Receivers Limit the Prevalence of Deception in Humans: Evidence from Diving Behaviour in Soccer Players

Deception remains a hotly debated topic in evolutionary and behavioural research. Our understanding of what impedes or facilitates the use and detection of deceptive signals in humans is still largely limited to studies of verbal deception under laboratory conditions. Recent theoretical models of non-human behaviour have suggested that the potential outcome for deceivers and the ability of receivers to discriminate signals can effectively maintain their honesty. In this paper, we empirically test these predictions in a real-world case of human deception, simulation in soccer. In support of theoretical predictions in signalling theory, we show that cost-free deceit by soccer players decreases as the potential outcome for the signaller becomes more costly. We further show that the ability of receivers (referees) to detect deceptive signals may limit the prevalence of deception by soccer players. Our study provides empirical support to recent theoretical models in signalling theory, and identifies conditions that may facilitate human deception and hinder its detection

The origin and maintenance of metabolic allometry in animals

Organisms vary widely in size, from microbes weighing 0.1 pg to trees weighing thousands of megagrams - a 10-fold range similar to the difference in mass between an elephant and the Earth. Mass has a pervasive influence on biological processes, but the effect is usually non-proportional; for example, a tenfold increase in mass is typically accompanied by just a four- to sevenfold increase in metabolic rate. Understanding the cause of allometric scaling has been a long-standing problem in biology. Here, we examine the evolution of metabolic allometry in animals by linking microevolutionary processes to macroevolutionary patterns. We show that the genetic correlation between mass and metabolic rate is strong and positive in insects, birds and mammals. We then use these data to simulate the macroevolution of mass and metabolic rate, and show that the interspecific relationship between these traits in animals is consistent with evolution under persistent multivariate selection on mass and metabolic rate over long periods of time

Phenotypic and genetic constraints on the reversible acclimation of thermal performance curves in the zebrafish, Danio rerio.

In response to seasonal variation in environmental temperature, many ectotherms are able to adjust the thermal dependence of their physiological processes via a plastic change in phenotype known as acclimation. Thermal acclimation can induce a reversible plasticity in the shape and position of thermally-sensitive physiological traits among environments. Although often assumed to be beneficial, acclimation is rarely perfect and selection experiments have demonstrated that thermal acclimation can induce both adaptive and non-adaptive plastic changes in phenotype between environments. A lack of consideration for the costs involved with large phenotypic changes may assist in explaining why an adaptive benefit to acclimation is not generally found. In this thesis, I examine three possible constraints on the acclimation of reversible thermal performance curves (TPCs) in the zebrafish, Danio rerio. These constraints are: the effect of cue reliability on the induction of seasonal acclimation responses, the distribution of genetic variance in reversible TPCs for selection in different environments and the influence of a thermodynamic effect on the evolution of TPCs. I tested the effect of correlated (seasonally matching) and conflicting (seasonally opposite) temperature and photoperiod cues on the acclimation of thermal sensitivity for two whole- animal performance traits. I found that thermal performance curves for burst swimming and feeding rate were significantly affected by acclimation to 18 or 30 °C, but that photoperiod had no effect on the shape or position of thermal performance curves in either trait. This study is the first that has found no effect of covariation between temperature and photoperiod cues on locomotor performance and supports the intuitive idea that animals living at low latitude are not heavily reliant on photoperiod as a seasonal cue for environmental variability. Second, I examined the quantitative genetic variation in thermal performance curves of male Danio rerio thermally acclimated to 16 and 32 °C. I found a significant genetic difference in the distribution of genetic variance between zebrafish acclimated to different temperatures. The results show that the genetic architecture of a reversible plastic trait changes between seasonal thermal environments within a single population of zebrafish. I found no evidence of a genetic trade-off between curve width and height in either acclimation temperature. Instead, I found positive genetic co-variance in performance at all  temperatures for 32 °C-acclimated males, with the greatest genetic variance found in environments with the greatest thermal stress. The results suggest that the height of TPC is not constrained in warm acclimated D. rerio but future selection for cold-adaptation in 16 °C-acclimated treatment may reduce performance in extreme warm temperatures tested in this study. Last, I examined whether the acclimation of TPCs in zebrafish are constrained by a thermodynamic effect known as ‘hotter is better’. Under hotter is better, warmer populations are predicted to have greater fitness or performance than cold populations due to the rate-limiting effect of temperature in cold conditions. I found that a genetic correlation indicating hotter is better was present in 16 °C-acclimated male zebrafish, but this correlation was reversed in 32 °C-acclimated fish. These results indicate that a thermodynamic constraint on reversible changes in thermal sensitivity may limit the evolution of plasticity of the thermal optimum in contrast to the predictions of current optimality models of reversible phenotypic plasticity. Together these results demonstrate that both phenotypic and genetic constraints on the production of reversible seasonal phenotypes may limit the acclimation of TPCs in some environments. Significantly, I found that the genetic architecture of reversible plastic thermal performance curves can vary within the same population of organisms exposed to different thermal environments. The evolution of TPCs in both warm- and cold- acclimated zebrafish is unconstrained by a thermal specialist-generalist trade-off but the evolution of TPCs in cold-acclimated D. rerio may be constrained by hotter is better. These results are the first to examine quantitative genetic variance in a reversible plastic response and one of the first to examine the evolution of thermal sensitivity in a vertebrate animal. I discuss the findings of these studies in light of predicted constraints on the evolution of thermal sensitivity and the potential significance of these results to the thermal adaptation of physiological traits under future climate change

Data from: Losing reduces maximum bite performance in house cricket contests

Whole-organism performance capacities influence male combat outcomes in many animal species. However, several species also exhibit winner and loser effects, and current theory predicts that losers are more likely to lose again due to a decrease in aggression following defeat, not because of any change in underlying maximum performance capacity. To test the effect of fight experience on performance, we measured the maximum bite force of male Acheta domesticus crickets that were pitted against size-matched opponents in staged fights. Winners then fought a second contest against other winners while losers fought other losers, after which we measured the change in bite force in all contest crickets and in a control group that did not take part in any contests. Bite force predicted fight outcomes in the first round, and losing the first fight had a significant effect on bite force, leading to a 20% decrease in relative bite force compared to crickets that won both rounds. However, winning did not increase performance as there was no difference between those that won the first round and those that never experienced a loss, nor did winning a second bout alleviate the negative effects on realized bite performance of losing an initial bout. Past defeats can therefore alter the realized short-term maximal performance of traits that contribute to contest outcomes independent of maximum performance limits set by morphology

A domesticus bite force

These data describe the effects of two rounds of combat and their outcomes on bite forces of A. domesticus males, as well as a control group that did not experience combat

Effect of thermal acclimation on female resistance to forced matings in the eastern mosquitofish

All copulations in the eastern mosquitofish, Gambusia holbrooki, are coercive-and-achieved by force. Female G. holbrooki never appear to cooperate with males, but vigorously resist matings at all times. We examined the role of females within a sexually coercive mating system by investigating the ability of female G. holbrooki to resist forced copulations after acclimation to 16 degrees C and 32 degrees C for 4-5 weeks. We also examined burst swimming performance of female G. holbrooki after acclimation, as this trait is likely to underlie a female's ability to resist forced matings. We predicted that if female G. holbrooki indiscriminately resist matings from all males, acclimation would enhance female resistance at their acclimation temperature. However, we found that it did not. We also predicted that if females are able to influence the outcome of mating interactions, acclimation to an optimal thermal environment may induce females to reduce resistance. In support of this prediction, females acclimated at 32 degrees C were able to modify their resistance behaviour between exposure to 16 degrees C and 32 degrees C. The rate of copulations experienced by 32 inverted perpendicular C-acclimated females was 2.5 times greater at 32 degrees C than at 16 degrees C. In addition, acclimation at 32 degrees C significantly enhanced burst swimming performance at 32 degrees C but no effect of acclimation was observed at 16 degrees C. Our results suggest that female G. holbrooki are able to play a greater role in determining the outcome of sexual coercive mating interactions than previously thought. (c) 2006 The Association for the Shidy of Animal Behavioor. Published by Elsevier Ltd. All rights reserved

Data from: Colder environments did not select for a faster metabolism during experimental evolution of Drosophila melanogaster

The effect of temperature on the evolution of metabolism has been the subject of debate for a century; however, no consistent patterns have emerged from comparisons of metabolic rate within and among species living at different temperatures. We used experimental evolution to determine how metabolism evolves in populations of Drosophila melanogaster exposed to one of three selective treatments: a constant 16°C, a constant 25°C, or temporal fluctuations between 16 and 25°C. We tested August Krogh's controversial hypothesis that colder environments select for a faster metabolism. Given that colder environments also experience greater seasonality, we also tested the hypothesis that temporal variation in temperature may be the factor that selects for a faster metabolism. We measured the metabolic rate of flies from each selective treatment at 16, 20.5, and 25°C. Although metabolism was faster at higher temperatures, flies from the selective treatments had similar metabolic rates at each measurement temperature. Based on variation among genotypes within populations, heritable variation in metabolism was likely sufficient for adaptation to occur. We conclude that colder or seasonal environments do not necessarily select for a faster metabolism. Rather, other factors besides temperature likely contribute to patterns of metabolic rate over thermal clines in nature

Data from: Temporal variation favors the evolution of generalists in experimental populations of Drosophila melanogaster

In variable environments, selection should favor generalists that maintain fitness across a range of conditions. However, costs of adaptation may generate fitness trade-offs and lead to some compromise between specialization and generalization that maximizes fitness. Here, we evaluate the evolution of specialization and generalization in 20 populations of Drosophila melanogaster experimentally evolved in constant and variable thermal environments for 3 years. We developed genotypes from each population at two temperatures after which we measured fecundity across eight temperatures. We predicted that constant environments would select for thermal specialists and that variable environments would select for thermal generalists. Contrary to our predictions, specialists and generalists did not evolve in constant and spatially variable environments, respectively. However, temporal variation produced a type of generalist that has rarely been considered by theoretical models of developmental plasticity. Specifically, genotypes from the temporally variable selective environment were more fecund across all temperatures than were genotypes from other environments. These patterns suggest certain allelic effects and should inspire new directions for modeling adaptation to fluctuating environments

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