Genomic variation from an extinct species is retained in the extant radiation following speciation reversal

Ecosystem degradation and biodiversity loss are major global challenges. When reproductive isolation between species is contingent on the interaction of intrinsic lineage traits with features of the environment, environmental change can weaken reproductive isolation and result in extinction through hybridization. By this process called speciation reversal, extinct species can leave traces in genomes of extant species through introgressive hybridization. Using historical and contemporary samples, we sequenced all four species of an Alpine whitefish radiation before and after anthropogenic lake eutrophication and the associated loss of one species through speciation reversal. Despite the extinction of this taxon, substantial fractions of its genome, including regions shaped by positive selection before eutrophication, persist within surviving species as a consequence of introgressive hybridization during eutrophication. Given the prevalence of environmental change, studying speciation reversal and its genomic consequences provides fundamental insights into evolutionary processes and informs biodiversity conservation. Genomic analysis of an Alpine whitefish radiation before and after human-driven lake eutrophication that led to the extinction of one species through hybridization shows that substantial parts of the genome of the extinct species persist within surviving species due to introgressive hybridization.

Automated summary

Environmental change can lead to species extinction through speciation reversal and hybridization, but the genomic analysis of an Alpine whitefish radiation shows that the genome of an extinct species can persist within surviving species due to introgressive hybridization.