Conflicted Signal in Transcriptomic Markers Leads to a Poorly Resolved Backbone Phylogeny of Chalcidoid Wasps (Hymenoptera: Chalcidoidea)

Authors: ZHANG, JUNXIA - Hebei University; LINDSEY, AMELIA R.I. - Indiana University; PETERS, RALPH - Zoological Research Museum Alexnder Koenig; HERATY, JOHN - University Of California; Hopper, Keith; WERREN, JOHN - University Of Rochester; MARTINSON, ELLEN - University Of Rochester; WOOLLEY, JAMES - Texas A&M University; YODER, MATT - Illinois Natural History Survey; KROGMANN, LARS - University Of Hohenheim

Submitted to: Systematic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2020
Publication Date: 2/9/2020
Citation: Zhang, J., Lindsey, A., Peters, R., Heraty, J.M., Hopper, K.R., Werren, J.H., Martinson, E.O., Woolley, J.B., Yoder, M.J., Krogmann, L. 2020. Conflicted Signal in Transcriptomic Markers Leads to a Poorly Resolved Backbone Phylogeny of Chalcidoid Wasps (Hymenoptera: Chalcidoidea). Systematic Entomology. https://doi.org/10.1111/syen.12427.
DOI: https://doi.org/10.1111/syen.12427

Interpretive Summary: Chalcidoidea are an extremely diverse group of wasps with an astounding diversity of morphology, biology, and hosts. Most species are parasites of insects and are among the most important natural controls of agricultural pests. Understanding how they have evolved is important for safe and effective biological control. Previous studies have not strongly supported relationships in the evolutionary tree of chalcidoids. In this study, we developed new trees based on DNA sequences of expressed genes that will help in understanding the biology and host relationships of these parasitic wasps.

Technical Abstract: Chalcidoidea (Hymenoptera) are a megadiverse superfamily of wasps with an astounding diversity of morphology, biology, and hosts. Most species are parasitoids and thus important natural enemies of insects in terrestrial ecosystems. Previous studies have not recovered strongly supported relationships along the backbone of the chalcidoid phylogeny. In this study we explored the transcriptome-based phylogeny of Chalcidoidea, and found that the poorly resolved relationships could only be marginally improved by adding more genes and taxa, proof-checking for errors of homology and contamination, and decreasing missing data. Results of concatenation analyses were consistent in supporting a hypothesis of egg parasitism as ancestral within Chalcidoidea (Trichogrammatidae sister to remaining Chalcidoidea after Mymaridae), whereas coalescent approaches provided a different hypothesis, unless filtered for the most highly supported loci. The results uncover a wide spectrum of gene discordance in the transcriptomic markers and identified a strong signal of functional bias in genes supporting alternative phylogenies that might be indicative of ancient adaptive introgression. An ancestral mode of egg parasitism remains the most highly supported hypothesis. However, the basal nodes of the phylogeny may be incorrectly biased by cascades of differential support from functional gene complexes. This study proposes that understanding and identifying mechanisms that result in gene tree discordance (incomplete lineage sorting or adaptive introgression) may be both beneficial and essential to sorting out the backbone relationships, especially for a group that has gone through a rapid post-Cretaceous radiation.