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 The Model of Fitness in a Heterogeneous Environment on Reaction Norms

2017 ◽  
Vol 71 (4) ◽  
pp. 303-306
Author(s):  
Volodymyr Gerasymenko
Keyword(s):  
Natural Selection ◽  
Environmental Conditions ◽  
Reaction Norm ◽  
Reaction Norms ◽  
Heterogeneous Environments ◽  
Norm Of Reaction ◽  
Adaptive Trait ◽  
Genetic Mechanisms ◽  
Algorithmic Model ◽  
Genetic Formula

Abstract The understanding of genetic mechanisms of natural selection to a large extent became possible as a result of modelling research carried out in the fields of evolutionary and population genetics. However, genetic models cannot be considered exhaustive in the description of natural selection because a phenotype of individual, environment and fitness remains beyond their framework. Consequently, the value of fitness is not derived from the algorithmic model but arbitrarily assigned by a researcher to genotypes in their genetic formula. This work proposes a model of genotype fitness in heterogeneous environments on reaction norms in connection with the genetic structure of the population. Two equations represent the model. The first is an incomplete second order polynomial that describes the dependence of fitness on the phenotype of an adaptive trait and environmental conditions. The second is a linear equation of the reaction norm of the adaptive trait that determines its phenotype in specific environmental conditions. According to the model algorithms, rating of fitness in the population, and, consequently, their probability of selection, is determined by phenotype optimality and their norm of reaction in certain environmental conditions.

scholarly journals Genomic and environmental determinants and their interplay underlying phenotypic plasticity

2018 ◽  
Vol 115 (26) ◽  
pp. 6679-6684 ◽  
Author(s):  
Xin Li ◽  
Tingting Guo ◽  
Qi Mu ◽  
Xianran Li ◽  
Jianming Yu
Keyword(s):  
Phenotypic Plasticity ◽  
Flowering Time ◽  
Performance Prediction ◽  
Gene Interaction ◽  
Reaction Norm ◽  
Environmental Index ◽  
Genetic Population ◽  
Genome Wide ◽  
And Performance ◽  
Living Organisms

Observed phenotypic variation in living organisms is shaped by genomes, environment, and their interactions. Flowering time under natural conditions can showcase the diverse outcome of the gene–environment interplay. However, identifying hidden patterns and specific factors underlying phenotypic plasticity under natural field conditions remains challenging. With a genetic population showing dynamic changes in flowering time, here we show that the integrated analyses of genomic responses to diverse environments is powerful to reveal the underlying genetic architecture. Specifically, the effect continuum of individual genes (Ma1,Ma6,FT, andELF3) was found to vary in size and in direction along an environmental gradient that was quantified by photothermal time, a combination of two environmental factors (photoperiod and temperature). Gene–gene interaction was also contributing to the observed phenotypic plasticity. With the identified environmental index to quantitatively connect environments, a systematic genome-wide performance prediction framework was established through either genotype-specific reaction-norm parameters or genome-wide marker-effect continua. These parallel genome-wide approaches were demonstrated for in-season and on-target performance prediction by simultaneously exploiting genomics, environment profiling, and performance information. Improved understanding of mechanisms for phenotypic plasticity enables a concerted exploration that turns challenge into opportunity.

scholarly journals Chromatin structure changes in Daphnia populations upon exposure to environmental cues – or – The discovery of Wolterecks “Matrix”

2019 ◽  
Author(s):  
Ronaldo de Carvalho Augusto ◽  
Aki Minoda ◽  
Oliver Rey ◽  
Céline Cosseau ◽  
Cristian Chaparro ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Chromatin Structure ◽  
Environmental Gradients ◽  
Gene Mutations ◽  
Reaction Norms ◽  
Environmental Cues ◽  
Global Changes ◽  
Open Chromatin ◽  
Norm Of Reaction ◽  
Structure Changes

AbstractPhenotypic plasticity is an important feature of biological systems that is likely to play a major role in the future adaptation of organisms to the ongoing global changes. It may allow an organism to produce alternative phenotypes in responses to environmental cues. Modifications in the phenotype can be reversible but are sometimes enduring and can even span over generations. The notion of phenotypic plasticity was conceptualized in the early 20th century by Richard Woltereck. He introduced the idea that the combined relations of a phenotypic character and all environmental gradients that influence on it can be defined as “norm of reaction”. Norms of reaction are specific to species and to lineages within species, and they are heritable. He postulated that reaction norms can progressively be shifted over generations depending on the environmental conditions. One of his biological models was the water-flee daphnia. Woltereck proposed that enduring phenotypic modifications and gene mutations could have similar adaptive effects, and he postulated that their molecular bases would be different. Mutations occurred in genes, while enduring modifications were based on something he called the Matrix. He suggested that this matrix (i) was associated with the chromosomes, (ii) that it was heritable, (iii) it changed during development of the organisms, and (iv) that changes of the matrix could be simple chemical substitutions of an unknown, but probably polymeric molecule. We reasoned that the chromatin has all postulated features of this matrix and revisited Woltereck’s classical experiments with daphnia. We developed a robust and rapid ATAC-seq technique that allows for analyzing chromatin of individual daphnia and show here (i) that this technique can be used with minimal expertise in molecular biology, and (ii) we used it to identify open chromatin structure in daphnia exposed to different environmental cues. Our result indicates that chromatin structure changes consistently in daphnia upon this exposure confirming Woltereck’s classical postulate.

scholarly journals Inter- and intraspecific phenotypic plasticity of three phytoplankton species in response to ocean acidification

2017 ◽  
Vol 13 (2) ◽  
pp. 20160774 ◽  
Author(s):  
Giannina S. I. Hattich ◽  
Luisa Listmann ◽  
Julia Raab ◽  
Dorthe Ozod-Seradj ◽  
Thorsten B. H. Reusch ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Ocean Acidification ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Population Level ◽  
Reaction Norms ◽  
Short Time Scale ◽  
Sampling Effort ◽  
Phytoplankton Species ◽  
Species Response

Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification on inter- and intraspecific reaction norms of three globally important phytoplankton species ( Emiliania huxleyi, Gephyrocapsa oceanica and Chaetoceros affinis ). Despite significant differences in growth rates between the species, they all showed a high potential for phenotypic buffering (similar growth rates between ambient and high CO 2 conditions). Only three coccolithophore genotypes showed a reduced growth in high CO 2 . Diverging responses to high CO 2 of single coccolithophore genotypes compared with the respective mean species responses, however, raise the question of whether an extrapolation to the population level is possible from single-genotype experiments. We therefore compared the mean response of all tested genotypes with a total species response comprising the same genotypes, which was not significantly different in the coccolithophores. Assessing species reaction norms to different environmental conditions on short time scale in a genotype-mix could thus reduce sampling effort while increasing predictive power.

scholarly journals МІЖПОПУЛЯЦІЙНА МІНЛИВІСТЬ ЗАБАРВЛЕННЯ ЧЕРЕПАШКИ РАВЛИКА ВЕЛИКОГО ЗВИЧАЙНОГО HELIX ALBESCENS ROSSMÄSSLER, 1839 (PULMONATA, HELICADAE) У ПІВНІЧНОЗАХІДНОМУ ПРИАЗОВ’Ї

2019 ◽  
pp. 90-96
Author(s):  
М. В. Генсицький ◽  
О. І. Кошелев
Keyword(s):  
Environmental Conditions ◽  
Climatic Factors ◽  
Population Diversity ◽  
Genetic Constitution ◽  
Morphological Parameters ◽  
Urban Habitats ◽  
Azov Region ◽  
Living Organisms ◽  
The City ◽  
Terrestrial Mollusks

The variability of any organism is highly dependent on environmental conditions. Morphological parameters of living organisms are determined by the genetic constitution of the animal, as well as formed under the influence of the environment, where climatic factors play an important role. Thus, the shell features of land-based mollusks are reliable indicators of the environmental conditions in which animals develop. Malacology has accumulated a large amount of factual material from various species of gastropods, which confirms this position. The article deals with the polymorphism on the striped shell of Helixalbescens terrestrial mollusks in the northwest og the Azov region. In the course of the research, the frequency of each morph in the sample was estimated as well as the average number of morphs (μ), the frequency of rare morphs (h), and the similarity of the samples according to the phenotype (r) was calculated. All 11 morphs were found in all populations of H. albescens from urban habitats. Three main morphs (12345, 1(23)45, 12045) were present in all studied samplings. The occurrence of rare morphs was different in urbanized and unbuilt biotopes. For example, morph 123 (45) was found only in urban biotopes, morph 12 (345) – only in the city and at point 9. The dominant morphs are 12345, 1(23)45, to which 22.6% and 32.9% of 1058 specimens or hollow shells respectively belonged. The indicator of intra-population diversity μ varied within rather narrow limits both in urbanized (from 4,899 to 7,581) and in unburied biotopes (from 4,152 to 6,697). In total, among 1058 shells and 10 samplings, 11 morphs were registered. The coloring of the shells of H. albescens differs in a considerable variety both in natural and in urbanized biotopes.

scholarly journals Neuroendocrine control of life histories: what do we need to know to understand the evolution of phenotypic plasticity?

2007 ◽  
Vol 363 (1497) ◽  
pp. 1589-1598 ◽  
Author(s):  
C(Kate). M Lessells
Keyword(s):  
Control System ◽  
Phenotypic Plasticity ◽  
Life Histories ◽  
Reaction Norm ◽  
Neuroendocrine System ◽  
Reaction Norms ◽  
Selection Pressures ◽  
Neuroendocrine Control ◽  
Optimal Reaction Norm ◽  
Optimal Reaction

Almost all life histories are phenotypically plastic: that is, life-history traits such as timing of breeding, family size or the investment in individual offspring vary with some aspect of the environment, such as temperature or food availability. One approach to understanding this phenotypic plasticity from an evolutionary point of view is to extend the optimality approach to the range of environments experienced by the organism. This approach attempts to understand the value of particular traits in terms of the selection pressures that act on them either directly or owing to trade-offs due to resource allocation and other factors such as predation risk. Because these selection pressures will between environments, the predicted optimal phenotype will too. The relationship expressing the optimal phenotype for different environments is the optimal reaction norm and describes the optimal phenotypic plasticity. However, this view of phenotypic plasticity ignores the fact that the reaction norm must be underlain by some sort of control system: cues about the environment must be collected by sense organs, integrated into a decision about the appropriate life history, and a message sent to the relevant organs to implement that decision. In multicellular animals, this control mechanism is the neuroendocrine system. The central question that this paper addresses is whether the control system affects the reaction norm that evolves. This might happen in two different ways: first, the control system will create constraints on the evolution of reaction norms if it cannot be configured to produce the optimal reaction norm and second, the control system will create additional selection pressures on reaction norms if the neuroendocrine system is costly. If either of these happens, a full understanding of the way in which selection shapes reaction norms must include details of the neuroendocrine control system. This paper presents the conceptual framework needed to explain what is meant by a constraint or cost being created by the neuroendocrine system and discusses the extent to which this occurs and some possible examples. The purpose of doing this is to encourage endocrinologists to take a fresh look at neuroendocrine mechanisms and help identify the properties of the system and situations in which these generate constraints and costs that impinge on the evolution of phenotypic plasticity.

scholarly journals When three traits make a line: Evolution of phenotypic plasticity and genetic assimilation through linear reaction norms in stochastic environments

2015 ◽  
Author(s):  
Torbjorn Ergon ◽  
Rolf Ergon
Keyword(s):  
Phenotypic Plasticity ◽  
Genetic Correlations ◽  
Reaction Norm ◽  
Genetic Effects ◽  
Environmental Perception ◽  
Genetic Assimilation ◽  
Reaction Norms ◽  
Environmental Value ◽  
Linear Reaction ◽  
Definition Of

Genetic assimilation results from selection on phenotypic plasticity, but quantitative genetics models of linear reaction norms considering intercept and slope as traits do not fully incorporate the process of genetic assimilation. We argue that intercept-slope reaction norm models are insufficient representations of genetic effects on linear reaction norms, and that considering reaction norm intercept as a trait is unfortunate because the definition of this trait relates to a specific environmental value (zero) and confounds genetic effects on reaction norm elevation with genetic effects on environmental perception. Instead we suggest a model with three traits representing genetic effects that respectively (i) are independent of the environment, (ii) alter the sensitivity of the phenotype to the environment, and (iii) determine how the organism perceives the environment. The model predicts that, given sufficient additive genetic variation in environmental perception, the environmental value at which reaction norms tend to cross will respond rapidly to selection after an abrupt environmental change, and eventually become equal to the new mean environment. This readjustment of the zone of canalization becomes completed without changes in genetic correlations, genetic drift or imposing any fitness costs on maintaining plasticity. The asymptotic evolutionary outcome of this three-trait linear reaction norm generally entails a lower degree of phenotypic plasticity than the two-trait model, and maximum expected fitness does not occur at the mean trait values in the population.

scholarly journals Untangling the Components of Phenotypic Plasticity in Nonlinear Reaction Norms of Drosophila Mediopunctata Pigmentation

2016 ◽  
Author(s):  
Felipe Bastos Rocha ◽  
Louis Bernard Klaczko
Keyword(s):  
Phenotypic Plasticity ◽  
Genetic Architecture ◽  
Empirical Studies ◽  
Strong Association ◽  
Experimental Studies ◽  
Reaction Norm ◽  
Developmental Model ◽  
Reaction Norms ◽  
Mean Values ◽  
Local Plasticity

AbstractPhenotypic plasticity may evolve as a generalist strategy to cope with environmental heterogeneity. Empirical studies, however, rarely find results confirming this prediction. This may be related to constraints imposed by the genetic architecture underlying plasticity variation. Three components of plasticity are central to characterize its variation: the intensity of response, the direction of response and the total amount of change. Reaction norm functions are a key analytical tool in plasticity studies. The more complex they are, the more plasticity components will vary independently, requiring more parameters to be described. Experimental studies are continuously collecting results showing that actual reaction norms are often nonlinear. This demands an analytical framework – yet to be developed – capable of straightforwardly untangling plasticity components. In Drosophila mediopunctata, the number of dark spots on the abdomen decreases as a response to increasing developmental temperatures. We have previously described a strong association between reaction norm curvature and across-environment mean values in homozygous strains. Here, we describe seven new reaction norms of heterozygous genotypes and further the investigation on the genetic architecture of this trait’s plasticity, testing three competing models from the literature – Overdominance, Epistasis and Pleiotropy. We use the curves of localized slopes of each reaction norm – Local Plasticity functions – to characterize the plastic response intensity and direction, and introduce a Global Plasticity parameter to quantify their total amount of change. Uncoupling plasticity components allowed us to discard the Overdominance model, weaken the Epistasis model and strengthen the support for the Pleiotropy model. Furthermore, this approach allows the elaboration of a coherent developmental model for the pigmentation of D. mediopunctata where genetic variation at one single feature explains the patterns of plasticity and overall expression of the trait. We claim that Global Plasticity and Local Plasticity may prove instrumental to the understanding of adaptive reaction norm evolution

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.

Evolution of Reaction Norms

2020 ◽  
Author(s):  
Rebekah A. Oomen ◽  
Jeffrey A. Hutchings
Keyword(s):  
Phenotypic Plasticity ◽  
Environmental Variability ◽  
Nonlinear Function ◽  
Environmental Variation ◽  
Reaction Norm ◽  
Reaction Norms ◽  
Phenotypic Trait ◽  
Phenotypic Variance ◽  
Linear Quadratic ◽  
Norm Evolution

Phenotypic variance is a function of genetic variability, environmental variation, and the ways in which genetic and environmental variation interact, i.e., VG×E. Reaction norms are a means of conceptually, graphically, and mathematically describing this total variance and are a powerful tool for decomposing it into its constituent parts (i.e., nature, nurture, and, critically, their interaction). A reaction norm is defined as the range of phenotypes expressed by a genotype along an environmental gradient. It is represented by a linear or nonlinear function which describes the value of a phenotypic trait for a particular genotype or group of genotypes in different environments. As such, it is closely related to the concept of phenotypic plasticity, which can be represented by a reaction norm with a non-zero slope (i.e., the phenotype varies with respect to the environment). While the term (which originated as Reaktionsnorm) has been in use for over one hundred years, there has been some debate about the most appropriate way to describe it mathematically. Nonetheless, there is general consensus that a reaction norm has multiple properties, each of which can be the target of selection. Reaction norms are typically described as consisting of: (1) an intercept, elevation, or offset, which describes the mean trait value across all environments, (2) a slope, which quantifies the degree of trait plasticity, and (3) shape or curvature (e.g., linear, quadratic, monotonic). Evidence that trait means and plasticities can evolve separately underscores the necessity of applying a reaction norm framework for studying ecological and evolutionary responses to the environment, because measuring phenotypes in a single environmental context does not necessarily reflect their relative values or diversities in a different context. These contextual differences are particularly important in a world of rapid anthropogenic change and increasing environmental variability. Therefore, in addition to being fundamental to ecological and evolutionary phenomena, reaction norm evolution is relevant for diverse biological fields, including behavior and psychology, conservation and natural resource management, global change biology, agriculture and breeding programs, and human health. Given that evolutionary change is defined by genetic change, we focus this article on variation among reaction norms from different genotypes (i.e., reaction norms that have potentially evolved to be divergent from one another) as well as the forces that promote and constrain reaction norm evolution. For an overview of the literature on plasticity itself (keeping in mind that reaction norms need not be plastic), see the separate Oxford Bibliographies in Evolutionary Biology article Phenotypic Plasticity.

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