Journal Article

The evolution of senescence in birds: evidence from animals in zoos

Abstract

Birds are characterized by a low rate of senescence relative to mammals. However, there is considerable variation in the patterns of senescence and other life history traits among different orders. We used life history data from bird species kept in zoos, where a great number of individuals are followed from birth until death. In a comparative approach we explored the variation of senescence and other life history traits on various phylogenetic levels to investigate the evolutionary plasticity of senescence. We found that the rate of senescence among birds shows largest variation among genera within families. Moreover we found that the patterns of senescence differ between phylogenetic orders, implying that different mechanisms influence the evolution of senescence: avian orders that are not dependent on flight (Struthioniformes, Galliformes) tend to have patterns of senescence that are reminiscent of non-flying mammals. These finding have important implications for our understanding of the mechanisms and the evolution of senescence.