Evolutionary tipping points in the capacity to adapt to environmental change

Abstract

In an era of rapid climate change, there is a pressing need to understand how organisms will cope with faster and less predictable variation in environmental conditions. Here we develop a unifying model that predicts evolutionary responses to environmentally driven fluctuating selection and use this theoretical framework to explore the potential consequences of altered environmental cycles. We first show that the parameter space determined by different combinations of predictability and timescale of environmental variation is partitioned into distinct regions where a single mode of response (reversible phenotypic plasticity, irreversible phenotypic plasticity, bet-hedging, or adaptive tracking) has a clear selective advantage over all others. We then demonstrate that, although significant environmental changes within these regions can be accommodated by evolution, most changes that involve transitions between regions result in rapid population collapse and often extinction. Thus, the boundaries between response mode regions in our model correspond to evolutionary tipping points, where even minor changes in environmental parameters can have dramatic and disproportionate consequences on population viability. Finally, we discuss how different life histories and genetic architectures may influence the location of tipping points in parameter space and the likelihood of extinction during such transitions. These insights can help identify and address some of the cryptic threats to natural populations that are likely to result from any natural or human-induced change in environmental conditions. They also demonstrate the potential value of evolutionary thinking in the study of global climate change.fluctuating selection | global change | phenotypic plasticity | bet-hedging | adaptive tracking

Three types of rescue can avert extinction in a changing environment

“…Recent research shows clearly that evolutionary processes affect ecological dynamics even over the course of a single generation (30)(31)(32). Our results for the effect of immigration on the dynamics of small populations support these findings and their application to rescuing vulnerable populations from extinction.…”

Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

“…The ability to acclimatize to changing thermal conditions is expected to be a primary factor that dictates the vulnerability of taxa to rising temperatures [4][5][6]10,20]. Our broad-scale analysis of thermal tolerance plasticity across ectotherms has many implications for our understanding of the interactions between plasticity and warming.…”

“…As a result, organisms across the globe will be more likely to experience temperatures beyond their physiological limits unless they can in some way buffer themselves from environmental change [2,3]. One mechanism that could greatly reduce the risk of overheating is physiological plasticity in thermal tolerance, such as the reversible changes in thermal tolerance known as acclimation (if measured in the laboratory) or acclimatization (if measured in the field) [4][5][6][7]. For example, the upper thermal tolerance limits of many organisms increase (within individuals) as mean body temperatures rise, meaning that physiological adjustments can potentially compensate for the negative consequences of rising habitat temperatures [8].…”

The importance of mechanisms for the evolution of cooperation

“…This view is now firmly established in the field of 'evo-devo' [6,7], where the interplay between (developmental) mechanisms and evolution is at centre stage. Similarly, studies on gene-regulatory networks [8][9][10] have revealed that network topology strongly affects both the robustness and evolvability of living systems, while recent 'integrative' models [11][12][13] reveal that the mechanisms underlying phenotypic responses can be important for a full understanding of eco-evolutionary processes.…”