Mapping phenotypes: canalization, plasticity and developmental stability

“Another measure of robustness is the degree of accuracy with which a genotype produces a particular phenotype across many isogenic siblings [36].”

“Developmental noise — was used originally by Waddington to refer to differences among homologous replicated parts within a single individual and to describe the absence of developmental stability [2].”

“Developmental noise is intrinsic variance in developmental processes (Debat & David, 2001) and can result in slight variation in autozooid morphology or ‘abnormal’ zooids (e.g. double polypides; Jebram, 1978).”

“The role of environmental canalization, low-level trait variation in response to environmental change, and its subsequent breakdown at environment extremes in the evolution of traits has been theorized about for decades [16,20].”

“The flip side of plasticity is canalization —the ability to buffer developmental processes against genetic and environmental perturbations (Debat and David, 2001); canalization allows organisms to achieve consistent levels of trait expression despite variable conditions.”

“More recently, though, several authors have begun to treat the evolution of phenotypic plasticity as a problem within developmental evolution, either as a variation on canalization ( Debat & David 2001 ) or as a case of the evolution of developmental covariance (Rice 2004b, chap.”

“Related terms, such as canalization or developmental buffering, mostly referring to the processes via which robustness is achieved, are often used interchangeably in the literature (Debat and David, 2001).”

“The reaction norm is thus a property of the genome: genetic canalization and phenotypic plasticity are not mutually exclusive and can combine to form canalized reaction norms [7,17].”

“adaptation, which instead implies the occurrence of genetic changes, over many generations and through natural selection (Debat and David 2001).”

“2012), and is broadly defined as the ability of a given genetic background to produce a constant phenotype, despite environmental variability (Debat and David 2001).”

“He divided developmental homeostasis into two subcomponents: canalization that buffers genetic and environmental effects, and developmental stability that buffers developmental noise [3].”

“Since the parameters of phenotypic plasticity are under genetic (and often adaptive) control, it makes little sense to pit genetic against environmental influences in the variable unfolding of the phenotype (Debat and David [2001]).”

“The classification of such temporal effects has been contentious (Debat and David, 2001), and here I will simply use the terms phenotypic plasticity (Bradshaw, 1965; Pigliucci, 2001; West-Eberhard, 2003) and phenotypic flexibility (Piersma and Lindström, 1997; Piersma and van Gils, 2010).”

“Alternatively, these results could reflect different mechanisms of sensitivity to environmental variation (Debat and David 2001) that result in size variation.”

“Developmental stability can be defined as the set of mechanisms selected to maintain relatively constant phenotypic expression in the face of environmental irregularities (Debat & David, 2001).”

“However, most recognised examples of developmental compensation relate to dramatic genetic or environmental insults [46] and it is unclear whether the generally smaller phenotypic differences induced by common functional polymorphisms, as used in our study, will be sufficient to induce compensatory responses.”

“A significant line effect can be interpreted as because of genetic differences among lines, whereas a significant cactus effect as phenotypic plasticity (Debat & David, 2001; Conner & Hartl, 2004; David et al., 2005).”

“Morphogenetic defects occur when developmental homeostasis is insufficient to compensate environmental stress [2], [18], [19], [20].”

“…to adapt to spatial and temporal variability in resources and offers a mechanism through which an individual may optimize the acquisition and utilization of scarce resources [Bradshaw, 1965; Collins and Bras, 2007; Debat and David, 2001; Robinson and Rorison, 1988; Stearns, 1989; Sultan, 1987].”

“It is widely postulated that traits strongly subjected to natural selection are more buffered against both developmental noise and environmental/genetic influences ( Debat & David, 2001 ).”

“Developmental stability is the ability of an organism to buffer nonadaptive phenotypic variation resulting from micro-environmental disturbances during development (developmental noise; Waddington, 1957; Debat & David, 2001 ).”

“Three major processes are involved in the control of phenotypic variability––canalization, developmental stability and plasticity ( Debat & David, 2001 ).”

“On the basis of this assumption, it could be hypothesized that the constant biotic and abiotic conditions experienced in captive environments make the high maintenance costs of phenotypic plasticity pointless, thus impairing genotype skill to generate different phenotypes under the thrust of changing external cues (a…”

“…and homogeneous subset of possible phenotypes for a given genotype in heterogeneous environments —also called its norm of reaction —is especially striking in plants due to their extended and sequential mode of development (Via et al., 1995; Pigliucci, 1996; Sultan, 2000; Debat and David, 2001).”

“Variation in animal morphology is influenced by environmental effects and genetic mutations (Debat and David, 2001).”

“Alternatively, and perhaps just as importantly, different genotypes can develop the same phenotype, or very similar phenotypes, a phenomenon known as canalization (Figure 2c; Debat & David, 2001; Hall, 1992; Hornstein & Shomron, 2006; Pál & Miklós, 1999).”

“Under the assumption that symmetry represents the optimum phenotype (Debat and David, 2001), several previous studies constructed facial images with different degrees of symmetry (Grammer and Thornhill, 1994; Little et al., 2001, 2007; Rhodes et al., 1998, 1999; Saxton et al., 2011; Swaddle and…”

“…matters and their study involves the assessment of the underlying genetic variation, liability to environmental conditions, and trait association with fitness, as well as the relationship with other aspects of the phenotype (Via et al., 1995; Schlichting & Pigliucci, 1998; Debat & David, 2001).”

“Transcriptional regulation is a variable trait that is subject to natural selection (Whitehead and Crawford 2006; Oleksiak and Crawford 2012) and of predicted importance for the evolution of phenotypic plasticity (Debat and David 2001).”

“There is, however, a recent and renewed interest in the variance, either in its nonheritable environmental component (Debat and David 2001; Polak 2003; Zhang and Hill 2005) or in its genetic component, and its capacity to change under stress conditions (Bijlsma and Loeschcke 1997; Hoffmann and…”

“The forward primer for each microsatellite locus was labeled with a fluorescent dye (FAM, NED, PET, VIC) chosen to allow the simultaneous analysis of several microsatellite loci, which were distributed in two sets.”

“…2011), (iii) canalization mechanisms that give rise to phenotypic conservation of important anatomical © 2013 John Wiley & Sons Ltd structures (Gibson & Wagner 2000; Debat & David 2001), (iv) the different taxa are not actually different species but just mitochondrially differentiated populations.”

“If gene expression is plastic, that is, it is responsive to environmental perturbations (Debat and David 2001), then the genes that differ among individuals should encode coherent functions operating in pathways that interact with the environment.”

“Such a difference in phenotypic variation between two groups reared in the same environment is often discussed in the context of canalization theory (Schmalhausen, 1949; Waddington,1957;Zakharov,1992;GibsonW Debat &David,2001 ).Canalizationisdefinedasasetofprocesses ensuring the production of a consistent phenotype in…”

“Although phenotypic plasticity has long been recognized (Woltereck 1909; Schmalhausen 1949; Scharloo 1991; Scheiner 1993; Debat and David 2001), the mechanism of how it affects the phenotypic mean and variance of quantitative traits that vary continuously is not well understood and documented in…”

“In the original meaning, a trait becomes canalized because the insensitivity to perturbations was considered to increase fitness (Waddington 1942, 1953; Wagner et al. 1997; Debat & David 2001).”

“Phenotypic plasticity is the ability of a single genotype to produce alternative phenotypes in response to different environmental factors [9, 23, 24].”

“Adaptive phenotypic plasticity can be defined as a set of processes historically selected to produce the highest fitness among different environments by means of various plastic traits (Debat and David 2001).”

“the result of natural selection, has led to the hypothesis that these different sources of variation are buffered by (undefined) developmental processes that have been selected for this function.(5) Genetic variation is supposed to be buffered by genetic canalization, environmental variation by environmental canalizat…”

“Hsp90 as a capacitor of phenotypic variation.”

“…of developmental noise often involve the measurement of fluctuating asymmetry (differences in bilateral symmetry) in sexually reproducing organisms (Debat & David, 2001; Lens et al., 2002; Hallgrímsson & Hall, 2005), whereas others examined the phenotypes of parthenogenetic organisms (Yampolsky &…”

“This relates to the contentious debate on the relative status of plasticity, canalization and developmental stability (Debat and David 2001).”

“Conversely, fixed trait expression is favored when a single trait value is optimal in multiple environments or when variation cannot be reliably predicted (Moran 1992, Lively 1999, Tufto 2000, Debat and Patrice 2001 ).”

“A common mechanism for balancing stability and instability at phenotypic levels is known as developmental stability, which is intimately related to canalization or robustness (Debat and David, 2001; Gibson and Dworkin, 2004).”

“There have been numerous definitions of canalization proposed (Debat and David 2001; Nijhout and Davidowitz 2003; Dworkin 2005a), and from each an associated metric can be derived.”

“In its broadest sense, canalization refers to the process whereby the variability of a trait is reduced by a developmental mechanism ([49]; see [50] for other definitions).”

“To test differences in the canalization pattern across treatments, the mean squares corresponding to ‘Individual’ factor in the ANOVA s were used as an estimator of among-individual variation (size and shape VAR; Debat et al., 2001, 2009) and standard F-tests were performed between treatments.”

“Therefore, discordance in monozygotic twins and deviation from bilateral symmetry, for example, have been ascribed to non-genetic effects arising from environmental influences and/or the stochasticity of biological processes [59, 85, 86].”

“This sensory habituation is thought to allow an animal to focus its cognitive resources on a newor changing odour and better respond to it [45].”

“This environmental canalisation, which refers to the insensitivity of a trait to environmental factors (Waddington, 1942; Wagner et al., 1997; Debat and David, 2001), protects these traits against environmental perturbation.”

“Within limits, biological systems maintain phenotypic stability when faced with perturbations from environmental changes, stochastic events (or developmental noise), or genetic variations or mutations (Debat and David, 2001; Nijhout, 2002).”

“Fourth, although canalization results in a decrease in phenotypic variation, phenotypic plasticity should increase phenotypic variation (Debat and David 2001).”

“The visual complex that tends to disap-pear with depth increase during the Frasnian, would suffer a relaxation of selection pressures leading to an increase in the variability of this organ and reflecting developmental instability (Debat and David, 2001).”

“In principle, phenotypic variation of the wing vein pattern can be explained as the interplay between various sources of variation, such as genetic differences, environmental effects, developmental errors and regulatory processes that buffer against such variation [27].”