence: 99%

First record of Closterocerus chamaeleon, parasitoid of the Eucalyptus Gall Wasp Ophelimus maskelli (Hymenoptera, Chalcidoidea, Eulophidae), in the New World

Burks¹,

Mottern²,

Pownall³

et al. 2015

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The uniparental parasitoid Closterocerus chamaeleon (Girault) is discovered to be fortuitously present on a population of the invasive Eucalyptus Gall Wasp Ophelimus maskelli (Ashmead) in Riverside, California. This is the first report from the New World of Closterocerus chamaeleon, which has proven to be a highly effective natural enemy of Ophelimus maskelli in the Mediterranean Basin. The taxonomy and identification of Closterocerus chamaeleon is discussed.

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Gene flow between sexual and asexual strains of parasitic wasps: a possible case of sympatric speciation caused by a parthenogenesis-inducing bacterium

Cited by 30 publications

References 46 publications

Genetic divergence between the sympatric queen morphs of the antMyrmica rubra

Genetic divergence between the sympatric queen morphs of the antMyrmica rubra

Integration of molecular, ecological, morphological and endosymbiont data for species delimitation within thePnigalio soemiuscomplex (Hymenoptera: Eulophidae)

First record of Closterocerus chamaeleon, parasitoid of the Eucalyptus Gall Wasp Ophelimus maskelli (Hymenoptera, Chalcidoidea, Eulophidae), in the New World

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