Student Research Projects
Abstract
The superclass Cyclostomata—hagfishes and lampreys—represents the only surviving lineage of jawless vertebrates (agnathans), offering a unique window into early vertebrate diversification. Once regarded as paraphyletic, cyclostomes are now supported as a monophyletic clade by molecular evidence. Yet, despite their evolutionary significance, a comprehensive phylogenomic analysis of the group has been lacking. Here, we present a comprehensive time-calibrated phylogeny of cyclostomes, using mitochondrial markers from 113 species, with additional genome and transcriptome data from 30 of those species, encompassing all publicly available phylogenetic markers for cyclostomes. Our analyses provide robust support for cyclostome monophyly and date the hagfish–lamprey split to the early Paleozoic. Although this divergence between hagfish and lamprey is ancient, diversification within both lineages is comparatively recent, beginning in the Mesozoic. By integrating mitochondrial and genomic data, we resolve several interspecific and intergeneric relationships and establish a comparative phylogenetic framework that spans all sequenced cyclostome species. We leverage this framework to investigate the biogeographic correlates of cyclostome diversity.
Subject
cyclostome phylogenomics
Date of Publication or Presentation
1-4-2026
Project Type
Undergraduate Research Project
Language
English
Medium
Poster presented at the Society for Integrative and Comparative Biology (SICB) Annual Meeting, Portland, OR, January 2026.
Recommended Citation
Christensen, E.J., Fudge, D.S., & Plachetzki, D.C. (2026). Time-calibrated phylogenomic analysis of cyclostome divergence, diversity, and biogeography [Poster]. Presented at the Society for Integrative and Comparative Biology (SICB) Annual Meeting, Portland, OR.
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