scholarly journals Sexual dichromatism, size dimorphism and microscale anatomy of white wing stripe in blue tit (Cyanistes caeruleus)

2020 ◽  
Author(s):  
Katarzyna Janas ◽  
Paulina Gaweł ◽  
Anna Łatkiewicz ◽  
Dorota Lutyk ◽  
Lars Gustafsson ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Spectral Characteristics ◽  
Bird Species ◽  
Common Element ◽  
Sexual Dichromatism ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Size Dimorphism ◽  
Wing Patch

Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signaling role in mate choice. Although the blue tit is a well-established model species in the studies on colouration, its white wing patch has never been examined in the context of sex-specific trait expression. In this exploratory study, we examined sexual size dimorphism and dichromatism of greater covert’s dots creating white wing patch and analysed its correlations with current body condition and crown colouration - a trait with established role in sexual selection. Further, we qualitatively analysed microstructural barb morphology underlying covert’s colouration. We found significant sexual dimorphism in the dot size independent of covert size, and sexual dichromatism in both white dot and blue outer covert’s vane spectral characteristics. Importantly, UV chroma of covert’s vane was positively correlated with crown UV chroma, which suggests that coverts colouration might be also an ornament assessed by females during courtship display. Internal structure of covert barbs within the white dot was similar to the one found in barbs from the blue part, i.e. with a medullary area consisting of dead keratinocytes containing channel-type ß-keratin spongy nanostructure and centrally located air cavities. However, it lacked melanosomes which was the main observed difference. Together with marked sexual dimorphism, it suggests that white dots may have emerged under sexual selection as an apomorphic trait on previously uniformly coloured feathers.

scholarly journals Sexual dichromatism, size dimorphism and microscale anatomy of white wing stripe in blue tits

2021 ◽  
Author(s):  
Katarzyna Janas ◽  
Paulina Gaweł ◽  
Anna Łatkiewicz ◽  
Dorota Lutyk ◽  
Lars Gustafsson ◽  
...  
Keyword(s):  
Spectral Characteristics ◽  
Bird Species ◽  
Common Element ◽  
Sexual Dichromatism ◽  
Cyanistes Caeruleus ◽  
Size Dimorphism ◽  
Specific Trait ◽  
The One ◽  
Air Cavities ◽  
Wing Patch

Abstract Achromatic patches are a common element of plumage patterns in many bird species and there is growing body of evidence that in many avian taxa they can play a signalling role in mate choice. Although the blue tit Cyanistes caeruleus is a well-established model species in the studies on colouration, its white wing patch has never been examined in the context of sex-specific trait expression. In this exploratory study, we examined sexual size dimorphism and dichromatism of greater covert’s dots creating white wing patch and analysed its correlations with current body condition and crown colouration - a trait with established role in sexual selection. Further, we qualitatively analysed microstructural barb morphology underlying covert’s colouration. We found significant sexual dimorphism in the dot size independent of covert size, and sexual dichromatism in both white dot and blue outer covert’s vane spectral characteristics. Internal structure of covert barbs within the white dot was similar to the one found in barbs from the blue part, i.e. with a medullary area consisting of dead keratinocytes containing channel-type ß-keratin spongy nanostructure and centrally located air cavities. However, it lacked melanosomes which was the main observed difference. Importantly, UV chroma of covert’s blue vane was positively correlated with crown UV chroma and current condition (the latter only in males), which should be a premise for further research on the signal function of the wing stripe.

scholarly journals Sexual selection explains Rensch's rule of allometry for sexual size dimorphism

2007 ◽  
Vol 274 (1628) ◽  
pp. 2971-2979 ◽  
Author(s):  
James Dale ◽  
Peter O Dunn ◽  
Jordi Figuerola ◽  
Terje Lislevand ◽  
Tamás Székely ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sexual Size Dimorphism ◽  
Bird Species ◽  
Confounding Factors ◽  
Allometric Relationship ◽  
Rensch’S Rule ◽  
Size Dimorphism ◽  
Rensch's Rule ◽  
Clear Solution ◽  
General Explanation

In 1950, Rensch first described that in groups of related species, sexual size dimorphism is more pronounced in larger species. This widespread and fundamental allometric relationship is now commonly referred to as ‘Rensch's rule’. However, despite numerous recent studies, we still do not have a general explanation for this allometry. Here we report that patterns of allometry in over 5300 bird species demonstrate that Rensch's rule is driven by a correlated evolutionary change in females to directional sexual selection on males. First, in detailed multivariate analysis, the strength of sexual selection was, by far, the strongest predictor of allometry. This was found to be the case even after controlling for numerous potential confounding factors, such as overall size, degree of ornamentation, phylogenetic history and the range and degree of size dimorphism. Second, in groups where sexual selection is stronger in females, allometry consistently goes in the opposite direction to Rensch's rule. Taken together, these results provide the first clear solution to the long-standing evolutionary problem of allometry for sexual size dimorphism: sexual selection causes size dimorphism to correlate with species size.

scholarly journals Is UV signalling involved in male-male territorial conflict in the blue tit (Cyanistes caeruleus)? A new experimental approach

Behaviour ◽  
2007 ◽  
Vol 144 (4) ◽  
pp. 447-470 ◽  
Author(s):  
Thomas Dijkstra ◽  
Peter Korsten ◽  
Jan Komdeur
Keyword(s):  
Experimental Approach ◽  
Bird Species ◽  
Female Mate Choice ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Fertile Period ◽  
Territorial Conflict ◽  
Uv Reflectance ◽  
Aggressive Reactions ◽  
Uv Coloration

Structurally-based ultraviolet (UV) coloration of plumage can signal male quality and plays a role in female mate choice in many bird species. UV-reflecting badges could also be important signals in male-male competition. We tested if territorial blue tit ( Cyanistes caeruleus ) males discriminate between conspecific male intruders which differ in the UV reflectance of their crown feathers. To this aim, we used a new experimental approach in which we simultaneously (instead of sequentially) introduced two male blue tit taxidermic mounts in the territories of resident males during the female fertile period; one mount with natural crown UV reflectance and one mount with reduced crown UV. The two mounts provoked strong aggressive reactions from resident males. Males specifically directed their aggression to conspecific intruders, as a male blue tit mount received substantially more aggression than a mount of a European robin ( Erithacus rubecula ). However, aggression of resident males did not vary between the UV-reduced and the control mount. Furthermore, the variation in natural crown UV reflectance of the resident males did not predict the intensity of their aggressive response. Contrary to previous findings our results suggest that UV signals play only a limited role in male-male interactions during territorial intrusions in the female fertile period.

The evolution of sexual dimorphism in the lizard Anolis polylepis (Iguania): evidence from intraspecific variation in foraging behavior and diet

1996 ◽  
Vol 74 (7) ◽  
pp. 1238-1245 ◽  
Author(s):  
Gad Perry
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Feeding Behavior ◽  
Rain Forest ◽  
Sexual Size Dimorphism ◽  
Costa Rican ◽  
Agonistic Interactions ◽  
Size Dimorphism ◽  
Food Items ◽  
Competing Hypotheses

Two main explanations, intraspecific niche divergence and sexual selection, have been proposed to explain the origin of sexual size dimorphism. To test these competing hypotheses I studied the ecology, feeding behavior, and diet of the lizard Anolis polylepis in a Costa Rican rain forest. Male A. polylepis were significantly larger and heavier than females but ate smaller food items and had lower stomach volumes, despite possessing longer and wider heads. Males were more sedentary than females or juveniles, chose higher perches, and were more likely to be involved in agonistic interactions. Diets of males, females, and juveniles were also significantly different taxonomically. These data are consistent with the sexual selection origin theory but not with an ecological one. Thus, observed dietary differences probably evolved once dimorphism had been attained through sexual selection.

scholarly journals Sexual size dimorphism and sexual selection in artiodactyls

2020 ◽  
Vol 31 (3) ◽  
pp. 792-797
Author(s):  
Marcelo H Cassini
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Group Size ◽  
Sexual Size Dimorphism ◽  
Alternative Hypothesis ◽  
Mammalian Species ◽  
Generalized Least Squares ◽  
Size Dimorphism ◽  
Selection For

Abstract Sexual size dimorphism is biased toward males in most mammalian species. The most common explanation is precopulatory intramale sexual selection. Large males win fights and mate more frequently. In artiodactyls, previous tests of this hypothesis consisted of interspecific correlations of sexual dimorphism with group size as a surrogate for the intensity of sexual selection (Is). However, group size is not a proper measure of sexual selection for several reasons as is largely recognized in other mammalian taxa. I conducted an interspecific test on the role of sexual selection in the evolution of sexual dimorphism using the variance in genetic paternity as a proxy for the Is. I reviewed the literature and found 17 studies that allowed estimating Is= V/(W2), where V and W are the variance and mean number of offspring per male, respectively. A phylogenetic generalized least squares analysis indicated that dimorphism (Wm/Wf) showed a significant positive regression with the intensity of sexual selection but not group size (multiple r2= 0.40; F3,17= 12.78, P = 0.002). This result suggests that sexual selection may have played a role in the evolution of sexual size dimorphism in Artiodactyla. An alternative hypothesis based on natural selection is discussed.

Sexual dimorphism and growth trade-offs in Blue Tit Cyanistes caeruleus nestlings

Ibis ◽  
2010 ◽  
Vol 153 (1) ◽  
pp. 175-179 ◽  
Author(s):  
MARK C. MAINWARING ◽  
MEGAN DICKENS ◽  
IAN R. HARTLEY
Keyword(s):  
Sexual Dimorphism ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Trade Offs

scholarly journals Sexual dichromatism and color diversity in the spiny lava lizard Tropidurus spinulosus using lizard visual modelling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. Rossi ◽  
S. Benitez-Vieyra ◽  
A. Cocucci ◽  
M. Chiaraviglio ◽  
G. Cardozo
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
The Body ◽  
Sexual Dichromatism ◽  
Social Signals ◽  
Size Dimorphism ◽  
Color Characteristics ◽  
Body Regions ◽  
Lava Lizard

Abstract Colors are important vehicles for social signals in many taxa. In Squamata, previous studies have linked color characteristics and chromatic diversity to sexual selection and, particularly, species showing male-biased body size dimorphism also showed male-biased dichromatism and color diversity. Sexual dichromatism may occur in body regions used for conspecific communication and it may be expressed at wavelengths, such as ultraviolet, easily perceivable by conspecifics. We tested this prediction in a social lizard model, Tropidurus spinulosus, using spectrophotometry and visual modelling which enable colors to be interpreted as the individuals of the same taxon see them. Our results indicate that sexual dichromatism occurs in the ventral regions and the flanks, which are the body regions involved in sexual displays. Males show greater color diversity, having larger color volumes and more contrasting colors. These findings reinforce the idea that sexual selection towards males is coupled with the evolution of male-biased, diverse, coloration which could act as a signal in social reproductive contexts.

scholarly journals Experimental evidence that UV/yellow colouration functions as a signal of parental quality in the blue tit

2020 ◽  
Author(s):  
Jorge García-Campa ◽  
Wendt Müller ◽  
Judith Morales
Keyword(s):  
Behavioural Change ◽  
Family Members ◽  
Bird Species ◽  
Life History Stage ◽  
Family Interactions ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Quality Signal ◽  
Parental Quality ◽  
Behavioural Strategies

AbstractIn bi-parental species, reproduction is not only a crucial life-history stage where individuals must take fitness-relevant decisions, but these decisions also need to be adjusted to the behavioural strategies of a partner. Hence, communication is required, which could be facilitated by condition-dependent signals of parental quality. Yet, these traits have (co-)evolved in multiple contexts within the family, as during reproduction different family members may coincide and interact at the site of breeding. In this study we explore whether a condition-dependent trait acts a quality signal and regulates intra-family interactions in a bird species, the blue tit (Cyanistes caeruleus). As a family is a complex network where signals could be perceived by multiple receivers, we expected that experimentally blocking the reflectance of an adult’s UV/yellow colouration of breast feathers may affect the behavioural strategies of all family members. We found an increase of parental investment in nests with an UV-blocked adult, as the partner compensated for the perceived lower rearing capacity. As the UV-blocked adult did not change its provisioning behaviour, as was to be expected, their partner must have responded to the (manipulated) signal but not to a behavioural change. However, offspring did not co-adjust their begging intensity to a signal of parental quality. Opposite to adults, we propose that offspring respond to the behaviour but not to the parental signal. Overall, our results show experimentally at the first time that UV/yellow colouration of blue tits acts as a quality signal revealing the rearing capacity to mates.

scholarly journals Faecal metabarcoding reveals pervasive long-distance impacts of garden bird feeding

2021 ◽  
Vol 288 (1951) ◽  
pp. 20210480
Author(s):  
Jack D. Shutt ◽  
Urmi H. Trivedi ◽  
James A. Nicholls
Keyword(s):  
Bird Species ◽  
Urban Ecosystems ◽  
Early Spring ◽  
Supplementary Feeding ◽  
Ecosystem Dynamics ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Long Distance ◽  
Supplementary Food ◽  
The Impact

Supplementary feeding of wildlife is widespread, being undertaken by more than half of households in many countries. However, the impact that these supplemental resources have is unclear, with impacts largely considered to be restricted to urban ecosystems. We reveal the pervasiveness of supplementary foodstuffs in the diet of a wild bird using metabarcoding of blue tit ( Cyanistes caeruleus ) faeces collected in early spring from a 220 km transect in Scotland with a large urbanization gradient. Supplementary foodstuffs were present in the majority of samples, with peanut ( Arachis hypogaea ) the single commonest (either natural or supplementary) dietary item. Consumption rates exhibited a distance decay from human habitation but remained high at several hundred metres from the nearest household and continued to our study limit of 1.4 km distant. Supplementary food consumption was associated with a near quadrupling of blue tit breeding density and a 5-day advancement of breeding phenology. We show that woodland bird species using supplementary food have increasing UK population trends, while species that do not, and/or are outcompeted by blue tits, are likely to be declining. We suggest that the impacts of supplementary feeding are larger and more spatially extensive than currently appreciated and could be disrupting population and ecosystem dynamics.

scholarly journals Size matters but hunger prevails—begging and provisioning rules in blue tit families

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5301 ◽  
Author(s):  
Nolwenn Fresneau ◽  
Arne Iserbyt ◽  
Carsten Lucass ◽  
Wendt Müller
Keyword(s):  
Food Deprivation ◽  
Competitive Ability ◽  
Bird Species ◽  
Blue Tit ◽  
Cyanistes Caeruleus ◽  
Parental Response ◽  
Begging Behaviour ◽  
Direct Benefits ◽  
Individual Offspring ◽  
Provisioning Rules

It is commonly observed in many bird species that dependent offspring vigorously solicit for food transfers provided by their parents. However, the likelihood of receiving food does not only depend on the parental response, but also on the degree of sibling competition, at least in species where parents raise several offspring simultaneously. To date, little is known about whether and how individual offspring adjusts its begging strategy according to the entwined effects of need, state and competitive ability of itself and its siblings. We here manipulated the hunger levels of either the two heaviest or the two lightest blue tit (Cyanistes caeruleus) nestlings in a short-term food deprivation experiment. Our results showed that the lightest nestlings consistently begged more than the heaviest nestlings, an effect that was overruled by the tremendous increase in begging behaviour after food deprivation. Meanwhile, the amplified begging signals after food deprivation were the only cue for providing parents in their decision process. Furthermore, we observed flexible but state-independent begging behaviour in response to changes in sibling need. As opposed to our expectations, nestlings consistently increased their begging behaviour when confronted with food deprived siblings. Overall, our study highlights that individual begging primarily aims at increasing direct benefits, but nevertheless reflects the complexity of a young birds’ family life, in addition to aspects of intrinsic need and state.

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