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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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Between-individual variation in DS as estimated for six empirical datasets
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Figure 5: Between-individual variation in DS as estimated for six empirical datasets

Mentions: Analyses of simulated data showed that the presented method provides reliable estimates of the distribution of DS under a variety of conditions. In addition, unless the MCMC failed to converge, the obtained distributions approximated the underlying ones. We therefore assume that convergence offers a good criterion for the reliability of obtained results. We apply the above model to 8 datasets from 5 different species and 7 different traits (Table 3), following the specifications detailed above. In two cases, the MCMC did not converge. The hypothetical repeatabilities in these cases were low (Table 3) and not significantly different from zero. Thus, the available data do not allow concluding that variation in individual DS was present. Distributions of between-individual variation in DS of the remaining six samples – which did show good convergence behaviour – are given in Figure 5. Distributions are remarkably similar in shape, all showing a highly left skewed distribution, irrespective of the value of the hypothetical repeatability. In addition, values of R were not correlated with the degree of variation in DS (Fig. 6).


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

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

Between-individual variation in DS as estimated for six empirical datasets
© Copyright Policy
Related In: Results  -  Collection

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

Figure 5: Between-individual variation in DS as estimated for six empirical datasets
Mentions: Analyses of simulated data showed that the presented method provides reliable estimates of the distribution of DS under a variety of conditions. In addition, unless the MCMC failed to converge, the obtained distributions approximated the underlying ones. We therefore assume that convergence offers a good criterion for the reliability of obtained results. We apply the above model to 8 datasets from 5 different species and 7 different traits (Table 3), following the specifications detailed above. In two cases, the MCMC did not converge. The hypothetical repeatabilities in these cases were low (Table 3) and not significantly different from zero. Thus, the available data do not allow concluding that variation in individual DS was present. Distributions of between-individual variation in DS of the remaining six samples – which did show good convergence behaviour – are given in Figure 5. Distributions are remarkably similar in shape, all showing a highly left skewed distribution, irrespective of the value of the hypothetical repeatability. In addition, values of R were not correlated with the degree of variation in DS (Fig. 6).

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