MALADAPTATION AS A SOURCE OF SENESCENCE IN HABITATS VARIABLE IN SPACE AND TIME

• Published in: Evolution Vol. 68; no. 9; pp. 2481 - 2493
• Main Authors: Cotto, Olivier, Ronce, Ophélie
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.09.2014; Wiley Subscription Services, Inc; Oxford University Press; Wiley
• Subjects: Adaptation; Adaptation, Biological - genetics; Age; Age structure; age-structured population; Aging; Aging - genetics; Animal Migration - physiology; Animals; Biodiversity; Biological Evolution; Cellular senescence; Ecosystem; Environmental conditions; Environmental Sciences; Evolution; Evolutionary genetics; Genetic Variation; Global Changes; Habitats; Life Sciences; Mortality; Phenotype; Phenotypes; Phenotypic traits; Population genetics; Populations and Evolution; Quantitative genetics; senescence; Time Factors; senescence; quantitative genetics; age-structured population; Adaptation
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/evo.12462

In this study, we use a quantitative genetics model of structured populations to investigate the evolution of senescence in a variable environment. Adaptation to local environments depends on phenotypic traits whose optimal values vary with age and with environmental conditions. We study different scenarios of environmental heterogeneity, where the environment changes abruptly, gradually, or cyclically with time and where the environment is heterogeneous in space with different populations connected by migration. The strength of selection decreases with age, which predicts slower adaptation of traits expressed late in the life cycle, potentially generating stronger senescence in habitats where selection changes in space or in time. This prediction is however complicated by the fact that the genetic variance also increases with age. Using numerical calculations, we found that the rate of senescence is generally increased when the environment varies. In particular, migration between different habitats is a source of senescence in heterogeneous landscapes. We also show that the rate of senescence can vary transiently when the population is not at equilibrium, with possible implications for experimental evolution and the study of invasive species. Our results highlight the need to study age-specific adaptation, as a changing environment can have a different impact on different age classes.