Conservation through the lens of (mal)adaptation: Concepts and meta‐analysis

Abstract

Evolutionary approaches are gaining popularity in conservation science, with diverse strategies applied in efforts to support adaptive population outcomes. Yet conservation strategies differ in the type of adaptive outcomes they promote as conservation goals. For instance, strategies based on genetic or demographic rescue implicitly target adaptive population states whereas strategies utilizing transgenerational plasticity or evolutionary rescue implicitly target adaptive processes. These two goals are somewhat polar: adaptive state strategies optimize current population fitness, which should reduce phenotypic and/or genetic variance, reducing adaptability in changing or uncertain environments; adaptive process strategies increase genetic variance, causing maladaptation in the short term, but increase adaptability over the long term. Maladaptation refers to suboptimal population fitness, adaptation refers to optimal population fitness, and (mal)adaptation refers to the continuum of fitness variation from maladaptation to adaptation. Here, we present a conceptual classification for conservation that implicitly considers (mal)adaptation in the short‐term and long‐term outcomes of conservation strategies. We describe cases of how (mal)adaptation is implicated in traditional conservation strategies, as well as strategies that have potential as a conservation tool but are relatively underutilized. We use a meta‐analysis of a small number of available studies to evaluate whether the different conservation strategies employed are better suited toward increasing population fitness across multiple generations. We found weakly increasing adaptation over time for transgenerational plasticity, genetic rescue, and evolutionary rescue. Demographic rescue was generally maladaptive, both immediately after conservation intervention and after several generations. Interspecific hybridization was adaptive only in the F1 generation, but then rapidly leads to maladaptation. Management decisions that are made to support the process of adaptation must adequately account for (mal)adaptation as a potential outcome and even as a tool to bolster adaptive capacity to changing conditions.

Environmental variability and the evolution of bet-hedging strategies

“…Our study is a much needed step towards understanding the evolution of two avoidance strategies: dispersal, dormancy, and their covariance, providing new insight into the environmental drivers of bet hedging. More empirical studies are needed to move towards a general, scalable knowledge of how to best manage populations and landscapes to support the evolutionary processes that prevent extinction (Derry et al 2019). More generally, bet hedging strategies are critical to theories of biodiversity maintenance in variable environments (e.g., storage effects (Abrams et al 2013), metacommunity archetypes (Leibold et al 2004)) and we document the evolution of these ecologically-important strategies.…”

Evolution is a double‐edged sword, not a silver bullet, to confront global change

“…Transgenerational plasticity evolves with a generational time lag, 102 meaning that under continuously changing environments, parental effects can evolve to past fitness optimum even in the current generation. With the hope that phenotypic plasticity may serve as even a temporary buffer to climate change, the idea that it could also prove maladaptive should not be ignored 14,103 …”

“…With evolution playing a prominent role in management and conservation efforts under global change, for example, through assisted evolution and assisted gene flow, 108,109 a stronger appreciation for the double‐edged nature of evolution might aid in avoiding maladaptive responses and evolutionary traps 14 …”

“…It is only quite recently that the study of maladaptation has achieved a critical mass in the literature 13 . Furthermore, it is especially recent that researchers have considered maladaptive responses to climate change and other rapid changes in the environment 14,15 . In this review and synthesis, we explore how global change can cause populations to become maladapted, and how populations in turn exhibit adaptive or maladaptive responses to global change.…”

Trapped by habitat choice: Ecological trap emerging from adaptation in an evolutionary experiment

“…Moreover, our experiment provides an empirical account of the emergence of an ecological trap. A direct genetic habitat choice for cucumber in our mites most likely evolved by natural selection in a context where this choice was adaptive (see Egas & Sabelis, 2001;Gotoh, Bruin, Sabelis, & Menken, 1993), for example because of cucumber being more nutritious at that time or protecting mites more efficiently from pred- in an endangered population by putting an even higher priority on increasing population sizes (Derry et al, 2019). Otherwise, conservators need to preserve the suitability of the preferred habitat to prevent an ecological trap or other forms of maladaptation.…”