What is the role of genome duplication in the evolution of complexity and diversity?

Gene and genome duplications provide a source of genetic material for mutation, drift, and selection to act upon, making new evolutionary opportunities possible. As a result, many have argued that genome duplication is a dominant factor in the evolution of complexity and diversity. However, a clear correlation between a genome duplication event and increased complexity and diversity is not apparent, and there are inconsistencies in the patterns of diversity invoked to support this claim. Interestingly, several estimates of genome duplication events in vertebrates are preceded by multiple extinct lineages, resulting in preduplication gaps in extant taxa. Here we argue that gen(om)e duplication could contribute to reduced risk of extinction via functional redundancy, mutational robustness, increased rates of evolution, and adaptation. The timeline for these processes to unfold would not predict immediate increases in species diversity after the duplication event. Rather, reduced probabilities of extinction would predict a latent period between a genome duplication and its effect on species diversity or complexity. In this paper, we will develop the idea that genome duplication could contribute to species diversity through reduced probability of extinction.