Male‐biased sexual selection, but not sexual dichromatism, predicts speciation in birds

Evolution ◽  
2021 ◽  
Vol 75 (4) ◽  
pp. 931-944
Author(s):  
Justin G. Cally ◽  
Devi Stuart‐Fox ◽  
Luke Holman ◽  
James Dale ◽  
Iliana Medina
Keyword(s):  
Sexual Selection ◽  
Sexual Dichromatism

scholarly journals Plumage iridescence is associated with distinct feather microbiota in a tropical passerine

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Veronika Gvoždíková Javůrková ◽  
Erik D. Enbody ◽  
Jakub Kreisinger ◽  
Kryštof Chmel ◽  
Jakub Mrázek ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Community Structure ◽  
Microbial Communities ◽  
Plumage Coloration ◽  
Microbial Load ◽  
Sexual Dichromatism ◽  
Physiological Processes ◽  
Fitness Consequences ◽  
Future Work

Abstract Birds present a stunning diversity of plumage colors that have long fascinated evolutionary ecologists. Although plumage coloration is often linked to sexual selection, it may impact a number of physiological processes, including microbial resistance. At present, the degree to which differences between pigment-based vs. structural plumage coloration may affect the feather microbiota remains unanswered. Using quantitative PCR and DGGE profiling, we investigated feather microbial load, diversity and community structure among two allopatric subspecies of White-shouldered Fairywren, Malurus alboscapulatus that vary in expression of melanin-based vs. structural plumage coloration. We found that microbial load tended to be lower and feather microbial diversity was significantly higher in the plumage of black iridescent males, compared to black matte females and brown individuals. Moreover, black iridescent males had distinct feather microbial communities compared to black matte females and brown individuals. We suggest that distinctive nanostructure properties of iridescent male feathers or different investment in preening influence feather microbiota community composition and load. This study is the first to point to structural plumage coloration as a factor that may significantly regulate feather microbiota. Future work might explore fitness consequences and the role of microorganisms in the evolution of avian sexual dichromatism, with particular reference to iridescence.

scholarly journals Migration and the evolution of sexual dichromatism: evolutionary loss of female coloration with migration among wood-warblers

2015 ◽  
Vol 282 (1809) ◽  
pp. 20150375 ◽  
Author(s):  
Richard K. Simpson ◽  
Michele A. Johnson ◽  
Troy G. Murphy
Keyword(s):  
Sexual Selection ◽  
Sexual Dichromatism ◽  
Ancestral State ◽  
Migration Distance ◽  
Female Ornamentation ◽  
Wood Warblers ◽  
Selection For ◽  
Evolution Of Migration ◽  
And Migration ◽  
Female Coloration

The mechanisms underlying evolutionary changes in sexual dimorphism have long been of interest to biologists. A striking gradient in sexual dichromatism exists among songbirds in North America, including the wood-warblers (Parulidae): males are generally more colourful than females at northern latitudes, while the sexes are similarly ornamented at lower latitudes. We use phylogenetically controlled comparative analysis to test three non-mutually exclusive hypotheses for the evolution of sexual dichromatism among wood-warblers. The first two hypotheses focus on the loss of female coloration with the evolution of migration, either owing to the costs imposed by visual predators during migration, or owing to the relaxation of selection for female social signalling at higher latitudes. The third hypothesis focuses on whether sexual dichromatism evolved owing to changes in male ornamentation as the strength of sexual selection increases with breeding latitude. To test these hypotheses, we compared sexual dichromatism to three variables: the presence of migration, migration distance, and breeding latitude. We found that the presence of migration and migration distance were both positively correlated with sexual dichromatism, but models including breeding latitude alone were not strongly supported. Ancestral state reconstruction supports the hypothesis that the ancestral wood-warblers were monochromatic, with both colourful males and females. Combined, these results are consistent with the hypotheses that the evolution of migration is associated with the relaxation of selection for social signalling among females and that there are increased predatory costs along longer migratory routes for colourful females. These results suggest that loss of female ornamentation can be a driver of sexual dichromatism and that social or natural selection may be a stronger contributor to variation in dichromatism than sexual selection.

scholarly journals Sexual selection, range size and population size

2012 ◽  
Vol 20 (1) ◽  
pp. 1-25 ◽  
Author(s):  
Anders Pape Møller ◽  
László Zsolt Garamszegi
Keyword(s):  
Sexual Selection ◽  
Population Size ◽  
Extinction Risk ◽  
Range Size ◽  
Sexual Dichromatism ◽  
Common Descent ◽  
Distribution Limits ◽  
Western Palaearctic ◽  
Linear Contrasts ◽  
Average Fitness

Abstract Sexual selection may impose fitness costs on both males and females due to the costs of developing and maintaining exaggerated sexual signals, reducing average fitness in strongly sexually selected species. Such reductions in average fitness could affect local extinction risk and hence distribution range. However, given that both sexually monochromatic and dichromatic species are common and widespread, benefits of sexual selection must be invoked to maintain equilibrium. We tested for differences in breeding range size and population size between monochromatic and dichromatic species of birds in a comparative analysis of species from the Western Palaearctic. In an analysis of standardized linear contrasts of the relationship between sexual dichromatism and range size and population size, respectively, that controlled for similarity among taxa due to common descent, we found no significant relationship. However, when we analyzed carotenoid-based sexual dichromatism sexually dichromatic species had larger distribution areas and higher northernmost distribution limits, but not southernmost distribution limits than sexually monochromatic species. In contrast, melanin-based sexual dichromatism was not significantly associated with range size or population size. Therefore, population density of sexually dichromatic species with carotenoid-based coloration was lower than that of monochromatic species, because dichromatic species had similar population sizes but larger ranges than monochromatic species. These findings suggest that the different physiological roles of pigments associated with sexual dichromatism have effects on total range size of birds.

scholarly journals Pre- and post-copulatory traits working in concert: sexual dichromatism in passerines is associated with sperm morphology

2020 ◽  
Vol 16 (1) ◽  
pp. 20190568
Author(s):  
Kate L. Durrant ◽  
Tom Reader ◽  
Matthew R. E. Symonds
Keyword(s):  
Sexual Selection ◽  
Sexual Dichromatism ◽  
Trade Off ◽  
Male Plumage ◽  
Negative Trait ◽  
Sperm Midpiece ◽  
Costly Traits ◽  
Phylogenetic Regression ◽  
Positive Covariance ◽  
Sperm Traits

Passerine birds produce costly traits under intense sexual selection, including elaborate sexually dichromatic plumage and sperm morphologies, to compete for fertilizations. Plumage and sperm traits vary markedly among species, but it is unknown if this reflects a trade-off between pre- and post-copulatory investment under strong sexual selection producing negative trait covariance, or variation in the strength of sexual selection among species producing positive covariance. Using phylogenetic regression, we analysed datasets describing plumage and sperm morphological traits for 278 passerine species. We found a significant positive relationship between sperm midpiece length and male plumage elaboration and sexual dichromatism. We did not find a relationship between plumage elaboration and testes mass. Our results do not support a trade-off between plumage and sperm traits, but may be indicative of variance among species in the strength of sexual selection to produce both brightly coloured plumage and costly sperm traits.

scholarly journals Objective Assessment of Sexual Plumage Dichromatism in the Picui Dove

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 248-254
Author(s):  
Bettina Mahler ◽  
Bart Kempenaers
Keyword(s):  
Sexual Selection ◽  
Objective Assessment ◽  
Spectral Shape ◽  
Sexual Dichromatism ◽  
Sexually Dimorphic ◽  
Near Ultraviolet ◽  
Body Regions ◽  
Color Differences ◽  
Objective Determination

Abstract The Picui Dove (Columbina picui) has been considered sexually monochromatic, with females slightly duller than males. This assessment has been based on colors perceived by the human eye. However, birds possess an additional, near-ultraviolet photoreceptor and thus are sensitive to wavelengths humans are not. Measurements of reflectance using spectroradiometry permit an objective determination of the coloration of the birds' plumage and of color differences between the sexes. We here show that the plumage coloration of the Picui Dove is clearly sexually dimorphic. Males were overall brighter than females, and several body regions showed a significant sex difference in spectral shape. These results imply that studies of sexual selection in this and related species should measure sexual dichromatism objectively, and should not rely on human color perception. Determinación Objetiva del Dicromatismo Sexual del Plumaje en Columbina picui Resumen. La especie Columbina picui ha sido considerada sexualmente monocromática, siendo las hembras levemente más opacas que los machos. Esta conclusión ha sido basada en la percepción humana del color. Sin embargo, las aves poseen un fotorreceptor adicional en el ultravioleta cercano y son, por lo tanto, sensibles a longitudes de onda que los humanos no perciben. La medición de la reflectancia por medio de la técnica de espectrofotometría permite una determinación objetiva del color del plumaje y de las diferencias de color entre los sexos. En este estudio mostramos que C. picui es claramente sexualmente dicromática, siendo los machos más brillantes que las hembras y presentando en algunas regiones del cuerpo diferencias en el espectro de las longitudes de onda reflejadas. Estos resultados demuestran que la determinación de dicromatismo sexual no debería basarse en la percepción humana y tiene, además, implicancias para los estudios de selección sexual en esta especie y especies relacionadas.

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 Dynamic sexual dichromatism in an explosively breeding Neotropical toad

2009 ◽  
Vol 6 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Stéphanie M. Doucet ◽  
Daniel J. Mennill
Keyword(s):  
Sexual Selection ◽  
Costa Rica ◽  
Rainy Season ◽  
Dynamic Change ◽  
Colour Change ◽  
Lemon Yellow ◽  
Sexual Dichromatism ◽  
Reflectance Spectrometry ◽  
Colour Signals ◽  
Male Coloration

Sexual selection often promotes the evolution of elaborate colour signals in males, but the importance of sexually selected colour signals remains poorly studied in amphibians. We used reflectance spectrometry to document pronounced sexual dichromatism and dramatic colour change in Bufo luetkenii , a toad that breeds in large aggregations at the onset of the rainy season in Costa Rica. Our observations suggest that males fade rapidly from a vibrant lemon yellow to a dull brown once they have paired with a female. We demonstrate this by showing that males are much brighter than females and that unpaired males are more colourful than males in amplexus. We also show that coloration fades rapidly when males are briefly held captive. This is, to our knowledge, the first study to document such dynamic change in male coloration and sexual dichromatism in anurans.

Testing the phenotype-linked fertility hypothesis in male Moor Frogs (Rana arvalis) exhibiting a conspicuous nuptial colouration

2009 ◽  
Vol 30 (4) ◽  
pp. 581-586 ◽  
Author(s):  
Attila Hettyey ◽  
Herbert Hoi ◽  
Gábor Herczeg
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Positive Relationship ◽  
Sperm Quality ◽  
Female Mate Choice ◽  
Good Genes ◽  
Sexual Dichromatism ◽  
Offspring Survival ◽  
Rana Arvalis ◽  
Moor Frog

AbstractThe conspicuous blue nuptial colouration of Moor Frog (Rana arvalis) males has been associated with sexual selection; it may provide females with information about benefits to be gained through mate choice. Here we investigated the phenotype-linked fertility hypothesis suggesting that exaggerated traits may advertise fertilization ability. We evaluated conspicuousness of males' colouration and related this to the number of sperm stored in their testes. Contrary to our expectation, we did not find a positive relationship between blueness of males and the number of sperm stored in the testes. We discuss this result in the light of alternative traits that may be advertised by colouration, such as sperm quality or good genes for offspring survival. We now need direct studies of female mate choice and the physiology of the blue nuptial colouration to clarify the evolutionary background of the striking temporal sexual dichromatism in the Moor Frog.

A genetic mechanism for sexual dichromatism in birds

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. 1270-1274 ◽  
Author(s):  
Małgorzata A. Gazda ◽  
Pedro M. Araújo ◽  
Ricardo J. Lopes ◽  
Matthew B. Toomey ◽  
Pedro Andrade ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Molecular Mechanisms ◽  
Major Effect ◽  
Common Mechanism ◽  
Sexual Dichromatism ◽  
Specific Variation ◽  
Males And Females ◽  
Selection For ◽  
Β Carotene ◽  
Carotenoid Degradation

Sexual dichromatism, a difference in coloration between males and females, may be due to sexual selection for ornamentation and mate choice. Here, we show that carotenoid-based dichromatism in mosaic canaries, a hybrid phenotype that arises in offspring of the sexually dichromatic red siskin and monochromatic canaries, is controlled by the gene that encodes the carotenoid-cleaving enzyme β-carotene oxygenase 2 (BCO2). Dichromatism in mosaic canaries is explained by differential carotenoid degradation in the integument, rather than sex-specific variation in physiological functions such as pigment uptake or transport. Transcriptome analyses suggest that carotenoid degradation in the integument might be a common mechanism contributing to sexual dichromatism across finches. These results suggest that differences in ornamental coloration between sexes can evolve through simple molecular mechanisms controlled by genes of major effect.

scholarly journals Body size and climate as predictors of plumage colouration and sexual dichromatism in parrots

2020 ◽  
Author(s):  
Luisana Carballo ◽  
Kaspar Delhey ◽  
Mihai Valcu ◽  
Bart Kempenaers
Keyword(s):  
Sexual Selection ◽  
Social Interactions ◽  
Life Histories ◽  
Sexual Dichromatism ◽  
Cavity Nesting ◽  
Mutual Mate Choice ◽  
Parrot Species ◽  
Males And Females ◽  
Selection For ◽  
Nesting Habits

AbstractPsittaciformes (parrots, cockatoos and lorikeets) comprise one of the most colourful clades of birds. Their unique pigments and cavity nesting habits are two potential explanations for their colourful character. However, plumage colour varies substantially between parrot species and sometimes also between males and females of the same species. Here, we use comparative analyses to evaluate what factors correlate with colour elaboration, colour diversity and sexual dichromatism. Specifically, we test the association between different aspects of parrot colouration and (1) the intensity of sexual selection and social interactions, (2) variation along the slow-fast life-history continuum and (3) climatic variation. We show that larger species and species that live in warm environments display more elaborated colours, yet smaller species have higher levels of sexual dichromatism. Larger parrots tend to have darker and more blue and red colours. Parrots that live in humid environments are darker and redder, whilst species inhabiting warm regions have more blue plumage colours. In general, the variables we considered explain small to moderate amounts of variation in parrot colouration (up to 20%). Our data suggest that sexual selection may be acting more strongly on males in small, short-lived parrots leading to sexual dichromatism. More elaborate colouration in both males and females of the larger, long-lived species with slow tropical life-histories suggests that mutual mate choice and reduced selection for crypsis may be important in these species, as has been shown for passerines.

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