As with other model systems used for aging-related research, strain-specific effects due to genetic diversity can have a large impact on longevity and other age-associated phenotypes in yeast. The importance of strain diversity for studies of aging consists of two distinct components. The first component of strain diversity is the large genetic variation between different laboratory strains commonly used in scientific research. Laboratory strains can have dramatically different life spans, ranging from an average of less than 10 generations to nearly 30 generations, for replicative life span (Kaeberlein et al., 2005a). This type of diversity is analogous to that seen between different inbred strains of mice, which also can have substantially different longevity and aging disease phenotypes. There have been no attempts to systematically characterize strain-specific effects on chronological life span, and only one attempt has been made to determine which genes are strain-specific and which are strain-independent with respect to replicative life span (Kaeberlein et al., 2005a).
The second type of diversity relevant to aging-related research is the genetic divergence between "domesticated" laboratory yeast and wild isolates of S. cerevisiae. This type of diversity and its impact on yeast aging is almost completely unstudied. Preliminary analysis of the aging properties of a polyploid lager yeast has been reported (Maskell et al., 2003; Powell et al., 2000), but it is currently unknown whether the same genes and pathways that influence longevity of lab yeast will be shared among yeast obtained from other environments. The aging properties of "wild" yeast obtained from natural populations have not been examined at all. In order to begin to address this question, it will be important to determine whether ERCs accumulate and cause replicative senescence in wild yeast as well as whether CR slows aging in natural isolates.
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When over eighty years of age, the poet Bryant said that he had added more than ten years to his life by taking a simple exercise while dressing in the morning. Those who knew Bryant and the facts of his life never doubted the truth of this statement.