| 1. |
- Vårdal, Hege, 1972-
(författare)
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OVARIAN EGG MORPHOLOGY IN CHALCIDOID WASPS(HYMENOPTERA: CHALCIDOIDEA) PARASITIZINGGALL WASPS (HYMENOPTERA: CYNIPIDAE)
- 2016
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Ingår i: Graellsia. - : Editorial CSIC. - 0367-5041 .- 1989-953X. ; 72:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- We provide morphological egg data of 26 species of 5 chalcidoid families associated with cynipid galls(Hymenoptera: Cynipidae) from western Palaearctic, including the first egg data for the family Ormyridae. Adultchalcidoid species were reared from galls, and eggs obtained from dissected female ovaries were examinedusing scanning electron microscopy (SEM). The shape of the eggs varies from oval to elongate and taperedat both ends. Eggs of Eurytomidae as well as some Eulophidae, Eupelmidae and Pteromalidae are equippedwith a peduncle at the anterior end. We found a positive correlation between long eggs and long ovipositorsand confirmed the expectation that eggs of endoparasitoids are generally shorter and narrower than eggs ofectoparasitoids. We were able to locate the sperm entrance or micropyle at the anterior pole of eggs of severalspecies. It is situated at the anterior end of the egg and at the end of the peduncle when present. In addition,the eggshells of the endoparasitoid Sycophila biguttata (Swederus, 1795) (Hymenoptera: Eurytomidae) andthe ectoparasitoid Cecidostiba fungosa (Geoffroy, 1785) (Hymenoptera: Pteromalidae), are for the first timedescribed.
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| 2. |
- Gobbo, Erik, et al.
(författare)
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Host manipulation by oak gall wasps: Insights from evolutionary signatures in the gall-wasp genome
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The oak gall-wasps (Cynipidae: Cynipini) make some of the most complex plant galls found in nature. The shape of the outer gall varies spectacularly among species, and is characterised by traits that appear to have evolved to defend the larva or larvae inside in an intense evolutionary arms race with predators and parasitoids. It is still unclear how the oak gall-wasps achieve this unusual level of host manipulation. Here, we take a comparative genomic approach to gain some insight into the underlying mechanisms, assuming that the arms race should result in unusually rapid evolution in the proteins involved. Specifically, we compared genomes of Cynipini species making complex and diverse outer galls to those of related lineages making simple galls. We analysed over 5,000 orthologous genes using the recent Bayescode tool, which controls for the background levels of evolution in the genes and lineages involved using a whole-genome approach. We then used gene set enrichment analysis to identify which Gene Ontology terms were more often associated with genes that had an unusually high rate of nonsynonymous evolution in the complex gallers. The complex gallers did not have an elevated number of such genes. However, the genes that had elevated rates in complex gallers were associated with biological-process gene ontology terms related to the formation of the egg follicle and to cell movement, suggesting that these genes may play a role in the formation of complex outer galls, and that they would be interesting target genes for experimental studies.
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| 3. |
- Hearn, Jack, et al.
(författare)
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Phylogenomic analysis of protein-coding genes resolves complex gall wasp relationships
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The phylogeny of gall wasps (Cynipidae) and their parasitic relatives has attracted considerable attention in recent years. The family is now widely recognized to fall into thirteen natural lineages, designated tribes, but the relationships among them have remained elusive. This has stymied any progress in understanding how cynipid gall inducers evolved from insect parasitoids, and what role inquilinism (development as a herbivore inside galls induced by other cynipids) might have played in this transition. A recent analysis of ultraconserved elements (UCEs) represents the first attempt at resolving these questions using phylogenomics. Here, we present the first analysis based on protein-coding sequences from genome and transcriptome assemblies. To address potential problems due to model misfit, we focus on models that accommodate site-specific amino-acid profiles and that are less sensitive than standard models to long-branch attraction. Our results show that the Cynipidae as previously circumscribed are not monophyletic. Specifically, the Paraulacini and a clade formed by Diplolepidini + Pediaspidini both fall outside a core clade (Cynipidae s. str.), which is more closely related to Figitidae. This result is robust to the exclusion of long-branch taxa that could potentially mislead the analysis, and it is consistent with the UCE analysis. Given this, we propose that the Cynipidae be divided into three families: the Paraulacidae, Diplolepididae and Cynipidae (s. str.). Our results suggest that the Eschatocerini are the sister group of the remaining Cynipidae (s. str.). Within the latter, our results are consistent with the UCE analysis but place two additional tribes: (1) the Aylacini (s. str.), more closely related to the oak gall wasps (Cynipini) and some of their inquilines (Ceroptresini) than to other herb gallers (Aulacideini and Phanacidini); and (2) the Qwaqwaiini, likely the sister group to Synergini (s. str.) + Rhoophilini. Several alternative scenarios for the evolution of cynipid life histories are compatible with the relationships suggested by our analysis, but all are complex and require multiple shifts between parasitoids, inquilines and gall inducers. Linking the different types of life-history transitions to specific genomic signatures may be one of the best ways of differentiating among these alternative scenarios. Our study represents the first step towards enabling such analyses.
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| 4. |
- Hearn, Jack, et al.
(författare)
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Phylogenomic analysis of protein-coding genes resolves complex gall wasp relationships
- 2024
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Ingår i: Systematic Entomology. - 0307-6970 .- 1365-3113. ; 49:1, s. 110-137
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Tidskriftsartikel (refereegranskat)abstract
- Gall wasps (Hymenoptera: Cynipidae) comprise 13 distinct tribes whose interrelationships remain incompletely understood. Recent analyses of ultra-conserved elements (UCEs) represent the first attempt at resolving these relationships using phylogenomics. Here, we present the first analysis based on protein-coding sequences from genome and transcriptome assemblies. Unlike UCEs, these data allow more sophisticated substitution models, which can potentially resolve issues with long-branch attraction. We include data for 37 cynipoid species, including two tribes missing in the UCE analysis: Aylacini (s. str.) and Qwaqwaiini. Our results confirm the UCE result that Cynipidae are not monophyletic. Specifically, the Paraulacini and Diplolepidini + Pediaspidini fall outside a core clade (Cynipidae s. str.), which is more closely related to the insect-parasitic Figitidae, and this result is robust to the exclusion of long-branch taxa that could mislead the analysis. Given this, we here divide the Cynipidae into three families: the Paraulacidae stat. prom., Diplolepididae stat. prom. and Cynipidae (s. str.). Our results suggest that the Eschatocerini are the sister group of the remaining Cynipidae (s. str.). Within the Cynipidae (s. str.), the Aylacini (s. str.) are more closely related to oak gall wasps (Cynipini) and some of their inquilines (Ceroptresini) than to other herb gallers (Aulacideini and Phanacidini), and the Qwaqwaiini likely form a clade together with Synergini (s. str.) and Rhoophilini. Several alternative scenarios for the evolution of cynipid life histories are compatible with the relationships suggested by our analysis, but all are complex and require multiple shifts among parasitoids, inquilines and gall inducers.
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| 5. |
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| 6. |
- Nylander, Johan A. A., et al.
(författare)
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Bayesian phylogenetic analysis of combined data
- 2004
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Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 53:1, s. 47-67
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The recent development of Bayesian phylogenetic inference using Markov chain Monte Carlo (MCMC) techniques has facilitated the exploration of parameter-rich evolutionary models. At the same time, stochastic models have become more realistic (and complex) and have been extended to new types of data, such as morphology. Based on this foundation, we developed a Bayesian MCMC approach to the analysis of combined data sets and explored its utility in inferring relationships among gall wasps based on data from morphology and four genes (nuclear and mitochondrial, ribosomal and protein coding). Examined models range in complexity from those recognizing only a morphological and a molecular partition to those having complex substitution models with independent parameters for each gene. Bayesian MCMC analysis deals efficiently with complex models: convergence occurs faster and more predictably for complex models, mixing is adequate for all parameters even under very complex models, and the parameter update cycle is virtually unaffected by model partitioning across sites. Morphology contributed only 5% of the characters in the data set but nevertheless influenced the combined-data tree, supporting the utility of morphological data in multigene analyses. We used Bayesian criteria (Bayes factors) to show that process heterogeneity across data partitions is a significant model component, although not as important as among-site rate variation. More complex evolutionary models are associated with more topological uncertainty and less conflict between morphology and molecules. Bayes factors sometimes favor simpler models over considerably more parameter-rich models, but the best model overall is also the most complex and Bayes factors do not support exclusion of apparently weak parameters from this model. Thus, Bayes factors appear to be useful for selecting among complex models, but it is still unclear whether their use strikes a reasonable balance between model complexity and error in parameter estimates.
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| 7. |
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| 8. |
- Ronquist, Fredrik, et al.
(författare)
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Life history of Parnips and the evolutionary origin of gall wasps
- 2018
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Ingår i: Journal of Hymenoptera Research. - : Pensoft Publishers. - 1070-9428 .- 1314-2607. ; 65, s. 91-110
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Tidskriftsartikel (refereegranskat)abstract
- By mechanisms that are still unknown, gall wasps (Cynipidae) induce plants to form complex galls, inside which their larvae develop. The family also includes inquilines (phytophagous forms that live inside the galls of other gall inducers) and possibly also parasitoids of gall inducers. The origin of cynipids is shrouded in mystery, but it has been clear for some time that a key group in making progress on this question is the ‘figitoid inquilines’. They are gall-associated relatives of cynipids, whose biology is poorly known. Here, we report the first detailed data on the life history of a figitoid inquiline, the genus Parnips. Dissections of mature galls show that Parnips nigripes is a parasitoid of Barbotinia oraniensis, a cynipid that induces single-chambered galls inside the seed capsules of annual poppies (Papaver rhoeas and P. dubium). Galls with pupae of Parnips nigripes always contain the remains of a terminal-instar larva of B. oraniensis. The mandibles of the terminal-instar larva of P. nigripes are small and equipped with a single sharp tooth, a shape that is characteristic of carnivorous larvae. The weight of P. nigripes pupae closely match that of the same sex of B. oraniensis pupae, indicating that Parnips makes efficient use of its host and suggesting that ovipositing Parnips females lay eggs that match the sex of the host larva. Dissection of young galls show that another species of Parnips, hitherto undescribed, spends its late larval life as an ectoparasitoid of Iraella hispanica, a cynipid that induces galls in flowers of annual poppies. These and other observations suggest that Parnips shares the early endoparasitic-late ectoparasitic life history described for all other cynipoid parasitoids. Our findings imply that gall wasps evolved from parasitoids of gall insects. The original hosts could not have been cynipids but possibly chalcidoids, which appear to be the hosts of several extant figitoid inquilines. It is still unclear whether the gall inducers evolved rapidly from these ancestral parasitoids, or whether they were preceded by a long series of intermediate forms that were phytophagous inquilines.
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| 9. |
- Ronquist, Fredrik, et al.
(författare)
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Phylogeny, evolution and classification of gall wasps : the plot thickens.
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Gall wasps (Cynipidae) represent the most spectacular radiation of gall-inducing insects. In addition to true gall formers, gall wasps also include phytophagous inquilines, which live inside the galls induced by gall wasps or other insects. Here we present the first comprehensive molecular and total-evidence analyses of higher-level gall wasp relationships. We studied more than 100 taxa representing a rich selection of outgroups and the majority of described cynipid genera outside the diverse oak gall wasps (Cynipini), which were more sparsely sampled. About 5 kb of nucleotide data from one mitochondrial (COI) and four nuclear (28S, LWRh, EF1alpha F1, and EF1alpha F2) markers were analyzed separately and in combination with morphological and life-history data. According to previous morphology-based studies, gall wasps evolved in the Northern Hemisphere and were initially herb gallers. Inquilines originated once from gall inducers that lost the ability to initiate galls. Our results, albeit not conclusive, suggest a different scenario. The first gall wasps were more likely associated with woody host plants, and there must have been multiple origins of gall inducers, inquilines or both. One possibility is that gall inducers arose independently from inquilines in several lineages. Except for these surprising results, our analyses are largely consistent with previous studies. They confirm that gall wasps are conservative in their host-plant preferences, and that herb-galling lineages have radiated repeatedly onto the same set of unrelated host plants. We propose a revised classification of the family into twelve tribes, which are strongly supported as monophyletic across independent datasets. Four are new: Aulacideini, Phanacidini, Diastrophini and Ceroptresini. We present a key to the tribes and discuss their morphological and biological diversity. Until the relationships among the tribes are resolved, the origin and early evolution of gall wasps will remain elusive.
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| 10. |
- Stone, Graham N., et al.
(författare)
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Evidence for widespread cryptic sexual generations in apparently purely asexual Andricus gallwasps
- 2008
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 17:2, s. 652-665
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Tidskriftsartikel (refereegranskat)abstract
- Oak gallwasps (Hymenoptera, Cynipidae, Cynipini) are one of seven major animal taxa that commonly reproduce by cyclical parthenogenesis (CP). A major question in research on CP taxa is the frequency with which lineages lose their sexual generations, and diversify as purely asexual radiations. Most oak gallwasp species are only known from an asexual generation, and secondary loss of sex has been conclusively demonstrated in several species, particularly members of the holarctic genus Andricus. This raises the possibility of widespread secondary loss of sex in the Cynipini, and of diversification within purely parthenogenetic lineages. We use two approaches based on analyses of allele frequency data to test for cryptic sexual generations in eight apparently asexual European species distributed through a major western palaearctic lineage of the gallwasp genus Andricus. All species showing adequate levels of polymorphism (7/8) showed signatures of sex compatible with cyclical parthenogenesis. We also use DNA sequence data to test the hypothesis that ignorance of these sexual generations (despite extensive study on this group) results from failure to discriminate among known but morphologically indistinguishable sexual generations. This hypothesis is supported: 35 sequences attributed by leading cynipid taxonomists to a single sexual adult morphospecies, Andricus burgundus, were found to represent the sexual generations of at least six Andricus species. We confirm cryptic sexual generations in a total of 11 Andricus species, suggesting that secondary loss of sex is rare in Andricus.
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