Linking evolutionary potential to extinction risk: applications and future directions

Abstract

Extinction-risk assessments play a major role in prioritizing conservation action at national and international levels. However, quantifying extinction risk is challenging, especially when including the full suite of adaptive responses to environmental change. In particular, evolutionary potential (EP) -the capacity to evolve genetically based changes that increase fitness under changing conditions -has proven difficult to evaluate, limiting its inclusion in risk assessments. Theory, experiments, simulations, and field studies all highlight the importance of EP in characterizing and mitigating extinction risk. Disregarding EP can therefore result in ineffective allocation of resources and inadequate recovery planning. Fortunately, proxies for EP can be estimated from environmental, phenotypic, and genetic data. Some proxies can be incorporated into quantitative extinction-risk assessments, whereas others better inform basic conservation actions that maximize resilience to future change. Integration of EP into conservation decision making is challenging but essential and remains an important issue for innovation in applied conservation science.

Genomics‐informed delineation of conservation units in a desert amphibian

“…Due to their smaller N e , lower genetic diversity and isolation, peripheral populations are at much higher risk of reduced fitness due to inbreeding depression and loss of evolutionary potential (Forester et al, in press ; Gilpin & Soulé, 1986 ). These populations are also at high risk from ecological processes such as demographic stochasticity, environmental extremes (particularly long‐duration drought events; Pilliod et al, 2021 ), invasive predatory species and disease (Arkle & Pilliod, 2015 ).…”

How density dependence, genetic erosion, and the extinction vortex impact evolutionary rescue

“…On the timescales we modeled, no extinctions occurred during the period after rescued populations reached carrying capacity (generations 20 – 50 in our simulations). However, over longer timescales, populations that fluctuate around a carrying capacity might be susceptible to drift (Frankham et al 1999) or have a low supply of beneficial mutations (Orr and Unckless 2008, Osmond and de Mazancourt 2013), reducing future evolutionary potential (Forester et al 2022). Furthermore, if there is future environmental change that necessitates further adaptation, populations at a constrained size (e.g., a carrying capacity) will begin adaptation from a smaller size than populations with unconstrained growth.…”

“…A corollary is that, in addition to other predictors of extinction risk under rescue (Bell and Gonzalez 2009, Kopp and Matuszewski 2014), the carrying capacity or degree of intraspecific competition should be considered when assessing risks to populations subject to novel habitat alteration, degradation, or reduction. Furthermore, managers implementing strategies to maximize evolutionary potential (Forester et al 2022) should consider how competition and population size may influence adaptation under environmental or climate change. These predictions highlight the effects of density dependence and loss of genetic diversity on populations exposed to environmental change, which is crucial information in an age of global anthropogenic changes that put populations at unprecedented risk of extinction.…”

Shifting effects of host physiological condition following pathogen establishment

“…In addition, supplemental feeding of wildlife may have unexpected negative consequences, including increases in predation, increases in susceptibility due to less nutritious food sources, and enhancement of pathogen spread due to host aggregation [50], and these potential negative effects should be carefully considered before widescale implementation. Species survival in the face of global change will likely require rapid adaptation and change itself may outpace the speed at which species can evolve [51,52]. For species and populations that persist, some traits that may be beneficial for initial survival may prove less important over time [9,53].…”