• Energy Research

AbstractThis chapter asks: How can evolutionary potential be measured? The question is deceptively simple: whilst evolutionary potential is typically defined on a per-trait basis, it has become clear that the complex genetic architecture of quantitative traits requires other ways to quantify evolutionary potential and constraints. This chapter reviews knowledge about multivariate evolutionary potential in the wild and the extent to which genetic covariances, as summarized in the G-matrix, impact evolutionary trajectories of natural populations both in terms of rate and direction. In terms of constraints, genetic covariances among traits can slow down the rate of adaptation, and influence the direction of the response to selection. However, the constraints posed by genetic covariances are insurmountable only if G-matrices are stable. The chapter thus reviews firstly theoretical predictions about the stability of G in relation to selection, migration and drift, and secondly methods available to test differentiation among matrices. To date, a majority of studies imply conservatism of G-matrices; however, a couple of recent studies have revealed that differentiation of G-matrices among wild populations can also be very fast, especially during colonisation of new habitats. Furthermore, as an increasing number of methods have been proposed for comparing G-matrices, we assessed how these methods perform under different hypothetical scenarios. The chapter shows that limited statistical power could often lead to erroneous conclusion of matrix conservatism, suggesting caution is needed in interpreting the results of matrix comparisons. The chapter concludes by identifying areas in need of further research.

AbstractSpatial and temporal phenotypic differentiation in mean body size is of commonplace occurrence, but the underlying causes remain often unclear: both genetic differentiation in response to selection (or drift) and environmentally induced plasticity can create similar phenotypic patterns. Studying changes in body mass in Siberian jays (Perisoreus infaustus) over three decades, we discovered that mean body mass declined drastically (ca. 10%) over the first two decades, but increased markedly thereafter back to almost the initial level. Quantitative genetic analyses revealed that although body mass was heritable (h2 = 0.46), the pronounced temporal decrease in body mass was mainly a product of phenotypic plasticity. However, a concomitant and statistically significant decrease in predicted breeding values suggests a genetic component to this change. The subsequent increase in mean body mass was indicated to be entirely due to plasticity. Selection on body mass was estimated to be too weak to fully account for the observed genetic decline in body mass, but bias in selection differential estimates due to environmental covariance between body mass and fitness is possible. Hence, the observed body mass changes appear to be driven mainly by phenotypic plasticity. Although we were not able to identify the ecological driver of the observed plastic changes, the results highlight the utility of quantitative genetic approaches in disentangling genetic and phenotypic changes in natural populations.

SignificanceUsing long-term demographic studies, we showed that warmer temperatures are associated with increased senescence rates and decreased lifespans in four amphibian species that are widely distributed across two continents (North America and Europe). Our study highlights the role of changing climatic conditions in the aging of ectotherms in the context of global warming.

Genetic diversity is a prerequisite for evolutionary change in all kinds of organisms. It is generally acknowledged that populations lacking genetic variation are unable to evolve in response to new environmental conditions (e.g., climate change) and thus may face an increased risk of extinction. Although the importance of incorporating genetic diversity into the design of conservation measures is now well understood, less attention has been paid to the distinction between neutral (NGV) and adaptive (AGV) genetic variation. In this review, we first focus on the utility of NGV by examining the ways to quantify it, reviewing applications of NGV to infer ecological and evolutionary processes, and by exploring its utility in designing conservation measures for plant populations and species. Against this background, we then summarize the ways to identify and estimate AGV and discuss its potential use in plant conservation. After comparing NGV and AGV and considering their pros and cons in a conservation context, we conclude that there is an urgent need for a better understanding of AGV and its role in climate change adaptation. To date, however, there are only a few AGV studies on non-model plant species aimed at deciphering the genetic and genomic basis of complex trait variation. Therefore, conservation researchers and practitioners should keep utilizing NGV to develop relevant strategies for rare and endangered plant species until more estimates of AGV are available.

Abstract Many populations need to adapt to changing environmental conditions, such as warming climate. Changing conditions generate directional selection for traits critical for fitness. For evolutionary responses to occur, these traits need to be heritable. However, changes in environmental conditions can alter the amount of heritable variation a population expresses, making predictions about expected responses difficult. The aim of this study was to evaluate the effects of ambient temperatures on evolutionary potential and strength of natural selection on the timing of reproduction in two passerine birds breeding in boreal forests. Long‐term data on individually marked Willow Tits Poecile montanus (1975–2018) and Great Tits Parus major (1969–2018) were analysed with random regression animal models to assess if spring temperatures affect the expressed amount of additive genetic variation (VA) and heritability (h2) in the timing of breeding. We assessed if ambient temperatures of different seasons influenced the direction and strength of selection on breeding time. We also evaluated if the strength of selection covaried with evolutionary potential. Levels of VA or h2 expressed in laying date were unaffected by spring temperatures in both study species. Selection for earlier breeding was found in the Willow Tit, but not in the Great Tit. In the Willow Tit, selection for earlier breeding was more intense when the temperatures of following autumns and winters were low. Different measures of evolutionary potential did not covary strongly with the strength of selection in either species. We conclude that there is no or little evidence that climate warming would either constrain or promote evolutionary potential in timing of breeding through changes in amount of genetic variance expressed in boreal Willow and Great Tits. However, selection on the timing of breeding, a life‐history event taking place in springtime, is regulated by temperatures of autumns and winters. Rapid warming of these periods have thus potential to reduce the rate of expected evolutionary response in reproductive timing.

AbstractClimate change is imposing intensified and novel selection pressures on organisms by altering abiotic and biotic environmental conditions on Earth, but studies demonstrating genetic adaptation to climate change mediated selection are still scarce. Evidence is accumulating to indicate that both genetic and ecological constrains may often limit populations' abilities to adapt to large scale effects of climate warming. These constraints may predispose many organisms to respond to climate change with range shifts and phenotypic plasticity, rather than through evolutionary adaptation. In general, broad conclusions about the role of evolutionary adaptation in mitigating climate change induced fitness loss in the wild are as yet difficult to make.Editor's suggested further reading in BioEssays: How will fish that evolved at constant sub‐zero temperatures cope with global warming? Notothenioids as a case study Abstract

AbstractBiological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.