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Individual behavioural consistency and plasticity in an urban spider

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Available online xxx MS. number 11-01000 Keywords: aggression behavioural polymorphism behavioural syndrome frequency-dependent selection heritability personality Behaviour is generally plastic to some degree and allows an animal to react appropriately to changing and novel conditions. Consequently, a degree of plasticity is predicted to be a key determinant of an organism's ability to cope with novel (e.g. urban) environments. Yet behavioural plasticity is often genetically determined and many animals exhibit personalities (i.e. consistent between-individual differences in behaviours). We explored the degree of behavioural plasticity versus personality in the bridge spider, Larinioides sclopetarius, which occurs in extremely high densities in urban areas over the Holarctic. The spiders show extraordinary plasticity in life history. We investigated between-and within-individual variability, correlations and heritability for aggressiveness, boldness, behaviours in novel environment, and voracity towards prey. We predicted that these spiders would show high individual behavioural plasticity or that there would be a mix of individuals with different personalities. We found temporal consistency and moderate heritability in intra-sex aggressiveness and boldness, whereas behaviours in novel environment were repeatable but not heritable. Most behavioural traits showed high between-individual variability. We discuss the idea that low heritability of behaviours related to foraging success and a lack of behavioural correlations may be a result of developmental plasticity as a mechanism that promotes success in cities. In the next step, we experimentally tested whether composition of aggressiveness types affects spiders' mass gain and survival in a high-density group. Groups of only aggressive types had highest mass but also showed highest mortality, although not significantly. Our results lend support to the hypothesis that living in high densities does not necessarily require a reduction of mean aggressiveness levels but that a polymorphism in aggressive personalities main-tained by negative frequency-dependent selection would be a possible scenario. Ó 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Urbanized environments are a progressively prominent feature of the earth's ecosystems. Urbanization has caused habitat alter-ations, pollution and changes in sensory stimuli, which lead to changes in biodiversity and community structure (Bonier et al. 2007; Godefroid & Koedam 2007). Most species have failed to tolerate environments that are altered and disturbed by humans; yet some species do persist and even thrive in cities (Møller 2010; Sih et al. 2011). Similarly to invasive species, many urban species can proliferate rapidly, increase in abundance in a short time, outcompete other less tolerant species and become locally domi-nant (Kolar & Lodge 2001; Colautti & MacIsaac 2004). Despite the countless ecological problems and large economic costs related to urban species, the characteristics distinguishing the species that flourish in the cities are poorly understood. The bridge spider, Larinioides sclopetarius Clerck (Araneidae), is an extremely successful colonizer of urban areas over the Holarctic (Heiling 1999; Schmitt 2004; Schmitt & Nioduschewski 2007). In this study we sought to explain its success in cities from a behav-ioural plasticity point of view, and tested predictions of two non-mutually exclusive hypotheses: (1) L. sclopetarius is a successful dweller of urban environments because of a high degree of behavioural plasticity; and/or (2) L. sclopetarius is a successful urban dweller because the population exhibits polymorphism in personalities, in particular in aggressiveness types. Previous studies have identified traits related to species' abilities to cope well in anthropogenic environments, such as fast growth and a short reproductive cycle, high mobility, high aggressiveness and activity, low neophobia (boldness), high phenotypic plasticity and tolerance to a wide range of environmental conditions (Lodge 1993; Sol et al. 2002; Rehage & Sih 2004; Snyder & Evans 2006; Pintor & Sih 2009; Cote et al. 2010, 2011; Møller 2010; Evans et al. 2011). A behavioural response to a change depends on the behav-ioural reaction norm (i.e. the set of behavioural phenotypes that a single individual produces in a given set of environments; Stamps & Groothuis 2010). The reaction norm and its plasticity is geneti-cally determined and thus a result of past evolutionary processes (Pigliucci 1998). Hence, animals from urban environments are

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... We used data generated by Kralj-Fišer and Schneider's (2012) study, in which the above behaviors were measured in males and females. In that study, the heritability of the different behaviors was assessed using parent-offspring regression, but combined across both sexes (Kralj-Fišer & Schneider, 2012). Here, we use the animal model (Kruuk & Hadfield, 2007) to test whether females and males differ in quantitative genetic estimates in these traits. ...
... whereas males cease web building after reaching maturity; adult males wander around in search of mates and feed mostly commensally in female webs. Based on these sex differences, we could predict that males exhibit higher mean levels of activity and exploration, but a previous laboratory study on this species failed to support this expectation (Kralj-Fišer & Schneider, 2012). However, that study also found higher mean repeatability in males compared with females in activity and exploration, but not in boldness (activ- Given that the repeatability of a trait represents an upper limit for its heritability (Falconer & Mackay, 1996;Lynch & Walsh, 1998), we expect to find that activity and exploration would have higher heritability estimates in males than in females. ...
... In both sexes, aggression is subjected to trade-offs; overt aggression is costly due to injuries and deaths (Kralj-Fišer & Schneider, 2012). ...
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The existence of consistent individual differences in behavior has been shown in a number of species, and several studies have found observable sex differences in these behaviors, yet their evolutionary implications remain unclear. Understanding the evolutionary dynamics of behavioral traits requires knowledge of their genetic architectures and whether this architecture differs between the sexes. We conducted a quantitative genetic study in a sexually size‐dimorphic spider, Larinioides sclopetarius, which exhibits sex differences in adult lifestyles. We observed pedigreed spiders for aggression, activity, exploration, and boldness and used animal models to disentangle genetic and environmental influences on these behaviors. We detected trends toward (i) higher additive genetic variances in aggression, activity, and exploration in males than females, and (ii) difference in variances due to common environment/maternal effects, permanent environment and residual variance in aggression and activity with the first two variances being higher in males for both behaviors. We found no sex differences in the amount of genetic and environmental variance in boldness. The mean heritability estimates of aggression, activity, exploration, and boldness range from 0.039 to 0.222 with no sizeable differences between females and males. We note that the credible intervals of the estimates are large, implying a high degree of uncertainty, which disallow a robust conclusion of sex differences in the quantitative genetic estimates. However, the observed estimates suggest that sex differences in the quantitative genetic architecture of the behaviors cannot be ruled out. Notably, the present study suggests that genetic underpinnings of behaviors may differ between sexes and it thus underscores the importance of taking sex differences into account in quantitative genetic studies.
... This is unfortunate, given that invertebrates represent 98% of species in the animal kingdom, and such taxonomic bias can hinder our understanding of the general pattern of personality heritability and thus personality evolution. For instance, moderate heritability has been shown for aggression (e.g., spider Larinioides sclopetarius, Kralj-Fišer & Schneider, 2012), activity (e.g., butterfly Heliothis armigera, Colvin & Gatehouse, 1993), and boldness (spider Agelenopsis pennsylvanica, Sweeney et al., 2013). Yet, several studies found no support for heritable variation in risk-taking behavior (pea aphids, Acyrthosiphon pisum, Schuett et al., 2011) -Fišer et al., 2017). ...
... In females, aggressiveness toward same-sex conspecifics serves a female to defend her territory (web) and thereby foraging patch. Territorial disputes between females are rare (Kralj-Fišer et al., 2017), probably because overt aggressiveness may have high fitness costs (Kralj-Fišer & Schneider, 2012). In view of this, we predicted that there would be evidence of sex differences in the genetic underpinning for aggressiveness. ...
... The spider immediately started to walk around the container. We recorded the latency to the first stop, hereafter termed as duration of initial activity in novel environment (e.g., Kralj-Fišer & Schneider, 2012), with the maximum duration of five minutes. As above, each individual from parental generation was tested twice in random order, whereas each individual from offspring generation was tested once. ...
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Abstract Sex differences in the genetic architecture of behavioral traits can offer critical insight into the processes of sex‐specific selection and sexual conflict dynamics. Here, we assess genetic variances and cross‐sex genetic correlations of two personality traits, aggression and activity, in a sexually size‐dimorphic spider, Nuctenea umbratica. Using a quantitative genetic approach, we show that both traits are heritable. Males have higher heritability estimates for aggressiveness compared to females, whereas the coefficient of additive genetic variation and evolvability did not differ between the sexes. Furthermore, we found sex differences in the coefficient of residual variance in aggressiveness with females exhibiting higher estimates. In contrast, the quantitative genetic estimates for activity suggest no significant differentiation between males and females. We interpret these results with caution as the estimates of additive genetic variances may be inflated by nonadditive genetic effects. The mean cross‐sex genetic correlations for aggression and activity were 0.5 and 0.6, respectively. Nonetheless, credible intervals of both estimates were broad, implying high uncertainty for these estimates. Future work using larger sample sizes would be needed to draw firmer conclusions on how sexual selection shapes sex differences in the genetic architecture of behavioral traits.
... Our results on repeatable individual differences in behaviors related to aggression are consistent with previous studies (reviewed in [3,39]), including other spider species, e.g., D. triton [13], L. sclopetarius [40], N. livida [22], Zygiella x-notata, and Nuctenea umbratica [41]. Furthermore, variation in aggression is moderately heritable (e.g., L. sclopetarius [21,40]) and N. umbratica ([42], reviewed in [43]) and often has fitness consequences (reviewed in [5]). For ...
... Our results on repeatable individual differences in behaviors related to aggression are consistent with previous studies (reviewed in [3,39]), including other spider species, e.g., D. triton [13], L. sclopetarius [40], N. livida [22], Zygiella x-notata, and Nuctenea umbratica [41]. Furthermore, variation in aggression is moderately heritable (e.g., L. sclopetarius [21,40]) and N. umbratica ( [42], reviewed in [43]) and often has fitness consequences (reviewed in [5]). ...
... Our results on repeatable individual differences in behaviors related to aggression are consistent with previous studies (reviewed in [3,39]), including other spider species, e.g., D. triton [13], L. sclopetarius [40], N. livida [22], Zygiella x-notata, and Nuctenea umbratica [41]. Furthermore, variation in aggression is moderately heritable (e.g., L. sclopetarius [21,40]) and N. umbratica ( [42], reviewed in [43]) and often has fitness consequences (reviewed in [5]). For example, aggression in L. sclopetarius males correlates positively to the number of sired offspring, suggesting that aggressive males have a sperm competition advantage [21]. ...
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Theory suggests that consistent individual variation in behavior relates to fitness, but few studies have empirically examined the role of personalities in mate choice, male-male competition and reproductive success. We observed the Mediterranean black widow, Latrodectus tredecimguttatus, in the individual and mating context, to test how body size measures and two functionally important aggressive behaviors, i.e., male aggression towards rivals and female voracity towards prey, affect mating behaviors, mating success and sexual cannibalism. We specifically selected voracity towards prey in females to test the “aggressive spillover hypothesis”, suggesting that more voracious females are more sexually cannibalistic. Both females and males exhibit consistent individual differences in the examined aggressive behaviors. While larger males win contests more often and achieve more copulations, neither male nor female size measures correlate to aggression. Female voracity does not correlate with aggression towards mates and sexual cannibalism, rejecting the “spillover hypothesis”. However, occurrence of sexual cannibalism positively relates to longer insertion duration. Furthermore, the smaller the ratio between male and female body length the more likely a female attacked and cannibalized a mate. We show that individual variation in aggression levels plays no direct role in the mating behavior of the Mediterranean black widow. Instead, body size affects male mating success and occurrences of sexual cannibalism in females.
... While numerous studies on personality and behavioral syndromes have focused on fish (e.g., , birds (e.g., Kluen & Brommer, 2013), and mammals (e.g., Réale et al., 2009), studies on arthropods have only become prevalent within the last 20 years (Modlmeier et al., 2015;Wright et al., 2019). Particularly, spiders have become an interesting group of arthropods to study personality and behavioral syndromes (e.g., Keiser et al., 2018;Kralj-Fišer & Schneider, 2012;Pruitt & Riechert, 2012;Sih & Bell, 2008) because they show a wide range of behavioral types (Table 1). Individuals fall along continua or axes (Table 1), such as boldness and aggressiveness (Keiser et al., 2018;Kralj-Fišer & Schneider, 2012;Pruitt & Riechert, 2012), activity and sociability (Beleyur et al., 2015;Lubin & Bilde, 2007), which can be assessed relatively easily across different contexts and situations (Pruitt & Riechert, 2012). ...
... Particularly, spiders have become an interesting group of arthropods to study personality and behavioral syndromes (e.g., Keiser et al., 2018;Kralj-Fišer & Schneider, 2012;Pruitt & Riechert, 2012;Sih & Bell, 2008) because they show a wide range of behavioral types (Table 1). Individuals fall along continua or axes (Table 1), such as boldness and aggressiveness (Keiser et al., 2018;Kralj-Fišer & Schneider, 2012;Pruitt & Riechert, 2012), activity and sociability (Beleyur et al., 2015;Lubin & Bilde, 2007), which can be assessed relatively easily across different contexts and situations (Pruitt & Riechert, 2012). ...
... Ecological and behavioral hypotheses related to spider personality (Kralj-Fišer & Schneider, 2012;Sih & Bell, 2008) can be tested across different social groups (social and solitary), clades (Mygalomorph and Araneomorph), life histories (Bonte et al., 2006), and habitats (Foelix, 2011). Spiders also show a variety of strategies for dispersal (Blandenier, 2009;Coyle, 1983), foraging (Jackson, 1992; and mating (Jackson, 1992). ...
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Spiders are useful models for testing different hypotheses and methodologies relating to animal personality and behavioral syndromes because they show a range of behavioral types and unique physiological traits (e.g., silk and venom) that are not observed in many other animals. These characteristics allow for a unique understanding of how physiology, behavioral plasticity, and personality interact across different contexts to affect spider's individual fitness and survival. However, the relative effect of extrinsic factors on physiological traits (silk, venom, and neurohormones) that play an important role in spider survival, and which may impact personality, has received less attention. The goal of this review is to explore how the environment, experience, ontogeny, and physiology interact to affect spider personality types across different contexts. We highlight physiological traits, such as neurohormones, and unique spider biochemical weapons, namely silks and venoms, to explore how the use of these traits might, or might not, be constrained or limited by particular behavioral types. We argue that, to develop a comprehensive understanding of the flexibility and persistence of specific behavioral types in spiders, it is necessary to incorporate these underlying mechanisms into a synthesized whole, alongside other extrinsic and intrinsic factors. Few studies have explored the mechanisms driving the expression of personality in spiders, and what effects extrinsic and intrinsic factors (and their interactions) have on the expression of personalities. Physiological traits, particularly venom and silk, may play an important role in the expression of personalities and/or behavioral flexibility in spiders
... Further, studies demonstrated that environmental conditions (e.g. predation pressure) can affect the relative numbers of different temperaments in a group, and that the number of different temperaments in a group can influence and be influenced by environmental conditions and can further influence group survival outcomes [26,28,46,[63][64][65][66]. However, the mechanisms by which these temperaments affect survival, reproduction and overall fitness are not yet clear. ...
... The aggression trait has been frequently associated with increased exploration and boldness ( [91]; [92]), and aggressive individuals tend to locate at the group periphery, be involved in group defence, and have enhanced foraging compared to less aggressive individuals (e.g. [65,93,94]). There are a limited number of studies on the relationship between aggression and physiological mechanisms in free-ranging animals. ...
Article
Animal behaviour research has experienced a renewed interest in consistent individual differences (i.e. animal personality or temperament). Recent ecological studies have identified environmental conditions that give rise to the development and evolution of temperaments and to fitness-related outcomes of temperament. Additional literature has also described relationships between temperaments and physiological regulation. However, one-to-one relationships between one behavioural trait and one physiological system do not account for co-selection of behavioural and physiological traits, nor the complex signalling among physiological systems. In the current paper, we review the literature on multiple physiological processes associated with temperament, propose temperament-specific physiological profiles, and focus on next steps to understand the functional significance, evolution and maintenance of temperaments. We propose that to understand causes and consequences of temperament we need to characterize integrative physiological profiles associated with different temperaments.
... Artificial selection is a powerful tool to favor relevant phenotypic expression of traits (Lommen et al. 2017;Dumont et al. 2016Dumont et al. , 2018Lirakis and Magalhães 2019;Bielza et al. 2020;Leung et al. 2020). Even though aggressiveness can be context-dependent (e.g., food-limited environment, stressful interaction with other individuals) (Maupin and Riechert 2000;Riechert and Hall 2000;Réale et al. 2007) it has also a genetic basis (Edwards et al. 2006;Kralj-Fišer and Schneider 2012). Moreover, the aggressiveness degree is not a fixed phenotypic expression as it exists along a continuum ranging from low to high phenotypic expression of aggressiveness (Réale et al. 2007). ...
... Aggressiveness is a trait that is possible to select, but its heritability differs between species. For instance, a heritability of aggressiveness ranging from 0.01 to 0.38 has already been calculated for drosophila (Edwards et al. 2006) and spiders (Kralj-Fišer and Schneider 2012). The lower the heritability is, the bigger the number of generations required for the trait to evolve will be. ...
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In agroecosystems, omnivorous predators are recognized as potential biological control agents because of the numerous pest species they prey on. Nonetheless, it could be possible to enhance their efficiency through artificial selection on traits of economical or ecological relevance. Aggressiveness, which defines the readiness of an individual to display agonistic actions toward other individuals, is expected to be related to zoophagy, diet preferences and to a higher attack rate. The study aimed to assess the aggressiveness degree of the damsel bug, Nabis americoferus, and to estimate its heritability. We hypothesized that a high aggressiveness degree can be selected, and that males are more aggressive than females. Using artificial selection, we reared two separate populations, each composed of nine genetically isolated lines characterized by their different aggressiveness degree (aggressive, docile and non-selected). After three generations, we had efficiently selected aggressive behavior. The realized heritability was 0.16 and 0.27 for aggressiveness and docility in the first population. It was 0.25 and 0.23 for the second population. Males were more aggressive than females only for the second population. The potential of these individuals as biological control agents and the ecological consequences of aggressiveness are discussed.
... After 90 min, we recorded the total number of killed flies. However, as the total number of killed flies includes consumed as well as overkilled prey (also called wasteful or superfluous killing; Riechert and Maupin 1998;Maupin and Riechert 2001;Kralj-Fišer and Schneider 2012), this measure includes aggressiveness as well as voracity. Therefore, during the second trial, we also recorded 1) the number of flies consumed, as a measure of voracity, and 2) the number of overkilled flies, as a measure of aggression (Riechert and Maupin 1998;Maupin and Riechert 2001;Kralj-Fišer and Schneider 2012). ...
... However, as the total number of killed flies includes consumed as well as overkilled prey (also called wasteful or superfluous killing; Riechert and Maupin 1998;Maupin and Riechert 2001;Kralj-Fišer and Schneider 2012), this measure includes aggressiveness as well as voracity. Therefore, during the second trial, we also recorded 1) the number of flies consumed, as a measure of voracity, and 2) the number of overkilled flies, as a measure of aggression (Riechert and Maupin 1998;Maupin and Riechert 2001;Kralj-Fišer and Schneider 2012). We then investigated the relationship between the total number of killed and proportion of overkilled flies to confirm that the total number of killed prey can be used as a measure of foraging aggression. ...
Article
There is a growing evidence that consistent interindividual differences in behavior, that is, behavioral types, can play an important role in key ecological processes such as predator–prey interactions, which in turn can have direct implications on biological control. Behavioral types of generalist predators may affect these interactions through individual differences in predators’ prey preferences and the breadth of predators’ trophic niches. This study examined how the multivariate nature of behavior, namely foraging aggressiveness, activity level, and risk-taking behavior, determines prey selection and trophic niche of the generalist agrobiont spider Philodromus cespitum. In laboratory experiments, we determined the repeatability of these behaviors and the preference between crickets, moths, fruit flies, and collembolans. We found that all three behaviors were moderately to strongly repeatable but there were no correlations between them, thus they did not form a behavioral syndrome. Only foraging aggressiveness influenced the prey selection of philodromid spiders and the more aggressive individuals had wider trophic niches because they incorporated prey that were more difficult to capture in their diet. In addition, more aggressive individuals killed a greater quantity of particular prey types while other prey types were killed at a similar rate by both aggressive and nonaggressive individuals. The differences in philodromids’ foraging aggressiveness, therefore, affected not only the overall prey density but also resulted in different prey community composition. As pest density and composition can both affect crop performance, further research needs to investigate how the interindividual behavioral differences of generalist natural enemies cascade down on the crops.
... jumping (Suter and Gruenwald 2000), shaking web (Jackson et al. 1992;Kralj-Fišer et al. 2011) and autotomy (Eisner and Camazine 1983;Punzo 1997). Their antipredator behaviour includes thanatosis (feigning death-this behaviour is characterized by curling legs and freezing, resulting in a body posture very similar to that of a dead spider) (Bilde et al. 2006;Kralj-Fišer and Schneider 2012) and "bailing out", in which the spider drops from the web and hangs motionless from a dragline with huddled legs . ...
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Spiders with around 48,000 recorded species are major terrestrial predators and thus crucially important for ecosystem functioning. They are widely used as research models and for biodiversity displays and sometimes also kept as pets. Nevertheless, we are not aware of any legal ethical rules bound to spider welfare during rearing or research. To set ethical standards, we first need to detect and assess how spiders “perceive” the external world. Based on the current knowledge of spiders’ sensory and nervous system, it is difficult to judge whether spiders feel pain, distress and suffering, although their behaviours like thanatosis, “bailing out”, autotomy and associative avoidance learning imply so. As is now known, arthropods are not simply mini-robots as traditionally believed. Thus, spider welfare deserves more research effort, and the ethical standards for rearing or using spiders in research need to be set. Here, we describe the variety of spider physiological and behavioural characteristics and how they apply to their rearing, housing, handling and experimental use. We hope reporting these methods will help ensuring welfare and well-being of spiders in captivity.
... Several behavioral adaptations were shown to be genetically determined, with differences within and between populations. These include rhythms, orientation, foraging behavior, parental care, mate preference and antipredator behavior (Pardi and Scapini, 1983;Scapini et al., 1985;Berthold et al., 1992;Sokolowski, 2001;Sinn et al., 2006;Kralj-Fišer and Schneider, 2012). Phenotypic plasticity and genetic variation may be considered as complementary attributes (Scapini et al., 1988;. ...
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Sandy beaches are severely under-represented in the literature on climate-change ecology, yet different lines of evidence suggest that the macrofauna inhabiting these narrow and dynamic environments located at the land-sea interface is being reorganized under the influence of this large scale and long-lasting stressor. This is reflected in macrofaunal sensitivity to increasing sea surface temperature, sea-level rise, extreme events and erosion of the narrow physical habitat. However, evidence of behavioral responses by sandy beach macrofauna that are consistent with expectations under climate change is scarce and fragmentary. In this paper, specific hypotheses are formulated for how behavioral adaptations in sandy beach macrofauna are predicted to respond to climate change impacts. Firstly, a conceptual framework and an overview of macrofauna behavioral adaptation features are provided. Secondly, the effects of main climate change drivers on sandy beaches are summarized. Thirdly, a conceptual framework is developed giving behavioral adaptations of sandy beach macrofauna under climate change pressure. The degree to which observations on behavioral adaptations of beach animals conform to expectations under specific climate change drivers (sea level rise, sea surface temperature, winds and storminess, rainfall, acidification and eutrophication) is explored. Taking into account the empirical evidence and the theoretical framework detailed in the paper, emergent hypotheses/predictions are proposed. Climate change drivers are expected to impact habitat features and consequently the behavioral expression of macrofauna as active responses to habitat changes. Behavioral adaptations are expected to be impaired, more variable or disrupted, thus decreasing fitness, causing local population extirpations and potentially triggering a range of cascading effects of ecological change in the beach ecosystem. Biodiversity loss will be the outcome of the negative pressures driven by climate change. The specificity of sandy beaches as narrow ecotones between sea and land may be lost under climate change pressure, adversely affecting fine-tuned macrofaunal adaptations and therefore ecosystem functioning. Strictly adapted endemic sandy beach fauna will be especially subjected to local extirpations, while species with a large reaction norm (i.e. phenotypic and behavioral plasticity) may face changes by dispersal and exploitation of new niches. Under climate change impacts, biodiversity loss is predicted, which would hamper beach ecosystem resilience. The limits to which sandy beach macrofauna responds and can behaviorally adapt to environmental change are worthy of exploration, in view of the increasing influence of the long-lasting climate driven stressors threatening these ecosystems at risk.
... Females were deemed to exhibit the subsocial strategy if only a singleton reproductive female resided in the nest, whereas females were deemed to exhibit the social strategy if two or more reproductive females cohabitated within the same next. To evaluate where females fell along the bold vs. shy axis, we transported nests back to laboratory at the University of Tennessee, Knoxville for startle tests, which are a common assay for evaluating boldness in spiders [25,31,44,52]. In brief, spiders were taken from their nests and placed within a square open field and given 30 s to acclimate. ...
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Background: Recent research has revealed that polymorphic behavioral strategies shape intra-and interspecific interactions and contribute to fitness in many animal species. A better understanding of the proximate mechanisms underlying these behavioral syndromes will enhance our grasp this phenomenon. Spiders in the genus Anelosimus exhibit inter-individual behavioral variation on several axes: individuals have consistent responses to stimuli (e.g. bold vs. shy individuals) and they are subsocial (exhibiting extended maternal care and sibling cooperation) across most of their range, but they sometimes form permanent social groups in northern temperate regions. Here, we seek genetic variants associated with boldness and with social structure in a socially polymorphic population of the spider Anelosimus studiosus. We also develop preliminary genomic resources, including a genome assembly and linkage map, that support this and future genomic research on this group. Results: Remarkably, we identify a small genomic scaffold (~ 1200 bp) that harbors seven single nucleotide polymorphisms (SNPs) associated with boldness. Moreover, heterozygotes are less common than expected based on Hardy-Weinberg equilibrium, suggesting that either assortative mating or selection against heterozygotes may be occurring in this system. We find no loci significantly associated with social organization. Our draft genome assembly allows us to localize SNPs of interest in this study and to carry out genetic comparisons with other published genomes, although it remains highly fragmented. Conclusions: By identifying a locus associated with a well-studied animal personality trait, this study opens up avenues for future research to link behavioral studies of animal personality with genotype and fitness.
... Based on these cut-off points we could identify 16 extreme piglets with an increasing slope (b > 0.06; 8 male/8 females) that had the largest increase over time and who probably became sensitized to the handling and 9 extreme piglets with a decreasing slope (b < -0.07; 5 males/4 females) which had the largest decrease over time and who probably became habituated to the handling. degree of plasticity is expected to be a crucial determinant of an individual's ability to cope with a novel and/or challenging environment (Kralj-Fišer and Schneider, 2012). As shown in our previous work (de Oliveira et al., 2015), tactile stimulation affected piglet's body weight and reduced fear towards humans. ...
Article
Individual variation in how animals react in challenging situations is an important topic since it relates to different coping strategies. Previous work with piglets has focused mainly on the backtest, which does not take into account variation within an individual in how it adapts to the challenge. Our aim was to assess individual pig’s reactions to human early handling by using different measures of individual variation, including how reactions by the same piglet change over time, and how these measures relate to piglet´s weight gain. We stroked 66 piglets on their back for two minutes each day, starting at five days of age. Piglets were scored immediately after each handling session (scale 1–4, lowest reactive to highest reactive), totalling 15 scored sessions. Individual variation was calculated by averaging the scores (AS) of all sessions and by calculating the b-coefficient (b) of linear regressions in order to assess changes in individuals over time. We assessed the relationship between these measures (AS and b) and piglet growth at 5, 9 and 12 weeks of age using generalized mixed models. We found a large variation in piglet scores, and also that there was a continuum on how individual score within a piglet varied over time (b). This measure (b) was related to the piglet’s overall weight gain (0–12 weeks of age) in that individuals who became calmer over time gained more weight than those who became more reactive over time (F = 3.87, P = 0.05). AS was positively related to weight gain, in that for each unit of increase in the reactive score, there was an increase of 1.3 kg in body weight at 9 weeks of age (F = 3.79, P = 0.05). We conclude that piglets show a large individual variation in their reaction to human handling, not only in the magnitude of their reactivity which has been shown previously, but also how their reactions change over time. For extreme individuals, this change probably implies habituating or sensitizing to the repeating handling. The change over time (b) was associated with weight gain, and we suggest that this association might be modulated by individual traits. We also suggest that individual traits interact with piglet’s developmental plasticity, which are likely influencing their ontogeny, and in turn influence the further development of the piglet. In future studies developmental plasticity measured by changes over time should be considered when assessing individual variation.
... Consistent between-individual differences in behaviour, called animal personality (Dingemanse and Wolf, 2010;Réale et al., 2007), are common across taxa and have been documented across the animal kingdom (e.g. Drent et al., 2003;Kralj-Fišer and Schneider, 2012;Réale et al., 2000). Personality traits are assumed to have a heritable, epigenetically and physiologically regulated basis (Dochtermann et al., 2015;van Oers et al., 2011). ...
Article
Consistent between-individual differences in behaviour have been documented across the animal kingdom. Such variation between individuals has been shown to be the basis for selection and to act as a pacemaker for evolutionary change. Recently, equivocal evidence suggests that such consistent between-individual variation is also present in hormones. This observation has sparked interest in understanding the mechanisms shaping individual differences, temporal consistency and heritability of hormonal phenotypes and to understand, if and to what extent hormonal mechanisms are involved in mediating consistent variation in behaviour between individuals. Here, we used zebra finches of the fourth generation of bi-directionally selected lines for three independent behaviours: aggression, exploration and fearlessness. We investigated how these behaviours responded to artificial selection and tested their repeatability. We further tested for repeatability of corticosterone and testosterone across and within lines. Moreover, we are presenting the decomposed variance components for within-individual variance (i.e. flexibility) and between-individual variance (i.e. more or less pronounced differences between individuals) and investigate their contribution to repeatability estimates. Both hormones as well as the exploration and fearlessness but not aggressiveness, were repeatable. However, variance components and hence repeatability differed between lines and were often lower than in unselected control animals, mainly because of a reduction in between-individual variance. Our data show that artificial selection (including active selection and genetic drift) can affect the mean and variance of traits. We stress the importance for understanding how variable a trait is both between and within individuals to assess the selective value of a trait.
... To ensure that the perceived threat would be somewhat similar among all animals, the same person performed every single experiment here reported, approaching the paintbrush at a similar speed and angle. Reports of comparable simulated predatory attacks are relatively common in the literature and have been successfully applied to a variety of animals, ranging from vertebrates (e.g., Snell et al., 1998) to invertebrates (e.g., Jones & Dornhaus, 2011), including spiders (e.g., Tolbert, 1975;Stankowich, 2009;Kralj-Fiser & Schneider, 2012). ...
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The handicap hypothesis predicts that more elaborate males attract more predators, but are also better able to escape attacks. Thus, a unit increase in trait elaboration has a lower cost for a high-quality male (i.e., differential cost). Although widely accepted, the handicap hypothesis has seldom been appropriately tested, especially concerning the differential cost assumption. Here, we tested this assumption using the jumping spider Hasarius adansoni. The courtship display of male H. adansoni involves bright white patches that contrast with their dark-coloured body. In experimental trials, we measured male escape capacity following a simulated predatory attack. Measurements of escape capacity were correlated to the size of white patches. Contrary to expectations, spiders with larger white patches did not exhibit better escape capacity. We conclude that this trait does not function as a handicap. It is possible that other sexual selection processes are at work.
... Finally, biological validity and importance of withinindividual behavioural variation not induced by environmental change, or in other words, the 'rigidity' of an individual's behaviour type in a certain environment (within-individual residual variation), were recognized recently (Stamps et al. 2012;Biro and Adriaenssens 2013;Briffa 2013;Briffa et al. 2013). Hence, within-individual behavioural plasticity (hereafter: behavioural plasticity) and within-individual residual variation (hereafter: residual variation) should be considered as potentially independent components of individual behavioural strategy Kralj-Fišer and Schneider 2012;Briffa 2013;Dingemanse and Wolf 2013;Westneat et al. 2013Westneat et al. , 2015Mitchell et al. 2016). However, background mechanisms affecting emergence of individual variation in behavioural plasticity and residual variation are less understood. ...
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Most studies on animal personality evaluate individual mean behaviour to describe individual behavioural strategy, while often neglecting behavioural variability on the within-individual level. However, within-individual behavioural plasticity (variation induced by environment) and within-individual residual variation (regulatory behavioural precision) are recognized as biologically valid components of individual behaviour, but the evolutionary ecology of these components is still less understood. Here, we tested whether behaviour of common pill bugs (Armadillidium vulgare) differs on the among- and within-individual level and whether it is affected by various individual specific state-related traits (sex, size and Wolbachia infection). To this aim, we assayed risk-taking in familiar vs. unfamiliar environments 30 times along 38 days and applied double modelling statistical technique to handle the complex hierarchical structure for both individual-specific trait means and variances. We found that there are significant among-individual differences not only in mean risk-taking behaviour but also in environment- and time-induced behavioural plasticity and residual variation. Wolbachia-infected individuals took less risk than healthy conspecifics; in addition, individuals became more risk-averse with time. Residual variation decreased with time, and individuals expressed higher residual variation in the unfamiliar environment. Further, sensitization was stronger in females and in larger individuals in general. Our results suggest that among-individual variation, behavioural plasticity and residual variation are all (i) biologically relevant components of an individual’s behavioural strategy and (ii) responsive to changes in environment or labile state variables. We propose pill bugs as promising models for personality research due to the relative ease of getting repeated behavioural measurements.
... Parameters are scaled (mean = 0, SD = 1) with the dots and error bars representing individual mean averages ± standard error (taken from the posteriors of the random effects from the multivariate MCMCglmm model; Table S2). Regression lines fitted to data are estimated by dividing the covariance of the traits by the variance of the trait on the x-axis (Hertel et al., 2019;Houslay & Wilson, 2017) TA B L E 3 Eigendecomposition on the between-individual covariance matrix to investigate major axis of among-individual variation ( data is that researchers can examine changes in movement parameters at an individual to quantify flexibility in personality (e.g., Betini & Norris, 2012;Briffa et al., 2008;Carere et al., 2005;Carter et al., 2013;Dingemanse et al., 2010;Frost et al., 2007;Kralj-Fiser & Schneider, 2012;Quinn & Cresswell, 2005). Statistically, this involves testing individuals' plasticity or "reaction norms" to different environments or contexts (Araya-Ajoy, Mathot, & Dingemanse, 2015;Cornwell, McCarthy, Snyder, & Biro, 2019;Dingemanse & Dochtermann, 2013). ...
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• Many animal personality traits have implicit movement‐based definitions and can directly or indirectly influence ecological and evolutionary processes. It has therefore been proposed that animal movement studies could benefit from acknowledging and studying consistent interindividual differences (personality), and, conversely, animal personality studies could adopt a more quantitative representation of movement patterns. • Using high‐resolution tracking data of three‐spined stickleback fish (Gasterosteus aculeatus), we examined the repeatability of four movement parameters commonly used in the analysis of discrete time series movement data (time stationary, step length, turning angle, burst frequency) and four behavioral parameters commonly used in animal personality studies (distance travelled, space use, time in free water, and time near objects). • Fish showed repeatable interindividual differences in both movement and behavioral parameters when observed in a simple environment with two, three, or five shelters present. Moreover, individuals that spent less time stationary, took more direct paths, and less commonly burst travelled (movement parameters), were found to travel farther, explored more of the tank, and spent more time in open water (behavioral parameters). • Our case study indicates that the two approaches—quantifying movement and behavioral parameters—are broadly equivalent, and we suggest that movement parameters can be viewed as “micropersonality” traits that give rise to broad‐scale consistent interindividual differences in behavior. This finding has implications for both personality and movement ecology research areas. For example, the study of movement parameters may provide a robust way to analyze individual personalities in species that are difficult or impossible to study using standardized behavioral assays.
... Nevertheless, some good examples emphasise the adaptive significance of consistent behavioural differences in certain spider species as compared to other species. Larinioides sclopetarius (Araneidae) easily colonize urban habitats, possibly due to personality, i.e., consistent boldness and increased activity in a novel environment (Kralj-Fišer and Schneider 2012;Kralj-Fišer et al. 2017). Besides this, certain arthropod taxa can form behavioural syndromes when behavioural traits measured in two or more functionally different ecological situations/contexts correlate with each other (Sih et al. 2004;Royauté et al. 2014;Michalko et al. 2017). ...
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Selection forces often generate sex-specific differences in various traits closely related to fitness. While in adult spiders (Araneae), sexes often differ in colouration, body size, antipredator or foraging behaviour, such sex-related differences are less pronounced amongst immatures. However, sex-specific life-history strategies may also be adaptive for immatures. Thus, we hypothesized that, among spiders, immature individuals show different life-history strategies that are expressed as sex-specific differences in body parameters and behavioural features, and also in their relationships. We used immature individuals of a protandrous jumping spider, Carrhotus xanthogramma, and examined sex-related differences. Results showed that males have higher mass and larger prosoma than females. Males were more active and more risk-tolerant than females. Male activity increased with time, and larger males tended to capture the prey faster than small ones, while females showed no such patterns. However, females reacted to the threatening abiotic stimuli more with the increasing number of test sessions. In both males and females, individuals with better body condition tended to be more risk-averse. Spiders showed no sex-specific differences in inter-individual behavioural consistency and in intra-individual behavioural variation in the measured behavioural traits. Finally, we also found evidence for behavioural syndromes (i.e. correlation between different behaviours), where in males only the activity correlated with the risk-taking behaviour, but in females all the measured behavioural traits were involved. The present study demonstrates that C. xanthogramma sexes follow different life-history strategies even before attaining maturity.
... This group is considered to depend strongly on the structure of vegetation and the diversity and density of prey (Miyashita et al. 1998;Mader et al. 2016). However, there is growing evidence of plasticity in site selection in urban habitats (Kralj-Fisêr and Schneider 2012;Lowe et al. 2014). We have observed in urban sites orb web weavers attaching their webs to wire mesh, concrete or brick walls, lighting poles, and other artificial features in parks. ...
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Spiders, natural enemies of several insects of economical and sanitary relevance, are sensitive to anthropogenic disturbances. Urban habitats, home to nearly half of the world’s human population, are growing in number and size. Consequently, natural habitats are lost and impervious surfaces increase. We compared the overall spider species and guilds assemblage characteristics associated with vegetation, between sites located within different urbanisation levels (urban and suburban) and in relation to local and landscape traits. The most abundant guilds were sheet web weavers and ambush hunters. The overall richness of spiders and richness and abundance of two guilds (space web weavers and stalker hunters) were higher in suburban than urban sites. The overall spider abundance, Shannon-Weaver diversity and the Shannon evenness index did not change between urban and suburban sites. While the species composition differed between urban and suburban sites, comprising the urban spider species a subset of those found in the suburban pool. Species abundances were negatively related with the percentage of bare ground, canopy cover, and urban level. Richness was positively related to low vegetation. Guilds’ responses differed concerning their life histories. At a landscape level, high consolidation (impervious surface) degree surrounding the green patches had negative effects while medium values had positive effects. Higher diversity was associated with intermediate mixtures of vegetation and impervious cover. In conclusion, the spider’s community and guild characteristics were associated with environmental, landscape and local factors through the urbanised landscape.
... Spiders are characterised by high ecological plasticity and, as key predators in the ecosystem, play a crucial role in natural and urban habitats (Turnbull 1973;Riechert 1974;McIntyre 2000;Kralj-Fišer and Schneider 2012). Their reaction on urbanisation is highly species specific and depends on the individual nature of the city. ...
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Increased urbanisation is leading to littering of the environment. However, some animals may adapt to live in such altered habitats. The aim of this study was to assess whether discarded containers can serve as a suitable microhabitat for spiders. The study was conducted in 10 woodland areas in the city of Wrocław, Poland. In September 2018, a total of 939 containers were collected, of which 33.5% contained evidence of spiders having resided therein: webs, dead or living spiders, exuviae or cocoons. A total of 22 species and several other taxa that could not be recognised so accurately were detected. The most common of these belonged to Linyphiidae and Theridiidae. Juveniles (N = 103) dominated over adults (N = 58), and females (N = 34) were more numerous than males (N = 24). In 15 containers , interspecies pairs were found. Among ecological guilds, sheet web spiders dominated (60%) followed by space web spiders (24%), ground hunters (9%), ambush hunters (3%), specialists (3%), and other hunters (2%). Spiders were significantly more often found in colourless (38.3%) and green (35.5%) than in brown bottles (25.2%). They were also more numerous in glass bottles for sweet drinks (50.0%) than in beer bottles (28.0%), and slightly more frequent than in glass vodka bottles (33.3%). Our study showed that discarded containers are fully exploitable microhabitats for spiders and are used by these animals for at least three different purposes: hunting, hiding and breeding, however the effect on their fitness remains unknown.
... However, again there was a weak trend for spiders showing attack behaviour in response to the tuning forks to have larger webs, although an opposite trend was found in response to the wire. Our findings are supported by a previous study relating female aggressiveness towards males and prey in the araneid spider Larinioides sclopetarius (Clerck, 1757), which found that aggressiveness was largely independent of female size [42]. ...
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Spiders and their webs are often used as model organisms to study a wide range of behaviours. However, these behavioural studies are often carried out in the laboratory, and the few field studies usually result in large amounts of video footage and subsequent labour-intensive data analysis. Thus, we aimed to devise a cost- and time-effective method for studying the behaviour of spiders in the field, using the now almost forgotten method of stimulating webs with tuning forks. Our study looked at the viability of using 256 Hz and 440 Hz tuning forks to stimulate, anti-predatory and predatory responses in the orb web spider Metellina segmentata, respectively. To assess the consistency of the behaviours produced, we compared these to direct mechanical stimulation with a metal wire. The results suggest that the tuning forks produce relatively consistent behaviours within and between two years in contrast to the metal wire. We furthermore found no significant effects of spider length or web area on spider reaction times. However, we found significant differences in reaction times between escape and prey capture behaviours, and between tuning forks and the wire. Thus, we demonstrated the potential of tuning forks to rapidly generate quantitative data in a field setting.
... Specifically, territoriality is lower, and territory sizes larger, where resource availability is lower (Justino et al. 2012;Mazzamuto et al. 2020). Individuals that persist in changed environments may do so because they show a high degree of behavioural plasticity, i.e. have shifted their levels of aggression and exploration, and/or because the population of persisting individuals show specific, consistent variation in behaviour, i.e. specific personality types (Kralj-Fišer and Schneider 2012). To reveal how differences in behaviour within and between individuals can affect responses to environmental change and how that alters the frequency of different behaviours within a population through plasticity or selection, or a combination of both , we must move beyond exploring behaviours in isolation and consider explicitly how multiple behaviours are correlated, and thus potentially trade-off against one another, in different contexts (Dall et al. 2004;Sih et al. 2004). ...
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Marine environments are subject to increasing disturbance events, and coral reef ecosystems are particularly vulnerable. During periods of environmental change, organisms respond initially through rapid behavioural modifications. Whilst mean population level modifications to behaviour are well documented, how these shifts vary between individuals, and the relative trade-offs that are induced, are unknown. We test whether the frequency and time invested in different behaviours varies both between and within individuals with varying resource availability. To do this, we quantify differences in four key behavioural categories (aggression, exploration, feeding and sociability) at two sites of different resource availability, using an obligate corallivore butterflyfish species (Chaetodon lunulatus). Individuals on a low resource site held larger territories, investing more time in exploration, which was traded off with less time invested on aggression, feeding and sociability. Repeatability measures indicated that behavioural differences between sites could plausibly be driven by both plasticity of behaviour within individuals and habitat patchiness within feeding territories. By combining population-level means, co-correlation of different behaviours and individual-level analyses, we reveal potential mechanisms behind behavioural variation in C. lunulatus due to differences in resource availability. Significance statement Using observational methods, we identify differences in the behaviour of an obligate corallivorous butterflyfish (Chaetodon lunulatus) between a high and a low resource site. We use a combination of density surveys, territory mapping and behavioural observation methods in a comparative analysis to relate behaviour directly to the environment in which it occurs. Bringing together insights from game theory and optimal foraging, we also use our results to highlight how understanding the correlations of different behaviours can inform our understanding of the extent to which behaviours are plastic or fixed. Furthermore, by considering how multiple behaviours are correlated, we move away from exploring individual behaviours in isolation and provide an in-depth insight into how differences in behaviour both between individuals and at the population level can affect responses to declining resource availability.
... We standardized spider hunger levels by starvation for 3 days before the experiment. The prey detection distance was measured in the foraging environment to quantify the response ability of the spider to prey, i.e., the distance from the center of the spider's head and chest to the middle of the mosquito when the spider responded to the prey during predation (Kralj-Fišer and Schneider, 2012;Philip and Shillington, 2010) (Fig. 1D). The experiment was recorded using a video camera (DSCRX1, Sony, Japan). ...
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Many studies have explored the effects of plastic particles on aquatic organisms. To date, however, few studies have reported on the effects of plastic particles on terrestrial invertebrates. Here, Culex quinquefasciatus (southern house mosquito, prey) and Pardosa pseudoannulata (wolf spider, predator) were used to explore the transmission of nanoplastics (NPs) from aquatic to terrestrial invertebrates and to verify the effects of NPs in prey on predators. Mosquito larvae were exposed to 0, 200, and 1000 NPs mL⁻¹ polystyrene, respectively, and then fed to spiders when they matured. Results showed that ingestion of NP-exposed mosquitoes affected the growth, development, and behavior of P. pseudoannulata, and the intestinal tissue structure, intestinal flora composition, and related enzymatic activities were also impacted. These results indicate that after spiders ingested NP-exposed mosquitoes, their growth, development, and predation ability were affected. This may prolong time to maturation and decrease the ability of spiders to survive and reproduce in the environment. Thus, plastic particles likely have a wide range of effects on organisms as well as the whole ecosystem.
... In S. tropicalis three different behavioural syndromes have been observed: bold, shy, and intermediate (Videlier et al., 2014). These three syndromes were moreover identified for both sexes (Videlier et al., 2015 Bell, 2007;Frost et al., 2007) with a curiosity to explore (Von Merten & Siemers, 2012) and are generally more aggressive (Kralj-Fišer & Schneider, 2012) compared to shy individuals. Despite the consistency of individuals in their behavioural response, intra-individual variation can been observed ( Dingemanse et al., 2007;Highcock & Carter, 2014). ...
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Behavioural plasticity is important for survival and to adapt to a dynamic environment. However, it is known that many animals exhibit fixed behavioural responses termed behavioural syndromes. That said, even when exhibiting such fixed behavioural responses, animals still show variability in their behaviour. We here evaluate the variability in exploration behaviour in the frog Silurana (Xenopus) tropicalis by quantifying two different metrics of variability: the absolute difference between two sets of measurements, and the individual stability statistic. Our results show differences in the intra-individual variability between groups of frogs that can be assigned to different behavioural syndromes. Marked differences in variability also occur between males and females, with males being more stereotyped in their responses. Frogs identified as belonging to different behavioural groups (i.e. shy, intermediate, and bold) differed in the variability of the expression of these strategies, with bold individuals being more stereotypic in the exploration of an identical, novel environment. These observations may have implications for the evolution of behaviour in natural populations.
... Behavioral flexibility is a key mechanism that can enable animals to cope with rapid human-induced environmental changes and can even allow them to thrive in heavily modified habitats like cities (Candolin and Wong 2012;Sol et al. 2013;van Baaren and Candolin 2018). Commonly reported behavioral shifts in response to novel anthropogenically driven conditions, such as urban landscapes or extra-limital introductions, include increases in activity (e.g., Pintor et al. 2008;Pintor and Sih 2009;Philpott et al. 2019), aggression (e.g., Pintor et al. 2008;Evans et al. 2010;Kralj-Fišer and Schneider 2012), boldness (e.g., Atwell et al. 2012;Batabyal et al. 2017;Hewes and Chaves-Campos 2018;Damas-Moreira et al. 2020;Mazza et al. 2020), and tendency to explore (e.g., Thompson et al. 2018;Damas-Moreira et al. 2019;Oliveira et al. 2020), but can vary between taxa and locations. Research on why these behavioral shifts occur indicates that urban-adapted and/or invasive populations can achieve higher growth rates and reproductive output in anthropogenically modified habitats (Peach et al. 2008;Pintor and Sih 2009; Sargent and Lodge 2014; Putman and Tippie 2020; Thawley and Kolbe 2020) by using novel ecological opportunities (e.g., González-Bernal et al. 2012;González-Bernal et al. 2016;Thawley and Kolbe 2020) and outcompeting native species (e.g., Pintor and Sih 2009;Damas-Moreira et al. 2020) while benefitting from reduced predation pressure (Brownscombe and Fox 2013;Eötvös et al. 2018;Westrick et al. 2019) and higher resource availability (Lowry et al. 2013;Tryjanowski et al. 2015;Hradsky et al. 2017); however, many questions remain regarding how these behavioral adaptations arise. ...
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Animals are increasingly challenged to respond to novel or rapidly changing habitats due to urbanization and/or displacement outside their native range by humans. Behavioral differences, such as increased boldness (i.e., propensity for risk-taking), are often observed in animals persisting in novel environments; however, in many cases, it is unclear how these differences arise (e.g., through developmental plasticity or evolution) or when they arise (i.e., at what age or developmental stage). In the Guttural Toad (Sclerophrys gutturalis), adult urban toads from both native and invasive ranges are bolder than conspe- cifics in natural habitats. Here, we reared Guttural Toad tadpoles in a common garden experiment, and tested for innate differences in boldness across their development and between individuals whose parents and lineage came from rural-native, urban-native, and urban-invasive localities (i.e., origin populations). Tadpoles did not differ in their boldness or in how their boldness changed over ontogeny based on their origin populations. In general, tadpoles typically became less bold as they aged, irrespective of origin population. Our findings indicate that differences in boldness in free-living adult Guttural Toads are not innate in the tadpole stage and we discuss three possible mechanisms driving phenotypic divergence in adult boldness for the focus of future research: habitat-dependent developmental effects on tadpole behavior, decoupled evolution between the tadpole and adult stage, and/or behavioral flexibility, learning, or acclimatization during the adult stage.
... Consistent among-individual variation in behavior (i.e., 'animal personality'), is a common feature of some invertebrate taxa including spiders (Kralj-Fiser and Schneider, 2012), aphids (Schuett et al., 2011), crickets (Rose et al., 2017), beetles (Schuett et al., 2018), bumblebees (Muller et al., 2010) and hermit crabs (Briffa et al., 2008). Behavior can vary as a result of differences in condition, energy reserves and size, and may lead to distinct and predictable responses by individuals that reflect different optimal behaviors within the same environment (Houston and McNamara, 1999;Mangel and Stamps, 2001). ...
Article
Animal personality can affect individual fitness and the dynamics of populations. This study tested variation in risk-avoiding (emergence from shells) and risk-taking behaviors (abandoning shells) within a cohort of hermit crabs (Clibanarius vittatus) under a range of environmental stimuli. The startle response (SR) of individuals to predators (negative stimuli) and cues that signal new shells (positive stimuli) was measured under contrasting scenarios of shell condition (intact vs. damaged). The abandonment response (AR) of the same individuals was then measured following entrapment to further test consistency in individual behavior. SR varied according to stimuli and shell condition, with individuals showing a faster response to predators when inhabiting intact shells, than damaged shells that made them more vulnerable. Interestingly, the response to gastropod cues was faster when individuals were in damaged shells, possibly reflecting greater motivation to investigate new resources. When assessing the SR of individual subjects, strong correlations were observed across the different trial combinations (14 out of the 15), suggesting that the behavior of an individual under one set of treatment conditions, is a good predictor of its behavior under other conditions. AR similarly varied with shell condition, with crabs more likely to abandon damaged, rather than intact shells. Multivariate analysis linking these suites of behaviors (predator SR + gastropod SR + entrapment AR) highlighted consistent among individual variation in behavior driven by distinct responses to stimuli. Overall, we show that hermit crabs can exhibit unique personality traits that will influence their survival and fitness in environments where predation risk and resource availability vary over short spatial and temporal scales.
... For example, an increase in boldness (i.e., an individual's propensity to take risks) is favored in some urbanized songbirds (Evans et al. 2010;Holtmann et al. 2017) and lizards (Pellitteri-Rosa et al. 2017;Baxter-Gilbert et al. 2019), and so too promotes invasion success within populations of crayfish (Pintor et al. 2008), fish (Rehage and Sih 2004;Myles-Gonzalez et al. 2015), lizards (Short and Petren 2008;Damas-Moreira et al. 2019), and rodents (Malange et al. 2016). Other examples of shifts in specific behavioral traits, like increased activity level, aggression, exploration, and neophilia, have been similarly observed in species living in either urban (Evans et al. 2010;Kralj-Fišer and Schneider 2012;Thompson et al. 2018) or invasive populations (Rehage and Sih 2004;Myles-Gonzalez et al. 2015;Damas-Moreira et al. 2019). Of course, these changes in behavior do not always consistently trend in the same direction, with examples of decreased levels of boldness (Putman et al. 2020) and increased neophobia (Miranda et al. 2013) occurring in some urban populations, as well as instances where no differences are shown for certain phenotypes (e.g., increased boldness in urban populations, but no differences in exploration and neophilia between urban and rural populations; Baxter-Gilbert et al. 2019). ...
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Many biological invasions occur within and between urban areas. If native species adapted to anthropogenically altered habitats are subsequently moved from an urban area in their native range to one within a novel region, then their urban-specialized phenotypes may provide them an advantage via prior adaptation. Here we examine if urban-derived behavioral traits are present within native guttural toad, Sclerophrys gutturalis, populations (Durban, South Africa) and investigate whether these localized phenotypes persisted within their invasive populations in Mauritius and Réunion. In our study, we measured boldness and exploration in populations along the toad’s invasion route and found that toads were significantly bolder in urban populations, within both native and invasive ranges. This suggests boldness increased when toads transitioned to urban living in their native range and these heightened levels of boldness were maintained within invaded urban areas. This provides evidence that a bolder phenotype was a prior adaptation that likely increased guttural toad’s invasion success. Interestingly, toad boldness returned to pre-urbanization levels within invasive populations that spread into natural areas, replicated on both islands. Exploration, on the other hand, was not increased above pre-urbanization, or pre-invasion, levels for any of the populations, and was lower in toads from Mauritius. Overall, our findings suggest that increased boldness is favored in urban habitats and that urban-derived behavioral traits may provide individuals an advantage when invading new urban landscapes. Significance statement Species adapting to anthropogenic landscapes have the ability to increase their invasive potential if the altered phenotypes they accrue can provide them advantages once they are transported outside their native range. Our study examined differences in behavioral traits, boldness, and exploration, along the invasion route of guttural toads, Sclerophrys gutturalis, between natural and urban sites from their native origin populations around Durban, South Africa, to their invasive populations in Mauritius and Réunion. We determined that populations were bolder in urban areas in their native range and that this increased boldness persisted in the other anthropogenic habitats within their invasive ranges, but reverted back to natural-native levels within populations that had spread into natural areas on both islands. Our findings support the growing trend that anthropogenically altered landscapes favor bolder individuals, as well as the assertion that urban-derived traits may bolster a species’ ability to establish and spread within novel landscapes.
... Yet, urban/rural behavior differences (e.g. urban bridge spiders have higher measures of boldness and voracity as compared to wild-caught spiders, Kralj-Fišer and Schneider 2012), are not full evidence of behavioral plasticity. Evidence that behavior actually shifts for individuals according to urban variables is less common. ...
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Urbanization can compromise biodiversity as cities expand further into native landscapes. The urban heat island (UHI) describes elevated urban temperatures due to heat retained by built structures (e.g. concrete surfaces). Animal behavior may be critical in determining an animal’s ability to thrive in the wake of human disturbance. Yet, we have a relatively poor understanding of how animal behavior is affected by the UHI. We examined sibling cannibalism in urban and desert juvenile black widow spiderling (Latrodectus hesperus) lineages exposed to extreme UHI temperatures (33 °C) or native Sonoran desert temperatures (27 °C). Family of origin had a significant impact on cannibalism, while the effects of temperature and habitat were dependent on spiderling density. Our most pronounced results came at the lower densities of three and two spiderlings. Here habitat and temperature interacted such that spiderlings at 33 °C were consistently more cannibalistic than spiderlings at 27 °C, and this result was consistently stronger for spiderlings from urban families than it was for spiders from desert families. If UHI-induced siblicide promotes the survival and growth of a subset of spiderlings from a clutch, then it might actually foster urban population growth. In contrast, if siblicide in the city simply reduces clutch size, then we might expect the UHI to slow urban infestations. Understanding behavioral phenotypes underlying the explosive population growth of urban pest species will aid in the development of safer and more effective deterrents to infestations, and allow us to better understand the mechanisms shaping urban biodiversity patterns.
... Individuals within a population can differ in prey preferences or the ability to evaluate prey characteristics. In addition, individuals can differ in foraging aggressiveness (Bolnick et al. 2003;Kralj-Fišer and Schneider 2012;Michalko and Pekár 2014). Therefore, individuals within a population of a generalist predator can differ in the key trophic functional traits that drive predator-prey interactions, and these interindividual differences can significantly affect ecological dynamics on the scale of the whole community (Bolnick et al. 2011;Royauté and Pruitt 2015). ...
Chapter
This proceedings contains papers dealing with issues affecting biological control, particularly pertaining to the use of parasitoids and predators as biological control agents. This includes all approaches to biological control: conservation, augmentation, and importation of natural enemy species for the control of arthropod targets, as well as other transversal issues related to its implementation. It has 14 sessions addressing the most relevant and current topics in the field of biological control of arthropods: (i) Accidental introductions of biocontrol agens: positive and negative aspects; (ii) The importance of pre and post release genetics in biological control; (iii) How well do we understand non-target impacts in arthropod biological control; (iv) Regulation and access and benefit sharing policies relevant for classical biological control approaches; (v) The role of native and alien natural enemy diversity in biological control; (vi) Frontiers in forest insect control; (vii) Biocontrol marketplace I; (viii) Weed and arthropod biological control: mutual benefits and challenges; (ix) Maximizing opportunities for biological control in Asia's rapidly changing agro-environments; (x) Biological control based integrated pest management: does it work?; (xi) Exploring the compatibility of arthropod biological control and pesticides: models and data; (xii) Successes and uptake of arthropod biological control in developing countries; (xiii) Socio-economic impacts of biological control; (xiv) Biocontrol marketplace II.
Article
Although flexibility in behavior is adaptive, this flexibility is limited, and the extent of variation and consistency of a trait could depend on the environment. In this study, we investigated repeatability in risk-taking during feeding among individuals and agonistic interactions among dyads of wild zebrafish, Danio rerio, collected from two habitats that differed in predation and flow regimes. We measured boldness as the latency to emerge from a shelter and feed in the presence of predators. We tested this for each individual from the two populations repeatedly across seven trials. We assessed aggression by subjecting size- and sex-matched pairs of fish to dyadic contests repeatedly across seven trials. Individuals from the high-predation stream population were bolder than individuals from the low-predation stagnant water population. Males were bolder than females, and in the low-predation population, larger individuals took greater risks to feed than smaller individuals. The high-predation stream population showed lower inter- and intraindividual variation in boldness than the low-predation stagnant water population. Further, both populations showed significant repeatability in risk-taking during feeding. The high-predation stream habitat fish were more aggressive than low-predation stagnant-water fish. Male dyads from the low-predation stagnant-water population were significantly more aggressive than female dyads. Most fish from the low-predation stagnant water population did not show aggressive behavior, resulting in low between-dyad but high within-dyad variation in aggression. The difference in behavioral responses between the populations and consistency in these traits within individuals is discussed in the light of confounding role of ecological and state-dependent factors.
Article
Personality defined as individual differences in behavioural traits, which are consistent through time and across situations, has been observed among individuals of the same population in several animal groups. However, it is well known that as selective pressures may act upon behaviour, they can potentially drive differences in personality; in this sense, the breeding season may function as a promotor of differences between males and females that allow them to maximize their fitness. Nevertheless, results from studies comparing differences in personality between males and females are still non‐conclusive. Therefore, we aimed to test the presence of differences in personality between males and females during the breeding season by evaluating the consistency over time and across situations of three behavioural traits in the black‐bellied bunch grass lizard Sceloporus aeneus. We found that males were more risk‐prone and active than females, whereas aggression was similar between sexes. Personality traits were observed in both sexes throughout the breeding season; however, they were more consistent in females than in males. Specifically, personality in males is characterized by higher levels of activity, boldness and aggressiveness; whereas females behave more cautiously, although aggressively when confronted with other females. Our results suggest that the personality differences between males and females observed in Sceloporus aeneus may be expressed to secure individual current reproductive value, and to enhance their fitness success.
Article
Vertical asymmetry is a widespread feature of orb webs, with the lower part larger than the upper, although its adaptive value is not fully understood. Gravity is thought to play a major role in the generation of asymmetry through increased running speed downwards from the hub. The relationship between spider orientation and gravity has been relatively well studied. However, webs' inclination from vertical has been less studied. Here we conducted a field study on the tetragnathid orb spider Metellina mengei Blackwall, 1869, which constructs webs that show a marked variation in inclination. Our findings revealed a significant influence of the degree of web inclination and web area on the level of vertical asymmetry, while environmental variables did not have any effect. Thus, our results support the hypothesis that the asymmetry in upwards and downwards running speeds due to gravity is an important determinant of web asymmetry. © 2018 American Museum of Natural History. All rights reserved.
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One of the strongest driving forces of evolution is environmental change. Within the modern era, some of the most rapid environmental change has occurred as a result of urbanisation. As such, recent research aims to understand how species are adapting to urban landscapes (urban evolution) and how natural selection is operating in unnatural environments (anthropic selection). This goal was the cornerstone of my thesis research, using Australian water dragons (Intellagama lesueurii) to examine how the selective forces within urban environments may shape their natural histories and alter their evolutionary trajectory. I took a multidisciplinary approach to explore water dragon urban evolution, by examining traits related to their behavioural ecology (social interactions and spatial organisation, behavioural traits, and innate antipredator responses; Chapters I, II, & III respectively), morphology (body length and size; Chapter IV), and physiology performance capacity; Chapters V & VI), using both field observations and laboratory experiments. The basis of most of this thesis’ research involved contrasting traits of lizards living in, or originating from, populations varying in their levels of urbanisation (urban, semi-natural, and natural). I also examined the mechanisms that may have caused urban-derived divergence of morphological and behavioural traits (i.e., heritable traits vs phenotypic plasticity). My research identified several urban-derived divergent phenotypes, including increased rates of aggressive encounters, increased boldness, decreased body size paired with increased limb and head size, and decreased endurance capacity. My research also identified that both divergent behavioural (boldness) and morphological (body length and size) traits have a genetic origin, suggesting they are heritable and may be adaptive. Overall, this thesis provides insight into the urban evolution of water dragons in the Sydney region, and provides a framework for using a multidisciplinary approach to rigorously examine mechanistic urban ecology and evolution.
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Urbanization typically leads to habitat destruction producing negative effects for native species, but some species may exploit these settings. This concept was investigated in the golden silk spider (Nephila clavipes), a large, formidable spider that commonly inhabits forest edges as well as open spaces in urban environments throughout its vast geographic range. Here, we compared variation of N. clavipes success as measured by body size, web size and web positioning along an urban–rural gradient in southern Florida. From morphological measurements collected in the field, urban spiders had 60% longer legs and 35% longer bodies than both park and rural spiders. Furthermore, webs of urban spiders were considerably larger and constructed significantly further from the ground than those of park and rural habitats. The combined observations of body size, web measurements and prominent web placement suggest that N. clavipes are successful exploiters of urban environments relative to park and rural settings in southern Florida. Although previous research has generally focused on the negative aspects of urbanization on animal welfare, this study provides evidence suggesting N. clavipes might benefit from these environmental changes.
Article
Generalist populations are often composed of individuals each specialized on only a subset of the resources exploited by the entire population. However, the traits underlying such niche variation remain underexplored. Classically, ecologists have focused on understanding why populations vary in their degree of intraspecific niche variation, with less attention paid to how individual-level traits lead to intraspecific differences in niches. We investigated how differences in behaviour, morphology and microhabitat affect niche variation between and within individuals in two species of spider Anelosimus studiosus and Theridion murarium. Our results convey that behaviour (i.e. individual aggressiveness) was a key driver of intraspecific trophic variation in both species. More aggressive individuals capture more prey, but particularly more Coleoptera, Hymenoptera and Diptera. These findings suggest that behavioural traits play a critical role in determining individuals' diet and that behaviour can be a powerful force in driving intraspecific niche variation.
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Several factors can influence individual and group behavioral variation that can have important fitness consequences. In this study, we tested how two habitat types (seminatural meadows and meadows invaded by Solidago plants) and factors like colony and worker size and nest density influence behavioral (activity, meanderness, exploration, aggression, and nest displacement) variation on different levels of the social organization of Myrmica rubra ants and how these might affect the colony productivity. We assumed that the factors within the two habitat types exert different selective pressures on individual and colony behavioral variation that affects colony productivity. Our results showed individual-/colony-specific expression of both mean and residual behavioral variation of the studied behavioral traits. Although habitat type did not have any direct effect, habitat-dependent factors, like colony size and nest density influenced the individual mean and residual variation of several traits. We also found personality at the individual-level and at the colony level. Exploration positively influenced the total-and worker production in both habitats. Worker aggression influenced all the productivity parameters in seminatural meadows, whereas activity had a positive effect on the worker and total production in invaded meadows. Our results suggest that habitat type, through its environmental characteristics, can affect different behavioral traits both at the individual and colony level and that those with the strongest effect on colony productivity primarily shape the personality of individuals. Our results highlight the need for complex environmental manipulations to fully understand the effects shaping behavior and reproduction in colony-living species.
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Urban environments are novel landscapes that markedly alter animal behavior. Divergence in behavior in response to urbanization may provide advantages in navigation, exploiting resources, and surviving under a novel suite of selective pressures. Relatively few studies, however, have identified population-level behavioral changes in response to urbanization that are not confounded by rearing environment and prior experience (e.g., an urban upbringing). To address this, we used the Australian water dragon (Intellagama lesueurii) to test whether populations under varying levels of urbanization (urban, semi-natural, and natural populations) differ in their innate behavioral traits; acquired either heritably or due to population-specific maternal effects. Eggs were collected from wild mothers and hatched in the lab. Hatchlings were then reared in the lab under standardized conditions (a common-garden experiment). We then assayed individual behavioral traits (boldness, exploration, and neophilia) five times across their first year of development. We compared behavioral traits, as well as their expression (repeatability), between urban, semi-natural, and natural populations. Neophilia and explorative behavior was similar among all populations. However, dragons from semi-natural populations were significantly bolder than those from natural populations. Urban dragons were also bolder than dragons from natural populations, although this trend was not significant because of high variance in boldness. Dragons from semi-natural and urban populations had similar boldness scores, suggesting a potentially biologically relevant difference in boldness between them and natural populations. We also saw some differences in the consistency of the expression of behavior. Boldness in individuals from urban environments was also the only repeatable trait. Overall, our study suggests that boldness is an innate, urban-derived divergent behavioral trait that likely contributes to the success of these lizards in anthropogenically altered environments. Significance statement Lizards from human-modified areas are innately bolder than ones from natural habitats. To determine this, we raised lizards from eggs collected from urban, semi-natural, and natural populations in a standardized environment, removing the effects of prior experience and developmental environment, and examined their behavioral traits over time. The difference we found in boldness was related to their origin population, rather than being shaped through experience, suggesting this trait may be heritable and is being selected for in anthropogenic landscapes. Our study addresses an important gap in studies of urban behavioral ecology by examining behavioral differences among replicated, differently urbanized, sites after experimentally accounting for both rearing environment and prior experience.
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Identifying the traits that foster group survival in contrasting environments is important for understanding local adaptation in social systems. Here we evaluate the relationship between the aggressiveness of social spider colonies and their persistence along an elevation gradient using the Amazonian spider, Anelosimus eximius. We found that colonies of A. eximius exhibit repeatable differences in their collective aggressiveness (latency to attack prey stimuli), and that colony aggressiveness is linked with persistence in a site‐specific manner. Less aggressive colonies are better able to persist at high‐elevation sites, which lack colony‐sustaining large‐bodied prey, whereas colony aggression was not related to chance of persistence at low‐elevation sites. This suggests that low aggressiveness promotes colony survival in high‐elevation, prey‐poor habitats, perhaps via increased tolerance to resource limitation. These data reveal that the collective phenotypes that relate to colony persistence vary by site, and thus, the path of social evolution in these environments is likely to be affected. This article is protected by copyright. All rights reserved.
Article
Consistent inter-individual differences in behavior has been shown in several animal groups, ranging from vertebrates to invertebrates. One of the most studied personality traits in animals is boldness, which is the tendency to expose to risky situations. Theory proposes that individuals’ state (e.g. body energy) would influence the expression of personality traits. In this study, we tested if boldness levels of the harvestman Mischonyx cuspidatus (measured as duration of death feigning/freezing after simulated predator attack) differ between two different states, namely sated and food deprived. We also tested if the degree of repeatability in boldness is affected by the individual state. We found no differences in the levels of boldness expressed by M. cuspidatus when comparing between different conditions (sated and food deprived) at a population level. However, we found that individuals showed more consistency in boldness when sated relative to a food deprived condition. Finally, we suggest new avenues for future studies addressing personality in harvestmen.
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Sexual cannibalism is an extreme sexual conflict in which females kill and feed on males before, during or after mating. This behavior may be costly to both sexes and the net balance between the costs and benefits of sexual cannibalism depends on the timing of occurrence with regards to mating, being more relevant when none of the partners has previously mated. For the female, this is more so if she has a low expected chance of finding additional males. Sexual cannibalism can also undermine female reproductive success if polyandry (female mating with multiple males) enhances offspring viability. However, when females accrue feeding benefits from killing males and have future mating expectations with other males, sexual cannibalism becomes an extreme sexual conflict, since females may be prone to sexual cannibalism while males should attempt to escape female attacks to search for, and mate with other females, especially if the male fails to do so with the cannibalistic female. This strong conflict have puzzled researchers for one century and a half, who wonder about the evolutionary origin of sexual cannibalism and its maintenance in natural populations. Recently, a new interpretation has been put forward which sees sexual cannibalism as a behavioral syndrome by which virgin females attack males, not because of the potential nutritional benefits, but because high aggressiveness (or voraciousness) is likely favored by natural selection in a context other than sexual, as it contributes to increasing growth rates and fecundity. This then leads aggressiveness to genetically spill over into indiscriminate attacks on males. This contrasts with the evidence that females of cannibalistic species tend to attack males only when the former has achieved the sperm necessary to fertilize their eggs following mating with other males, and also runs contrary to the prediction by a published model that a female will attack males only if she is food limited. The present Ph.D. thesis contributes to answering some of these questions by using the Iberian tarantula (Lycosa hispanica) as a model organism. Sexual size in this species is relatively low, and males are therefore relatively very large prey items as compared to natural prey. In the manuscript I, the relationship between the consumption of a male and female fitness was experimentally tested using several estimates of female reproductive success. Additionally, the present work served to reveal whether sexual cannibalism is a common behavior in nature and to experimentally test whether it depends on male availability. The results of this study show first, that the experimentally-induced consumption of a male significantly increases female reproductive success relative to females not feeding on a male. Second, that sexual cannibalism is more likely to occur once females have mated with a male, and third that the rates of sexual cannibalism increase with male availability. Despite the fact that sexual cannibalism seems to be an adaptive strategy for most females, in some cases it was associated with the lack of egg fertilization, as some cannibalistic females that attacked males when the former was still virgin were unable to produce an egg sac, suggesting that spillover aggression is present in some females and that they indiscriminately attack males. In manuscript II, I investigated the relationship between the levels of female feeding voraciousness and her tendency towards pre-copulatory sexual cannibalism (spillover). The results of this study show that the probability that a virgin female attacks an approaching male increases with her voracity prior to her first mating. In addition, I demonstrated for the first time that highly aggressive females (consistent with a spillover behavioral syndrome) did not discriminate among the phenotypes of the males they killed, whereas virgin females of low voracity killed males before mating only if males had the relatively poor condition. In manuscript III, I tested the diversifying hypothesis of polyandry, according to which the offspring of polyandrous mothers are genetically (and thus phenotypically) more variable than the offspring of monandrous mothers (i.e., those mating with a single male), which could serve to cope with environmental stochasticity by favoring the survival probability of at least some offspring when the environment changes unpredictably (bet-hedging hypothesis). To this end, I analyzed field and laboratory data from two consecutive years of experiments in which females had differential access to males. The results of this study show that polyandry affects positively the variability in offspring size and growth rates, but contrary to the predictions of the bet-hedging hypothesis, the reproductive fitness of polyandrous mothers (i.e. estimated though the geometric mean fitness of spiderlings growth and survival across two feeding laboratory environments varying in prey quantity) was not significantly higher than that of monandrous mothers. In manuscript IV, we develop individual based models aimed to unveil whether two genetically-based behavioral types, aggressive spillover and plastically docile, can coexist in natural populations. The results of this study show that an alternative aggressive spillover strategy in which high aggressiveness leads to early maturation and to indiscriminate attacks to males can coexist with a strategy in which females first mate to grant sperm and subsequently attack the additional males visiting them. Analyses of field data show that both strategies can be present in a natural population of L. hispanica, and it is particularly intriguing the fact that females showing the docile strategy will not feed until they have achieved their first copulation with a male, at which moment turn into highly voracious, even more so than spillover females. These results contribute to our understanding about the evolution of animal personalities and to explaining the presence of behavioral polymorphisms in animal populations
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Urban wildlife faces a novel set of challenges resulting in selective pressure that can lead to population-level changes. We studied Australian water dragons (Intellagama lesueurii) from urban and natural populations to test if urban populations differed in body size, shape, and performance capacity. If urban-derived morphology has arisen through selection, we predicted distinct morphological differences between wild dragons from urban and natural areas in both adult and hatchling life-stages. Urban hatchlings were morphologically distinct (shorter body lengths and longer limbs) from natural populations, while urban adult males continued this trend but only for body size (shorter body lengths). We then experimentally reared hatchlings originating from urban and natural populations within urban-and natural-style enclosures (2 × 2 factorial design) for a year to determine if differences in morphology and performance capacity (sprint speed, endurance, and clinging ability) were related to either the individual's origin population or developmental environment. Yearlings reared in urban-style enclosures, irrespective of population origin, had smaller body sizes compared to those from natural-style enclosures, suggesting developmental environment was affecting their morphology. Despite this difference in body size, yearling dragon performance capacity was not significantly different between treatments. Overall, this study provides evidence of a complex relationship driving urban-divergent morphology whereby urban dragons emerge as smaller hatchlings with longer limbs (innate traits) and are then further influenced by the urban environments that they develop in (phenotypic plasticity); however, and potentially owing to behavioral, ecological, and demographical differences, these changes appear to be sex-specific.
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Consistent interindividual differences in behaviour (i.e. animal personality variation) can influence a range of ecological and evolutionary processes, including predation. Variation between individual predators in commonly measured personality traits, such as boldness and activity, has previously been linked to encounter rates with their prey. Given the strong selection on predators to respond to prey, individual predators may also vary consistently in their response to prey in a manner that is specific to the context of predation. By studying wild piscivorous fish (pike cichlids, Crenicichla frenata) in their natural environment using experimental presentations of prey and control stimuli, we show that individual predators differ consistently in the amount of time spent near prey. Crucially, these differences were not explained by the behaviour of the same individuals in control presentations (the same apparatus lacking prey), suggesting that variation in the response to prey reflects a ‘predator personality trait’ that is independent from other individual traits (body size, boldness and/or neophobia) and environmental factors. Pike cichlids that spent more time near prey also attacked prey at a higher rate. These findings imply that the likely risk posed by individual predators cannot always be adequately predicted from typically studied axes of personality variation.
Article
Successful biological invasions are characterized by the spread of a population across a landscape. Range expansion conditions can favour different phenotypes at the leading edges of the range compared to those at the core. Although Cyrtophora citricola is a non-native spider species that was documented in Florida, U.S.A. almost two decades ago, the status of its populations remains unstudied. We report two populations that have spread northward along both eastern and western coasts from a putative common origin. We asked whether the leading edges of these two range expansions are composed of different personality types compared to the original core and whether core-to-edge patterns in personality are consistent between the two replicate populations. More voracious, more exploratory and bolder spiders were predicted to occupy the leading edge, because these personality types are assumed to be associated with dispersive, successful colonizers in novel environments. While leading-edge spiders were indeed faster to respond and attack prey stimuli and active longer in novel environments compared to spiders from the core, the two populations diverged in boldness. On average, western spiders were less bold and exploratory towards newer colonization sites, whereas eastern spiders were bolder at newer sites. The divergence in exploratory behaviour and boldness between these populations highlights the difficulties in generalizing how traits may become assorted across an expanding range and stress the importance of using replicate populations when possible. These results suggest that range level processes can be inconsistent and highlight the importance of investigating how the strength of local adaptation may swamp processes such as spatial sorting.
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This article investigates inter-individual repeatability in distance moved in an open-field test for larval Limnephilus lunatus Curtis, 1834. Repeatability across four trials (two-day trial intervals) was comparable to previous studies on arthropod species (repeatabil-ity: R ¼ 0.37), indicating that L. lunatus is a suitable model species in this research field. Two potential nuisance factors were corrected for: (1) progressively declining activity over consecutive trials and (2) case mass:body mass ratio, affecting activity negatively. These factors require consideration in behavioural experiments on larval caddisflies. Pairwise correlations of distance moved among trial days showed that behaviour in the first trial did not correspond well with behaviour in the following trials. Re-analysing the data using only trials 2 to 4 increased the repeatability (repeatabil-ity: R = 0.50), suggesting that future studies should consider not including data derived from initial trials, as the initial trial may constitute a different context than the following ones.
Article
Ecology is a diverse field with many researchers interested in drivers and consequences of variability within populations. Two aspects of variability that have been addressed are behavioral and physiological. While these have been shown to separately influence ecological outcomes such as survival, reproductive success and fitness, combined they could better predict within-population variability in survival and fitness. Recently there has been a focus on potential fitness outcomes of consistent behavioral traits that are referred to as personality or temperament (e.g. boldness, sociability, exploration, etc.). Given this recent focus, it is an optimal time to identify areas to supplement in this field, particularly in determining the relationship between temperament and physiological traits. To maximize progress, in this perspective paper we propose that the following two areas be addressed: (1) increased diversity of species, and (2) increased number of physiological processes studied, with an eye toward using more representative and relatively consistent measures across studies. We first highlight information that has been gleaned from species that are frequently studied to determine how animal personality relates to physiology and/or survival/fitness. We then shine a spotlight on important taxa that have been understudied and that can contribute meaningful, complementary information to this area of research. And last, we propose a brief array of physiological processes to relate to temperament, and that can significantly impact fitness, and that may be accessible in field studies.
Thesis
Une approche prometteuse pour améliorer l’utilisation des agents de lutte biologique en protection des cultures repose sur la prise en compte de leurs variations intra-spécifiques sur des traits liés aux capacités des agents de lutte à être élevés en masse ou à contrôler les ravageurs au champ. Dans ce contexte, les variations comportementales interindividuelles qui sont stables au cours du temps et des situations (appelées aussi personnalité) n’ont jamais été considérées dans les programmes de lutte biologique, alors qu’elles (i) peuvent être héritables et (ii) sont corrélées à des traits liés à la valeur sélective et peuvent donc impacter l’efficacité des auxiliaires des cultures. Les deux objectifs majeurs de cette thèse étaient (i) de développer des protocoles expérimentaux permettant de mesurer les traits de personnalité chez l’auxiliaire de lutte biologique parasitoïdes d’œufs Trichogramma evanescens, et (ii) d’évaluer la faisabilité et l’intérêt de l’utilisation des phénotypages de personnalité dans des programmes d’amélioration génétique de cet auxiliaire : estimer l’héritabilité des traits de personnalité et étudier leurs relations avec des traits liés à la fitness et aux performances de lutte biologique. Dans ce but, nous avons développé un protocole de suivi vidéo permettant de mesurer des traits de personnalité et avons pu caractériser des traits liés à la personnalité (mais également la fécondité, la longévité et la taille) sur plus de mille femelles issues de 24 lignées isogéniques de T. evanescens. Nous avons mis en évidence pour la première fois chez cette espèce l’existence de variations interindividuelles stables dans des traits comportementaux liées à l’audace, à l’activité et à l’exploration. Nous avons montré des différences de personnalité entre les 24 lignées isogéniques utilisées, ce qui souligne que les variations comportementales observées ont une part d’origine génétique (les valeurs d’héritabilité au sens large que nous avons estimées varient de 0,06 à 0,11). Nous avons également mis en évidence l’existence d’un compromis évolutif (ou trade-off) entre l’exploration et la fécondité chez ces lignées. Nous avons ensuite mené des expérimentations dans des champs de maïs, sur 38 points de lâchers, afin d’attribuer à ces lignées des variables liées à leurs mouvements et parasitisme sur le terrain, comme le nombre d’agrégats d’œufs hôtes parasités et les distances moyenne et maximale observées le point de lâcher et les sites de ponte. Nos résultats suggèrent que la personnalité a un effet sur la distance entre point de lâcher et site de ponte chez T. evanescens sur le terrain, alors que nous n’avons observé aucun effet des variables liées à des traits classiquement considérés dans les programmes de lutte biologique (fécondité, longévité et taille). Pour conclure, nous avons pour la première fois évalué le lien entre des traits de personnalité mesurés en laboratoire et le mouvement d’un auxiliaire de lutte biologique sur le terrain, et nous discutons des perspectives d’études à venir et de développements nécessaires pour permettre d’intégrer les traits de personnalité dans les programmes de sélection des auxiliaires de lutte biologique dans le but d’augmenter l’efficacité de ces derniers.
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Animal personalities and behavioural syndromes have overarching implications for in�dividual survival, fitness and cooperative task participation. In social spiders, person�ality in boldness and aggression, and their association into behavioural syndromes, are thought to play a role in individual participation and task specialisation in collective behaviours, such as prey capture. However, recent retractions of key publications in this field have exposed gaps and uncertainties in our understanding of factors govern�ing task performance in social spider colonies. Here, we analyse an already-published data set on animal personalities in the Indian social spider Stegodyphus sarasinorum to investigate whether boldness and aggression form a behavioural syndrome and assess its persistence over the short- and long-term, and across age classes. Boldness and aggression were negatively correlated traits, forming a syndrome, but only over the long-term in subadult spiders, and not over the short-term in subadults or in juveniles. These results provide evidence for the existence of a behavioural syndrome in at least one social spider species. However, more work is now required to fully understand the observed inconsistencies in behavioural syndrome structures and animal person�alities, as well as their possible role(s) in mediating task partitioning and collective performance in social spider colonies.
Article
Expanding populations are often characterized by phenotypic shifts across the range. Processes like spatial sorting predict that phenotypes may be distributed along a range based on dispersal ability, where the most dispersive individuals are found at the leading edges and the least dispersive remain at the population core. Thus, traits correlated to dispersal may also become spatially distributed in the same pattern. Cyrtophora citricola is an orb-web spider with two expanding populations originating from the same core in its non-native Florida range. Since spiders at the leading edges were previously found to differ in various personality traits from those at the core, we measured dispersal latency and likelihood in laboratory-raised spiderlings to determine whether spatial sorting can account for these patterns. Only one of the two populations showed evidence of spatial sorting, suggesting this phenomenon is likely context dependent and is not always generalizable to expanding populations. Spiders from the leading edge of the eastern population were more dispersive than those at the core, although western spiders were the least dispersive of the three populations. Dispersal likelihood was correlated with the activity and exploratory tendencies of individuals. Population-level differences we had previously observed for foraging aggression and activity were not found in the captive-raised spiders, suggesting that they represent plastic responses to environmental conditions instead of being a result of dispersal-correlated trait evolution. However, mean population-level differences in exploration and boldness were maintained in captivity, suggesting that these behaviors have a heritable component. Overall, the eastern spiders were characterized as being bolder, whereas the western spiders were the least bold and exploratory. While this study provides evidence of spatial sorting of more dispersive, exploratory, and active individuals in the eastern population, the divergence in risk-taking behaviors between the two populations highlights the potential context dependency in spatial sorting and the importance of understanding the interactions between natural and spatial selection.
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Invertebrates comprise the most diversified animal group on Earth. Due to their long evolutionary history and small size, invertebrates occupy a remarkable range of ecological niches, and play an important role as “ecosystem engineers” by structuring networks of mutualistic and antagonistic ecological interactions in almost all terrestrial ecosystems. Urban forests provide critical ecosystem services to humans, and, as in other systems, invertebrates are central to structuring and maintaining the functioning of urban forests. Identifying the role of invertebrates in urban forests can help elucidate their importance to practitioners and the public, not only to preserve biodiversity in urban environments, but also to make the public aware of their functional importance in maintaining healthy greenspaces. In this review, we examine the multiple functional roles that invertebrates play in urban forests that contribute to ecosystem service provisioning, including pollination, predation, herbivory, seed and microorganism dispersal and organic matter decomposition, but also those that lead to disservices, primarily from a public health perspective, e.g., transmission of invertebrate-borne diseases. We then identify a number of ecological filters that structure urban forest invertebrate communities, such as changes in habitat structure, increased landscape imperviousness, microclimatic changes and pollution. We also discuss the complexity of ways that forest invertebrates respond to urbanisation, including acclimation, local extinction and evolution. Finally, we present management recommendations to support and conserve viable and diverse urban forest invertebrate populations into the future.
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Males and females are often subjected to different selection pressures for homologous traits, resulting in sex-specific optima. Because organismal attributes usually share their genetic architectures, sex-specific selection may lead to intralocus sexual conflict. Evolution of sexual dimorphism may resolve this conflict, depending on the degree of cross-sex genetic correlation (rMF) and the strength of sex-specific selection. In theory, high rMF implies that sexes largely share the genetic base for a given trait and are consequently sexually monomorphic, while low rMF indicates a sex-specific genetic base and sexual dimorphism. Here, we broadly test this hypothesis on three spider species with varying degrees of female-biased sexual size dimorphism, Larinioides sclopetarius (sexual dimorphism index, SDI = 0.85), Nuctenea umbratica (SDI = 0.60), and Zygiella x-notata (SDI = 0.46). We assess rMF via same-sex and opposite-sex heritability estimates. We find moderate body mass heritability but no obvious patterns in sex-specific heritability. Against the prediction, the degree of sexual size dimorphism is unrelated to the relative strength of same-sex versus opposite-sex heritability. Our results do not support the hypothesis that sexual size dimorphism is negatively associated with rMF. We conclude that sex-specific genetic architecture may not be necessary for the evolution of a sexually dimorphic trait.
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Rapid urbanization has become an area of crucial concern in conservation owing to the radical changes in habitat structure and loss of species engendered by urban and suburban development. Here, we draw on recent mechanistic ecological studies to argue that, in addition to altered habitat structure, three major processes contribute to the patterns of reduced species diversity and elevated abundance of many species in urban environments. These activities, in turn, lead to changes in animal behavior, morphology and genetics, as well as in selection pressures on animals and plants. Thus, the key to understanding urban patterns is to balance studying processes at the individual level with an integrated examination of environmental forces at the ecosystem scale.
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An increasing number of studies report the presence of consistent individual differences in behavior and/or physiology over time and context, known as animal personality. A pivotal question in animal personality research concerns the mechanism(s) responsible for its evolution and maintenance. Negative frequency–dependent selection is considered to be one of these important mechanisms, although evidence for this is largely absent. Here, we studied whether the feeding performance of barnacle geese was negative frequency-dependent in a producer–scrounger game. We studied the feeding time of one bold or one shy individual in groups consisting of only bold or shy companions to study if the rare type in the group performs best. A previous study with this species showed that scrounging increased with shyness. Hence, we expected shy individuals to do better in the presence of bold companions due to the increased scrounging opportunity and bold individuals to do better in the presence of shy companions as there were ample opportunities to produce food. We found no evidence for negative frequency–dependent feeding success; rather, we found that, independent of their boldness score, all individuals enjoyed higher feeding success when foraging with bold than with shy companions. The higher foraging success of individuals foraging with bold companions is explained by a higher joining proportion in the presence of bold companions. Our results provide no evidence for negative frequency– dependent feeding success in barnacle geese but indicate that both bold and shy individuals can increase their foraging returns by associating with bold individuals.
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Arthropod generalist predators (AGP) are widespread and abundant in both aquatic and terrestrial ecosystems. They feed upon herbivores, detritivores, and predators, and also on plant material and detritus. In turn, AGP serve as prey for larger predators. Several prominent AGP have become invasive when moved by humans beyond their native range. With complex trophic roles, AGP have diverse effects on other species in their introduced ranges. The invaders displace similar native species, primarily through competition, intraguild predation, transmission of disease, and escape from predation and/or parasites. Invasive AGP often reach higher densities and/or biomass than the native predators they replace, sometimes strengthening herbivore regulation when invasive AGP feed on key herbivores, but sometimes weakening herbivore suppression when they eat key predators. The complexity and unpredictability of ecological effects of invasive AGP underscores the high risk of adverse consequences of intentional in...
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The relative contribution of genetic and non-genetic factors in shaping personality traits is of fundamental relevance to biologists and social scientists. Individual animals vary in the way they cope with challenges in their environment, comparable with variation in human personalities. This variation has a substantial genetic basis. Here we describe experiments showing the strength of environmental factors (food availability and sibling competition) in shaping personality traits in a passerine bird (Parus major). We manipulated the early rearing condition in two lines (F4) bidirectionally selected for different personalities (fast line: high exploration speed and high aggression; slow line: low exploration speed and low aggression) with a food rationing protocol inducing an impairment in growth rate and an enhancement in levels of offspring solicitation (begging behaviour). Growth impairment was more marked in the slow line. In a first experiment each nest contained experimental and control siblings of the same line (within-nests design). Slow chicks became much faster than their parents in the exploration tests regardless of the treatment, whereas fast chicks had scores similar to their parents and showed no treatment effect. As a consequence, the line difference in exploration behaviour of the offspring was not apparent in the juvenile phase. Six months later the offspring of the slow line was still relatively fast, but lines differed in exploration, since the fast line became even more fast. Food-rationed birds of the fast line were more aggressive than both controls and their fathers, while treatment did not affect the slow line. In a second experiment, carried out only in the slow line, each nest contained either control or experimental siblings (between-nests design). Now, only the food-rationed chicks became faster in exploration. We suggest that the shift in the controls in the within-nests design was due to enhanced sibling competition, forced by the experimental chick. Indeed, the control chicks in the first experiment begged more persistently and had higher exploration scores than the control chicks in the between-nests design. Environmental factors during ontogeny modulate the expression of phenotypic traits against the background of the reaction norm allowed by the genome even in selected lines of animals resulting in profound and reliable differences in behaviour [KEYWORDS: GREAT TIT ; ONTOGENY ; FOOD AVAILABILITY ; PERSONALITY ; EXPLORATION ; AGGRESSION ; SIBLING COMPETITION]
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Understanding/predicting ecological invasions is an important challenge in modern ecology because of their immense economical and ecological costs. Recent studies have revealed that within-species variation in behaviour (i.e. animal personality) can shed light on the invasion process. The general hypothesis is that individuals' personality type may affect their colonization success, suggesting that some individuals might be better invaders than others. We have recently shown that, in the invasive mosquitofish (Gambusia affinis), social personality trait was an important indicator of dispersal distance, with more asocial individuals dispersing further. Here, we tested how mean personality within a population, in addition to individual personality type, affect dispersal and settlement decisions in the mosquitofish. We found that individual dispersal tendencies were influenced by the population's mean boldness and sociability score. For example, individuals from populations with more asocial individuals or with more bold individuals are more likely to disperse regardless of their own personality type. We suggest that identifying behavioural traits facilitating invasions, even at the group level, can thus have direct applications in pest management.
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