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Modelling developmental instability as the joint action of noise and stability: a Bayesian approach.

Van Dongen S, Lens L - BMC Evol. Biol. (2002)

Bottom Line: However, the recent literature does not support an ubiquitous relationship.More research is urgently needed to get better insights in the developmental mechanisms of noise and stability.In spite of the fact that the model is likely to represent an oversimplification of reality, the accumulation of new insights could be incorporated in the Bayesian statistical approach to obtain more reliable estimation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Global Biometrics and Reporting Janssen Pharmaceutica Beerse, Belgium. svdongen@janbe.jnj.com

ABSTRACT

Background: Fluctuating asymmetry is assumed to measure individual and population level developmental stability. The latter may in turn show an association with stress, which can be observed through asymmetry-stress correlations. However, the recent literature does not support an ubiquitous relationship. Very little is known why some studies show relatively strong associations while others completely fail to find such a correlation. We propose a new Bayesian statistical framework to examine these associations

Results: We are considering developmental stability - i.e. the individual buffering capacity - as the biologically relevant trait and show that (i) little variation in developmental stability can explain observed variation in fluctuating asymmetry when the distribution of developmental stability is highly skewed, and (ii) that a previously developed tool (i.e. the hypothetical repeatability of fluctuating asymmetry) contains only limited information about variation in developmental stability, which stands in sharp contrast to the earlier established close association between the repeatability and developmental instability.

Conclusion: We provide tools to generate valuable information about the distribution of between-individual variation in developmental stability. A simple linear transformation of a previous model lead to completely different conclusions. Thus, theoretical modelling of asymmetry and stability appears to be very sensitive to the scale of inference. More research is urgently needed to get better insights in the developmental mechanisms of noise and stability. In spite of the fact that the model is likely to represent an oversimplification of reality, the accumulation of new insights could be incorporated in the Bayesian statistical approach to obtain more reliable estimation.

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Related in: MedlinePlus

Overview of distributions of DS that were used to simulate datasets The bottom three rows of distributions are skewed to the left. The same right-skewed distributions (obtained by interchanging β1 and β2) are also used (Table 1)
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Figure 1: Overview of distributions of DS that were used to simulate datasets The bottom three rows of distributions are skewed to the left. The same right-skewed distributions (obtained by interchanging β1 and β2) are also used (Table 1)

Mentions: Assume that the development of a particular trait of interest experiences the same amount of noise in each individual (i.e. DN constant), but that variation in DS exists. The beta-distribution is a good candidate distribution to model variation in DS because it is bounded between 0 and 1 and can take many different shapes. It is determined by two parameters β1 and β2 that can only take positive values. When both parameters exceed 1 the distribution is unimodal and when β1 equals β2 it is symmetric. When β1<β2 or β1>β2 the distribution is skewed to the right and the left respectively. When both β1 and β2 are smaller than 1 the distribution becomes bimodal. Distributions used here are represented graphically in Figure 1. For each parameter combination, 1000 samples of 10000 individuals were generated in WINBUGS (Version 1.3 freely available at ), and the coefficients of variation in DS and DI as well as R were estimated. Mean values were calculated across the 1000 samples to keep stochastic variation minimal.


Modelling developmental instability as the joint action of noise and stability: a Bayesian approach.

Van Dongen S, Lens L - BMC Evol. Biol. (2002)

Overview of distributions of DS that were used to simulate datasets The bottom three rows of distributions are skewed to the left. The same right-skewed distributions (obtained by interchanging β1 and β2) are also used (Table 1)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC117071&req=5

Figure 1: Overview of distributions of DS that were used to simulate datasets The bottom three rows of distributions are skewed to the left. The same right-skewed distributions (obtained by interchanging β1 and β2) are also used (Table 1)
Mentions: Assume that the development of a particular trait of interest experiences the same amount of noise in each individual (i.e. DN constant), but that variation in DS exists. The beta-distribution is a good candidate distribution to model variation in DS because it is bounded between 0 and 1 and can take many different shapes. It is determined by two parameters β1 and β2 that can only take positive values. When both parameters exceed 1 the distribution is unimodal and when β1 equals β2 it is symmetric. When β1<β2 or β1>β2 the distribution is skewed to the right and the left respectively. When both β1 and β2 are smaller than 1 the distribution becomes bimodal. Distributions used here are represented graphically in Figure 1. For each parameter combination, 1000 samples of 10000 individuals were generated in WINBUGS (Version 1.3 freely available at ), and the coefficients of variation in DS and DI as well as R were estimated. Mean values were calculated across the 1000 samples to keep stochastic variation minimal.

Bottom Line: However, the recent literature does not support an ubiquitous relationship.More research is urgently needed to get better insights in the developmental mechanisms of noise and stability.In spite of the fact that the model is likely to represent an oversimplification of reality, the accumulation of new insights could be incorporated in the Bayesian statistical approach to obtain more reliable estimation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Global Biometrics and Reporting Janssen Pharmaceutica Beerse, Belgium. svdongen@janbe.jnj.com

ABSTRACT

Background: Fluctuating asymmetry is assumed to measure individual and population level developmental stability. The latter may in turn show an association with stress, which can be observed through asymmetry-stress correlations. However, the recent literature does not support an ubiquitous relationship. Very little is known why some studies show relatively strong associations while others completely fail to find such a correlation. We propose a new Bayesian statistical framework to examine these associations

Results: We are considering developmental stability - i.e. the individual buffering capacity - as the biologically relevant trait and show that (i) little variation in developmental stability can explain observed variation in fluctuating asymmetry when the distribution of developmental stability is highly skewed, and (ii) that a previously developed tool (i.e. the hypothetical repeatability of fluctuating asymmetry) contains only limited information about variation in developmental stability, which stands in sharp contrast to the earlier established close association between the repeatability and developmental instability.

Conclusion: We provide tools to generate valuable information about the distribution of between-individual variation in developmental stability. A simple linear transformation of a previous model lead to completely different conclusions. Thus, theoretical modelling of asymmetry and stability appears to be very sensitive to the scale of inference. More research is urgently needed to get better insights in the developmental mechanisms of noise and stability. In spite of the fact that the model is likely to represent an oversimplification of reality, the accumulation of new insights could be incorporated in the Bayesian statistical approach to obtain more reliable estimation.

Show MeSH
Related in: MedlinePlus