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Abstract The recent advances in sequencing technologies, phylogenomics and divergence dating methods call for an integrative review of the current state of Hymenoptera systematics. We here explore the impact of these latest developments on the Hymenoptera phylogeny and our understanding of the timing of Hymenoptera evolution, while identifying the current methodological constraints and persistent knowledge gaps that warrant further investigation. Our review highlights the lack of consensus among the backbone phylogeny of Hymenoptera between key phylogenomic studies, as the higher level phylogeny remains unresolved in key nodes such as the relationships among Eusymphyta, the relationships within the Infraorder Proctotrupomorpha and the placements of the superfamilies Ichneumonoidea, Ceraphronoidea and Vespoidea. Furthermore, we underline the huge variation in divergence age estimates for Hymenoptera and detect several major gaps and/or disagreements between the fossil record and available age estimates, either due to the poorly studied fossil record or problematic age estimates, or both. To better understand the timing of Hymenoptera evolution and the role of key diversification factors, we will need continuous efforts to (i) reconcile conflicts among morphological and molecular phylogenies, by improving taxon sampling of underrepresented lineages, applying novel techniques to study morphology, making use of genome‐scale data and critically assessing incongruences in genetic markers; (ii) improve the Hymenoptera fossil record, by exercising integrative taxonomy and bringing together paleontologists and neontologists; and (iii) reconcile age estimates, by relying on tip dating approaches to bridge fossils, morphology and genomes across time.
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Scaphopoda is the sister taxon to Bivalvia: Evidence of ancient incomplete lineage sorting
The almost simultaneous emergence of major animal phyla during the early Cambrian shaped modern animal biodiversity. Reconstructing evolutionary relationships among such closely spaced branches in the animal tree of life has proven to be a major challenge, hindering understanding of early animal evolution and the fossil record. This is particularly true in the species-rich and highly varied Mollusca where dramatic inconsistency among paleontological, morphological, and molecular evidence has led to a long-standing debate about the group’s phylogeny and the nature of dozens of enigmatic fossil taxa. A critical step needed to overcome this issue is to supplement available genomic data, which is plentiful for well-studied lineages, with genomes from rare but key lineages, such as Scaphopoda. Here, by presenting chromosome-level genomes from both extant scaphopod orders and leveraging complete genomes spanning Mollusca, we provide strong support for Scaphopoda as the sister taxon of Bivalvia, revitalizing the morphology-based Diasoma hypothesis originally proposed 50 years ago. Our molecular clock analysis confidently dates the split between Bivalvia and Scaphopoda at ~520 Ma, prompting a reinterpretation of controversial laterally compressed Early Cambrian fossils, includingAnabarella,Watsonella,andMellopegma,as stem diasomes. Moreover, we show that incongruence in the phylogenetic placement of Scaphopoda in previous phylogenomic studies was due to ancient incomplete lineage sorting (ILS) that occurred during the rapid radiation of Conchifera. Our findings highlight the need to consider ILS as a potential source of error in deep phylogeny reconstruction, especially in the context of the unique nature of the Cambrian Explosion.
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- Award ID(s):
- 1846174
- PAR ID:
- 10538309
- Publisher / Repository:
- PNAS
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 120
- Issue:
- 40
- ISSN:
- 0027-8424
- Subject(s) / Keyword(s):
- Scaphopoda mollusc phylogeny mollusc fossils incomplete lineage sorting Cambrian explosion
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1073/pnas.2302361120
