The effects of selection for early and late reproduction on fecundity and longevity in bean weevil (Acanthoscelides obtectus)

Pleiotropy, constraint, and modularity in the evolution of life histories: insights from genomic analyses

Multicellular organisms display an enormous range of life history (LH) strategies and present an evolutionary conundrum; despite strong natural selection, LH traits are characterized by high levels of genetic variation. To understand the evolution of life histories and maintenance of this variation, the specific phenotypic effects of segregating alleles and the genetic networks in which they act need to be elucidated. In particular, the extent to which LH evolution is constrained by the pleiotropy of alleles contributing to LH variation is generally unknown. Here, we review recent empirical results that shed light on this question, with an emphasis on studies employing genomic analyses. While genome-scale analyses are increasingly practical and affordable, they face limitations of genetic resolution and statistical power. We describe new research approaches that we believe can produce new insights and evaluate their promise and applicability to different kinds of organisms. Two approaches seem particularly promising: experiments that manipulate selection in multiple dimensions and measure phenotypic and genomic response and analytical approaches that take into account genome-wide associations between markers and phenotypes, rather than applying a traditional marker-by-marker approach.

Advice to an aging scientist

Fifty years ago, Peter Medawar and George Williams developed two now-classic theories for the evolution of senescence. In the past 20 years, evolutionary biologists studying aging have developed explicit mathematical models of these theories, used these models to derive explicit predictions, and tested these predictions using a variety of approaches. But, we argue here, our singular focus on these models may have hindered progress in evolutionary studies of aging. Research in this area has not kept pace with dramatic advances in evolutionary theory and molecular genetics. Progress in evolutionary studies of aging will depend on a bold, integrative approach, incorporating evolutionary and molecular advances from other fields, along with the powerful statistical and mathematical tools now available. We discuss several specific examples where we may gain new insight into the causes of aging by looking to other evolutionary phenomena, including sexual conflict and the evolution of social behavior. In addition, we present new results which suggest that the analysis of gene networks may lend particular insight into the genetic underpinnings of the aging process.