Most species evolve within fluctuating environments, and have developed adaptations to meet the challenges posed by environmental heterogeneity. One such adaptation is phenotypic plasticity, or the ability of a single...Most species evolve within fluctuating environments, and have developed adaptations to meet the challenges posed by environmental heterogeneity. One such adaptation is phenotypic plasticity, or the ability of a single genotype to produce multiple environmentally-induced phenotypes. Yet, not all plasticity is adaptive. Despite the renewed interest in adaptive phenotypic plas- ticity and its consequences for evolution, much less is known about maladaptive plasticity. However, maladaptive plasticity is likely an important driver of phenotypic similarity among populations living in different environments. This paper traces four strategies for overcoming maladaptive plasticity that result in phenotypic similarity, two of which involve genetic changes （standing genetic variation, genetic compensation） and two of which do not （standing epigenetic variation, plastic compensation）. Plastic compensation is defined as adaptive plasticity overcoming maladaptive plasticity. In particular, plastic compensation may increase the likelihood of genetic compensation by facilitating population persistence. We provide key terms to disentangle these aspects of phenotypic plasticity and introduce examples to reinforce the potential importance of plastic compensation for under- standing evolutionary change展开更多
Speciation research has seen a renewed interest in ecological speciation, which emphasises divergent ecological se- lection leading to the evolution of reproductive isolation. Selection from divergent ecologies means ...Speciation research has seen a renewed interest in ecological speciation, which emphasises divergent ecological se- lection leading to the evolution of reproductive isolation. Selection from divergent ecologies means that phenotypic plasticity can play an important role in ecological speciation. Phenotypic plasticity involves the induction of phenotypes over the lifetime of an organism and emerging evidence suggests that epigenetic marks such as cytosine and protein （histone） modifications might regu- late such environmental induction. Epigenetic marks play a wide role in a variety of processes including development, sex dif- ferentiation and allocation, sexual conflict, regulation of transposable elements and phenotypic plasticity. Here we describe recent studies that investigate epigenetic mechanisms in a variety of contexts. There is mounting evidence for environmentally induced epigenetic variation and for the stable inheritance of epigenetic marks between generations. Thus, epigenetically-based pheno- typic plasticity may play a role in adaptation and ecological speciation. However, there is less evidence for the inheritance of in- duced epigenetic variation across multiple generations in animals. Currently few studies of ecological speciation incorporate the potential for the involvement of epigenetically-based induction of phenotypes, and we argue that this is an important omission [Current Zoology 59 （5）： 686-696, 2013 ].展开更多
Individual-based studies allow quantification ofphenotypic plasticity in behavioural, life-history and other labile traits The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives ...Individual-based studies allow quantification ofphenotypic plasticity in behavioural, life-history and other labile traits The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives （1） whether plasticity itself can evolve or is constrained by its genetic architecture, and （2） whether plasticity is associated to other traits, including fitness （selection）. I describe the main statistical approach for how repeated records of individuals and a description of the environment （E） allow quantification of variation in plasticity across individuals （IxE） and genotypes （GxE） in wild populations. Based on a literature review of life-history and behavioural studies on plasticity in the wild, I discuss the present state of the two objectives listed above. Few studies have quantified GxE of labile traits in wild populations, and it is likely that power to detect statistically sig- nificant GxE is lacking. Apart from the issue of whether it is heritable, plasticity tends to correlate with average trait expression （not fully supported by the few genetic estimates available） and may thus be evolutionary constrained in this way. Individ- ual-specific estimates of plasticity tend to be related to other traits of the individual （including fitness）, but these analyses may be anti-conservative because they predominantly concern stats-on-stats. Despite the increased interest in plasticity in wild popula- tions, the putative lack of power to detect GxE in such populations hinders achieving general insights. I discuss possible steps to invigorate the field by moving away from simply testing for presence of GxE to analyses that ＇scale up＇ to population level proce-sses and by the development of new behavioural theory to identify quantitative genetic parameters which can be estimated展开更多
It is generally accepted that taxa exhibit genetic variation in phenotypic plasticity, but many questions remain unan- swered about how divergent plastic responses evolve under dissimilar ecological conditions. Hormon...It is generally accepted that taxa exhibit genetic variation in phenotypic plasticity, but many questions remain unan- swered about how divergent plastic responses evolve under dissimilar ecological conditions. Hormones are signaling molecules that act as proximate mediators of phenotype expression by regulating a variety of cellular, physiological, and behavioral re- sponses. Hormones not only change cellular and physiological states but also influence gene expression directly or indirectly, thereby linking environmental conditions to phenotypic development. Studying how hormonal pathways respond to environ- mental variation and how those responses differ between individuals, populations, and species can expand our understanding of the evolution of phenotypic plasticity. Here, we explore the ways that the study of hormone signaling is providing new insights into the underlying proximate bases for individual, population or species variation in plasticity. Using several studies as exem- plars, we examine how a ＇norm of reaction＇ approach can be used in investigations of hormone-mediated plasticity to inform the following： 1） how environmental cues affect the component hormones, receptors and enzymes that comprise any endocrine sig- naling pathway, 2） how genetic and epigenetic variation in endocrine-associated genes can generate variation in plasticity among these diverse components, and 3） how phenotypes mediated by the same hormone can be coupled and decoupled via independent plastic responses of signaling components across target tissues. Future studies that apply approaches such as reaction norms and network modeling to questions concerning how hormones link environmental stimuli to ecologically-relevant phenotypic re- sponses should help unravel how phenotypic plasticity evolves展开更多
文摘Most species evolve within fluctuating environments, and have developed adaptations to meet the challenges posed by environmental heterogeneity. One such adaptation is phenotypic plasticity, or the ability of a single genotype to produce multiple environmentally-induced phenotypes. Yet, not all plasticity is adaptive. Despite the renewed interest in adaptive phenotypic plas- ticity and its consequences for evolution, much less is known about maladaptive plasticity. However, maladaptive plasticity is likely an important driver of phenotypic similarity among populations living in different environments. This paper traces four strategies for overcoming maladaptive plasticity that result in phenotypic similarity, two of which involve genetic changes （standing genetic variation, genetic compensation） and two of which do not （standing epigenetic variation, plastic compensation）. Plastic compensation is defined as adaptive plasticity overcoming maladaptive plasticity. In particular, plastic compensation may increase the likelihood of genetic compensation by facilitating population persistence. We provide key terms to disentangle these aspects of phenotypic plasticity and introduce examples to reinforce the potential importance of plastic compensation for under- standing evolutionary change
文摘Speciation research has seen a renewed interest in ecological speciation, which emphasises divergent ecological se- lection leading to the evolution of reproductive isolation. Selection from divergent ecologies means that phenotypic plasticity can play an important role in ecological speciation. Phenotypic plasticity involves the induction of phenotypes over the lifetime of an organism and emerging evidence suggests that epigenetic marks such as cytosine and protein （histone） modifications might regu- late such environmental induction. Epigenetic marks play a wide role in a variety of processes including development, sex dif- ferentiation and allocation, sexual conflict, regulation of transposable elements and phenotypic plasticity. Here we describe recent studies that investigate epigenetic mechanisms in a variety of contexts. There is mounting evidence for environmentally induced epigenetic variation and for the stable inheritance of epigenetic marks between generations. Thus, epigenetically-based pheno- typic plasticity may play a role in adaptation and ecological speciation. However, there is less evidence for the inheritance of in- duced epigenetic variation across multiple generations in animals. Currently few studies of ecological speciation incorporate the potential for the involvement of epigenetically-based induction of phenotypes, and we argue that this is an important omission [Current Zoology 59 （5）： 686-696, 2013 ].
文摘Individual-based studies allow quantification ofphenotypic plasticity in behavioural, life-history and other labile traits The study of phenotypic plasticity in the wild can shed new light on the ultimate objectives （1） whether plasticity itself can evolve or is constrained by its genetic architecture, and （2） whether plasticity is associated to other traits, including fitness （selection）. I describe the main statistical approach for how repeated records of individuals and a description of the environment （E） allow quantification of variation in plasticity across individuals （IxE） and genotypes （GxE） in wild populations. Based on a literature review of life-history and behavioural studies on plasticity in the wild, I discuss the present state of the two objectives listed above. Few studies have quantified GxE of labile traits in wild populations, and it is likely that power to detect statistically sig- nificant GxE is lacking. Apart from the issue of whether it is heritable, plasticity tends to correlate with average trait expression （not fully supported by the few genetic estimates available） and may thus be evolutionary constrained in this way. Individ- ual-specific estimates of plasticity tend to be related to other traits of the individual （including fitness）, but these analyses may be anti-conservative because they predominantly concern stats-on-stats. Despite the increased interest in plasticity in wild popula- tions, the putative lack of power to detect GxE in such populations hinders achieving general insights. I discuss possible steps to invigorate the field by moving away from simply testing for presence of GxE to analyses that ＇scale up＇ to population level proce-sses and by the development of new behavioural theory to identify quantitative genetic parameters which can be estimated
文摘It is generally accepted that taxa exhibit genetic variation in phenotypic plasticity, but many questions remain unan- swered about how divergent plastic responses evolve under dissimilar ecological conditions. Hormones are signaling molecules that act as proximate mediators of phenotype expression by regulating a variety of cellular, physiological, and behavioral re- sponses. Hormones not only change cellular and physiological states but also influence gene expression directly or indirectly, thereby linking environmental conditions to phenotypic development. Studying how hormonal pathways respond to environ- mental variation and how those responses differ between individuals, populations, and species can expand our understanding of the evolution of phenotypic plasticity. Here, we explore the ways that the study of hormone signaling is providing new insights into the underlying proximate bases for individual, population or species variation in plasticity. Using several studies as exem- plars, we examine how a ＇norm of reaction＇ approach can be used in investigations of hormone-mediated plasticity to inform the following： 1） how environmental cues affect the component hormones, receptors and enzymes that comprise any endocrine sig- naling pathway, 2） how genetic and epigenetic variation in endocrine-associated genes can generate variation in plasticity among these diverse components, and 3） how phenotypes mediated by the same hormone can be coupled and decoupled via independent plastic responses of signaling components across target tissues. Future studies that apply approaches such as reaction norms and network modeling to questions concerning how hormones link environmental stimuli to ecologically-relevant phenotypic re- sponses should help unravel how phenotypic plasticity evolves
