The donation game with roles played between relatives

We consider a social game with two choices, played between two relatives, where roles are assigned to individuals so that the interaction is asymmetric. Behaviour in each of the two roles is determined by a separate genetic locus. Such asymmetric interactions between relatives, in which individuals occupy different behavioural contexts, may occur in nature, for example between adult parents and juvenile offspring. The social game considered is known to be equivalent to a donation game with non-additive payoffs, and has previously been analysed for the single locus case, both for discrete and continuous strategy traits. We present an inclusive fitness analysis of the discrete trait game with roles and recover equilibrium conditions including fixation of selfish or altruistic behaviour under both behavioural contexts, or fixation of selfish behaviour under one context and altruistic behaviour under the other context. These equilibrium solutions assume that the payoff matrices under each behavioural context are identical. The equilibria possible do depend crucially, however, on the deviation from payoff additivity that occurs when both interacting individuals act altruistically.     

Long-term repeatability of behaviours in zebrafish (Danio rerio)

Animal personality is defined as individual variation in behaviour that is consistent over time and/or across contexts. Animal personality is now considered a fundamental aspect in the fields of animal behaviour and behavioural ecology, yet the majority of studies assess repeatability of behaviours over only relatively short time periods (e.g. a week) using just two measures. Understanding whether behavioural traits are repeatable over longer periods is important for the assessment of individual differences in behaviour. Using zebrafish (Danio rerio), we investigated the repeatability of activity and exploratory behaviours, including distance travelled, time spent in the bottom of the arena, stationary time and overall exploration of the novel arena over a 28-week period, using five intervals. All measures were repeatable over 28 weeks, but the repeatability estimates were much lower when comparing the initial week one and week two behaviours. There were clear sex differences in aspects of activity, with males more active than females. Importantly, our behavioural assays suggest that zebrafish require an initial “tank experience,” prior to the main phenotyping session, to ensure that behaviours being measured are repeatable—these effects are often not considered, but have implications for the many studies that measure behaviour at a single time point only.     

Absence of a Context‐General Behavioural Syndrome in a Solitary Predator

The correlation of seemingly unrelated behaviours into behavioural syndromes has been established in a wide range of species and taxa. However, most studies report on short‐term behavioural correlations without insight into individual consistency or temporal stability of the behavioural syndrome. Here, we examine the individual repeatability of single behaviours, and the presence and temporal stability of a context‐general behavioural syndrome in a solitary piscivorous predator, the pike (Esox lucius). Behavioural measurements on the same individuals were quantified independently through time and across three contexts: activity in the presence of a competitor, exploration of a novel environment and boldness under predation risk. There was no indication of a temporally stable behavioural syndrome, consisting of boldness, activity and exploration, nor were individuals consistent in the separate behaviours, contradicting the general assertion of its taxonomic prevalence. Furthermore, the study did not provide support for size or growth‐dependent behaviour in this size‐dimorphic species in conditions of limited food availability. The study highlights the importance of independent multiple observations of individual behaviour across time or contexts when measuring behavioural repeatability and covariation.     

An explanatory framework for adaptive personality differences

We develop a conceptual framework for the understanding of animal personalities in terms of adaptive evolution. We focus on two basic questions. First, why do behavioural types exhibit limited behavioural plasticity, that is, behavioural correlations both across contexts and over time? Second, how can multiple behavioural types coexist within a single population? We emphasize differences in 'state' among individuals in combination with state-dependent behaviour. Some states are inherently stable and individual differences in such states can explain stable differences in suites of behaviour if it is adaptive to make behaviour in various contexts dependent on such states. Behavioural stability and cross-context correlations in behaviour are more difficult to explain if individual states are potentially more variable. In such cases stable personalities can result from state-dependent behaviour if state and behaviour mutually reinforce each other by feedback mechanisms. We discuss various evolutionary mechanisms for the maintenance of variation (in states and/or behaviour), including frequency-dependent selection, spatial variation with incomplete matching between habitat and phenotype, bet-hedging in a temporally fluctuating environment, and non-equilibrium dynamics. Although state differences are important, we also discuss how social conventions and social signalling can give rise to adaptive personality differences in the absence of state differences.     

A quantitative study of the grooming behaviour of the mymarid wasp Alaptus fusculus

ABSTRACT. The grooming behaviour of Alaptus fusculus is described. Data on the frequencies of occurrence of seventeen different actions and their sequences were analysed. A single link cluster-analysis of preceding-following actions showed that in any bout of grooming the probabilities of actions by one leg being followed by actions initiated by the same leg (or its contralateral) are high. On the assumption that the behavioural sequences were Markovian, a vector of the species' 'average behaviour', in terms of relative frequencies of occurrence, was computed from transition probabilities. Further analysis, however, using indices derived from information theory shows that the behaviour has higher order dependencies; that is that an event is influenced by events further back in the sequence than the one immediately preceding it.     

Pareto front analysis of flight time and energy use in long-distance bird migration

Optimality models are frequently used in studies of long distance bird migration to help understand and predict migration routes, stopover strategies and fuelling behaviour in a spatially varying environment. These models typically evaluate bird behaviour by focusing on a single optimization currency, such as total migration time or energy-use, without explicitly considering trade-offs between the involved objectives. In this paper, we demonstrate that this classic single-objective approach downplays the importance of variability in bird behaviour. In the light of these considerations, we therefore propose to use a full multi-criteria optimization method to isolate the set of non-dominated, efficient or Pareto optimal solutions. Unlike single-objective optimization where there is only one combination of bird behaviour maximizing fitness, the Pareto solution set represents a range of optimal solutions to conflicting objectives. Our results demonstrate that this multi-objective approach provides important new ways of analyzing how environmental factors and behavioural constraints have driven the evolution of migratory behaviour.     

Behaviour‐driven micro‐scale niche differentiation in carabid beetles

Carabid beetles form rich and abundant communities in arable landscapes. Their generalist feeding behaviour and similar environmental requirements raise questions about the mechanisms allowing the coexistence of such species‐rich assemblages. We hypothesized that subtle niche partitioning comes into play on spatial, temporal, or trophic basis. To test this, we performed experiments and made observations on the behaviour of two sympatric carabid species of similar size and life cycle, Bembidion quadrimaculatum L. and Phyla obtusa Audinet‐Serville (both Coleoptera: Carabidae: Bembidiini). We compared plant climbing behaviour, daily activity patterns, and trophic preferences between the two carabid species under laboratory conditions. Whereas no clear difference in trophic preference was observed, our results suggest temporal niche differentiation at the nychthemeron scale (a period of 24 consecutive hours), with one of the species being more diurnal and the other more nocturnal, and spatial differentiation in their habitat use at the plant stratum scale. Intra‐specific variation suggests that micro‐scale spatio‐temporal niche differentiation could be mediated by behavioural plasticity in these two carabid species. We speculate that such behavioural plasticity may provide carabid beetles with a high adaptive potential in intensively managed agricultural areas.     

Patterns of response to sex pheromone by young and mature adult male cockroaches, Periplaneta americana

Male American cockroaches were isolated from females upon becoming adults and were exposed one single time to sex pheromone on days 1 to 11, 13, or 15 after adult ecdysis. The behavioural components of adult male sexual behaviour are rapid antennation, erect body posture, locomotion, running, wing raising, and abdominal extension. These components appear after the adult ecdysis in the same sequence as they appear in later adult life in response to different concentrations of sex pheromone. The appearance of these behavioural components is described using two theoretical concepts, threshold and a “sequencer”. It is proposed that the components are ordered sequentially before or during ecdysis by the same “sequencer” that organizes the responses to different concentrations of pheromone. The appearance of the components during development is due to decreasing thresholds as the adult male matures.     

Consistent behavioural traits and behavioural syndromes in pairs of the false clown anemonefish Amphiprion ocellaris

Using the social clown anemonefish Amphiprion ocellaris, whether individuals exhibited consistency in activity levels, boldness and sociability in a paired context, and whether these three behavioural traits were positively correlated within a single behavioural syndrome, was investigated. The results highlight that consistent individual differences in behaviour are expressed in a social fish and suggest that consistent behavioural traits and behavioural syndromes could influence the structure and functioning of their societies.     

Strong temporal consistency in the individual foraging behaviour of Imperial Shags Phalacrocorax atriceps

Individual consistency in foraging behaviour can generate behavioural variability within populations and may, ultimately, lead to species diversification. However, individual‐based long‐term behavioural studies are particularly scarce in seabird species. Between 2008 and 2011, breeding Imperial Shags Phalacrocorax atriceps at the Punta León colony, Argentina, were tracked with GPS devices to evaluate behavioural consistency during their foraging trips. Within a breeding season, individuals were highly consistent in the maximum distances they reached from the shore and the colony, as well as in the time invested in flight and diving across consecutive days during early chick rearing. In addition, each individual had its specific foraging area distinct from the foraging area of other individuals. Comparing between early and late chick rearing in the same season, individuals were consistent, to a lesser degree, in the maximum distance they reached from the colony and the shore, increasing in consistency later on in the season. Within the season, females were more consistent than males in the maximum distance they moved from the colony and the shore, the sexes segregated in their foraging areas and individual females were segregated from one another. Twenty‐eight individuals tracked in different breeding seasons were marginally consistent in their trip durations and maximum distance reached from shore across seasons. Among seasons, foraging locations differed between sexes and among individual females. Individuals from this colony exhibited consistency over time in several aspects of foraging behaviour, which may be due to a combination of individual characteristics such as learning abilities, breeding experience or health, as well as targeted prey type and stability of the environment at this location.     

Protean defence by prey animals

Summary Attention is drawn to the widespread occurrence ofprotean phenomena, in which the appearance and behaviour of prey animals are rendered variable and irregular, as a weapon in the biological arms race between predators and their prey. Protean behaviour is defined as that behaviour which is sufficiently unsystematic to prevent a reactor predicting in detail the position or actions of the actor.Single prey animals frequently flee from a predator in an irregular manner, zigzagging, spinning, looping, or bouncing. Thissingle erratic display occurs widely in the Animal Kingdom, and may also be utilised in everyday movements of potential prey as insurance against possible attack. Examples are given.In a group of prey animals the protean aspect of escape is enhanced by the effect of numbers. In scatter reactions the effect is of multiple choice and of the simultaneous operation of several single erratics. In mobbing displays there are also successive changes in the actors' behavioural role. In protean deterrence the shuffling of individuals within a tightly packed group prevents a predator from singling one out for attack.In many species the confusing effect of changes in movement and behavioural role is enhanced by rapid changes in appearance, particularly colour.It is suggested that those prey individuals which employ escape patterns unfamiliar to the predator will tend to be at a selective advantage. During phylogeny this is likely to lead to intra-specific and inter-specific increase in the number and diversity of escape behaviours. Apostatic polymorphism is seen as a special case of protean variation within populations.There is evidence that protean displays operate by arousing neurological conflict, thereby delaying the predator's reactions and reducing the effectiveness of predatory mechanisms. Also they insure against learned countermeasures by incorporating irregularities as a basic principle. It is stressed that the irregular variability of protean displays is not accidental but has been selected for in phylogeny. A number of poorly understood behavioural aspects of the ecology of predator-prey relationships are thus united in a single theory.     

Rapid response to intraclonal selection in the pea aphid (Acyrthosiphon pisum)

Summary Pea aphids show intraclonal variability in antipredator behaviour. Among the offspring of a single parthenogenetically reproducing female, some individuals drop from the plant in response to alarm pheromone while others remain on the plant. We demonstrate that this intraclonal behavioural variability can be altered by selection. The proportion of aphids dropping in response to alarm pheromone was significantly greater in lines in which this behaviour was selected than in clonally identical lines in which the opposite phenotype was favoured. This change occurred within one generation and could not be attributed to grand-maternal effects, nor to environmental effects. These results demonstrate the ability of clonal aphids to adapt to changes in the environment within a single generation.     

Behavioural plasticity: an interaction between evolution and experience

Animals adjust their behaviour in response to complex environmental conditions. This form of plasticity requires the formation of association between information and an appropriate behavioural response. Such a connection is the result of a complex interaction between evolutionary pre-programmed cue-response behaviour (innate behavioural response) and cumulated lifetime experience (learning). The evolution of learning and innate behavioural responses is likely to depend on their respective fitness costs and benefits. However, as natural selection will indirectly affect each form through global behavioural plasticity, it is critical to understand how each form interacts with the other. The inclusion of innate behavioural plasticity and learning in behaviour is likely to result in more than the mere sum of each plastic form. In this review we investigate the costs and benefits of learning and innate behavioural responses and the effect of one on the other in their evolution. We highlight the need for more explicit study of the interaction between innate behavioural response and learning in natural systems for a better understanding of behavioural plasticity.     

Song mimicry of Black-bellied Firefinch Lagonosticta rara and other finches by the brood-parasitic Cameroon Indigobird Vidua camerunensis in West Africa

Brood-parasitic finches Vidua spp. mimic songs of their foster species, with most Vidua species both mimicking songs and parasitizing nests of a single estrildid finch species. We describe a behavioural radiation in the Cameroon Indigobird Vidua camerunensis . Local populations are polymorphic in behaviour, each male mimicking songs of a single species, with certain males mimicking songs of one species and other males mimicking songs of another host species. The species most often mimicked in song are Black-bellied Firefinch Lagonosticta rara and African Firefinch L. rubricata ; other species mimicked in song are Brown Twinspot Clytospiza monteiri and Dybowski's Twinspot Euschistospiza dybowskii . Indigobirds in the different mimicry song populations do not differ morphologically in plumage colour or size. The lack of morphological differences between male indigobirds with different mimicry songs is consistent with a recent behavioural radiation through host shifts, perhaps facilitated by environmental change associated with prehistoric cultivation of grain. The mimicry song populations of indigobirds, behaviourally imprinted upon different host species, support the idea of a process of speciation driven by a shift to new host species.     

Duration of behaviour patterns during oviposition by the bruchid beetle, Callosobruchus maculatus

The behaviour of insects between making contact with a potential oviposition site and the act of oviposition itself determines the conditions in which their progeny begin development and, in many cases, whether a crop or commodity is damaged. In this paper the behaviour of female cowpea seed beetles, Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae), during this period has been examined. The duration of discrete behaviour patterns within this period and the transitional frequencies between them have been used to compare the behaviour of beetles on two different hosts. In a 30-min period, beetles laid more eggs on mung than adzuki beans and rejected mung as an oviposition site much less frequently. A log-linear contingency table analysis of the transitional frequencies indicated a highly significant interaction between successive behaviours and between the second of the two behaviours and the host seed, indicating that the sequence of behaviours is partially determined by the host seed. Grooming, departure from the seed and loops in behavioural sequences occur more often on adzuki than mung and are indicative of a less acceptable host. Discriminant analysis showed that the total time spent exhibiting different behaviour patterns was significantly different on the two hosts. Mann–Whitney tests revealed small but significant differences in the mean durations of only three behaviour patterns on the two seed types. Measurement of the duration of each behavioural pattern confirms what can be deduced about host acceptability by observing the simple occurrence of different behavioural patterns and the determination of the frequency of transitions between them. Differences in acceptability were predominantly reflected in the frequency of certain behaviour patterns and of particular transitions from one pattern to another, not in the mean duration of each exhibition of a defined behaviour pattern. It is argued that the utility of measuring the duration of behavioural elements could only be demonstrated because behavioural patterns or categories were precisely defined.     

Behaviour of Arctic charr Salvelinus alpinus during an induced mating season in captivity: how male relative size influences male behavioural investment and female preference over time

The behaviour of sexually mature Arctic charr Salvelinus alpinus specimens (fifth farm generation) was observed in captivity for four consecutive days. Only agonistic interactions between males of different size were facilitated on the first 2 days, while both agonistic and courtship interactions were possible from the third day up to the end of the experiment. The reliability of behavioural analysis was assessed in order to reduce the possibility of observer errors within the generated datasets. The behavioural investment of big males, small males and females was analysed using general linear models (two‐way repeated measures ANOVAs with time and male size as factors). A peak in the agonistic interactions between males occurred during the first day of interactions, where the agonistic investment of big males was significantly higher than that of small males. This resulted in an increased investment in submissive behaviour by the small males, who consistently performed submissive behaviours from the second day of interactions up to the end of the trial. Big males were found to invest significantly more than small males in courtship behaviours for the duration of the trial. Even though females performed inter‐sexual behaviours towards both big and small males for the entire observation period, female interaction rate towards big males was higher than towards small males. This study suggests that both male investment in mating behaviour and female preference might be related to male characteristics such as body length and that S. alpinus behavioural patterns and mate choice cues might be strongly context‐related and characterized by high levels of behavioural plasticity (i.e. presence–absence of certain behavioural units or potential reversal of a mate choice cue) within the same species. Finally, in light of this, some conservation measures are discussed. In particular, effective management plans should take into account the high level of behavioural plasticity likely to be occurring in this species.     

Blockade of corticoliberin receptors prevents development of poststressor psychopathology in rats with active strategy of adaptive behaviour

Active as well as passive Wistar rats were subjected to a single water-immersion action that gave rise signs of poststressor depression in them. Administration of CRH-R1-receptor peptide blocker astressin prevented development of behavioural deficiency in active rats and did not affect behaviour of passive rats. This suggests that the corticoliberin receptor blockers are only effective for treatment of poststressor depressions in individuals with initially behavioural strategy.     

Resonant neurons and bushcricket behaviour

The resonant properties of the intrinsic dynamics of single neurons could play a direct role in behaviour. One plausible role is in the recognition of temporal patterns, such as that seen in the auditory communication systems of Orthoptera. Recent behavioural data from bushcrickets suggests that this behaviour has interesting resonance properties, but the underlying mechanism is unknown. Here we show that a very simple and general model for neural resonance could directly account for the different behavioural responses of bushcrickets to different song patterns.     

Individual differences in plasticity and sampling when playing behavioural games

When engaged in behavioural games, animals can adjust their use of alternative tactics until groups reach stable equilibria. Recent theory on behavioural plasticity in games predicts that individuals should differ in their plasticity or responsiveness and hence in their degree of behavioural adjustment. Moreover, individuals are predicted to be consistent in their plasticity within and across biological contexts. These predictions have yet to be tested empirically and so we examine the behavioural adjustment of individual nutmeg mannikins (Lonchura punctulata), gregarious ground-feeding passerines, when playing two different social foraging games: producer-scrounger (PS) and patch-choice (PC) games. We found: (i) significant individual differences in plasticity and sampling behaviour in each of the two games, (ii) individual differences in sampling behaviour were consistent over different test conditions within a game (PC) and over a six month period (PS), (iii) but neither individual plasticity nor sampling behaviour was correlated from one social foraging game to another. The rate at which birds sampled alternative tactics was positively associated with seed intake in PS trials but negatively associated in PC trials. These results suggest that games with frequency dependence of pay-offs can maintain differences in behavioural plasticity but that an important component of this plasticity is group- and/or context-specific.     

Miniaturized orb-weaving spiders: behavioural precision is not limited by small size

The special problems confronted by very small animals in nervous system design that may impose limitations on their behaviour and evolution are reviewed. Previous attempts to test for such behavioural limitations have suffered from lack of detail in behavioural observations of tiny species and unsatisfactory measurements of their behavioural capacities. This study presents partial solutions to both problems. The orb-web construction behaviour of spiders provided data on the comparative behavioural capabilities of tiny animals in heretofore unparalleled detail; species ranged about five orders of magnitude in weight, from approximately 50-100mg down to some of the smallest spiders known (less than 0.005mg), whose small size is a derived trait. Previous attempts to quantify the 'complexity' of behaviour were abandoned in favour of using comparisons of behavioural imprecision in performing the same task. The prediction of the size limitation hypothesis that very small spiders would have a reduced ability to repeat one particular behaviour pattern precisely was not confirmed. The anatomical and physiological mechanisms by which these tiny animals achieve this precision and the possibility that they are more limited in the performance of higher-order behaviour patterns await further investigation.