Biology subjects

Delvare, G.

Publications and source records attributed to Delvare, G..

3 recordsLinked to original sources

bioRxiv2025

Phasing in and out of phytophagy: phylogeny and evolution of the family Eurytomidae (Hymenoptera: Chalcidoidea) based on Ultraconserved Elements

We present the first global molecular phylogenetic hypothesis for the family Eurytomidae, a group of chalcidoid wasps with diverse biology, with a representative sampling (197 ingroups and 11 outgroups) that covers all described subfamilies, and 70% of the known genera. Analyses of 962 Ultra-Conserved Elements (UCEs) with concatenation (IQ-TREE) and multispecies coalescent approaches (ASTRAL) resulted in highly supported topologies in recovering the monophyly of Eurytomidae and its four subfamilies. The taxonomy of Eurytomidae, and in particular the large subfamily Eurytominae, needs major revisions as most large genera are recovered as para- or polyphyletic, and the erection of multiple new genera is required in the future to accommodate these taxa. Here, we synonymize the genera Cathilaria (C. certa, C. globiventris, C. opuntiae, and C. rigidae) and the monotypic Aiolomorphus rhopaloides within Tetramesa syn. nov., Parabruchophagus (P. kazakhstanicus, P. nikolskaji, P. rasnitsyni, P. saxatilis, and P. tauricus) and Exeurytoma (E. anatolica, E. caraganae, and E. kebanensis) within Bruchophagus syn. nov.. We also provide 137 DNA barcode COI fragments extracted from the UCE contigs to aid in future identifications of Eurytomidae using this popular genetic marker. Eurytomidae most likely originated in South America with an estimated crown age of 83.37 Ma. Ancestral state reconstruction indicates that secondary phytophagy has evolved at least seven times within the subfamily Eurytominae, showcasing the evolutionary flexibility of these vastly understudied wasps.

zoology↗

bioRxiv2022

The Chalcidoidea bush of life - a massive radiation blurred by mutational saturation

Capturing phylogenetic signal from a massive radiation can be daunting. The superfamily Chalcidoidea is an excellent example of a hyperdiverse group that has remained recalcitrant to phylogenetic resolution. Chalcidoidea are mostly parasitoid wasps that until now included 27 families, 87 subfamilies and as many as 500,000 estimated species. We combined 1007 exons obtained with Anchored Hybrid Enrichment with 1048 Ultra-Conserved Elements (UCEs) for 433 taxa including all extant families, over 95% of all subfamilies and 356 genera chosen to represent the vast diversity of the superfamily. Going back and forth between molecular results and our collective morphological and biological knowledge, we detected insidious bias driven by the saturation of nucleotide data and highlighted morphological convergences. Our final results are based on a concatenated analysis of the least saturated exons and UCE data sets (2054 loci, 284,106 sites). Our analyses support a sister relationship with Mymarommatoidea. Seven of the previously recognized families were not monophyletic, so foundations for a new classification are discussed. Biology appears potentially more informative than morphology, as illustrated by the elucidation of a clade of plant gall associates and a clade of taxa with planidial first-instar larvae. The phylogeny suggests a shift from smaller soft-bodied wasps to larger and more heavily sclerotized wasps. Deep divergences in Chalcidoidea coincide with an increase in insect families in the fossil record, and an early shift to phytophagy corresponds with the beginning of the "Angiosperm Terrestrial Revolution". Our dating analyses suggest a Middle Jurassic origin of 174 Ma (167.3-180.5 Ma) and a crown age of 162.2 Ma (153.9-169.8 Ma) for Chalcidoidea. During the Cretaceous, Chalcidoidea underwent a rapid radiation in southern Gondwana with subsequent dispersals to the Northern Hemisphere. This scenario is discussed with regard to knowledge about host taxa of chalcid wasps, their fossil record, and Earths paleogeographic history.

evolutionary biology↗

bioRxiv2019

Ultra-Conserved Elements and morphology reciprocally illuminate conflicting phylogenetic hypotheses in Chalcididae (Hymenoptera, Chalcidoidea)

Recent technical advances combined with novel computational approaches promised the acceleration of our understanding of the tree of life. However, when it comes to hyperdiverse and poorly known groups of invertebrates, studies are still scarce. As published phylogenies will be rarely challenged by future taxonomists, careful attention must be paid to potential analytical bias. We present the first molecular phylogenetic hypothesis for the family Chalcididae, an emblematic group of parasitoid wasps, with a representative sampling (144 ingroups and 7 outgroups) that covers all described subfamilies and tribes and 82% of the known genera. Analyses of 538 Ultra-Conserved Elements (UCEs) with supermatrix (RAxML and IQTREE) and gene-tree reconciliation approaches (ASTRAL, ASTRID) resulted in highly supported topologies in overall agreement with morphology but reveal conflicting topologies for some of the deepest nodes. To resolve these conflicts, we explored the phylogenetic tree space with clustering and gene genealogy interrogation methods, analyzed marker and taxon properties that could bias inferences and performed a thorough morphological analysis (130 characters encoded for 40 taxa representative of the diversity). This joint analysis reveals that UCEs enable attainment of resolution between ancestry and convergent /divergent evolution when morphology is not informative enough, but also shows that a systematic exploration of bias with different analytical methods and a careful analysis of morphological features is required to prevent publication of artefactual results. We highlight a GC-content bias for ML approaches, an artefactual mid-point rooting of the ASTRAL tree and a deleterious effect of high percentage of missing data on gene tree reconciliation methods. Based on the results we propose a new classification of the family into eight subfamilies and 10 tribes that lay the foundation for future studies on the evolutionary history of Chalcididae.

evolutionary biology↗