Evolutionary analysis of life span, competition, and adaptive radiation, motivated by the Pacific rockfishes...

The Pacific rockfishes (Sebastes spp) are remarkable for both their diversity (on the order of 100 species) and range of maximum life span ( approximately 10 years for Calico rockfish to approximately 200 years for Rougheye rockfish). We describe the natural history and patterns of diversity and life span in these species and then use independent contrasts to explore correlates of these. When phylogenetic history is taken into account, maximum life span is explained by age at maturity, size at maturity, and the interaction of these two. We introduce a life-history model that allows insight into the origin of these correlations. We then describe a variety of mechanisms that may increase lifepans and diversity. These include fluctuating environments (in which organisms basically have to "wait out" bad periods to reproduce successfully), diversity, and longevity inspired by interspecific competition and physiological complexity in growth and accumulation of cellular damage. All of the results point toward the importance of flat or "indifferent" fitness surfaces as a key element in the evolution of diversity. We conclude that further development of the theory of flat or indifferent fitness surfaces as applied to diversity and life span is clearly warranted.