Feedback between environment and traits under selection in a seasonal environment: consequences for experimental evolution

Abstract

Batch cultures are frequently used in experimental evolution to study the dynamics of adaptation. Although they are generally considered to simply drive a growth rate increase, other fitness components can also be selected for. Indeed, recurrent batches form a seasonal environment where different phases repeat periodically and different traits can be under selection in the different seasons. Moreover, the system being closed, organisms may have a strong impact on the environment. Thus, the study of adaptation should take into account the environment and eco-evolutionary feedbacks. Using data from an experimental evolution on yeast , we developed a mathematical model to understand which traits are under selection, and what is the impact of the environment for selection in a batch culture. We showed that two kinds of traits are under selection in seasonal environments: life-history traits, related to growth and mortality, but also transition traits, related to the ability to react to environmental changes. The impact of environmental conditions can be summarized by the length of the different seasons which weight selection on each trait: the longer a season is, the higher the selection on associated traits. Since phenotypes drive season length, eco-evolutionary feedbacks emerge. Our results show how evolution in successive batches can affect season lengths and strength of selection on different traits.

Data integration uncovers the metabolic bases of phenotypic variation in yeast

“…This broadly corresponds to the well-known r-K trade-off in ecology [37]. More recently, [38] suggested that such a trade-off could arise from eco-evolutionary feedback loops because competing strains also modify their environment through the production of different sets of metabolites. The HeterosYeast dataset shows that the choice of a strategy is plastic [21] and can be modified by the environment (here the fermentation temperature).…”

Reduced phenotypic plasticity evolves in less predictable environments

“…These consecutive morphological states of cells, which we here described as an ontogenic sequence (Gilbert 2000), can also be interpreted as alternative phenotypes favored at different population densities (r vs Kselection (MacArthur 1962;Saether et al 2016)), or plastic responses to environmental variables other than salinity that change along time in a batch culture (e.g. resource abundance and quality) (Collot et al 2018).…”

Reduced phenotypic plasticity evolves in less predictable environments

“…These consecutive morphological states of cells, which we here described as an ontogenic sequence (Gilbert, 2000), can also be interpreted as alternative phenotypes favored at different population densities [ r vs. K ‐selection (MacArthur, 1962; Sæther et al ., 2016)], or plastic responses to environmental variables other than salinity that change along time in a batch culture (e.g. resource abundance and quality) (Collot et al ., 2018).…”