Engines of innovation: biological origins of genome evolution

Abstract Genome change does not occur accidentally. The conventional Modern Synthesis view of gradual evolution guided solely by natural selection fails to incorporate many important lessons from direct examination of genome structure by cytogeneticists and modern genomic sequencers. Among other discoveries is the major role that interspecific hybridization has played in the rapid generation of new species. Interspecific hybrids display altered epigenetic regulation and genome expression, great genome variability (including activation of transposable elements and chromosome rearrangements), and frequently whole genome duplication (WGD) as well. These changes produce novel species with adaptively altered phenotypes and reproductive isolation due to meiotic incompatibility with the progenitor species. Genomics has revealed that hybrid speciation and WGD have been widespread among all types of eukaryotes, from yeast and diatoms to flowering plants and primates. The maintenance of the biological responses to interspecific hybridization across virtually all eukaryotic history indicates that eukaryotes have continuously inheritted a capability for rapid evolutionary change. In other words, the best-documented path to the origin of species we have is an inherited biological process, not a series of accidents.