Phillips, Anna J.; Dornburg, A.; Zapfe, K. L.; Anderson, F. E.; James, S. W.; Erséus, C.; Moriarty Lemmon, E.; Lemmon, A. R.; Williams, B. W. (2019). Phylogenomic analysis of a putative missing link sparks reinterpretation of leech evolution. Genome Biology and Evolution. 11(11): 3082–3093.
Rewritten version. The first publication of this work in June 2019 (journal 11(7): 1712-1722) was retracted due to an incorrect phylogeny derived from contaminated sequences. See page 3084 & in acknowledgments, also see Journal editor's explanation
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Leeches (Hirudinida) comprise a charismatic, yet often maligned group of worms. Despite their ecological, economic, and medical importance, a general consensus on the phylogenetic relationships of major hirudinidan lineages is lacking. This absence of a consistent, robust phylogeny of early-diverging lineages has hindered our understanding of the underlying processes that enabled evolutionary diversification of this clade. Here, we used an anchored hybrid enrichment-based phylogenomic approach, capturing hundreds of loci to investigate phylogenetic relationships among major hirudinidan lineages and their closest living relatives. We recovered Branchiobdellida as sister to a clade that includes all major lineages of hirudinidans and Acanthobdella, casting doubt on the utility of Acanthobdella as a "missing link" between hirudinidans and the clitellate group formerly known as Oligochaeta. Further, our results corroborate the reciprocal monophyly of jawed and proboscis-bearing leeches. Our phylogenomic resolution of early-diverging leeches provides a useful framework for illuminating the evolution of key adaptations and host-symbiont associations that have allowed leeches to colonize a wide diversity of habitats worldwide.
