Hand Asymmetry Does Not Relate to Key Life History Traits in Post-Menopausal Contemporary Finnish Women

Associations between fluctuating asymmetry (FA, a putative marker of developmental instability, DI) and life history traits have received a great deal of attention in the non-human literature. However, the patterns found are very heterogeneous and generalizations are difficult to make. In humans, only a few studies have related FA to life histories and fitness. In this paper we study such relationships using hand FA and several key life history traits in 209 post-menopausal Finnish women born between 1946 and 1958. Asymmetry measurements were based on scans of the hands and the life histories of these women were collected using questionnaires. No significant associations were detected and trends were opposite to expectations. We did find evidence for directional asymmetry, as traits in the right hand were larger on average. This may be due to handedness, questioning the usefulness of hand FA as a measure of DI. We conclude that future studies in humans should carefully examine the usefulness of traits as measures of DI

Publisher Correction: Truncated FGFR2 is a clinically actionable oncogene in multiple cancers.

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Correlated development, organism-wide asymmetry and patterns of asymmetry in two moth species

Understanding the mechanisms that determine the development of a bilaterally symmetrical trait is crucial to the interpretation of patterns of fluctuating asymmetry (FA). Experimental and theoretical studies have indicated that feedback mechanisms both within and between developing traits, may participate in the developmental control of asymmetry. This study provides evidence that naturally occurring patterns of FA are affected by interactions between different traits. We found positive between-trait correlations in signed FA values for tibia lengths on different legs, but not between wing and tibia FA in two moth species. Further research should investigate if trait functionality is related to this presumed correlated development. An extension of the Rashevsky-Turing model of morphogenesis further showed that correlations between the signed FA values can be generated by feedback mechanisms that regulate growth patterns between traits. We argue that such feedback mechanisms can be expected to be widespread and show that between-trait correlations in the unsigned FA then become confounded with correlations in the signed FA. In addition, correlated development appeared to invalidate the use of the hypothetical repeatability to translate correlations between the unsigned FA values into correlations in the presumed underlying developmental instability. In conclusion, the presence of an organism-wide asymmetry, which are most frequently found in morphologically integrated traits, may be even less common than previously thought

Heritability of tibia fluctuating asymmetry and developmental instability in the winter moth (Operophtera brumata L.) (Lepidoptera, Geometridae)

Broad-sense heritability of fluctuating asymmetry and developmental instability in the winter moth were analysed in a full-sib breeding experiment. Effects of both genetic background and common environment on both tibia FA (measured for the three pairs of legs) and body size were studied. As body size has previously been shown to be a reliable indicator of larval feeding success and expected fitness, the relationship between FA and body size was investigated as well. This relationship is of interest because it has been argued that the low heritability of FA results from a strong relationship between FA and fitness. Broad-sense h2 of body size equalled zero whereas the effect of common environment was strong. The heritability of FA was low and not statistically significant for separate tibias. For FA based on the average of the three tibias h2 equalled 0.07 and differed significantly from zero. The heritability of developmental instability equalled 0.09. Thus the use of the hypothetical repeatability to translate the h2 of FA to h2 of developmental instability did not result in a strong increase in this species. Individual asymmetry was not correlated with fitness (as estimated by body size), indicating that the low heritabilities of FA are not a consequence of a strong correlation with fitness. Between-trait correlations in the unsigned FA were significant. However, these correlations are not necessarily indicative of an individual asymmetry parameter as the signed FA values were positively correlated as well, suggesting interdependent development of the three pairs of legs. Further research is necessary to investigate what the effects of interdependent development are on patterns in FA

Fitness components of male and female winter moths (Operophtera brumata L.) (Lepidoptera, Geometridae) relative to measures of body size and asymmetry

In this article we present data from two experiments on the association between individual asymmetry and fitness in the winter moth. We performed a mate selection experiment and compared asymmetry and body size of mated and unmated males collected in the field. Individual asymmetry was not associated with copulation probability, adult life span, or body size, even though body size is a reliable indicator of larval and pupal survival, female fecundity, adult life span, and thus expected fitness. There was only a weak positive effect of body size on mating success, contrary to the strong effect of female size on male choice found in previous experiments. Both males and females were capable of repeated mating, and the number of matings was correlated with female size, but neither with male body size nor with adult asymmetry. Yet, females engaged in repeated matings more frequently if they were first mated to a more asymmetrical male. This may indicate that more asymmetrical males lose paternity due to female remating, although direct paternity analyses need to be carried out. In addition, repeated mating may be uncommon under field situations. In conclusion, the relationship between individual asymmetry and fitness seems to be at best weak in the winter moth

Overview of significance tests for associations between individual life history traits and hand asymmetry.

<p>Tests were obtained from the multivariate regression model. Tests are provided for associations with hand asymmetry using all traits and only traits showing no directional asymmetry (DA). The multivariate F-test was not significant for both analyses (for all traits: F_7,195 = 1.20, p = 0.30; for traits without DA: F_7,195 = 0.23, p = 0.98).</p

Association between hand asymmetry (all traits) and age of first reproduction (top), offspring sex ratio (middle) and number of children (bottom) in post-menopausal Finnish women.

<p>None of the associations was statistically significant, but these associations showed the highest effect sizes (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034661#pone-0034661-t002" target="_blank">Table 2</a>). The sign of the slopes were opposite to what was found in previous studies (see text).</p

Pearsons correlations in signed asymmetries of digit lengths and hand palm width.

<p>Significant correlations (p<0.05) are indicated in bold.</p

Associations in the signed asymmetries between digit lengths and hand palm width.

<p>Associations in the signed asymmetries between digit lengths and hand palm width.</p