Genomic Evidence for Convergent Adaptation through Tandem Gene Duplications in Carnivorous Butterworts and Bladderworts

Abstract Cases of convergent adaptation, especially between close relatives within a lineage, provide insights into constraints underlying the mechanisms of evolution. We examined this in the carnivorous plant family Lentibulariaceae, with its highly divergent trap designs but shared need for prey digestion, by generating a chromosome-level genome for Pinguicula gigantea, the giant butterwort. Our work reveals a history of whole-genome duplication in the genus and provides strong phylogenomic evidence for a sister-group relationship between Lentibulariaceae and Acanthaceae. The genome also shows that a key digestive adaptation, the expansion of cysteine protease genes, arose through independent tandem duplications in Pinguicula and its close relative Utricularia. These parallel expansions arose on homologous regions in both genomes, consistent with a common ancestral gene occupying the same chromosomal context. This study provides genomic evidence for convergent evolution of digestive potential in a carnivorous plant lineage and illustrates how similar selective pressures can repeatedly shape genomes in analogous ways.