scholarly journals Quantitative genetics and behavioural correlates of digit ratio in the zebra finch

2005 ◽  
Vol 272 (1581) ◽  
pp. 2641-2649 ◽  
Author(s):  
Wolfgang Forstmeier
Keyword(s):  
Zebra Finch ◽  
Quantitative Genetics ◽  
Mating Behaviour ◽  
Genetic Correlations ◽  
Relative Length ◽  
Digit Ratio ◽  
Laying Order ◽  
Egg Deposition ◽  
Offspring Sex ◽  
Choice Chamber

A recent study on a captive zebra finch population suggested that variation in digit ratio (i.e. the relative length of the second to the fourth toe) might be an indicator of the action of sex steroids during embryo development, as is widely assumed for human digits. Zebra finch digit ratio was found to vary with offspring sex, laying order of eggs within a clutch, and to predict aspects of female mating behaviour. Hence, it was proposed that the measurement of digit ratio would give insights into how an individual's behaviour is shaped by its maternal environment. Studying 500 individuals of a different zebra finch population I set out to: (1) determine the proximate causes of variation in digit ratio by means of quantitative genetics and (2) to search for phenotypic and genetic correlations between digit ratio, sexual behaviour and aspects of fitness. In contrast to the earlier study, I found no sexual dimorphism in digit ratio and no effect of either laying order or experimentally altered hatching order on digit ratio. Instead, I found that variation in digit ratio was almost entirely additive genetic, with heritability estimates ranging from 71 to 84%. The rearing environment (from egg deposition to independence) explained an additional 5–6% of the variation in digit ratio, but there was no indication of any maternal effects transmitted through the egg. I found highly significant phenotypic correlations (and genetic correlations of similar size) between digit ratio and male song rate (positive correlation) as well as between digit ratio and female hopping activity in a choice chamber (negative correlation). Rather surprisingly, the strength of these correlations differed significantly between subsequent generations of the same population, illustrating how quickly such correlations can appear and disappear probably due to genotype–environment interactions.

scholarly journals A polymorphism in the oestrogen receptor gene explains covariance between digit ratio and mating behaviour

2010 ◽  
Vol 277 (1698) ◽  
pp. 3353-3361 ◽  
Author(s):  
Wolfgang Forstmeier ◽  
Jakob C. Mueller ◽  
Bart Kempenaers
Keyword(s):  
Oestrogen Receptor ◽  
Hormone Receptors ◽  
Hox Genes ◽  
Mating Behaviour ◽  
Receptor Gene ◽  
Relative Length ◽  
Sex Hormone ◽  
Digit Ratio ◽  
Male And Female ◽  
Female Mating

In vertebrates, including humans, the relative length of the second to the fourth digit correlates with sex hormone-dependent behavioural, psychological and physiological traits. However, despite a decade of research, the underlying mechanism linking digit ratio to these sex hormone-dependent traits remains unclear. Previous work suggests that during embryo development, circulating levels of plasma androgens or oestrogens may act through their receptors to affect transcription levels of posterior HOX genes in the developing digits, thereby possibly influencing their relative length. The correlation between digit ratio and sex hormone-dependent traits might thus stem from variation in expression or sensitivity of the sex hormone receptors, or from variation in sex hormone levels in the embryo. Here, we show that in a population of 1156 zebra finches Taeniopygia guttata , a polymorphism in the oestrogen receptor α gene (ESR1) explains 11.3 per cent of the variation in digit ratio, and is also associated with male and female-mating behaviour. By contrast, we found no associations between digit ratio or mating behaviours and polymorphisms in the androgen receptor gene. Thus, our results (i) provide an explanation for the observed significant genetic covariance between digit ratio and male and female mating behaviour and (ii) strongly confirm the indicator function of digit ratio through the oestrogen pathway. Finally, we note that the commonly invoked effect of foetal testosterone on human digit ratio seems to be substantially weaker than the effect described here.

The second to fourth digit ratio, sociosexuality, and offspring sex ratio

2005 ◽  
Vol 28 (2) ◽  
pp. 283-284 ◽  
Author(s):  
Bernhard Fink ◽  
John T. Manning ◽  
Nick Neave
Keyword(s):  
Sex Ratio ◽  
Index Finger ◽  
Ring Finger ◽  
Relative Length ◽  
Digit Ratio ◽  
Sexually Dimorphic ◽  
Offspring Sex Ratio ◽  
Fourth Digit ◽  
Offspring Sex ◽  
Different Populations

Previous research has suggested that offspring sex ratio may be influenced by the actions of prenatal sex steroids, principally androgens. The relative length of the second (index finger) to the fourth digit (ring finger) has been reported to be a proxy to prenatal testosterone levels. This trait is sexually dimorphic, such that males display a significantly lower 2D:4D ratio (indicating higher testosterone exposure), and this dimorphism appears robust across different populations. We suggest that digit ratio (2D:4D) may form a useful marker to help explain variation in sex ratio and sociosexuality.

scholarly journals Relationship between Ratio of Second and Fourth Digit and Obesity Traits among Different Ethnic Groups in Ilorin, North Central Nigeria

2016 ◽  
Vol 8 (4) ◽  
pp. 396-400 ◽  
Author(s):  
Bolaji Fatai OYEYEMI ◽  
John Oluwafemi ADEBAYO ◽  
Abass Toba ANIFOWOSHE ◽  
Oluyinka Ajibola IYIOLA
Keyword(s):  
Ethnic Groups ◽  
Pearson Correlation ◽  
Standard Procedure ◽  
Surrogate Marker ◽  
Relative Length ◽  
Cross Sectional Study ◽  
Digit Ratio ◽  
Sectional Study ◽  
Cross Sectional ◽  
Significant Difference

Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. There are contradicting reports on its relationship with ethnicity/race, whereas convincing studies show it is related to obesity. This cross-sectional study was undertaken to demystify ethnic difference in 2D:4D ratio and to analyze its relationship with obesity among adults in Ilorin Nigeria. The cross-sectional study included 701 individuals. Finger lengths were measured with electronic calipers and other anthropometric traits were measured with standard procedure. Student t test and one-way ANOVA were used to detect differences among groups and relationship was computed with Pearson correlation. The receiver operator characteristic curves were used to detect the diagnostic effect of 2D:4D for obesity. The obtained results showed sexual dimorphism in 2D:4D ratio and other anthropometrics at p < 0.01. Obesity was associated with significantly higher mean of 2D:4D in both genders (female 0.9814 ± 0.012:0.9700 ± 0.012; male 0.9700 ± 0.010:0.9592 ± 0.010 at p < 0.001). The area under the curve was 0.753 (95% CI 0.677-0.829, p < 0.01) and 0.798 (95% CI 0.756-0.804, p < 0.01) in female and male R2D:4D respectively for obesity, implying that 2D:4D might be a surrogate marker for obesity in future.  No significant difference was found in 2D:4D among different ethnic groups studied (p >0.05); this result proved that there was no ethnic specificity in 2D:4D ratio among study’ participants. Thus, it can be reported that the digit ratio was related to high 2D:4D, but this cannot be said for different ethnic groups. The results imply that 2D:4D might be a good surrogate indicator for obesity, but not ethnicity.  

scholarly journals Testosterone measured from amniotic fluid and maternal plasma shows no significant association with directional asymmetry in newborn digit ratio (2D:4D)

2018 ◽  
Vol 10 (3) ◽  
pp. 362-367 ◽  
Author(s):  
G. Richards ◽  
M. Gomes ◽  
T. Ventura
Keyword(s):  
Amniotic Fluid ◽  
Secondary Analysis ◽  
Relative Length ◽  
Maternal Plasma ◽  
Mean Value ◽  
Digit Ratio ◽  
Directional Asymmetry ◽  
Second Trimester ◽  
Maternal Circulation ◽  
Left Hand

AbstractFoetal sex hormones can have powerful and far-reaching effects on later phenotype. However, obtaining accurate measurements is difficult for ethical reasons, and researchers often employ proxy variables to examine their effects. The relative length of the second and fourth fingers (digit ratio or 2D:4D) is frequently used for this purpose, as it is hypothesized to index variance in prenatal androgen and oestrogen exposure. Most studies employing this method examine digit ratio for the right hand (R2D:4D) and/or left hand (L2D:4D), though the mean value (M2D:4D) (i.e., the average of R2D:4D and L2D:4D) and directional asymmetry (D[R–L]) (i.e., R2D:4D minus L2D:4D) are also commonly used. As no published studies have examined M2D:4D or D[R-L] in relation to testosterone measured from amniotic fluid, we conducted a secondary analysis of data published by Ventura et al. The sample comprises 106 mothers from Portugal who underwent amniocentesis during the second trimester and their neonates. Newborn M2D:4D was negatively correlated with amniotic testosterone in females (P<0.05) but not in males; no significant association was observed between amniotic testosterone and D[R–L] in either sex. In addition, we examined testosterone measured from maternal circulation during the second trimester, and found that it was not a significant predictor of M2D:4D or D[R–L] in male or female infants. Further research should aim to measure the ratio of testosterone to oestradiol present in amniotic fluid and maternal plasma, to examine whether either is a predictor of digit ratio variables at different stages of postnatal development.

scholarly journals A simplified calculation of the correlations between relatives

2020 ◽  
Author(s):  
Reginald D. Smith
Keyword(s):  
Path Analysis ◽  
Quantitative Genetics ◽  
Genetic Correlations ◽  
Genomic Data ◽  
Complex Task ◽  
Outbred Population ◽  
Common Task ◽  
Rapid Calculation ◽  
Simplified Calculation

AbstractThe correlations between relatives is one of the fundamental ideas and earliest success of quantitative genetics. Whether using genomic data to infer relationships between individuals or estimating heritability from correlations of phenotypes amongst relatives, understanding the theoretical genetic correlations is a common task. Calculating the correlations between arbitrary relatives in an outbred population, however, can be a careful and somewhat complex task for increasingly distant relatives. This paper introduces an equation based method that consolidates the results of path analysis and uses easily obtainable data from non-inbred pedigrees to allow the rapid calculation of additive or dominance correlations between relatives even in more complicated situations such as cousins sharing more than two grandparents and inbreeding.

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