scholarly journals Testosterone-mediated trade-offs in the old age: a new approach to the immunocompetence handicap and carotenoid-based sexual signalling

2009 ◽  
Vol 276 (1664) ◽  
pp. 2093-2101 ◽  
Author(s):  
C. Alonso-Alvarez ◽  
Lorenzo Pérez-Rodríguez ◽  
Jesus T. Garcia ◽  
Javier Viñuela
Keyword(s):  
Antioxidant Properties ◽  
Optimal Solution ◽  
Cell Mediated Immunity ◽  
Sexual Signals ◽  
Middle Aged ◽  
New Approach ◽  
Trade Off ◽  
Trade Offs ◽  
Sexual Signalling ◽  
Handicap Hypothesis

The immunocompetence handicap hypothesis proposes that testosterone mediates a trade-off between sexual signalling and immunocompetence in males. Such a trade-off could favour the reliability of sexual signals on the basis that testosterone required for signal expression also promotes immunosuppression. However, the immunosuppressive activity of testosterone has not been convincingly demonstrated. We propose that the optimal solution to the testosterone-mediated trade-off should change with age, explaining ambiguous results in the past. Testosterone and ageing would promote two simultaneous immunosuppressive challenges unaffordable for low-quality males. Oxidative stress, as intimately related to ageing and immunosenescence, could contribute to enhance signal reliability. In this context, traits coloured by carotenoids (yellow–red traits) could play a crucial role due to the immunostimulatory and antioxidant properties of these pigments. Here, old and middle-aged male red-legged partridges were treated with testosterone or manipulated as controls. In the presence of high-testosterone levels, middle-aged males increased both circulating carotenoid levels and colour expression, whereas their cell-mediated immunity was not significantly altered. However, in old males, neither circulating carotenoids nor sexual signalling increased when treated with testosterone, but immunosuppression was detected. The link between testosterone and carotenoids could favour the reliability of sexual signals throughout the life.

scholarly journals Trade-off between warning signal efficacy and mating success in the wood tiger moth

2011 ◽  
Vol 279 (1727) ◽  
pp. 257-265 ◽  
Author(s):  
Ossi Nokelainen ◽  
Robert H. Hegna ◽  
Joanneke H. Reudler ◽  
Carita Lindstedt ◽  
Johanna Mappes
Keyword(s):  
Mating Success ◽  
Warning Signal ◽  
Trade Off ◽  
White Males ◽  
Survival Selection ◽  
Signal Efficacy ◽  
Trade Offs ◽  
Tiger Moth ◽  
Sexual Signalling ◽  
Colour Morphs

The coloration of species can have multiple functions, such as predator avoidance and sexual signalling, that directly affect fitness. As selection should favour traits that positively affect fitness, the genes underlying the trait should reach fixation, thereby preventing the evolution of polymorphisms. This is particularly true for aposematic species that rely on coloration as a warning signal to advertise their unprofitability to predators. Nonetheless, there are numerous examples of aposematic species showing remarkable colour polymorphisms. We examined whether colour polymorphism in the wood tiger moth is maintained by trade-offs between different functions of coloration. In Finland, males of this species have two distinct colour morphs: white and yellow. The efficacy of the warning signal of these morphs was tested by offering them to blue tits in the laboratory. Birds hesitated significantly longer to attack yellow than white males. In a field experiment, the survival of the yellow males was also higher than white males. However, mating experiments in the laboratory revealed that yellow males had lower mating success than white males. Our results offer an explanation for the maintenance of polymorphism via trade-off between survival selection and mating success.

scholarly journals “Satisficing” and trade-offs: evaluating rebuilding strategies for Greenland halibut off the east coast of Canada

2010 ◽  
Vol 67 (9) ◽  
pp. 1896-1902 ◽  
Author(s):  
David C. M. Miller ◽  
Peter A. Shelton
Keyword(s):  
Management Strategy ◽  
East Coast ◽  
A Priori ◽  
Management Strategies ◽  
Optimal Solution ◽  
Greenland Halibut ◽  
Trade Off ◽  
Trade Offs ◽  
Survey Estimates ◽  
Performance Statistics

Abstract Miller, D. C. M., and Shelton, P. A. 2010. “Satisficing” and trade-offs: evaluating rebuilding strategies for Greenland halibut off the east coast of Canada. – ICES Journal of Marine Science, 67: 1896–1902. To be effective, management strategy evaluation (MSE) requires a well-defined procedure for comparing the merits of candidate management strategies. We explore a two-step approach of “satisficing” followed by a trade-off analysis. “Satisficing” (a portmanteau of “satisfy” and “suffice”) is a decision-making procedure that attempts to meet criteria for adequacy, rather than identify an optimal solution. As a case study, we consider the results from a comprehensive MSE for Greenland halibut off the east coast of Canada, carried out under the auspices of the Northwest Atlantic Fisheries Organization. First, we apply satisficing to the results to determine which rebuilding strategies achieve pre-specified thresholds set for imperative performance statistics relating to resource conservation, yield, and stability of the fishery. Next, trade-offs among important, but not necessarily imperative, performance statistics are evaluated for those strategies that pass the satisficing step. For Greenland halibut, a management strategy containing a simple feedback harvest-control rule based on recent trends in survey estimates of abundance satisfices all imperative requirements and provides the best trade-off in other performance statistics. The approach necessitates translating objectives for stock rebuilding and sustainable fisheries into operationally explicit terms and incorporates a priori consideration of stakeholders' concerns.

scholarly journals Sex-biased parasitism and expression of a sexual signal

2020 ◽  
Vol 131 (4) ◽  
pp. 785-800
Author(s):  
Adam A Rosso ◽  
Daniel J Nicholson ◽  
Michael L Logan ◽  
Albert K Chung ◽  
John David Curlis ◽  
...  
Keyword(s):  
Attachment Site ◽  
Cost Of Reproduction ◽  
Good Genes ◽  
Sexual Signals ◽  
Sexual Signal ◽  
Trade Offs ◽  
Parasite Infections ◽  
Handicap Hypothesis ◽  
Fat Bodies ◽  
The Relationship

Abstract Given that sexual signals are often expressed more highly in one sex than the other, they can impose a sex-specific cost of reproduction through parasitism. The two primary paradigms regarding the relationship of parasites to sexual signals are the good genes hypothesis and the immunocompetence handicap hypothesis; however, there are other ecological, morphological and energetic factors that might influence parasite infections in a sex-specific fashion. We tested the relationship between expression of a sexual signal (the dewlap) and ecological, morphological and energetic factors mediating ectoparasite (mite) load between male and female Panamanian slender anoles (Anolis apletophallus). We found that males were more highly parasitized than females because of the preponderance of ectoparasites on the larger dewlap of males. Indeed, ectoparasite infection increased with both body size and dewlap size in males but not in females, and parasite infection was related to energy storage in a sex-specific fashion for the fat bodies, liver and gonads. Our work and previous work on testosterone in anoles suggests that this pattern did not arise solely from immunosuppression by testosterone, but that mites prefer the dewlap as an attachment site. Thus, the expression of this sexual signal could incur a fitness cost that might structure life-history trade-offs.

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 A NEW ANALYTICAL METHODOLOGY TO HANDLE TIME-COST TRADE-OFF PROBLEM WITH CONSIDERING QUALITY LOSS COST UNDER INTERVAL-VALUED FUZZY UNCERTAINTY

2019 ◽  
Vol 25 (2) ◽  
pp. 277-299 ◽  
Author(s):  
Mohammad Hossein Haghighi ◽  
Seyed Meysam Mousavi ◽  
Jurgita Antuchevičienė ◽  
Vahid Mohagheghi
Keyword(s):  
Critical Path ◽  
Quality Loss ◽  
Time Cost ◽  
Analytical Methodology ◽  
New Approach ◽  
Trade Off ◽  
Trade Offs ◽  
And Performance ◽  
Interval Valued

This paper proposes a new framework in addressing time-cost trade-off problem (TCTP) under uncertainty. First critical path analysis is carried out based on developing a new interval-valued fuzzy (IVF)-program evaluation and review technique (PERT) approach. Then, non-conformance risks that influence on execution quality of activities are identified and evaluated based on a new approach that considers probability of risk along with impacts on time, cost, and performance. Then, a new mathematical model under IVF uncertainty is presented to decrease project total time while considering time, cost and quality loss cost that is determined in form of rework or modification cost. Finally, the approach categorizes the activities in three groups based on their level of criticality. Outcome of this methodology is a scheduling that addresses time, cost and quality trade-offs in addition to categorizing activities in different groups based on being on the critical path. Therefore, the project manager not only gets a scheduling based on the TCTP with considering quality loss cost but also has a knowledge of activities that require extra attentions. To show the steps of this methodology, an existing application from the literature is adopted and solved.

Adjusting Trade-Offs in Multi-Criteria Decision-Making Problems

2021 ◽  
pp. 1-19
Author(s):  
Siamak Kheybari
Keyword(s):  
Decision Making ◽  
Decision Maker ◽  
Multi Criteria Decision Making ◽  
New Approach ◽  
Trade Off ◽  
Trade Offs ◽  
Lower Expectation ◽  
Decision Making Problem ◽  
Individual Criterion ◽  
The Individual

In multi-criteria decision-making (MCDM) methods, allowing trade-offs between the decision criteria may result in inappropriate conclusions. Allowing trade-offs implies that the weaknesses of an alternative in some criteria may be compensated by its strengths in other criteria. While, with some problems, there are no concerns with regard to allowing a full trade-off, in other cases, such a trade-off may not follow the actual decision-making problem. This paper proposes a new approach based on defining an upper and lower expectation level for each decision-making criterion. Indeed, the proposed approach is a framework by which the requirements of a decision-maker are considered in the criteria involved in MCDM problems. That distinction generates two primary and secondary performance matrices. The primary matrix includes the values of the alternatives with respect to the individual criterion up to the upper expectation levels of the decision-maker, while the secondary matrix, which is defined by the amounts above the upper levels and below the lower levels of the decision-maker’s expectations, contains each alternative in all the criteria and, to some extent, can exceed the upper levels of the decision-maker’s expectations. The final result of each alternative is calculated by adding its outcome in the two matrices. The results of a numerical example involving cellphone selection show how controlling the trade-offs could affect the results.

scholarly journals On the evolution of visual female sexual signalling

2018 ◽  
Vol 285 (1879) ◽  
pp. 20172875 ◽  
Author(s):  
Kelly Rooker ◽  
Sergey Gavrilets
Keyword(s):  
Group Size ◽  
Genetic Heterogeneity ◽  
Sexual Signals ◽  
Agent Based ◽  
Agent Based Modelling ◽  
Sexual Swellings ◽  
Genetic Benefits ◽  
Trade Offs ◽  
Sexual Signalling

A long-standing evolutionary puzzle surrounds female sexual signals visible around the time of ovulation. Even among just primates, why do some species have substantial sexual swellings and/or bright colorations visible around females' genital regions, while other species are like humans, with no signs of ovulation visible? What is the evolutionary purpose behind not just these signs, but also this great variation seen among species? Here, we examine the evolutionary trade-offs associated with visual ovulation signalling using agent-based modelling. Our model predicts how various factors, including male genetic heterogeneity and reproductive inequality, female physiological costs, group size, and the weighting of genetic versus non-genetic benefits coming from males, each influence the strength of ovulation signalling. Our model also predicts that increasing the impacts of infanticide will increase ovulation signalling. We use comparative primate data to show that, as predicted by our model, larger group size and higher risk of infanticide each correlate with having stronger visual ovulation signs. Overall, our work resolves some old controversies and sheds new light on the evolution of visual female sexual signalling.

scholarly journals Effects of neuromuscular lags on controlling contact transitions

2009 ◽  
Vol 367 (1891) ◽  
pp. 1163-1179 ◽  
Author(s):  
Madhusudhan Venkadesan ◽  
Francisco J Valero-Cuevas
Keyword(s):  
Neural Control ◽  
Deterministic Model ◽  
Optimal Solution ◽  
Trade Off ◽  
Joint Torques ◽  
Human Data ◽  
Force Magnitude ◽  
Trade Offs ◽  
Speed Accuracy ◽  
Force Vectors

We present a numerical exploration of contact transitions with the fingertip. When picking up objects our fingertips must make contact at specific locations, and—upon contact—maintain posture while producing well-directed force vectors. However, the joint torques for moving the fingertip towards a surface ( τ m ) are different from those for producing static force vectors ( τ f ). We previously described the neural control of such abrupt transitions in humans, and found that unavoidable errors arise because sensorimotor time delays and lags prevent an instantaneous switch between different torques. Here, we use numerical optimization on a finger model to reveal physical bounds for controlling such rapid contact transitions. Resembling human data, it is necessary to anticipatorily switch joint torques to τ f at about 30 ms before contact to minimize the initial misdirection of the fingertip force vector. This anticipatory strategy arises in our deterministic model from neuromuscular lags, and not from optimizing for robustness to noise/uncertainties. Importantly, the optimal solution also leads to a trade-off between the speed of force magnitude increase versus the accuracy of initial force direction. This is an alternative to prevailing theories that propose multiplicative noise in muscles as the driver of speed–accuracy trade-offs. We instead find that the speed–accuracy trade-off arises solely from neuromuscular lags. Finally, because our model intentionally uses idealized assumptions, its agreement with human data suggests that the biological system is controlled in a way that approaches the physical boundaries of performance.

scholarly journals Immunocompetence handicap hypothesis in tree frog: trade-off between sexual signals and immunity?

2015 ◽  
Vol 26 (4) ◽  
pp. 1138-1146 ◽  
Author(s):  
Julia L. Desprat ◽  
Thierry Lengagne ◽  
Adeline Dumet ◽  
Emmanuel Desouhant ◽  
Nathalie Mondy
Keyword(s):  
Tree Frog ◽  
Sexual Signals ◽  
Trade Off ◽  
Immunocompetence Handicap Hypothesis ◽  
Handicap Hypothesis

scholarly journals Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds

2014 ◽  
Vol 281 (1788) ◽  
pp. 20140967 ◽  
Author(s):  
Nicholas A. Mason ◽  
Allison J. Shultz ◽  
Kevin J. Burns
Keyword(s):  
Comparative Study ◽  
Evolutionary Biology ◽  
Inverse Correlation ◽  
Acoustic Signals ◽  
Sexual Signals ◽  
Sexual Signal ◽  
Trade Off ◽  
Selective Pressures ◽  
Sexual Signalling ◽  
The Relationship

The concept of a macroevolutionary trade-off among sexual signals has a storied history in evolutionary biology. Theory predicts that if multiple sexual signals are costly for males to produce or maintain and females prefer a single, sexually selected trait, then an inverse correlation between sexual signal elaborations is expected among species. However, empirical evidence for what has been termed the ‘transfer hypothesis’ is mixed, which may reflect different selective pressures among lineages, evolutionary covariates or methodological differences among studies. Here, we examine interspecific correlations between song and plumage elaboration in a phenotypically diverse, widespread radiation of songbirds, the tanagers. The tanagers (Thraupidae) are the largest family of songbirds, representing nearly 10% of all songbirds. We assess variation in song and plumage elaboration across 301 species, representing the largest scale comparative study of multimodal sexual signalling to date. We consider whether evolutionary covariates, including habitat, structural and carotenoid-based coloration, and subfamily groupings influence the relationship between song and plumage elaboration. We find that song and plumage elaboration are uncorrelated when considering all tanagers, although the relationship between song and plumage complexity varies among subfamilies. Taken together, we find that elaborate visual and vocal sexual signals evolve independently among tanagers.

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