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.

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 Macroevolutionary consequences of sexual conflict

2018 ◽  
Vol 14 (6) ◽  
pp. 20180186
Author(s):  
Jo S. Hermansen ◽  
Jostein Starrfelt ◽  
Kjetil L. Voje ◽  
Nils C. Stenseth
Keyword(s):  
Sexual Selection ◽  
Genetic Architecture ◽  
Time Frame ◽  
Sexual Conflicts ◽  
Males And Females ◽  
Selection For ◽  
Evolutionary Consequences ◽  
Future Work ◽  
Shared Genetic

Intralocus sexual conflicts arise whenever the fitness optima for a trait expressed in both males and females differ between the sexes and shared genetic architecture constrains the sexes from evolving independently towards their respective optima. Such sexual conflicts are commonplace in nature, yet their long-term evolutionary consequences remain unexplored. Using a Bayesian phylogenetic comparative framework, we studied the macroevolutionary dynamics of intersexual trait integration in stalk-eyed flies (Diopsidae) spanning a time frame of more than 25 Myr. We report that increased intensity of sexual selection on male eyestalks is associated with reduced intersexual eyestalk integration, as well as sex-specific rates of eyestalk evolution. Despite this, lineages where males have been under strong sexual selection for millions of years still exhibit high levels of intersexual trait integration. This low level of decoupling between the sexes may indicate that exaggerated female eyestalks are in fact adaptive—or alternatively, that there are strong constraints on reducing trait integration between the sexes. Future work should seek to clarify the relative roles of constraints and selection in contributing to the varying levels of intersexual trait integration in stalk-eyed flies, and in this way clarify whether sexual conflicts can act as constraints on adaptive evolution even on macroevolutionary time scales.

scholarly journals Sexual selection is a form of social selection

2012 ◽  
Vol 367 (1600) ◽  
pp. 2266-2273 ◽  
Author(s):  
Bruce E. Lyon ◽  
Robert Montgomerie
Keyword(s):  
Sexual Selection ◽  
Social Interactions ◽  
Social Selection ◽  
Reproductive Competition ◽  
Selection Theory ◽  
Males And Females ◽  
Female Roles ◽  
Comprehensive Framework ◽  
Natural And Sexual Selection ◽  
Lines Of Evidence

Social selection influences the evolution of weapons, ornaments and behaviour in both males and females. Thus, social interactions in both sexual and non-sexual contexts can have a powerful influence on the evolution of traits that would otherwise appear to be detrimental to survival. Although clearly outlined by West-Eberhard in the early 1980s, the idea that social selection is a comprehensive framework for the study of ornaments and weapons has largely been ignored. In West-Eberhard's view, sexual selection is a form of social selection—a concept supported by several lines of evidence. Darwin's distinction between natural and sexual selection has been useful, but recent confusion about the limits of sexual selection suggests that some traits are not easily categorized as naturally or sexually selected. Because social selection theory has much to offer the current debates about both sexual selection and reproductive competition in females, it is sometimes viewed, narrowly, to be most useful when considering female roles. However, social selection theory encompasses much more than female reproductive competition. Our goal here was to provide that broader perspective.

Rhythms and Reproduction

2020 ◽  
pp. 472-502
Author(s):  
Stefan Dennenmoser ◽  
John H. Christy ◽  
Martin Thiel
Keyword(s):  
Sexual Selection ◽  
Predation Risk ◽  
Operational Sex Ratio ◽  
Factors Affecting ◽  
Broadcast Spawning ◽  
Males And Females ◽  
Selection For ◽  
Depth Gradients ◽  
Newly Hatched Larvae ◽  
Density Dependent Selection

Reproductive rhythms can be found in numerous crustacean species. This chapter reviews the temporal scales of rhythms and how these rhythms are entrained and maintained by external cues and endogenous clocks. The occurrence and synchrony of rhythms vary along latitudinal and depth gradients, which may depend on the availability of zeitgebers (e.g., temperature and photoperiod), changing selective pressures such as predation risk, and variability in larval development rates that affect the timing and synchrony of reproductive rhythms. Commonly observed rhythms are reproductive migrations and synchronized larval release, which are often timed to reduce predation risk for newly hatched larvae. In crustaceans, reproductive rhythms rarely evolve under pure density-dependent selection for synchrony. Pure density dependence is common in marine broadcast-spawning invertebrates like corals, which rely on accumulation of gametes in time and space to ensure fertilization. Instead, (density-independent) selection for synchrony with environmental cycles that track changes in factors affecting fitness such as energy expenditure, predation risk, or food availability seems to be the rule, although some exceptions may exist. In contrast to natural selection, the possible contribution of sexual selection on reproductive rhythms has rarely been considered. Selection for enhanced mating possibilities should favor reproductive synchrony, but deviations from synchrony will affect the operational sex ratio and influence sexual selection. Finally, the chapter discusses the possibility of sexual conflict over reproductive timing between males and females and explores circumstances under which synchronous reproductive rhythms might be abandoned.

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 dichromatism in frogs: natural selection, sexual selection and unexpected diversity

2012 ◽  
Vol 279 (1748) ◽  
pp. 4687-4693 ◽  
Author(s):  
Rayna C. Bell ◽  
Kelly R. Zamudio
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Phylogenetic Signal ◽  
Colour Change ◽  
Sexual Dichromatism ◽  
Evolutionary Mechanisms ◽  
Males And Females ◽  
Colour Dimorphism ◽  
Natural And Sexual Selection ◽  
High Diversity

Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

Reproductive behavior

2018 ◽  
Author(s):  
Rachel Olzer ◽  
Rebecca L. Ehrlich ◽  
Justa L. Heinen-Kay ◽  
Jessie Tanner ◽  
Marlene Zuk
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Female Choice ◽  
Reproductive Behavior ◽  
Mating Systems ◽  
Insect Behavior ◽  
Sequential Approach ◽  
Evolutionary Mechanisms ◽  
Anatomy And Physiology ◽  
Males And Females

Sex and reproduction lie at the heart of studies of insect behavior. We begin by providing a brief overview of insect anatomy and physiology, followed by an introduction to the overarching themes of parental investment, sexual selection, and mating systems. We then take a sequential approach to illustrate the diversity of phenomena and concepts behind insect reproductive behavior from pre-copulatory mate signalling through copulatory sperm transfer, mating positions, and sexual conflict, to post-copulatory sperm competition, and cryptic female choice. We provide an overview of the evolutionary mechanisms driving reproductive behavior. These events are linked by the economic defendability of mates or resources, and how these are allocated in each sex. Under the framework of economic defendability, the reader can better understand how sexual antagonistic behaviors arise as the result of competing optimal fitness strategies between males and females.

Mating in the harvestman Leiobunum vittatum (Arachnida: Opiliones): from premating struggles to solicitous tactile engagement

Behaviour ◽  
2014 ◽  
Vol 151 (12-13) ◽  
pp. 1663-1686 ◽  
Author(s):  
Kasey D. Fowler-Finn ◽  
Emilia Triana ◽  
Owen G. Miller
Keyword(s):  
Morphological Traits ◽  
Nuptial Gift ◽  
Multiple Sources ◽  
Male Size ◽  
Mechanical Advantage ◽  
Qualitative And Quantitative ◽  
Mutual Mate Choice ◽  
Males And Females ◽  
Qualitative And Quantitative Study ◽  
Multiple Stages

When mating interactions are influenced by multiple sources of selection, they may involve multiple stages of mate assessment. At each stage, a different set of morphological and behavioural traits may be important in determining the outcome of the interaction. Here, we test the potential for multiple sources of selection to shape mating interactions in Leiobunum vittatum harvestmen, commonly known as ‘daddy longlegs’. We provide a qualitative and quantitative study of mating interactions, and investigate the influence of multiple morphological traits on each of several distinct stages of their mating interactions. Mating interactions start with a struggle between males and females during which the male attempts to secure the females in a mating embrace. Success at this stage depends on the length of the male’s clasping pedipalps: those with shorter pedipalps (and thus greater mechanical advantage) were more successful. Male size relative to the female determines how quickly males achieve this embrace. Mating interactions then proceed to tactile exchanges between males and females, indicating the potential for mutual mate choice and/or peri- and post-copulatory selection. We found no morphological predictors of the timing of these later stages of the mating interactions, and suggest that the exchange of a nuptial gift is important for the dynamics of these stages. Overall, our results highlight L. vittatum as a potentially highly informative group for studying how traits involved in mating are shaped by the interaction of selection across multiple stages in mating interactions.

Sex differences in melanotic encapsulation responses (immunocompetence) in the damselfly Lestes forcipatus Rambur

2002 ◽  
Vol 80 (9) ◽  
pp. 1578-1583 ◽  
Author(s):  
Christopher P Yourth ◽  
Mark R Forbes ◽  
Robert L Baker
Keyword(s):  
Sex Differences ◽  
Immune Responses ◽  
Life Histories ◽  
Mass Gain ◽  
Sexually Dimorphic ◽  
Foreign Objects ◽  
Males And Females ◽  
And Gender ◽  
Parasitic Mites ◽  
Melanotic Encapsulation

A few studies have shown that male and female invertebrates differ in immunity and that these differences appear related to differences in sexual dimorphism and gender differences in life histories. Melanotic encapsulation of foreign objects in insects is one form of immunity. The damselfly Lestes forcipatus Rambur is moderately sexually dimorphic, and much is known about patterns of mass gain in congeners relating to differences in life history between males and females. In this study, females were more immunoresponsive than males under controlled temperatures, following emergence, and at a time when parasitic mites were challenging these hosts. However, males and females that overlapped in mass at emergence did not differ in their immune responses. Males in better condition at emergence were more immunoresponsive than lighter males, but this relation was not found in females. Sex differences in immune expression may have implications for how females versus males are able to deal with challenges from parasites, under varying environmental conditions.

scholarly journals Cooperation and the evolution of intelligence

2012 ◽  
Vol 279 (1740) ◽  
pp. 3027-3034 ◽  
Author(s):  
Luke McNally ◽  
Sam P. Brown ◽  
Andrew L. Jackson
Keyword(s):  
Decision Making ◽  
Social Interactions ◽  
Cognitive Abilities ◽  
Artificial Neural Network Model ◽  
Social Intelligence ◽  
Arms Race ◽  
Selection Pressures ◽  
Social Intelligence Hypothesis ◽  
The Social ◽  
Selection For

The high levels of intelligence seen in humans, other primates, certain cetaceans and birds remain a major puzzle for evolutionary biologists, anthropologists and psychologists. It has long been held that social interactions provide the selection pressures necessary for the evolution of advanced cognitive abilities (the ‘social intelligence hypothesis’), and in recent years decision-making in the context of cooperative social interactions has been conjectured to be of particular importance. Here we use an artificial neural network model to show that selection for efficient decision-making in cooperative dilemmas can give rise to selection pressures for greater cognitive abilities, and that intelligent strategies can themselves select for greater intelligence, leading to a Machiavellian arms race. Our results provide mechanistic support for the social intelligence hypothesis, highlight the potential importance of cooperative behaviour in the evolution of intelligence and may help us to explain the distribution of cooperation with intelligence across taxa.

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