scholarly journals Structural colours reflect individual quality: a meta-analysis

2020 ◽  
Vol 16 (4) ◽  
pp. 20200001
Author(s):  
Thomas E. White
Keyword(s):  
Immune Function ◽  
Body Condition ◽  
Meta Analysis ◽  
Visual Ecology ◽  
Individual Quality ◽  
Sexual Signals ◽  
Parasite Resistance ◽  
Structural Coloration ◽  
Exchange Of Information ◽  
The Relationship

Colourful ornaments often communicate salient information to mates, and theory predicts covariance between signal expression and individual quality. This has borne out among pigment-based signals, but the potential for ‘honesty’ in structural coloration is unresolved. Here, I synthesized the available evidence to test this prediction via meta-analysis and found that, overall, the expression of structurally coloured sexual signals is positively associated with individual quality. The effects varied by the measure of quality, however, with body condition and immune function reliably encoded across taxa, but not age nor parasite resistance. The relationship was apparent for both the colour and brightness of signals and was slightly stronger for iridescent ornaments. These results suggest diverse pathways to the encoding and exchange of information among structural colours while highlighting outstanding questions as to the development, visual ecology and evolution of this striking adornment.

scholarly journals Structural colours reflect individual quality: a meta-analysis

2020 ◽  
Author(s):  
Thomas E. White
Keyword(s):  
Immune Function ◽  
Body Condition ◽  
Meta Analysis ◽  
Visual Ecology ◽  
Individual Quality ◽  
Sexual Signals ◽  
Parasite Resistance ◽  
Exchange Of Information ◽  
Structural Colouration ◽  
The Relationship

AbstractOrnamental colouration often communicates salient information to mates, and theory predicts covariance between signal expression and individual quality. This has borne out among pigment-based signals, but the potential for ‘honesty’ in structural colouration is unresolved. Here I synthesised the available evidence to test this prediction via meta-analysis and found that, overall, the expression of structurally coloured sexual signals is positively associated with individual quality. The effects varied by measure of quality, however, with body condition and immune function reliably encoded across taxa, but not age nor parasite resistance. The relationship was apparent for both the colour and brightness of signals and was slightly stronger for iridescent ornaments. These results suggest diverse pathways to the encoding and exchange of information among structural colours, while highlighting outstanding questions as to the development, visual ecology, and evolution of this striking adornment.

scholarly journals Immune activation suppresses plasma testosterone level: a meta-analysis

2008 ◽  
Vol 4 (6) ◽  
pp. 741-744 ◽  
Author(s):  
Jelle J Boonekamp ◽  
Albert H.F Ros ◽  
Simon Verhulst
Keyword(s):  
Immune Function ◽  
Immune Activation ◽  
Meta Analysis ◽  
Mechanistic Explanation ◽  
Suppressive Effect ◽  
Plasma Testosterone ◽  
Sexual Signals ◽  
Trade Off ◽  
Testosterone Levels ◽  
Handicap Hypothesis

Females often select mates on the basis of sexual signals, which can be reliable indicators of male quality when the costliness of these signals prevents cheating. The immunocompetence handicap hypothesis (ICHH) provides a mechanistic explanation of these costs, by proposing a trade-off between immune function and sexual displays. This trade-off arises because testosterone enhances sexual signals, but suppresses immune function. Many studies have investigated the ICHH by administrating testosterone, and a recent meta-analysis found little evidence that testosterone suppressed immune function. However, another component of the ICHH, which has received less empirical interest, suggests that there may also be an interaction in the other direction, with immune activation suppressing testosterone levels. We present a meta-analysis to test for this effect. Overall, there was a strong suppressive effect of experimental immune activation on testosterone levels ( r =−0.52), regardless of whether live pathogens or non-pathogenic antigens were used to challenge the immune system. The latter is important because it shows that immune activation per se suppresses testosterone levels. Thus, a trade-off between immunocompetence and sexual displays may primarily be generated by the effect of immune activation on testosterone, rather than the opposite effect that has received most attention.

scholarly journals On the relationship between body condition and parasite infection in wildlife: a review and meta-analysis

2018 ◽  
Vol 21 (12) ◽  
pp. 1869-1884 ◽  
Author(s):  
Cecilia A. Sánchez ◽  
Daniel J. Becker ◽  
Claire S. Teitelbaum ◽  
Paola Barriga ◽  
Leone M. Brown ◽  
...  
Keyword(s):  
Body Condition ◽  
Meta Analysis ◽  
Parasite Infection ◽  
The Relationship

scholarly journals Signalling with a cryptic trait: the regularity of barred plumage in common waxbills

2016 ◽  
Vol 3 (5) ◽  
pp. 160195 ◽  
Author(s):  
Cristiana I. J. Marques ◽  
Helena R. Batalha ◽  
Gonçalo C. Cardoso
Keyword(s):  
Social Interactions ◽  
Body Condition ◽  
Sex Roles ◽  
Individual Quality ◽  
Sexual Signals ◽  
Adult Males ◽  
Sexual Signalling ◽  
Close Range ◽  
Feather Development ◽  
Regular Patterns

Sexual signals often compromise camouflage because of their conspicuousness. Pigmentation patterns, on the contrary, aid in camouflage. It was hypothesized that a particular type of pattern—barred plumage in birds, whereby pigmented bars extend across feathers—could simultaneously signal individual quality, because disruptions of these patterns should be perceptually salient at close range and help assess plumage condition. Here we show that common waxbills ( Estrilda astrild ), which have extensive barred plumage, have more regular patterns as adults than as juveniles, and that adult males have more regular patterns than females. Both these differences are indicative of sexual signalling in species with conventional sex roles. More regular barred plumage was related to better body condition in adult males. Colour ornamentation traits were also related to aspects of quality, either the same as barred plumage (body condition) or a different one (good feather development), supporting both the ‘redundant message’ and the ‘multiple message’ hypotheses for the coexistence of multiple sexual signals. Although receiver responses to the regularity of barred plumage were not studied here, research on other species has shown that barred plumage can mediate social interactions. We conclude that using barred plumage as a signal of quality helps circumvent the functional compromise between camouflage and communication.

scholarly journals Beak coloration of starling (Sturnus unicolor) males depends on the length of their throat feathers

2020 ◽  
Vol 31 (4) ◽  
pp. 933-942 ◽  
Author(s):  
Manuel Azcárate-García ◽  
Magdalena Ruiz-Rodríguez ◽  
Cristina Ruiz-Castellano ◽  
Silvia Díaz-Lora ◽  
Gustavo Tomás ◽  
...  
Keyword(s):  
Body Condition ◽  
Causal Link ◽  
Sexually Dimorphic ◽  
Individual Quality ◽  
Sexual Signaling ◽  
Sturnus Unicolor ◽  
Negative Effect ◽  
Multiple Signaling ◽  
First Time ◽  
The Relationship

Abstract Within the context of complex sexual signaling, most research has focused on exploring the associations between several signals and/or their relationships with different proxies of individual quality. However, very few studies have focused on checking whether the expression of one signal is conditioned by the expression of the others. Here, by experimentally shortening the throat feathers of male spotless starlings (Sturnus unicolor), we evaluated the influence of this trait on the color expression of the beak base. In addition, we tested the relationship between these two sexually dimorphic characters with traits indicating individual qualities, such as body condition and color reflectance at the wavelength related to carotenes in the tip of the beak. Our results show that the coloration of the beak base in males, but not in females, is positively related to body condition and to the length of ornamental throat feathers. Moreover, the experimental shortening of throat feathers in males had a negative effect on the blue chroma intensity of their beak base 1 year after manipulation. These results support for the first time a causal link between the expression of two sexually dimorphic characters, which is essential to understand their functionality in a multiple signaling framework.

scholarly journals Effects of Hematozoan Parasites on Condition and Return Rates of American Kestrels

The Auk ◽  
2000 ◽  
Vol 117 (2) ◽  
pp. 373-380 ◽  
Author(s):  
Russell D. Dawson ◽  
Gary R. Bortolotti
Keyword(s):  
Immune Function ◽  
Body Condition ◽  
Good Condition ◽  
Egg Laying ◽  
Blood Parasites ◽  
Chronic Infections ◽  
Return Rates ◽  
American Kestrels ◽  
Dispersal Probability ◽  
The Relationship

Abstract We evaluated the relationship between blood parasites and body condition of American Kestrels (Falco sparverius) during the breeding season. Females that were infected with at least one species of parasite were in poorer condition than those without parasites during incubation but not prior to egg laying. We suggest that the relationship between parasitism and condition was masked before laying because of large increases in body mass of females during egg formation. Reduced condition of males during incubation also was associated with higher intensity of infections by Haemoproteus in one of two years. The negative association between condition and intensity of infection suggests that blood parasites impose costs on kestrels owing to competition for nutrients or allocation of energy by hosts to immune function or tissue repair. Alternatively, kestrels in poor condition may be more likely to have relapses of chronic infections, or they may be less able to control new infections because of resource limitations. In contrast to results during incubation, during the prelaying period the prevalence of parasites tended to be higher, and in one year infections were more intense, among males in good condition. One possible explanation for these results is that body condition of males during courtship is an important determinant of the quality of mate they are able to obtain, and males may be accumulating body reserves at the expense of decreased immune function. Return rates of female kestrels to the study area declined as the intensity of their Haemoproteus infections increased, suggesting that blood parasitism is associated with reduced survival or increased dispersal probability.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

A Meta-Analysis of Interviews and Cognitive Ability

2013 ◽  
Vol 12 (4) ◽  
pp. 157-169 ◽  
Author(s):  
Philip L. Roth ◽  
Allen I. Huffcutt
Keyword(s):  
Cognitive Ability ◽  
Meta Analysis ◽  
Incremental Validity ◽  
Employment Interviews ◽  
Moderator Analysis ◽  
The Future ◽  
Research Questions ◽  
Meta Analyses ◽  
The Relationship

The topic of what interviews measure has received a great deal of attention over the years. One line of research has investigated the relationship between interviews and the construct of cognitive ability. A previous meta-analysis reported an overall corrected correlation of .40 ( Huffcutt, Roth, & McDaniel, 1996 ). A more recent meta-analysis reported a noticeably lower corrected correlation of .27 ( Berry, Sackett, & Landers, 2007 ). After reviewing both meta-analyses, it appears that the two studies posed different research questions. Further, there were a number of coding judgments in Berry et al. that merit review, and there was no moderator analysis for educational versus employment interviews. As a result, we reanalyzed the work by Berry et al. and found a corrected correlation of .42 for employment interviews (.15 higher than Berry et al., a 56% increase). Further, educational interviews were associated with a corrected correlation of .21, supporting their influence as a moderator. We suggest a better estimate of the correlation between employment interviews and cognitive ability is .42, and this takes us “back to the future” in that the better overall estimate of the employment interviews – cognitive ability relationship is roughly .40. This difference has implications for what is being measured by interviews and their incremental validity.

The Relationship Between Immorality and Cleansing

2018 ◽  
Vol 49 (5) ◽  
pp. 303-309 ◽  
Author(s):  
Jedidiah Siev ◽  
Shelby E. Zuckerman ◽  
Joseph J. Siev
Keyword(s):  
Effect Size ◽  
Meta Analysis ◽  
Weighted Mean ◽  
The Relationship

Abstract. In a widely publicized set of studies, participants who were primed to consider unethical events preferred cleansing products more than did those primed with ethical events ( Zhong & Liljenquist, 2006 ). This tendency to respond to moral threat with physical cleansing is known as the Macbeth Effect. Several subsequent efforts, however, did not replicate this relationship. The present manuscript reports the results of a meta-analysis of 15 studies testing this relationship. The weighted mean effect size was small across all studies (g = 0.17, 95% CI [0.04, 0.31]), and nonsignificant across studies conducted in independent laboratories (g = 0.07, 95% CI [−0.04, 0.19]). We conclude that there is little evidence for an overall Macbeth Effect; however, there may be a Macbeth Effect under certain conditions.

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