scholarly journals Individual reversible plasticity as a genotype-level bet-hedging strategy

2020 ◽  
Author(s):  
T.R. Haaland ◽  
J. Wright ◽  
I.I. Ratikainen
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Environmental Conditions ◽  
Life History Theory ◽  
Reaction Norm ◽  
Phenotypic Traits ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Individual Level ◽  
Environmental Fluctuations

AbstractReversible plasticity in phenotypic traits allows organisms to cope with environmental variation within lifetimes, but costs of plasticity may limit just how well the phenotype matches the environmental optimum. An additional adaptive advantage of plasticity might be to reduce fitness variance, or bet-hedging to maximize geometric (rather than simply arithmetic) mean fitness. Here we model the evolution of reaction norm slopes, with increasing costs as the slope or degree of plasticity increases. We find that greater investment in plasticity (i.e. steeper reaction norm slopes) is favoured in scenarios promoting bet-hedging as a response to multiplicative fitness accumulation (i.e. coarser environmental grains and fewer time steps prior to reproduction), because plasticity lowers fitness variance across environmental conditions. In contrast, in scenarios with finer environmental grain and many time steps prior to reproduction, bet-hedging plays less of a role and individual-level optimization favours evolution of shallower reaction norm slopes. We discuss contrasting predictions from this partitioning of the different adaptive causes of plasticity into short-term individual benefits versus long-term genotypic (bet-hedging) benefits under different costs of plasticity scenarios, thereby enhancing our understanding of the evolution of optimum levels of plasticity in examples from thermal physiology to advances in avian lay dates.Impact summaryPhenotypic plasticity is a key mechanism by which organisms cope with environmental change. Plasticity relies on the existence of some reliable environmental cue that allows organisms to infer current or future conditions, and adjust their traits in response to better match the environment. In contrast, when environmental fluctuations are unpredictable, bet-hedging favours lineages that persist by lowering their fitness variance, either among or within individuals. Plasticity and bet-hedging are therefore often considered to be alternative modes of adaptation to environmental change. However, we here make the point that plasticity also has the capacity to change an organism’s variance in fitness across different environmental conditions, and could thus itself be part of – and not an alternative to – a bet-hedging strategy. We show that bet-hedging at the genotype level affects the optimal degree of plasticity that individuals use to track environmental fluctuations, because despite a reduction in expected fitness at the individual level, costly investment in the ability to be plastic also lowers variance in fitness. We also discuss alternative predictions that arise from scenarios with different types of costs of plasticity. Evolutionary bet-hedging and phenotypic plasticity are both topics experiencing a renewed surge of interest as researchers seek to better integrate different adaptations to ongoing rapid environmental change in a range of areas of literature within ecology and evolution, including behavioural ecology, evolutionary physiology and life-history theory. We believe that demonstrating an important novel link between these two mechanisms is of interest to research in many different fields, and opens new avenues for understanding organismal adaptation to environmental change.

scholarly journals Diapause is not selected as a bet-hedging strategy in insects: a meta-analysis of reaction norm shapes

2019 ◽  
Author(s):  
Jens Joschinski ◽  
Dries Bonte
Keyword(s):  
Climate Change ◽  
Phenotypic Plasticity ◽  
Meta Analysis ◽  
Reaction Norm ◽  
Geographic Range ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Apparent Lack ◽  
Environmental Predictability ◽  
Hedging Strategies

AbstractMany organisms escape from lethal climatological conditions by entering a resistant resting stage called diapause, which needs to be optimally timed with seasonal change. As climate change exerts selection pressure on phenology, the evolution of mean diapause timing, but also of phenotypic plasticity and bet-hedging strategies is expected. Especially the latter as a strategy to cope with unpredictability is little considered in the context of climate change.Contemporary patterns of phenological strategies across a geographic range may provide information about their evolvability. We thus extracted 458 diapause reaction norms from 60 studies. First, we correlated mean diapause timing with mean winter onset. Then we partitioned the reaction norm variance into a temporal component (phenotypic plasticity) and among-offspring variance (diversified bet-hedging) and correlated this variance composition with predictability of winter onset. Mean diapause timing correlated reasonably well with mean winter onset, except for populations at high latitudes, which apparently failed to track early onsets. Variance among offspring was, however, limited and correlated only weakly with environmental predictability, indicating little scope for bet-hedging. The apparent lack of phenological bet-hedging strategies may pose a risk in a less predictable climate, but we also highlight the need for more data on alternative strategies.

scholarly journals Ecological specialization, variability in activity patterns and response to environmental change

2018 ◽  
Vol 14 (6) ◽  
pp. 20180115 ◽  
Author(s):  
Talisin T. Hammond ◽  
Rupert Palme ◽  
Eileen A. Lacey
Keyword(s):  
Environmental Change ◽  
Environmental Conditions ◽  
Phenotypic Variability ◽  
Activity Patterns ◽  
Temporal Patterns ◽  
Past Century ◽  
Ambient Conditions ◽  
Ecological Specialization ◽  
Sympatric Populations ◽  
Individual Level

Differences in temporal patterns of activity can modulate the ambient conditions to which organisms are exposed, providing an important mechanism for responding to environmental change. Such differences may be particularly relevant to ecological generalists, which are expected to encounter a wider range of environmental conditions. Here, we compare temporal patterns of activity for partially sympatric populations of a generalist (the lodgepole chipmunk, Tamias speciosus ) and a more specialized congener (the alpine chipmunk, Tamias alpinus ) that have displayed divergent responses to the past century of environmental change. Although mean activity budgets were similar between species, analyses of individual-level variation in locomotion revealed that T. alpinus exhibited a narrower range of activity patterns than T . speciosus . Further analyses revealed that T. alpinus was more active earlier in the day, when temperatures were cooler, and that activity patterns for both species changed with increased interspecific co-occurrence. These results are consistent with the greater responsiveness of T. alpinus to changes in environmental conditions. In addition to highlighting the utility of accelerometers for collecting behavioural data, our findings add to a growing body of evidence, suggesting that the greater phenotypic variability displayed by ecological generalists may be critical to in situ responses to environmental change.

scholarly journals Adaptive phenotypic plasticity in malaria parasites is not constrained by previous responses to environmental change

2019 ◽  
Vol 2019 (1) ◽  
pp. 190-198
Author(s):  
Philip L G Birget ◽  
Petra Schneider ◽  
Aidan J O’Donnell ◽  
Sarah E Reece
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Life History Theory ◽  
Environmental Changes ◽  
Negative Consequences ◽  
Plastic Response ◽  
Malaria Parasites ◽  
Host Environment ◽  
Adaptive Phenotypic Plasticity ◽  
Plastic Responses

Abstract Background and objectives Phenotypic plasticity enables organisms to maximize fitness by matching trait values to different environments. Such adaptive phenotypic plasticity is exhibited by parasites, which experience frequent environmental changes during their life cycle, between individual hosts and also in within-host conditions experienced during infections. Life history theory predicts that the evolution of adaptive phenotypic plasticity is limited by costs and constraints, but tests of these concepts are scarce. Methodology Here, we induce phenotypic plasticity in malaria parasites to test whether mounting a plastic response to an environmental perturbation constrains subsequent plastic responses to further environmental change. Specifically, we perturb red blood cell resource availability to induce Plasmodium chabaudi to alter the trait values of several phenotypes underpinning within-host replication and between-host transmission. We then transfer parasites to unperturbed hosts to examine whether constraints govern the parasites’ ability to alter these phenotypes in response to their new in-host environment. Results Parasites alter trait values in response to the within-host environment they are exposed to. We do not detect negative consequences, for within-host replication or between-host transmission, of previously mounting a plastic response to a perturbed within-host environment. Conclusions and implications We suggest that malaria parasites are highly plastic and adapted to adjusting their phenotypes in response to the frequent changes in the within-host conditions they experience during infections. Our findings support the growing body of evidence that medical interventions, such as anti-parasite drugs, induce plastic responses that are adaptive and can facilitate the survival and potentially, drug resistance of parasites. Lay Summary Malaria parasites have evolved flexible strategies to cope with the changing conditions they experience during infections. We show that using such flexible strategies does not impact upon the parasites’ ability to grow (resulting in disease symptoms) or transmit (spreading the disease).

scholarly journals Serotoninergic Modulation of Phototactic Variability Underpins a Bet-Hedging Strategy in Drosophila melanogaster

2021 ◽  
Vol 15 ◽  
Author(s):  
Indrikis A. Krams ◽  
Tatjana Krama ◽  
Ronalds Krams ◽  
Giedrius Trakimas ◽  
Sergejs Popovs ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Environmental Conditions ◽  
Tropical Climate ◽  
Fruit Flies ◽  
Bet Hedging ◽  
Hedging Strategy ◽  
Opposite Pattern ◽  
Mechanistic Basis ◽  
Lower Variability ◽  
Boreal Climate

When organisms’ environmental conditions vary unpredictably in time, it can be advantageous for individuals to hedge their phenotypic bets. It has been shown that a bet-hedging strategy possibly underlies the high inter-individual diversity of phototactic choice in Drosophila melanogaster. This study shows that fruit flies from a population living in a boreal and relatively unpredictable climate have more variable variable phototactic biases than fruit flies from a more stable tropical climate, consistent with bet-hedging theory. We experimentally show that phototactic variability of D. melanogaster is regulated by the neurotransmitter serotonin (5-HT), which acts as a suppressor of the variability of phototactic choices. When fed 5-HT precursor, boreal flies exhibited lower variability, and they were insensitive to 5-HT inhibitor. The opposite pattern was seen in the tropical flies. Thus, the reduction of 5-HT in fruit flies’ brains may be the mechanistic basis of an adaptive bet-hedging strategy in a less predictable boreal climate.

Phenotypic Plasticity

2001 ◽  
Author(s):  
Massimo Pigliucci
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Reaction Norm ◽  
Reaction Norms ◽  
Genetic Constitution ◽  
Genotype 3 ◽  
Norm Of Reaction ◽  
Living Organisms ◽  
And Behavior

Phenotypic plasticity is the property of a genotype to produce different phenotypes in response to different environmental conditions (Bradshaw 1965; Mazer and Damuth, this volume, chapter 2). Simply put, students of phenotypic plasticity deal with the way nature (genes) and nurture (environment) interact to yield the anatomy, morphology, and behavior of living organisms. Of course, not all genotypes respond differentially to changes in the environment, and not all environmental changes elicit a different phenotype given a particular genotype. Furthermore, while the distinction between genotype and phenotype is in principle very clear, several complicating factors immediately ensue. For example, the genotype can be modified by environmental action, as in the case of DNA methylation patterns (e.g., Sano et al. 1990; Mazer and Damuth, this volume, chapter 2). More intuitively, since environments are constantly changed by the organisms that live in them, the genetic constitution of a population influences the environment itself. Perhaps the most intuitive way to visualize phenotypic plasticity is through what is termed a norm of reaction. This genotype-specific function relates the phenotypes produced to the environments in which they are produced. The figure presents a simple example with a population made of three different genotypes experiencing a series of environmental conditions. Genotype 1 yields a low phenotypic value toward the left end of the environmental continuum (say, an insect with small wings at low temperature) but a high phenotypic value at the opposite environmental extreme (say, large wings at high temperature). Genotype 3, however, does the exact opposite, while genotype 2 is unresponsive to environmental changes, always producing the same phenotype regardless of the conditions (within the range of environments considered). Even though the case presented in figure 5.1 is very simple (notice, for example, that the reaction norms are linear, which is unlikely in real situations), several general principles are readily understood following a closer analysis: . . . 1. Let us consider the relationship between phenotypic plasticity and reaction norms. While the two terms are often used as synonyms, they are clearly not. A reaction norm is the trajectory in environment- phenotype space that is typical of a given genotype; plasticity is the degree to which that reaction norm deviates from a flat line parallel to the environmental axis. . . .

scholarly journals Beyond buying time: the role of plasticity in phenotypic adaptation to rapid environmental change

2019 ◽  
Vol 374 (1768) ◽  
pp. 20180174 ◽  
Author(s):  
Rebecca J. Fox ◽  
Jennifer M. Donelson ◽  
Celia Schunter ◽  
Timothy Ravasi ◽  
Juan D. Gaitán-Espitia
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Environmental Conditions ◽  
Theme Issue ◽  
The Future ◽  
Selection For ◽  
The Individual ◽  
Plastic Responses ◽  
Rapid Environmental Change

How populations and species respond to modified environmental conditions is critical to their persistence both now and into the future, particularly given the increasing pace of environmental change. The process of adaptation to novel environmental conditions can occur via two mechanisms: (1) the expression of phenotypic plasticity (the ability of one genotype to express varying phenotypes when exposed to different environmental conditions), and (2) evolution via selection for particular phenotypes, resulting in the modification of genetic variation in the population. Plasticity, because it acts at the level of the individual, is often hailed as a rapid-response mechanism that will enable organisms to adapt and survive in our rapidly changing world. But plasticity can also retard adaptation by shifting the distribution of phenotypes in the population, shielding it from natural selection. In addition to which, not all plastic responses are adaptive—now well-documented in cases of ecological traps. In this theme issue, we aim to present a considered view of plasticity and the role it could play in facilitating or hindering adaption to environmental change. This introduction provides a re-examination of our current understanding of the role of phenotypic plasticity in adaptation and sets the theme issue's contributions in their broader context. Four key themes emerge: the need to measure plasticity across both space and time; the importance of the past in predicting the future; the importance of the link between plasticity and sexual selection; and the need to understand more about the nature of selection on plasticity itself. We conclude by advocating the need for cross-disciplinary collaborations to settle the question of whether plasticity will promote or retard species' rates of adaptation to ever-more stressful environmental conditions. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.

scholarly journals Rapid local adaptation in both sexual and asexual invasive populations of monkeyflowers (Mimulus spp.)

2020 ◽  
Author(s):  
Violeta I. Simón-Porcar ◽  
Jose L. Silva ◽  
Mario Vallejo-Marín
Keyword(s):  
Phenotypic Plasticity ◽  
Local Adaptation ◽  
Environmental Conditions ◽  
Phenotypic Selection ◽  
Fruit Production ◽  
Phenotypic Traits ◽  
Transplant Experiment ◽  
Reciprocal Transplant Experiment ◽  
Fitness Advantage ◽  
The Uk

AbstractBackground and AimsTraditionally, local adaptation has been seen as the outcome of a long evolutionary history, particularly in sexual lineages. In contrast, phenotypic plasticity has been thought to be most important during the initial stages of population establishment and in asexual species. We evaluated the roles of adaptive evolution and phenotypic plasticity in the invasive success of two closely related species of invasive monkeyflowers (Mimulus) in the United Kingdom (UK) that have contrasting reproductive strategies: M. guttatus combines sexual (seeds) and asexual (clonal growth) reproduction while M. × robertsii is entirely asexual.MethodsWe compared the clonality (number of stolons), floral and vegetative phenotype, and phenotypic plasticity of native (M. guttatus) and invasive (M. guttatus and M. × robertsii) populations grown in controlled environment chambers under the environmental conditions at each latitudinal extreme of the UK. The goal was to discern the roles of temperature and photoperiod on the expression of phenotypic traits. Next, we tested the existence of local adaptation in the two species within the invasive range with a reciprocal transplant experiment at two field sites in the latitudinal extremes of the UK, and analysed which phenotypic traits underlie potential local fitness advantage in each species.Key ResultsPopulations of M. guttatus in the UK showed local adaptation through sexual function (fruit production), while M. × robertsii showed local adaptation via asexual function (stolon production). Phenotypic selection analyses revealed that different traits are associated with fitness in each species. Invasive and native populations of M. guttatus had similar phenotypic plasticity and clonality. M. × robertsii presents greater plasticity and clonality than native M. guttatus, but most populations have restricted clonality under the warm conditions of the south of UK.ConclusionsOur study provides experimental evidence of local adaptation in a strictly asexual invasive species with high clonality and phenotypic plasticity. This indicates that even asexual taxa can rapidly (< 200 years) adapt to novel environmental conditions in which alternative strategies may not ensure the persistence of populations.

scholarly journals Selection on phenotypic plasticity favors thermal canalization

2020 ◽  
Vol 117 (47) ◽  
pp. 29767-29774
Author(s):  
Erik I. Svensson ◽  
Miguel Gomez-Llano ◽  
John T. Waller
Keyword(s):  
Climate Change ◽  
Sexual Selection ◽  
Natural Selection ◽  
Phenotypic Plasticity ◽  
Reaction Norm ◽  
Thermal Reaction ◽  
Phenotypic Traits ◽  
Common View ◽  
Thermal Plasticity ◽  
Natural And Sexual Selection

Climate change affects organisms worldwide with profound ecological and evolutionary consequences, often increasing population extinction risk. Climatic factors can increase the strength, variability, or direction of natural selection on phenotypic traits, potentially driving adaptive evolution. Phenotypic plasticity in relation to temperature can allow organisms to maintain fitness in response to increasing temperatures, thereby “buying time” for subsequent genetic adaptation and promoting evolutionary rescue. Although many studies have shown that organisms respond plastically to increasing temperatures, it is unclear if such thermal plasticity is adaptive. Moreover, we know little about how natural and sexual selection operate on thermal reaction norms, reflecting such plasticity. Here, we investigate how natural and sexual selection shape phenotypic plasticity in two congeneric and phenotypically similar sympatric insect species. We show that the thermal optima for longevity and mating success differ, suggesting temperature-dependent trade-offs between survival and reproduction in both sexes. Males in these species have similar thermal reaction norm slopes but have diverged in baseline body temperature (intercepts), being higher for the more northern species. Natural selection favored reduced thermal reaction norm slopes at high ambient temperatures, suggesting that the current level of thermal plasticity is maladaptive in the context of anthropogenic climate change and that selection now promotes thermal canalization and robustness. Our results show that ectothermic animals also at high latitudes can suffer from overheating and challenge the common view of phenotypic plasticity as being beneficial in harsh and novel environments.

Phenotypic plasticity

2018 ◽  
Author(s):  
Karen D. Williams ◽  
Marla B. Sokolowski
Keyword(s):  
Gene Expression ◽  
Phenotypic Plasticity ◽  
Environmental Change ◽  
Behavioral Plasticity ◽  
Behavioral Flexibility ◽  
Insect Behavior ◽  
Behavioral Variability ◽  
Gene By Environment Interactions ◽  
Affect Gene Expression

Why is there so much variation in insect behavior? This chapter will address the sources of behavioral variability, with a particular focus on phenotypic plasticity. Variation in social, nutritional, and seasonal environmental contexts during development and adulthood can give rise to phenotypic plasticity. To delve into mechanism underlying behavioral flexibility in insects, examples of polyphenisms, a type of phenotypic plasticity, will be discussed. Selected examples reveal that environmental change can affect gene expression, which in turn can affect behavioral plasticity. These changes in gene expression together with gene-by-environment interactions are discussed to illuminate our understanding of insect behavioral plasticity.

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