Pace-of-life Syndrome Research Articles

Swimming performance, but not metabolism, is related to a boldness-activity syndrome in schoolmaster snapper (Lutjanus apodus).

Commercial overexploitation and climate change can alter the physiology and behavior of marine organisms, although intraspecific phenotypic responses to such changes can vary greatly depending on the environment, species, and severity of the stressor. Under the pace-of-life syndrome (POLS) hypothesis, behavior, physiology, and life-history traits are linked, and thus, affected by selection targeting any aspect of organismal biology. However, these links are understudied in tropical marine fishes, and further work is needed to better understand the impacts of fisheries and climate change on wild stocks. Moreover, tropical regions have a greater reliance on fisheries; thus investigations should focus on species with substantial socioeconomic value to ensure benefits at the local level. This study aimed to address this need by measuring the behavior (boldness and activity), metabolism, and swimming performance (using a critical swim speed [Ucrit] test) of schoolmaster snapper Lutjanus apodus in Eleuthera, the Bahamas. We report a strong positive correlation between boldness and activity, high repeatability of these behavioral metrics, and two groupings that were consistent with "proactive" and "reactive" behavioral types. These behavioral types differed significantly in their swimming performance, with reactive individuals having a 13.1% higher mean Ucrit. In contrast, no significant differences were found in the measured metabolic parameters between behavioral types. This study is the first to investigate the intraspecific links between behavior and physiology in a snapper species, using the novel and ecologically relevant comparison of Ucrit with behavioral syndrome types. These data suggest that additional research is needed to better predict the success of proactive/reactive tropical fish if overexploited and as influenced by climate change.

Does the development environment cause the pace of life to change in a rainforest lizard?

Life history theory emphasizes that finite resources result in allocation trade-offs among the competing interests of self-maintenance, growth, reproduction, and survival. Environmental conditions, particularly during development, can influence these life history trade-offs, leading to the coupling of physiological and behavioural traits with life history strategies. Thus, populations may vary in the pattern of trait covariation, clustering along a fast-slow continuum, termed the extended pace-of-life syndrome (POLS) theory. We aimed to test how variation in ecological conditions influence life history trade-offs and their association with behaviour and physiology by comparing captive bred and wild-collected southern rainforest sunskink (Lampropholis similis). The captive bred skinks were the offspring of the wild-caught skinks, and all tests were conducted in the laboratory. We found that the groups differed, on average, in growth rate, body condition, thermal preferences, sprint performance, and activity. Counter to our expectation, wild-caught skinks exhibited a faster pace of life relative to captive-bred skinks despite experiencing more challenging environmental conditions. Furthermore, life history trade-offs were not detected, nor were traits correlated to form the syndrome. Studies are needed to identify the proximate mechanisms causing life history trade-offs and how they lead to the coupling, or decoupling, of physiological and behavioural traits. Such information will provide vital insight into how ecological forces drive the evolution of traits.

Sex-specific associations of the maturation locus vgll3 with exploratory behavior and boldness in Atlantic salmon juveniles.

Studies linking genetics, behavior and life history in any species are rare. In Atlantic salmon (Salmo salar), age at maturity is a key life-history trait and associates strongly with the vgll3 locus, whereby the vgll3*E allele is linked with younger age at maturity, and higher body condition than the vgll3*L allele. However, the relationship between this genetic variation and behaviors like boldness and exploration which may impact growth and reproductive strategies is poorly understood. The pace-of-life syndrome (POLS) framework provides predictions, whereby heightened exploratory behavior and boldness are predicted in individuals with the early maturation-associated vgll3 genotype (EE). Here, we tested these predictions by investigating the relationship between vgll3 genotypes and exploration and boldness behaviors in 129 juveniles using the novel environment and novel object trials. Our results indicated that contrary to POLS predictions, vgll3*LL fish were bolder and more explorative, suggesting a genotype-level syndrome including several behaviors. Interestingly, clear sex differences were observed in the latency to move in a new environment, with vgll3*EE males, but not females, taking longer to move than their vgll3*LL counterparts. Our results provide further empirical support for recent calls to consider more nuanced explanations than the pace of life theory for integrating behavior into life-history theory.

Boldness suppresses hoarding behavior in food hoarding season and reduces over-wintering survival in a social rodent.

The "pace-of-life" syndrome (POLS) framework can encompass multiple personality axes that drive important functional behaviors (e.g., foraging behavior) and that co-vary with multiple life history traits. Food hoarding is an adaptive behavior important for an animal's ability to adapt to seasonal fluctuations in food availability. However, the empirical evidence for the relationships between animal personality and hoarding behavior remains unclear, including its fitness consequences in the POLS framework. In this study, the Mongolian gerbil (Meriones unguiculatus), a social rodent, was used as a model system to investigate how boldness or shyness is associated with food hoarding strategies during the food hoarding season and their impact on over-winter survival and reproduction at both individual and group levels. The results of this study showed that, compared with shy gerbils, bold gerbils had a lower effort foraging strategy during the food hoarding season and exhibited lower over-winter survival rates. However, bold-shy personality differences had no effect on over-winter reproduction. These findings suggest that the personality is a crucial factor influencing the foraging strategy during the food hoarding season in Mongolian gerbils. Personality may be related to energy states or the reaction to environmental changes (e.g., predation risk and food availability) in bold or shy social animals. These results reflect animal life history trade-offs between current versus future reproduction and reproduction versus self-maintenance, thereby helping Mongolian gerbils in adapting to seasonal fluctuations in their habitat.

Distribution and some features of the biology of voles of the genus Blanfordimys (Rodentia, Arvicolinae)

The following data was acquired from literary sources and obtained by us as a result of field studies on the distribution, stationality, abundance and reproduction of voles of the genus Blanfordimys Argyropulo, 1933: Afghan vole B. afghanus (Thomas, 1912) with subspecies B. a. afghanus and B. a. balchanensis (Heptner et Shukurov, 1950), Bukhara vole B. bucharensis (Vinogradov, 1930), with subspecies B. b. bucharensis and B. b. davydovi (Golenishchev et Sablina, 1991) and Pamir vole B. juldaschi (Severtzov, 1879) with subspecies B. j. carruthersi (Thomas, 1909) and B. j. juldaschi in natural conditions on the territory of Turkmenistan, Tajikistan and Kyrgyzstan. According to the elevation gradient from low to high altitude, these voles are distributed as follows: Afghan, Bukhara, Pamir, respectively. The features of reproduction and postembryonic ontogenesis in captivity have also been studied. Reproduction took place year-round with low intensity: the number of newborns in the litter of all the species considered is small, 3 cubs on average, the average interval between litters is about 50 days. The young of voles living at lower altitudes (B. afghanus and B. bucharensis) develop somewhat faster compared to higher-altitude ones (B. juldaschi). In general, the studied species showed signs of slow development and delay in the appearance of the most important signs in postembryonic ontogenesis (eruption of incisors, epiphany) compared to most of the lowland representatives of the Arvicolini tribe voles. These features are more pronounced in B. j. juldaschi, living at high altitudes. Thus, considering the theory of pace-of-life syndrome (POLS), we observe a shift from a faster pace of life (r-strategy), characteristic of most lowland rodents, to a slower one (k-strategy). The vulnerability of voles of the genus Blanfordimys in the process of climate aridization and in conditions of anthropogenic pressure is noted.

Sex-dependent integration of ornamentation, personality, morphology, and life history

Abstract Phenotypic integration can be defined as the patterns and strength of the covariances between traits in an organism. The pace of life syndrome (POLS) hypothesis provides a testable case of phenotypic integration as it predicts that traits that mediate the trade-off between current and future reproduction should have coevolved with the slow-fast life-history continuum and may thus covary across individuals of a population. Although the POLS hypothesis has received increasing attention over the last decade, there is a need for investigating whether POLS are sex-specific and whether ornamental traits can be included within the POLS framework. We used 9 years of data to describe the integration patterns of ornamental coloration, personality, morphology, and life history in blue tits (Cyanistes caeruleus) and whether they differed between males and females. With that aim, we fitted multivariate mixed models separating the among- from the within-individual covariances. We found that the overall integration between the studied traits was weak, but our results suggested some sex-specific covariances at the among- and within-individual levels. Finally, using structural equation models (SEM), we tested for the presence of trait modules (i.e., covariances between traits involved in the same biological function) within each sex. SEMs suggested the presence of a morphological module but no modules for coloration or behavioral traits. Also, results obtained from the SEM did not support the POLS hypothesis. Overall, this work highlights the importance of considering sex when studying phenotypic integration and the relevance of SEM to test POLS hypothesis.

Standard metabolic rate differs between rainbow trout (Oncorhynchus mykiss) growth forms

In variable environments, repeatable phenotypic differences between individuals provide the variation required for natural selection. The pace-of-life syndrome (POLS) provides a conceptual framework linking individual physiology and life histories to behaviour, where rapidly growing individuals demonstrate higher rates of resting or “standard” metabolic rate (SMR). If differences in SMR are consistent between fast- and slow-growing individuals, these differences may be important to capture in bioenergetic relationships used to describe their growth, energy acquisition, and allocation. We compared growth rates and SMR between a domesticated and wild strain of rainbow trout ( Oncorhynchus mykiss (Walbaum, 1792)) using intermittent flow respirometry. Though mass-scaling exponents were similar between strains, mass-scaling coefficients of SMR for fast-growing rainbow trout were 1.25 times higher than those for slower growing fish. These observed differences in mass-scaling coefficients between fast- and slow-growing rainbow trout were consistent with data extracted from several other studies. Bioenergetic estimates of consumption for domestic strain fish increased as the difference in SMR and wild strain fish increased, and increased as activity level increased. Our results indicate patterns of SMR consistent with POLS, and suggest that strain-specific SMR equations may be important for applications to active populations (i.e., field observations).

Pace-of-life syndrome: linking personality, metabolism and colour ornamentation in male guppies

Within populations, there commonly exists consistent among-individual differences in behaviour. As a potential mechanism maintaining this variation, the pace-of-life-syndrome (POLS) hypothesis posits that consistent differences in the behaviour of individuals (i.e. ‘personality’) are intercorrelated and have coevolved with consistent individual differences in metabolism and life-history traits. Here, using adult male guppies, Poecilia reticulata , we tested under laboratory conditions (1) whether behavioural and metabolic traits vary consistently among individuals over time (≤7 days) and (2) the POLS prediction that repeatable behavioural traits should be intercorrelated with each other and with repeatable metabolic rate at the among-individual level. Furthermore, based on indicator models of sexual selection, we expected that sexually selected male colour ornamentation would predict individual personality and metabolic rate. We repeatedly assayed three behavioural traits (sociability, boldness, exploration) and three metabolic traits (resting metabolic rate, maximal metabolic rate, aerobic scope) in a set of males that varied in body size and colour ornamentation. All behavioural trait measures were repeatable, consistent with individual personality. Of the three metabolic traits, only resting metabolic rate (RMR) was repeatable. Behavioural trait measures were significantly intercorrelated and thus integrated in a behavioural syndrome. More ‘proactive’ males were bolder, more exploratory and more sociable than ‘reactive’ ones. However, contrary to the POLS hypothesis, RMR was not significantly correlated with any of the behavioural trait measures, suggesting that consistent individual differences in RMR do not drive or support differences in personality, or vice versa. Male colour ornamentation did not covary with behaviour or RMR and thus does not appear to be a reliable predictor of either behavioural or metabolic phenotypes. We therefore did not find any compelling support for the POLS hypothesis, suggesting that individual differences in metabolism do not underlie the evolution and maintenance of among-individual behavioural variation in our study population. • We tested for behaviour–metabolism covariation in guppies (pace-of-life syndrome, POLS). • Behaviour and resting metabolic rate (RMR) differed consistently among males. • Behavioural differences between males, however, did not covary with their RMR. • Male colour ornamentation did not predict either their personality or metabolism. • Overall, our results do not support the central prediction of the POLS hypothesis.

Concerted evolution of metabolic rate, economics of mating, ecology, and pace of life across seed beetles

Male-female coevolution has taken different paths among closely related species, but our understanding of the factors that govern its direction is limited. While it is clear that ecological factors, life history, and the economics of reproduction are connected, the divergent links are often obscure. We propose that a complete understanding requires the conceptual integration of metabolic phenotypes. Metabolic rate, a nexus of life history evolution, is constrained by ecological factors and may exert important direct and indirect effects on the evolution of sexual dimorphism. We performed standardized experiments in 12 seed beetle species to gain a rich set of sex-specific measures of metabolic phenotypes, life history traits, and the economics of mating and analyzed our multivariate data using phylogenetic comparative methods. Resting metabolic rate (RMR) showed extensive evolution and evolved more rapidly in males than in females. The evolution of RMR was tightly coupled with a suite of life history traits, describing a pace-of-life syndrome (POLS), with indirect effects on the economics of mating. As predicted, high resource competition was associated with a low RMR and a slow POLS. The cost of mating showed sexually antagonistic coevolution, a hallmark of sexual conflict. The sex-specific costs and benefits of mating were predictably related to ecology, primarily through the evolution of male ejaculate size. Overall, our results support the tenet that resource competition affects metabolic processes that, in turn, have predictable effects on both life history evolution and reproduction, such that ecology shows both direct and indirect effects on male-female coevolution.

Zoonotic Disease Risk and Life-History Traits: Are Reservoirs Fast Life Species?

The relationship between humans, wildlife and disease transmission can be complex and context-dependent, and disease dynamics may be determined by idiosyncratic species. Therefore, an outstanding question is how general is the finding that species with faster life histories are more probable hosts of zoonoses. Ecological knowledge on species, jointly with public health data, can provide relevant information on species that should be targeted for epidemiological surveillance or management. We investigated whether mammal species traits can be good indicators of zoonotic reservoir status in an intensified agricultural region of Argentina. We find support for a relationship between reservoir status and the pace of life syndrome, confirming that fast life histories can be a factor of zoonotic risk. Nonetheless, we observed that for certain zoonosis, reservoirs may display a slow pace of life, suggesting that idiosyncratic interactions can occur. We conclude that applying knowledge from the life history-disease relationship can contribute significantly to disease risk assessment. Such an approach may be especially valuable in the current context of environmental change and agricultural intensification.

Telomere length positively correlates with pace-of-life in a sex- and cohort-specific way and elongates with age in a wild mammal.

Understanding ageing and the diversity of life histories is a cornerstone in biology. Telomeres, the protecting caps of chromosomes, are thought to be involved in ageing, cancer risks and life-history strategies. They shorten with cell division and age in somatic tissues of most species, possibly limiting lifespan. The resource allocation trade-off hypothesis predicts that short telomeres have thus coevolved with early reproduction, proactive behaviour and reduced lifespan, that is, a fast pace-of-life syndrome (POLS). Conversely, since short telomeres may also reduce the risks of cancer, the anticancer hypothesis advances that they should be associated with slow POLS. Conclusion on which hypothesis best supports the role of telomeres as mediators of life-history strategies is hampered by a lack of study on wild short-lived vertebrates, apart from birds. Using seven years of data on wild Eastern chipmunks Tamias striatus, we highlighted that telomeres elongate with age (n=204 and n=20) and do not limit lifespan in this species (n=51). Furthermore, short telomeres correlated with a slow POLS in a sex-specific way (n=37). Females with short telomeres had a delayed age at first breeding and a lower fecundity rate than females with long telomeres, while we found no differences in males. Our findings support most predictions adapted from the anticancer hypothesis, but none of those from the resource allocation trade-off hypothesis. Results are in line with an increasing body of evidence suggesting that other evolutionary forces than resource allocation trade-offs shape the diversity of telomere length in adult somatic cells and the relationships between telomere length and life-histories.

Declining metabolic scaling parallels an ontogenetic change from elongate to deep-bodied shapes in juvenile Brown trout.

Body shape and metabolic rate can be important determinants of animal performance, yet often their effects on influential traits are evaluated in a non-integrated way. This creates an important gap because the integration between shape and metabolism may be crucial to evaluate metabolic scaling theories. Here, we measured standard metabolic rate in 1- and 2-years old juvenile brown trout Salmo trutta, and used a geometric morphometrics approach to extricate the effects of ontogeny and size on the link between shape and metabolic scaling. We evidenced near-isometric ontogenetic scaling of metabolic rate with size, but also a biphasic pattern driven by a significant change in metabolic scaling, from positive to negative allometry. Moreover, the change in metabolic allometry parallels an ontogenetic change from elongate to deep-bodied shapes. This is consistent with the dynamic energy budget (DEB) and surface area (SA) theories, but not with the resource transport network theory which predicts increasing allometric exponents for trends towards more robust, three-dimensional bodies. In addition, we found a relationship between body shape and size independent metabolic rate, with a positive correlation between robustness and metabolic rate, which fits well within the view of Pace-of-Life Syndromes (POLS). Finally, our results align with previous studies that question the universality of metabolic scaling exponents and propose other mechanistic models explaining the diversity of metabolic scaling relationships or emphasizing the potential contribution of ecological factors.

Alternative migratory strategies related to life history differences in the Walleye (Sander vitreus)

BackgroundWhile Pace of Life Syndrome predicts behavioural differences between individuals with differential growth and survival, testing these predictions in nature is challenging due to difficulties with measuring individual behaviour in the field. However, recent advances in acoustic telemetry technology have facilitated measurements of individual behaviour at scales not previously possible in aquatic ecosystems.MethodsUsing a Walleye (Sander vitreus) population inhabiting Black Bay, Lake Superior, we examine whether life history characteristics differ between more and less mobile individuals as predicted by Pace of Life Syndrome. We tracked the movement of 192 individuals from 2016 to 2019 using an acoustic telemetry study, relating patterns in annual migratory behaviour to individual growth, and seasonal changes in optimal thermal-optical habitat.ResultsWe observed two consistent movement patterns in our study population—migratory individuals left Black Bay during late summer to early fall before returning to the bay, whereas residents remained within the bay year-round. The average maximum length of migrant Walleye was 5.5 cm longer than residents, and the sex ratios of Walleye caught during fall surveys was increasingly female-biased towards the mouth of Black Bay, suggesting that a majority of migrants were females. Further, Walleye occupancy outside of Black Bay was positively associated with increasing thermal-optical habitat.ConclusionsWalleye in Black Bay appear to conform to Pace of Life Syndrome, with migrant individuals gaining increased fitness through increased maximum size, which, given size-dependent fecundity in this species, likely results in greater reproductive success (via greater egg deposition vs. non-migrants). Further, apparent environmental (thermal) controls on migration suggest that migratory Walleye (more so than residents) may be more sensitive to changing environmental conditions (e.g., warming climate) than residents.

Fluctuations in Density-Dependent Selection Drive the Evolution of a Pace-of-Life Syndrome Within and Between Populations

AbstractThe pace-of-life syndrome (POLS) hypothesis posits that suites of traits are correlated along a slow-fast continuum owing to life history trade-offs. Despite widespread adoption, environmental conditions driving the emergence of POLS remain unclear. A recently proposed conceptual framework of POLS suggests that a slow-fast continuum should align to fluctuations in density-dependent selection. We tested three key predictions made by this framework with an eco-evolutionary agent-based population model. Selection acted on responsiveness (behavioral trait) to interpatch resource differences and the reproductive investment threshold (life history trait). Across environments with density fluctuations of different magnitudes, we observed the emergence of a common axis of trait covariation between and within populations (i.e., the evolution of a POLS). Slow-type (fast-type) populations with high (low) responsiveness and low (high) reproductive investment threshold were selected at high (low) population densities and less (more) intense and frequent density fluctuations. In support of the predictions, fast-type populations contained a higher degree of variation in traits and were associated with higher intrinsic reproductive rate (r0) and higher sensitivity to intraspecific competition (γ), pointing to a universal trade-off. While our findings support that POLS aligns with density-dependent selection, we discuss possible mechanisms that may lead to alternative evolutionary pathways.

Integrating humans into pace-of-life studies: The Big Five personality traits and metabolic rate in young adults.

The pace-of-life syndrome (POLS) predicts that personality and metabolism should be correlated if they function as an integrated unit along a slow-fast continuum. Over the last decade, this conceptual framework has been tested in several empirical studies over a wide array of non-human animal taxa, across multiple personality traits and using standardized measures of metabolism. However, studies associating metabolic rate and personality in humans have been surprisingly scarce. Here, we tested whether there was covariation among personality scores, measured using the Big Five Inventory test, resting metabolic rate (RMR) and preferred walking speed (PWS) in a cohort of young human adults aged between 18 and 27 years old. We found a significant, negative relationship between RMR and Extraversion; less extraverted individuals had a 30% higher RMR than the most extraverted ones. No other personality traits correlated with RMR and none correlated with PWS. The negative correlation between Extraversion and RMR may suggest an allocation energy trade-off between personality and basal metabolism. Our results yielded equivocal support for the POLS and emphasized the need for more research on human to test the generality of this conceptual framework and further assess its validity.

The effects of personality on survival and trappability in a wild mouse during a population cycle

The pace-of-life syndrome (POLS) theory provides an evolutionary explanation for the existence of consistent among-individual variation in behaviour, or animal personality. Herein, individuals with a fast lifestyle are considered to be bolder and should take more risks resulting in a lower life expectancy compared to shyer individuals with a slower lifestyle. However, this assumption depends on the levels of intra-specific competition that the individuals experience which has rarely been tested in species that experience large changes in competition on a very short time scale. We used the multimammate mice (Mastomys natalensis) as a model system to study the POLS assumption by investigating the effects of two personality traits (exploration and stress-sensitivity) on survival, maturation (a proxy for reproductive investment) and recapture probability during one population cycle (Nindividuals = 201). Such a cycle consists of two phases in which the levels of intra-specific competition vary drastically. We found that only one personality trait, namely stress-sensitivity, had a negative effect on both survival and recapture probability but none of them affected maturation. This suggests that less stress-sensitive individuals take more risks in the wild and have a higher survival probability compared to high stress-sensitive individuals. However, the effect of personality on survival was only present during the population decrease phase, when the levels of intra-specific competition are high due to a scarcity of food. This suggests that seasonal changes in competition might be important in the evolution and maintenance of animal personalities in species whose population dynamics have a clear seasonal component.

Personality-driven life history trade-offs differ in two subpopulations of free-ranging predators.

Consistent individual differences in behaviour (i.e. personality) can be explained in an evolutionary context if they are favoured by life history trade-offs as conceptualized in the pace-of-life syndrome (POLS) hypothesis. Theory predicts that faster-growing individuals suffer higher mortality and that this trade-off is mediated through exploration/risk-taking personality, but empirical support for this remains limited and ambiguous. Equivocal support to the POLS hypothesis suggests that the link between life history and personality may only emerge under certain circumstances. Understanding personality-driven trade-offs would be facilitated by long-term studies in wild populations experiencing different ecological conditions. Here, we tested whether personality measured in semi-captivity was associated with a growth-mortality trade-off via risk-taking in the wild in two subpopulations of juvenile lemon sharks Negaprion brevirostris known to differ in their predator abundance. We expected stronger personality-driven trade-offs in the predator-rich environment as compared to the predator-poor environment. Sharks were captured yearly from 1995 onwards allowing us to obtain long-term data on growth and apparent survival in each subpopulation. We then used a novel open-field assay to test sharks for exploration personality yearly from 2012 to 2017. A subset of the tested sharks was monitored in the field using telemetry to document risk-taking behaviours. We tested (a) if fast explorers in captivity took more risks and grew faster in the wild and (b) if natural selection acted against more explorative, faster-growing sharks. In the subpopulation with fewer predators, more explorative sharks in captivity took more risks in the wild and grew faster. In turn, larger, fast-growing sharks had lower apparent survival. In the predator-rich subpopulation, despite finding selection on fast growth, we found no link between exploration personality and the growth-mortality trade-off. Our study demonstrates that the association between personality and life history is favoured in some ecological contexts but not in others. We identify predator and resource abundance as two main potential drivers of the personality-mediated trade-off and emphasize that future work on the POLS hypothesis would benefit from an approach integrating behaviour and life history across ecological conditions.

Individual-level pace-of-life syndromes in annual killifish are mediated by intersexual and interspecific differences

Pace-of-life syndromes (POLS) describe covariations between life history (such as growth rate and age at maturity), behaviour (e.g. activity or boldness) and physiology (e.g. metabolic rate) along an axis from fast to slow lifestyles. This powerful concept can be applicable at a range of scales, from broad interspecific contrasts to the individual intra-population level, though its generality has recently been questioned. Using two species of African annual fishes with fast lifestyles, we tested how individual-level POLS covary between the sexes and contrasting social environments. Measuring three key metabolic parameters (standard metabolic rate, SMR; maximum metabolic rate, MMR; and aerobic scope, AS), we found extensive variation between species and sexes in the expression of POLS. Social environment affected individual metabolic traits, but not their covariation with behaviour and life history traits. In accordance with the POLS prediction, we observed a positive association between MMR, AS and boldness, and a negative association between MMR, AS and lifespan in Nothobranchius orthonotus males, although trait covariations were opposite in N. orthonotus females. In Nothobranchius pienaari, we confirmed the predicted negative correlation between SMR and lifespan which was not sex-specific. Contrary to POLS predictions, we observed a negative correlation between SMR and boldness in N. pienaari. Finally, there was no link between activity levels or size at maturity and metabolic traits in either species. Overall, we demonstrated limited support for POLS predictions, but found that specific pace-of-life trait associations were mediated by both interspecific and intersexual differences.

Existential Threats of Immigration and Terrorism Predict Voting for Brexit and Trump

The year 2016 witnessed historic political change with the ascension to power of Donald Trump and the UK’s vote to leave the European Union (i.e. Brexit). Research has sought to explain these once-deemed unlikely events, yet an evolutionary theoretical account remains unexplored. From a life history perspective, a rise in existential threat, potentially caused by increased media coverage of the War in Syria and immigration issues, may have prompted a shift to a faster life history strategy (LHS)/pace of life syndrome (POLS). Immediate answers were sought despite long-term consequences. In this multiple study paper, we shed light on this thesis. Firstly, in establishing a perceived increase in existential threats between 2014 and 2016. Secondly, by examining if LHS/POLS and associated proxies, as well as fear of terrorism and immigration predicted voting for Brexit or Trump. Trump voters feared terrorism, and Brexit voters feared immigration, but LHS/POLS was not directly, nor ultimately influential in their vote choice; however, for those that did not vote, it was. Nevertheless, other life history proxies were important factors in voting. Thus, the link between LHS/POLS and voting is complex but affords new insight into voter psychology during the EU referendum and US presidential election.

Integration of physiology, behaviour and life history traits: personality and pace of life in a marine gastropod

Attempts to unravel the proximate and ultimate causes of individual behavioural and life history variation have often pointed to predicted correlations between behavioural, physiological and life history traits, forming pace-of-life syndromes (POLS). The POLS hypothesis predicts that high levels of production (growth, fecundity) require high levels of foraging effort and risk taking, supported by high metabolism. Despite tremendous interest in this topic, the POLS hypothesis still has limited empirical support, which has led to calls for more stringent empirical tests of the hypothesis and its assumptions. To that end, we examined the associations between risk-taking behaviour (boldness), resting metabolic rate (RMR) and somatic growth rate in a marine gastropod, Littoraria irrorata, under controlled laboratory conditions using a longitudinal repeated measures design. After accounting for the effects of sex, size and time (trial number), a multivariate mixed model revealed that bolder individuals had higher RMR, and grew faster, whereas RMR and growth were not strongly correlated. Further, if individuals were bolder than their average on a given day, then their RMR was also higher. Our study represents rare and compelling support for the POLS hypothesis, simultaneously studying its three key components (behaviour, energetics and life history), the success of which we attribute to careful control, concurrent sampling of each trait, and rigorous analysis of the among- and within-individual patterns of variation and covariance.