scholarly journals Availability of non-carotenoid antioxidants affects the expression of a carotenoid-based sexual ornament

2007 ◽  
Vol 3 (4) ◽  
pp. 353-356 ◽  
Author(s):  
Thomas W Pike ◽  
Jonathan D Blount ◽  
Jan Lindström ◽  
Neil B Metcalfe
Keyword(s):  
Mate Choice ◽  
Gasterosteus Aculeatus ◽  
Multiple Roles ◽  
Visual Signal ◽  
Honest Signal ◽  
Animal Kingdom ◽  
Yellow Orange ◽  
Sexual Ornament ◽  
Positive Correlations ◽  
Antioxidant Diet

Carotenoids are responsible for much of the yellow, orange and red pigmentation in the animal kingdom, and the importance of such coloration as an honest signal of individual quality has received widespread attention. In particular, owing to the multiple roles of carotenoids as pigments, antioxidants and immunostimulants, carotenoid-based coloration has been suggested to advertise an individual's antioxidant or immune defence capacity. However, it has recently been argued that carotenoid-based signals may in fact be advertising the availability of different antioxidants, many of which (including various vitamins, antioxidant enzymes and minerals) are colourless and so would be uninformative as components of a visual signal, yet often have greater biological activity than carotenoids. We tested this hypothesis by feeding male sticklebacks ( Gasterosteus aculeatus ) a diet containing a fixed level of carotenoids and either low or high, but biologically realistic levels of the colourless antioxidant vitamins C and E. High-antioxidant diet males produced significantly more intensely coloured (but not larger) carotenoid-based regions of nuptial coloration and were preferred over size-matched males of the opposite diet treatment in mate-choice trials. Furthermore, there were positive correlations between an individual's somatic antioxidant activity and signal intensity. Our data suggest that carotenoid-based ornaments may honestly signal an individual's availability of non-carotenoid antioxidants, allowing females to make adaptive mate-choice decisions.

scholarly journals Carotenoids, oxidative stress and female mating preference for longer lived males

2007 ◽  
Vol 274 (1618) ◽  
pp. 1591-1596 ◽  
Author(s):  
Thomas W Pike ◽  
Jonathan D Blount ◽  
Bjørn Bjerkeng ◽  
Jan Lindström ◽  
Neil B Metcalfe
Keyword(s):  
Oxidative Stress ◽  
Mate Choice ◽  
Gasterosteus Aculeatus ◽  
Reproductive Investment ◽  
Mating Preference ◽  
Implicit Assumption ◽  
Sexual Ornaments ◽  
Sexual Ornament ◽  
Breeding Attempt ◽  
Rate Of Ageing

Some of the most spectacular exaggerated sexual ornaments are carotenoid dependent. It has been suggested that such ornaments have evolved because carotenoid pigments are limiting for both signal expression and in their role as antioxidants and immunostimulants. An implicit assumption of this hypothesis is that males which can afford to produce more elaborate carotenoid-dependent displays are signalling their enhanced ability to resist parasites, disease or oxidative stress and hence would be predicted to live longer. Therefore, in species with carotenoid-dependent ornaments where a parent's future longevity is crucial for determining offspring survival, there should be a mating preference for partners that present the lowest risk of mortality during the breeding attempt, as signalled by the ability to allocate carotenoids to sexual displays. In an experimental study using three-spined sticklebacks ( Gasterosteus aculeatus ), we show that when dietary carotenoid intake is limited, males attempt to maintain their sexual ornament at the expense of body carotenoids and hence suffer from reduced reproductive investment and a shorter lifespan. These males also suffer from an increased susceptibility to oxidative stress, suggesting that this may constitute the mechanism underlying the increased rate of ageing. Furthermore, in pairwise mate-choice trials, females preferred males that had a greater access to carotenoids and chance of surviving the breeding season, suggesting that females can make adaptive mate choice decisions based on a male's carotenoid status and potential future longevity.

scholarly journals Mauritian coloured nectar no longer a mystery: a visual signal for lizard pollinators

2006 ◽  
Vol 2 (2) ◽  
pp. 165-168 ◽  
Author(s):  
Dennis M Hansen ◽  
Karin Beer ◽  
Christine B Müller
Keyword(s):  
Experimental Evidence ◽  
Plant Species ◽  
Flowering Plants ◽  
Visual Signal ◽  
Honest Signal ◽  
Endemic Plant ◽  
Floral Trait ◽  
Flower Visitation ◽  
Artificial Flowers ◽  
Endemic Plant Species

Most floral nectars are clear as water, and the enigmatic coloured nectar in three endemic plant species in Mauritius has puzzled scientists studying it. One hypothesis about the possible ecological function of coloured nectar is that it serves as a visual signal for pollinators. Recent studies have shown that at least two of the three Mauritian plant species with coloured nectar are visited and pollinated by endemic Phelsuma geckos. We here provide experimental evidence for the visual signal hypothesis by showing that Phelsuma ornata geckos prefer coloured over clear nectar in artificial flowers. In flowering plants, coloured nectar could additionally function as an honest signal that allows pollinators to assert the presence and judge the size of a reward prior to flower visitation, and to adjust their behaviour accordingly, leading to increased pollinator efficiency. Our study provides a first step in understanding this rare and intriguing floral trait.

scholarly journals Sexual selection after gamete release in broadcast spawning invertebrates

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200069 ◽  
Author(s):  
Jonathan P. Evans ◽  
Rowan A. Lymbery
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sperm Competition ◽  
Sexual Conflict ◽  
Gamete Release ◽  
Theme Issue ◽  
Animal Kingdom ◽  
External Fertilization ◽  
Broadcast Spawning ◽  
Males And Females

Broadcast spawning invertebrates offer highly tractable models for evaluating sperm competition, gamete-level mate choice and sexual conflict. By displaying the ancestral mating strategy of external fertilization, where sexual selection is constrained to act after gamete release, broadcast spawners also offer potential evolutionary insights into the cascade of events that led to sexual reproduction in more ‘derived’ groups (including humans). Moreover, the dynamic reproductive conditions faced by these animals mean that the strength and direction of sexual selection on both males and females can vary considerably. These attributes make broadcast spawning invertebrate systems uniquely suited to testing, extending, and sometimes challenging classic and contemporary ideas in sperm competition, many of which were first captured in Parker's seminal papers on the topic. Here, we provide a synthesis outlining progress in these fields, and highlight the burgeoning potential for broadcast spawners to provide both evolutionary and mechanistic understanding into gamete-level sexual selection more broadly across the animal kingdom. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals Within-generation and transgenerational plasticity of mate choice in oceanic stickleback under climate change

2019 ◽  
Vol 374 (1768) ◽  
pp. 20180183 ◽  
Author(s):  
Lukas Fuxjäger ◽  
Sylvia Wanzenböck ◽  
Eva Ringler ◽  
K. Mathias Wegner ◽  
Harald Ahnelt ◽  
...  
Keyword(s):  
Mate Choice ◽  
Environmental Change ◽  
Mating Success ◽  
Gasterosteus Aculeatus ◽  
Ocean Warming ◽  
Acclimation Temperature ◽  
Transgenerational Plasticity ◽  
Developmental Temperature ◽  
Sexual Traits

Plasticity, both within and across generations, can shape sexual traits involved in mate choice and reproductive success, and thus direct measures of fitness. Especially, transgenerational plasticity (TGP), where parental environment influences offspring plasticity in future environments, could compensate for otherwise negative effects of environmental change on offspring sexual traits. We conducted a mate choice experiment using stickleback ( Gasterosteus aculeatus ) with different thermal histories (ambient 17°C or elevated 21°C) within and across generations under simulated ocean warming using outdoor mesocosms. Parentage analysis of egg clutches revealed that maternal developmental temperature and reproductive (mesocosm) environment affected egg size, with females that developed at 17°C laying smaller eggs in 21°C mesocosms, likely owing to metabolic costs at elevated temperature. Paternal developmental temperature interacted with the reproductive environment to influence mating success, particularly under simulated ocean warming, with males that developed at 21°C showing lower overall mating success compared with 17°C males, but higher mating success in 21°C mesocosms. Furthermore, mating success of males was influenced by the interaction between F1 developmental temperature and F0 parent acclimation temperature, demonstrating the potential role of both TGP and within-generation plasticity in shaping traits involved in sexual selection and mate choice, potentially facilitating rapid responses to environmental change. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.

scholarly journals Endless forms of sexual selection

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7988 ◽  
Author(s):  
Willow R. Lindsay ◽  
Staffan Andersson ◽  
Badreddine Bererhi ◽  
Jacob Höglund ◽  
Arild Johnsen ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Genetic Architecture ◽  
Mating Systems ◽  
Molecular Techniques ◽  
Population Divergence ◽  
Signal Design ◽  
Honest Signal ◽  
Secondary Sexual Traits ◽  
Sexually Selected Traits

In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a “stock-taking” workshop on sexual selection and sexual conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite sex, with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the ‘aesthetic sense’ proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate ‘null model’ of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.

Coevolutionary Dynamics of Costly Bonding Ritual and Altruism

2016 ◽  
Author(s):  
Karl Frost
Keyword(s):  
Movement Behavior ◽  
Altruistic Behavior ◽  
Genetic Evolution ◽  
Costs And Benefits ◽  
Honest Signal ◽  
Behavioral Sciences ◽  
Animal Kingdom ◽  
Population Mean ◽  
Or Groups ◽  
Mean Fitness

AbstractWhile altruistic behavior and bonding in altruistic pairs or groups of cooperators is observed throughout the animal kingdom, the genetic evolution of such is on an ongoing source of debate, curiosity, and conflict in the behavioral sciences. Many such bonded groups and pairs are observed to take part in costly ritualized movement behavior that is hypothesized to trigger or maintain altruistic sentiments amongst the participants. Such costly ritualized practices could have evolved if they engaged pre-existing behavioral instincts that manifest as altruism in the new context of ritual bonding. While this seems at first to be a ‘Green Beard’ hypothesis (‘marker (ie., ‘green beard’) as honest signal of altruistic intent', an hypothesis well-known to be problematic), it is distinct in two important ways. First, the ritual as marker is costly, and second the ritual engages a pre-existing behavioral potential caused by genes which, importantly, have some other benefit. This paper models the genetic coevolutionary dynamics both analytically and through simulation. It finds that such coevolution can lead to fixation of altruism in a population or to cycling of altruism in the population, depending on the balance of costs and benefits. Where cycling occurs, even though altruism is consistently present in the population, population mean fitness declines with the introduction of these bonding rituals.

Sex-Role Reversal in the Black-Chinned Tilapia, Sarotherodon Melanotheron (RÜPpel) (Cichlidae)

Behaviour ◽  
1995 ◽  
Vol 132 (11-12) ◽  
pp. 861-874 ◽  
Author(s):  
Sigal Balshine-Earn ◽  
Brendan J. Mcandrew
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sex Roles ◽  
Sex Role ◽  
Role Reversal ◽  
Recent Theory ◽  
Animal Kingdom ◽  
Sex Role Reversal ◽  
Reproductive Rates ◽  
Sarotherodon Melanotheron

AbstractIn the animal kingdom most species follow standard sex roles: males compete more intensely for mates and females exert greater mate choice. Recent theory suggests that the direction of sexual selection is the outcome of sexual differences in potential reproductive rates (PRRs): the sex with the higher PRR will compete for mates and the sex with the lower PRR will be most selective. This study tests the theory experimentally by examining competition for mates and mate choice in the black-chinned tilapia, Sarotherodon melanotheron, a paternal mouth brooding cichlid. In this species, the PRR of males is lower than that of females. In laboratory competition trials, females were more aggressive: they bit, chased and initiated mouth fights more often than males. Dominant females were also much better at monopolising potential mates compared to dominant males. A second experiment confirmed that males were choosy for size, preferring large partners over small ones, while females did not discriminate for size. Therefore, the prediction of sex role reversal (competitive females and discriminating males) is confirmed.

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