A vertebrate adaptive radiation is assembled from an ancient and disjunct spatiotemporal landscape
Emilie J. Richards, Joseph A. McGirr, Jeremy Wang, Michelle E. St. John, Jelmer W. Poelstra, Maria J. Solano, Delaney C. O’Connell, Bruce J. Turner, Christopher H. Martin
Abstract
Significance Most biodiversity evolved in rapid bursts of new species, adaptations, and ecological niches. However, this process of adaptive radiation is poorly understood. We used large-scale genomic sequencing across the entire Caribbean range of pupfishes to understand why radiation in this group is restricted to a single Bahamian island. We found that twofold higher gene flow to this island brought in new combinations of ancient adaptive mutations needed for colonizing novel ecological niches of scale-eating and snail-eating. Adaptation occurred in stages: first selection on feeding behavior, then selection for trophic morphology, and finally refinement through gene coding change. We demonstrate that young, localized radiations can emerge from a vast pool of adaptive genetic variation spread across time and space.