biostudies-literatureKauai FEuropean Research CouncilUniversiteit Gent (UGent)Universiteit Gente2400018121https://www.ebi.ac.uk/biostudies/studies/S-EPMC11126971biostudies-literatureUnknown121(21)Hybridization blurs species boundaries and leads to intertwined lineages resulting in reticulate evolution. Polyploidy, the outcome of whole genome duplication (WGD), has more recently been implicated in promoting and facilitating hybridization between polyploid species, potentially leading to adaptive introgression. However, because polyploid lineages are usually ephemeral states in the evolutionary history of life it is unclear whether WGD-potentiated hybridization has any appreciable effect on their diploid counterparts. Here, we develop a model of cytotype dynamics within mixed-ploidy populations to demonstrate that polyploidy can in fact serve as a bridge for gene flow between diploid lineages, where introgression is fully or partially hampered by the species barrier. Polyploid bridgeProceedings of the National Academy of Sciences of the United States of AmericaInterspecific transfer of genetic information through polyploid bridges.PMC11126971833522Methusalem BOF.MET.2021.0005.01Bafort QVan Montagu MKauai FMortier FBonte DVan de Peer YfalseInterspecific transfer of genetic information through polyploid bridges.Hybridization blurs species boundaries and leads to intertwined lineages resulting in reticulate evolution. Polyploidy, the outcome of whole genome duplication (WGD), has more recently been implicated in promoting and facilitating hybridization between polyploid species, potentially leading to adaptive introgression. However, because polyploid lineages are usually ephemeral states in the evolutionary history of life it is unclear whether WGD-potentiated hybridization has any appreciable effect on their diploid counterparts. Here, we develop a model of cytotype dynamics within mixed-ploidy populations to demonstrate that polyploidy can in fact serve as a bridge for gene flow between diploid lineages, where introgression is fully or partially hampered by the species barrier. Polyploid bridge2024-01-01T00:00:00Z2024 May2026-07-16T20:20:57.571Z2025-04-04T14:51:50.527ZS-EPMC111269713874857610.1073/pnas.2400018121