The Experts below are selected from a list of 8040 Experts worldwide ranked by ideXlab platform
Michael D Greenfield - One of the best experts on this subject based on the ideXlab platform.
-
Reaction Norm variants for male calling song in populations of achroia grisella lepidoptera pyralidae toward a resolution of the lek paradox
Evolution, 2008Co-Authors: Yihong Zhou, Jennifer M. Gleason, Michael D Greenfield, Heidi K Kuster, Jeffrey S Pettis, Robert G DankaAbstract:Significant additive genetic variance often occurs for male advertisement traits in spite of the directional selection imposed by female choice, a problem generally known in evolutionary biology as the lek paradox. One hypothesis, which has limited support from recent studies, for the resolution of this paradox is the role of genotype × environment interaction in which no one genotype exhibits the superior performance in all environments—a crossover of Reaction Norms. However, these studies have not characterized the actual variation of Reaction Norms present in natural populations, and the extent to which crossover maintains genetic variance remains unknown. Here, we present a study of genotype × environment interaction for the male calling song in populations of Achroia grisella (Lepidoptera: Pyralidae; lesser waxmoth). We report significant variance among Reaction Norms for male calling song in two North American populations of A. grisella as measured along temperature, food availability, and density gradients, and there is a relatively high incidence of crossover of the temperature Reaction Norms. This range of Reaction Norm variants and their crossover may reflect the co-occurrence of plastic and canalized genotypes, and we argue that the different responses of these variants along environmental gradients may contribute toward the maintenance of genetic variance for male song.
A D Rijnsdorp - One of the best experts on this subject based on the ideXlab platform.
-
reconstructing the effects of fishing on life history evolution in north sea plaice pleuronectes platessa
Marine Ecology Progress Series, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, A D RijnsdorpAbstract:Growing evidence suggests that fishing may induce rapid contemporary evolution in certain life-history traits. This study analyzes fisheries-induced changes in life-history traits describing growth, maturation, and reproduction, using an individual-based eco-genetic model that captures both the population dynamics and changes in genetic trait values. The model was successfully calibrated to match the observed life-history traits of female North Sea plaice 'Pleuronectes platessa' around the years 1900 and 2000. On this basis, we report the fllowing findings. First, the model indicates changes in 3 evolving life-history traits: the intercept of the maturation Reaction Norm decreases by 27%, the weight-specific reproductive-investment rate increases by 10%, and the weight-specific energy-acquisition rate increases by 1%. Together, these changes reduce the weight at maturation by 46% and the asymptotic body weight by 28% relative to the intensification of fishing around 1900. Second, while the maturation Reaction Norm and reproductive-investment rate change monotonically over time, the energy-acquisition rate follows a more complex course: after an initial increase during the first 50 yr, it remains constant for about 30 yr and then starts to decline. Third, our analysis indicates that North Sea plaice has not yet attained a new evolutionary equilibrium: it must be expected to evolve further towards earlier maturation, increased reproductive investment, and lower adult body size. Fourth, when fishing continues in our model 100 yr into the future, the pace of evolution slows down for the maturation Reaction Norm and the rate of energy acquisition, whereas no such slowing down is expected for the rate of reproductive investment.
-
fisheries induced evolutionary changes in maturation Reaction Norms in north sea sole solea solea
Marine Ecology Progress Series, 2007Co-Authors: Fabian M Mollet, Sarah B M Kraak, A D RijnsdorpAbstract:Age and size at maturation decreased in several commercially exploited fish stocks, which, according to life history theory, may be due to fisheries-induced evolutionary change. How- ever, the observed changes may also represent a plastic response to environmental variability. To dis- entangle phenotypic plasticity from evolutionary change, the probabilistic Reaction Norm approach was applied to 43 cohorts (1960 to 2002) of female sole Solea solea from market samples. The Reaction Norm for age and size at first maturation has significantly shifted towards younger age and smaller size. Size at 50% probability of maturation at Age 3 decreased from 28.6 cm (251 g) to 24.6 cm (128 g). This change was even stronger when condition was included as a third dimension in the Reaction Norm estimation. The influence of alternative factors was tested on the population level by regression of Reaction Norm midpoints on annual estimates of condition, temperature and competitive biomass. Although effects of temperature and competitive biomass were significant, the variation in the midpoints was best explained by the decreasing time trend. Therefore, the results provide strong evidence for a fisheries-induced evolutionary change in the onset of sexual maturity.
-
fisheries induced trends in Reaction Norms for maturation in north sea plaice
Marine Ecology Progress Series, 2003Co-Authors: R E Grift, A D Rijnsdorp, Sebastien Barot, Mikko Heino, Ulf DieckmannAbstract:We analyse how intensive exploitation may have caused evolutionary changes in the age and length at maturation in North Sea plaice Pleuronectes platessa. Such evolutionary change in the onset of maturation is expected, given that fishing mortality is more than 4 times higher than natural mortality. In order to disentangle phenotypic plasticity from evolutionary change, we employ the probabilistic Reaction-Norm approach. This technique allows us to estimate the probabilities of maturing at each relevant age and size, and to disentangle the plasticity in age and size at maturation that results from changes in growth rates from evolutionary changes in maturation propensities themselves. This recently developed method is applied here to females of 41 cohorts (1955 to 1995) of North Sea plaice. We focus on trends in fishing mortality, in growth rates, and in the probabilities of maturing, and test the hypothesis that the decrease in age and length at maturation is partly caused by fisheries-induced adaptive change. We find that the Reaction Norm for age and length at maturation has indeed significantly shifted towards younger age and smaller length. The Reaction-Norm analysis suggests a picture in which short-term fluctuations originating from plastic responses are superimposed on a persistent long-term trend resulting from genetic responses and higher body growth.
Niels Jeroen Dingemanse - One of the best experts on this subject based on the ideXlab platform.
-
repeatability heritability and age dependence of seasonal plasticity in aggressiveness in a wild passerine bird
Journal of Animal Ecology, 2017Co-Authors: Niels Jeroen Dingemanse, Yimen G ArayaajoyAbstract:1.Labile characters allow individuals to flexibly adjust their phenotype to changes in environmental conditions. There is growing evidence that individuals can differ both in average expression of and level of plasticity in this type of character. Both of these aspects are studied in conjunction within a Reaction Norm framework. 2.Theoreticians have investigated the factors promoting variation in Reaction Norm intercepts (average phenotype) and slopes (level of plasticity) of a key labile character: behaviour. A general prediction from their work is that selection will favour the evolution of repeatable individual variation in level of plasticity only under certain ecological conditions. While factors promoting individual repeatability of plasticity have thus been identified, empirical estimates of this phenomenon are largely lacking for wild populations. 3.We assayed aggressiveness of individual male great tits (Parus major) twice during their egg-laying stage and twice during their egg-incubation stage to quantify each male's level of seasonal plasticity. This procedure was applied during six consecutive years; all males breeding in our plots during those years were assayed, resulting in repeated measures of individual Reaction Norms for any individual breeding in multiple years. We quantified among- and within-individual variation in Reaction Norm components, allowing us to estimate repeatability of seasonal plasticity. Using social pedigree information, we further partitioned Reaction Norm components into their additive genetic and permanent environmental counterparts. 4.Cross-year individual repeatability for the intercepts (average aggressiveness) and slopes (level of seasonal plasticity) of the aggressiveness Reaction Norms were 0.574 and 0.516 respectively. The posterior modes of the estimates suggested modest heritabilities (h2=0.260 for intercepts; h2=0.266 for slopes) that were relatively uncertain. Males behaved more aggressively in areas with higher breeding densities, and became less aggressive and less plastic with increasing age; plasticity thus varied within individuals and was multidimensional in nature. 5.This empirical study quantified cross-year individual repeatability, heritability, and age-related reversible plasticity in behaviour. Acknowledging such patterns of multi-level variation is important not only for testing behavioural ecology theory concerning the evolution of repeatable differences in behavioural plasticity but also for predicting how reversible plasticity may evolve in natural populations. This article is protected by copyright. All rights reserved.
-
an approach to estimate short term long term and Reaction Norm repeatability
Methods in Ecology and Evolution, 2015Co-Authors: Yimen G Arayaajoy, Niels Jeroen Dingemanse, Kimberley J MathotAbstract:Evolutionary ecologists increasingly study Reaction Norms that are expressed repeatedly within the same individual's lifetime. For example, foragers continuously alter anti-predator vigilance in response to moment-to-moment changes in predation risk. Variation in this form of plasticity occurs both among and within individuals. Among-individual variation in plasticity (individual by environment interaction or I × E) is commonly studied; by contrast, despite increasing interest in its evolution and ecology, within-individual variation in phenotypic plasticity is not. We outline a study design based on repeated measures and a multilevel extension of random regression models that enables quantification of variation in Reaction Norms at different hierarchical levels (such as among and within individuals). The approach enables the calculation of repeatability of Reaction Norm intercepts (average phenotype) and slopes (level of phenotypic plasticity); these indices are not specific to measurement or scaling and are readily comparable across data sets. The proposed study design also enables calculation of repeatability at different temporal scales (such as short- and long-term repeatability), thereby answering calls for the development of approaches enabling scale-dependent repeatability calculations. We introduce a simulation package in the R statistical language to assess power, imprecision and bias for multilevel random regression that may be utilised for realistic data sets (unequal sample sizes across individuals, missing data, etc). We apply the idea to a worked example to illustrate its utility. We conclude that consideration of multilevel variation in Reaction Norms deepens our understanding of the hierarchical structuring of labile characters and helps reveal the biology in heterogeneous patterns of within-individual variance that would otherwise remain ‘unexplained’ residual variance.
-
interacting personalities behavioural ecology meets quantitative genetics
Trends in Ecology and Evolution, 2015Co-Authors: Niels Jeroen Dingemanse, Yimen G ArayaajoyAbstract:Behavioural ecologists increasingly study behavioural variation within and among individuals in conjunction, thereby integrating research on phenotypic plasticity and animal personality within a single adaptive framework. Interactions between individuals (cf. social environments) constitute a major causative factor of behavioural variation at both of these hierarchical levels. Social interactions give rise to complex ‘interactive phenotypes' and group-level emergent properties. This type of phenotype has intriguing evolutionary implications, warranting a cohesive framework for its study. We detail here how a Reaction-Norm framework might be applied to usefully integrate social environment theory developed in behavioural ecology and quantitative genetics. The proposed emergent framework facilitates firm integration of social environments in adaptive research on phenotypic characters that vary within and among individuals.
-
quantitative genetics of behavioural Reaction Norms genetic correlations between personality and behavioural plasticity vary across stickleback populations
Journal of Evolutionary Biology, 2012Co-Authors: Niels Jeroen Dingemanse, Jonathan Wright, Iain Barber, Jon E BrommerAbstract:Behavioural ecologists have proposed various evolutionary mechanisms as to why different personality types coexist. Our ability to understand the evolutionary trajectories of personality traits requires insights from the quantitative genetics of behavioural Reaction Norms. We assayed > 1000 pedigreed stickleback for initial exploration behaviour of a novel environment, and subsequent changes in exploration over a few hours, representing their capacity to adjust their behaviour to changes in perceived novelty and risk. We found heritable variation in both the average level of exploration and behavioural plasticity, and population differences in the sign of the genetic correlation between these two Reaction Norm components. The phenotypic correlation was not a good indicator of the genetic correlation, implying that quantitative genetics are necessary to appropriately evaluate evolutionary hypotheses in cases such as these. Our findings therefore have important implications for future studies concerning the evolution of personality and plasticity.
G. De Jong - One of the best experts on this subject based on the ideXlab platform.
-
genotype environment interaction for protein yield in dutch dairy cattle as quantified by different models
Journal of Dairy Science, 2002Co-Authors: M P L Calus, A F Groen, G. De JongAbstract:Variance components and breeding values for protein yield were estimated with REML without and with correction for heterogeneity of variances. Three different sire models were applied, which all accounted for genotype × environment (G × E) interaction. The first model included a sire × herd-year-season subclass (HYS) interaction. The second model divided all records in four different types of management groups, based on estimated HYS subclass effect. The third model, the Reaction Norm model, performed a random linear regression on the estimated HYS effect. For comparison, a standard model that did not take G × E interaction into account was also applied. Data consisted of 102,899 305-d first-lactation protein records of Holstein Friesians of 1000 of the largest Dutch dairy herds. All animals calved in 1997, 1998, or 1999. Estimated breeding values (EBV) for 2150 bulls with at least five daughters were calculated. The interaction model detected an interaction variance of 2.5% of the phenotypic variance. The EBV showed a correlation of 1.00 with those of the standard model without interaction. The model with the division in groups showed correlations between groups ranging from 0.73 to 0.86. The EBV showed correlations from 0.84 to 0.91 with the EBV of the standard model. The Reaction Norm model calculated EBV that had a correlation of 1.00 with the EBV of the standard model. The Reaction Norm model was not able to detect significant variance of the slope for the protein data corrected for heterogeneity of variances.
-
genotype environment interaction for protein yield in dutch dairy cattle as quantified by different models
Journal of Dairy Science, 2002Co-Authors: M P L Calus, A F Groen, G. De JongAbstract:Variance components and breeding values for protein yield were estimated with REML without and with correction for heterogeneity of variances. Three different sire models were applied, which all accounted for genotype × environment (G × E) interaction. The first model included a sire × herd-year-season subclass (HYS) interaction. The second model divided all records in four different types of management groups, based on estimated HYS subclass effect. The third model, the Reaction Norm model, performed a random linear regression on the estimated HYS effect. For comparison, a standard model that did not take G × E interaction into account was also applied. Data consisted of 102,899 305-d first-lactation protein records of Holstein Friesians of 1000 of the largest Dutch dairy herds. All animals calved in 1997, 1998, or 1999. Estimated breeding values (EBV) for 2150 bulls with at least five daughters were calculated. The interaction model detected an interaction variance of 2.5% of the phenotypic variance. The EBV showed a correlation of 1.00 with those of the standard model without interaction. The model with the division in groups showed correlations between groups ranging from 0.73 to 0.86. The EBV showed correlations from 0.84 to 0.91 with the EBV of the standard model. The Reaction Norm model calculated EBV that had a correlation of 1.00 with the EBV of the standard model. The Reaction Norm model was not able to detect significant variance of the slope for the protein data corrected for heterogeneity of variances.
-
Phenotypic Plasticity as a Product of Selection in a Variable Environment
The American Naturalist, 1995Co-Authors: G. De JongAbstract:Phenotypic plasticity has been described by character states and by a Reaction Norm. In an environment that is heterogeneous with regard to a continuous environmental variable, selection on the character within each environment can be described by two models of selection on phenotypic plasticity: a model of selection on character states and a model of selection on the coefficients of the Reaction Norm. The two selection models are a linear transformation of each other and mathematically equivalent. The Reaction Norm model seems to be simpler and to give rise to more predictions. The description of genetic variation in phenotypic plasticity by the genotype-environment interaction variance is related to the Reaction Norm model.
Ulf Dieckmann - One of the best experts on this subject based on the ideXlab platform.
-
reconstructing the effects of fishing on life history evolution in north sea plaice pleuronectes platessa
Marine Ecology Progress Series, 2016Co-Authors: Fabian M Mollet, Ulf Dieckmann, A D RijnsdorpAbstract:Growing evidence suggests that fishing may induce rapid contemporary evolution in certain life-history traits. This study analyzes fisheries-induced changes in life-history traits describing growth, maturation, and reproduction, using an individual-based eco-genetic model that captures both the population dynamics and changes in genetic trait values. The model was successfully calibrated to match the observed life-history traits of female North Sea plaice 'Pleuronectes platessa' around the years 1900 and 2000. On this basis, we report the fllowing findings. First, the model indicates changes in 3 evolving life-history traits: the intercept of the maturation Reaction Norm decreases by 27%, the weight-specific reproductive-investment rate increases by 10%, and the weight-specific energy-acquisition rate increases by 1%. Together, these changes reduce the weight at maturation by 46% and the asymptotic body weight by 28% relative to the intensification of fishing around 1900. Second, while the maturation Reaction Norm and reproductive-investment rate change monotonically over time, the energy-acquisition rate follows a more complex course: after an initial increase during the first 50 yr, it remains constant for about 30 yr and then starts to decline. Third, our analysis indicates that North Sea plaice has not yet attained a new evolutionary equilibrium: it must be expected to evolve further towards earlier maturation, increased reproductive investment, and lower adult body size. Fourth, when fishing continues in our model 100 yr into the future, the pace of evolution slows down for the maturation Reaction Norm and the rate of energy acquisition, whereas no such slowing down is expected for the rate of reproductive investment.
-
fisheries induced trends in Reaction Norms for maturation in north sea plaice
Marine Ecology Progress Series, 2003Co-Authors: R E Grift, A D Rijnsdorp, Sebastien Barot, Mikko Heino, Ulf DieckmannAbstract:We analyse how intensive exploitation may have caused evolutionary changes in the age and length at maturation in North Sea plaice Pleuronectes platessa. Such evolutionary change in the onset of maturation is expected, given that fishing mortality is more than 4 times higher than natural mortality. In order to disentangle phenotypic plasticity from evolutionary change, we employ the probabilistic Reaction-Norm approach. This technique allows us to estimate the probabilities of maturing at each relevant age and size, and to disentangle the plasticity in age and size at maturation that results from changes in growth rates from evolutionary changes in maturation propensities themselves. This recently developed method is applied here to females of 41 cohorts (1955 to 1995) of North Sea plaice. We focus on trends in fishing mortality, in growth rates, and in the probabilities of maturing, and test the hypothesis that the decrease in age and length at maturation is partly caused by fisheries-induced adaptive change. We find that the Reaction Norm for age and length at maturation has indeed significantly shifted towards younger age and smaller length. The Reaction-Norm analysis suggests a picture in which short-term fluctuations originating from plastic responses are superimposed on a persistent long-term trend resulting from genetic responses and higher body growth.
