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Background Endurance rivalry and female choice are two important mechanisms of sexual selection in lek-breeding species. Endurance rivalry is when males compete for opportunities to mate by spending more time in leks than others (interaction-independent male-male competition). Because high-quality males can afford to have high lek attendance, females have a higher chance of mating with good-quality males even when they mate randomly. The good gene hypothesis proposes that females can pass good genes on to their offspring by choosing males that display elaborate morphological and/or behavioral traits that reflect the males’ genetic quality. The relative importance of lek attendance and female choice to males’ mating success in anurans is rarely evaluated. In this study, we investigated how these two mechanisms might jointly shape males’ morphological traits in the lek-chorusing emerald treefrog Zhangixalus prasinatus. Results Our results show that (1) male lek attendance is positively correlated with body size and condition, and males with higher lek attendance have higher mating success, (2) the dominant frequency of males’ advertisement calls are negatively correlated with body size and males producing lower frequency calls have higher mating success, (3) male body size, but not body condition, has a non-significant positive relationship with mating success and (4) females show preference for calls with lower dominant frequencies in two-choice playback. Conclusions Overall, both endurance rivalry and female choice play an important role in the mating success of male emerald treefrogs in the field and both are influenced by male body size/condition. By mating with males that have higher lek attendance and produce lower frequency calls, selection may indirectly favor larger males.

Animals may base contest decisions on their fighting ability alone (self-assessment) or also their opponents' (mutual assessment). Many male stag beetles develop disproportionately enlarged mandibles and use them as weapons. Information on their assessment strategy is limited. To investigate their assessment strategy and whether they adopt the same strategy at different stages of contests, we used food to encourage male Cyclommatus mniszechi of different (random pairings) or similar (ML-matched pairings) mandible length (ML) to interact. For the random pairings, losers had shorter mandibles than winners and were faster to feed. Overall contest duration and the tendency to escalate to tussles associated positively with winners' ML and average ML in the random and the ML-matched pairings, respectively, consistent with self-assessment. Non-tussle phase duration associated positively with average ML in the ML-matched pairings, consistent with self-assessment. Tussle phase duration, however, positively associated with losers' ML in the random pairings and had no association with average ML in the ML-matched pairings, consistent with mutual assessment. These results show that (1) the males employ both assessment strategies, (2) winners have more control over contest intensity than losers, and (3) males with shorter mandibles are quicker to feed and also more likely to lose fights.

Male stag beetles (Coleoptera: Lucanidae) use their mandibles as weapons to compete for resources and reproduction. Mandible size in stag beetles can be associated with different behaviours and the outcome of male contests. We investigated the allometric relationship between mandible and body size in males of the stag beetle Cyclommatus mniszechi to uncover distinct morphs. The results divided male C. mniszechi into majors and minors with the switch point of mandible length at 14.01 mm. The allometric slope of mandibles was positive for both morphs but was steeper for the minors. We also characterised the fighting behaviour of the different morphs in size-matched contests using sequential analyses. Males matched each other’s behaviour in contests with many physical contacts, no injury and a progression from low towards high aggression and rare de-escalation. Major and minor males employed the same behavioural elements in contests, but major males were more likely to escalate directly into more aggressive phases and minor males tended to stay within phases. This finding suggests that major males may compete more aggressively than minor males in contests.

This study examined the relative importance of contest experience and size differences to behavioral decisions over the course of contests. Using a mangrove rivulus fish, Kryptolebias marmoratus, we showed that although contest experience and size differences jointly determined contest outcomes, they affected contestants' interactions at different stages of contests. Contest experience affected behavioral decisions at earlier stages of contests, including the tendency and latency to launch attacks, the tendency to escalate contests into mutual attacks and the outcome of non-escalated contests. Once contests were escalated into mutual attacks, the degree of size difference affected the fish's persistence in escalation and chance of winning, but contest experience did not. These results support the hypothesis that contest experience modifies individuals' estimation of their fighting ability rather than their actual strength. Furthermore, (1) in contests between two naïve contestants, more than 60 % of fish that were 2-3 mm smaller than their opponent escalated the contest to physical fights, even though their larger opponents eventually won 92 % of escalated fights and (2) fish with a losing experience were very likely to retreat in the face of an opponent 2-3 mm smaller than them without escalating. The result that a 2-3 mm size advantage could not offset the influence of a losing experience on the tendency to escalate suggests that, as well as depending on body size, the fish's physical strength is influenced by other factors which require further investigation.

Personality and physiological traits often have close relationships with dominance status, but the significance and/or direction of the relationships vary between studies. This study examines whether two personality traits (aggressiveness and boldness) and three physiological traits (testosterone and cortisol levels and oxygen consumption rates) are associated with contest decisions/performance using a mangrove killifish Kryptolebias marmoratus. The results show that individuals that attacked their own mirror images (an aggressiveness index) at higher rates or had higher levels of testosterone were more likely to attack their opponent and win non-escalated contests, while individuals that had higher levels of cortisol were more likely to lose. After the contests, (1) individuals that had attacked their opponents or won had higher post-contest oxygen consumption rates, and (2) individuals that had attacked their opponents also had higher post-contest levels of cortisol. Although no significant correlations were detected among pre-contest physiological traits, post-contest levels of cortisol were positively correlated with oxygen consumption rates. Overall, personality and physiological traits provide useful predictors for the fish's contest decisions/performance. Contest interactions subsequently modified post-contest physiological traits and potentially also promoted associations between them. Nevertheless, the fish's physiological traits remained rather consistent over the entire study period.

Male stag beetles (Coleoptera: Lucanidae) use their mandibles as weapons to compete for resources and reproduction. Mandible size in stag beetles can be associated with different behaviours and the outcome of male contests. We investigated the allometric relationship between mandible and body size in males of the stag beetle Cyclommatus mniszechi to uncover distinct morphs. The results divided male C. mniszechi into majors and minors with the switch point of mandible length at 14.01 mm. The allometric slope of mandibles was positive for both morphs but was steeper for the minors. We also characterised the fighting behaviour of the different morphs in size-matched contests using sequential analyses. Males matched each other&rsquo, s behaviour in contests with many physical contacts, no injury and a progression from low towards high aggression and rare de-escalation. Major and minor males employed the same behavioural elements in contests, but major males were more likely to escalate directly into more aggressive phases and minor males tended to stay within phases. This finding suggests that major males may compete more aggressively than minor males in contests.

Detail protocol of hormone extractions and the complete statistic results of sex differences in aggression and hormonal responses

Resource ownership often increases an individual's aggressiveness and its probability of defeating a competitor. Individuals contesting resource owners could therefore incur higher costs, making individuals reluctant to compete with owners. We tested the hypothesis that animals use asymmetry in resource ownership as a cue for contest costs and adjust contest decisions accordingly. Using a mangrove rivulus fish (Kryptolebias marmoratus), we staged (1) contests with a randomly assigned asymmetry in resource ownership (one fish was provided with a shelter) and (2) contests in which neither fish had a shelter. Owners that were in their shelters at the contest start showed a greater tendency to fight and won more contests than their intruder opponents; those outside the shelter at the start did not. Compared with fish in contests with no shelters at stake, shelter owners had a higher tendency to fight whether or not they were in their shelters at the start; intruders, however, had a lower tendency to fight only against owners that were inside the shelter at the start. These results demonstrate (1) that ownership status influences both owners’ and intruders’ contest decisions (and in opposite directions), producing a detectable ownership advantage and (2) that intruders required confirmation of their opponents’ ownership status before retreating without challenging them. Ownership status per se is therefore important to the fish's contest decisions.

Despite the dog’s long mutualistic association with humans, global attitudes toward the species, Canis familiaris, are exceedingly diverse, ranging from overwhelmingly positive in most Western countries to predominantly negative in many developing nations. Since attitudes are important predictors of dog-related behavior, knowledge of the forces and factors that affect people’s attitudes to dogs can make an important contribution to improving dog-human relations, global public health, and canine welfare. This chapter explores some of the key factors influencing dog-related attitudes and behavior, with particular reference to the results of a case study of attitudes to dogs in Taiwan. The findings suggest that people’s attitudes to dogs involve both affective/emotional and instrumental/practical components, and that a significant minority of people in Taiwan are opposed to the killing/euthanasia of unwanted dogs. The most important determinant of both positive affective attitudes to dogs and opposition to killing/euthanasia was the experience of growing up with household dogs. The significance of these and other findings are discussed from the perspective of animal attitude development, and dog welfare and population management.

Synopsis A suite of correlated behaviors reflecting between-individual consistency in behavior across multiple situations is termed a ‘‘behavioral syndrome.’’ Researchers have suggested that a cause for the correlation between different behaviors might lie in the neuroendocrine system. In this study, we examined the relationships between aggressiveness (a fish’s readiness to perform gill display to its mirror image) and each of boldness (the readiness to emerge from a shelter), exploratory tendency (the readiness to approach a novel shelter), and learning performance (the probability of entering the correct reservoir in a T-maze test) in a mangrove rivulus, Kryptolebias marmoratus. We explored the possibility that the relationships between them arise because these behaviors are all modulated by cortisol and testosterone. We also tested the stability of the relationships between these behaviors shortly after using a winning or losing experience to alter individuals’ aggressiveness. The results were that aggressiveness correlated positively with boldness and the tendency to explore, and that these three behavioral traits were all positively correlated with pre-experience testosterone levels. Aggressiveness and boldness also positively correlated with pre-experience cortisol levels; exploratory tendency did not. The relationship between aggressiveness and boldness appeared to be stronger than that between either of them and exploratory tendency. These results suggest that testosterone and cortisol play important roles in mediating the correlations between these behavioral traits. Learning performance was not significantly correlated with the other behavioral traits or with levels of testosterone or cortisol. Recent experience in contests influenced individuals’ aggressiveness, tendency to explore, and learning performance but not their boldness; individuals that received a winning experience were quicker to display to their mirror image and performed better in the learning task but were slower to approach a novel object than were individuals that lost. Contest experience did not, however, significantly influence the relationships between aggressiveness and any of boldness, exploratory tendency, or learning performance. The results show that the individual components of a suite of correlated behaviors can preserve a flexibility to respond differently to environmental stimuli.

Recent contest experience can influence an individual’s behaviour in subsequent contests. When the probability of winning a subsequent contest is used to quantify experience effects, a loser effect usually lasts longer than a winner effect. This conclusion, however, may be caused by this probability understating the persistence of the influence of a winning experience on contest decisions. Using Kryptolebias marmoratus, a mangrove killifish, as the study organism, we investigated whether different conclusions about the relative persistence of winning and losing experiences would be reached when different aspects of contest behaviour (probability of initiating attacks, probability of winning non-escalated and escalated contests, escalation rate and contest duration) were measured. The results indicated that the apparent persistence of the effect of winning or losing experiences varied with the behaviour studied. When the likelihood to initiate attacks was used, no winner effect was detected while the loser effect lasted for

In many species, males tend to behave more aggressively than females and female aggression often occurs during particular life stages such as maternal defence of offspring. Though many studies have revealed differences in aggression between the sexes, few studies have compared the sexes in terms of their neuroendocrine responses to contest experience. We investigated sex differences in the endocrine response to social challenge using mangrove rivulus fish, Kryptolebias marmoratus . In this species, sex is determined environmentally, allowing us to produce males and hermaphrodites with identical genotypes. We hypothesized that males would show elevated androgen levels (testosterone and 11-ketotestosterone) following social challenge but that hermaphrodite responses might be constrained by having to maintain both testicular and ovarian tissue. To test this hypothesis, we staged fights between males and between hermaphrodites, and then compared contest behaviour and hormone responses between the sexes. Hermaphrodites had significantly higher oestradiol but lower 11-ketotestosterone than males before contests. Males took longer to initiate contests but tended to fight more aggressively and sustain longer fights than hermaphrodites. Males showed a dramatic post-fight increase in 11-ketotestosterone but hermaphrodites did not. Thus, despite being genetically identical, males and hermaphrodites exhibit dramatically different fighting strategies and endocrine responses to contests.

This study used The Canine Behavioral Assessment and Research Questionnaire (C-BARQ) and regression models to explore the relative importance of dog and owner characteristics, living environment and owner–dog interaction to household dogs' aggressiveness towards strangers, owners and other dogs. Exploratory factor analysis revealed 10 interpretable factors from the Chinese translation of C-BARQ: stranger-directed aggression, owner-directed aggression, dog-directed aggression, social fear, nonsocial fear, separation-related behavior, attachment or attention-seeking behavior, trainability, excitability and pain sensitivity. The factor structure of our study largely resembled that reported in Hsu and Serpell (2003) and van den Berg et al. (2006; Dutch translation of C-BARQ). All factors of the translated C-BARQ have adequate reliability (Cronbach α : 0.74–0.93) and are thus suitable for measuring temperament traits in Taiwan's pet dogs. Intrinsic and environmental variables important to the three aggression subscales were not entirely the same, but breed ( P ≤0.020) and physical punishment ( P ≤0.053) had significant relationships with all of them. Golden Retriever scored the lowest while dogs subjected to physical reprimands scored significantly higher on aggression subscales. In addition, higher scores on stranger-directed aggression were associated ( P ≤0.027) with living in rural areas, in houses with yard space and with more household members and being acquired either as puppies or for guarding purposes. Higher scores on owner-directed aggression were associated ( P ≤0.040) with male and older dogs, being neutered/spayed, having female owners, fewer other dogs in the household and being kept outside the house. Higher scores on dog-directed aggression, on the other hand, were associated ( P ≤0.050) with living in houses with either yard space or more household members and with spending less time with owners. Stranger- and dog-directed aggression had more important intrinsic and environmental variables common to them than did owner-directed aggression, which suggests that aggression towards owners may be regulated by different mechanisms from aggression towards strangers and other dogs. Although no causal relationship between dog aggression and environmental variables can be implied from observational studies, the results of this and other studies lend support to the possibility of reducing dogs' aggressive responses through proper management by owners.

Animals’ contest performance is influenced by their recent contest experiences. This influence could either be exerted by individuals re-estimating their own fighting ability (self-assessment) or by their opponents responding to status-related cues (social-cue mechanism) or both. Individuals of Kryptolebias marmoratus, a hermaphroditic killifish, were given different contest experiences to examine how two opponents’ prior experiences combined to determine their contest interaction and to test both of these mechanisms as potential causes of the observed experience effect. Our data showed that losers’ decisions to retreat at different stages of a contest were influenced by their own but not by the winners’ contest experience—a result consistent with self-assessment but not with the social-cue mechanism. An association between the fish initiating and winning contests thus probably arose because both were correlated with an individual’s assessment of its fighting ability, but not because initiating contests made opponents more inclined to retreat.

Canine aggression poses serious public health and animal welfare concerns. Most of what is understood about breed differences in aggression comes from reports based on bite statistics, behavior clinic caseloads, and experts’ opinions. Information on breed-specific aggressiveness derived from such sources may be misleading due to biases attributable to a disproportionate risk of injury associated with larger and/or more physically powerful breeds and the existence of breed stereotypes. The present study surveyed the owners of more than 30 breeds of dogs using the Canine Behavioral Assessment and Research Questionnaire (CBARQ), a validated and reliable instrument for assessing dogs’ typical and recent responses to a variety of common stimuli and situations. Two independent data samples (a random sample of breed club members and an online sample) yielded significant differences among breeds in aggression directed toward strangers, owners and dogs (Kruskal–Wallis tests, P < 0.0001). Eight breeds common to both datasets (Dachshund, English Springer Spaniel, Golden Retriever, Labrador Retriever, Poodle, Rottweiler, Shetland Sheepdog and Siberian Husky) ranked similarly, rs = 0.723, P < 0.05; rs = 0.929, P < 0.001; rs = 0.592, P = 0.123, for aggression directed toward strangers, dogs and owners, respectively. Some breeds scored higher than average for aggression directed toward both humans and dogs (e.g., Chihuahuas and Dachshunds) while other breeds scored high only for specific targets (e.g., dog-directed aggression among Akitas and Pit Bull Terriers). In general, aggression was most severe when directed toward other dogs followed by unfamiliar people and household members. Breeds with the greatest percentage of dogs exhibiting serious aggression (bites or bite attempts) toward humans included Dachshunds, Chihuahuas and Jack Russell Terriers (toward strangers and owners); Australian Cattle Dogs (toward strangers); and American Cocker Spaniels and Beagles (toward owners). More than 20% of Akitas, Jack Russell Terriers and Pit Bull Terriers were reported as displaying serious aggression toward unfamiliar dogs. Golden Retrievers, Labradors Retrievers, Bernese Mountain Dogs, Brittany Spaniels, Greyhounds and Whippets were the least aggressive toward both humans and dogs. Among English Springer Spaniels

To determine whether animals assess each other's fighting ability in contests, researchers usually regress contest duration over the sizes of the contestants. The predominant trend in recent studies is for the contest duration to correlate positively with the size of the smaller opponent but to have no obvious relationship with the size of the larger opponent. This indicates that animals make contest decisions based on their own abilities (‘self assessment’) and displaces the once-popular belief that they assess their opponents (‘mutual assessment’). These tests, however, are based on the implicit but never stated assumption that animals adopt only one assessment approach throughout an entire contest. By examining the contest behaviours of a killifish, we show that (1) the fish adopt mutual assessment at earlier stages when deciding whether to escalate the contest from the mutual display to the attack phase and (2) once a contest is escalated, the fish switch to self assessment to decide how long to escalate. Our results show that individuals may adopt multiple assessment approaches in one contest; contest behaviours in different stages (where applicable) of a contest should be analysed separately to better elucidate animal contest assessment strategies.

Given the dramatic behavioral effects of winning and losing contests, and pronounced changes in stress and sex steroid hormones post-fight, it is reasonable to suppose that these hormones also dictate future behavior. We sampled water-borne cortisol, testosterone (T), and 11-ketotestosterone (KT) before and after contests in the mangrove killifish, Kryptolebias marmoratus, to determine how endogenous steroid hormone levels might predict and respond to contest dynamics or success. Pre-fight cortisol related negatively, and pre-fight T related positively to contest initiation and winning, particularly in the smaller opponent. In the pairs where a larger fish won the contest, winners with higher pre-fight T and lower pre-fight cortisol delivered more attacks to the losers. Contest duration and escalation influenced post-fight hormone concentrations primarily in losers. Escalation significantly increased post-fight cortisol, T, and KT for losers but not for winners. However, winners that attacked losers at higher rates had higher levels of post-fight cortisol. Losers also demonstrate the most consistent post-fight hormone responses, particularly to contest escalation and duration. Despite the bidirectional relationship between hormones and contest behavior, we found no overall mean differences in pre- or post-fight cortisol, T, or KT between eventual winners and losers. Thus, it is evident that the categorical states of winner and loser cannot alone reveal the complex, reciprocal associations between endocrine systems and social behavior.

1. We compared the thermal tolerances of a high-altitude skink, Sphenomorphus taiwanensis with that of the lowland S. incognitus to test whether their thermal tolerances correspond to their altitudinal distributions. 2. We measured the critical body temperatures, the CTMax and the CTMin, of the two species under three different acclimation temperature regimes (low: 10 °C for S. taiwanensis ; 15 °C for S. incognitus , medium: 20 °C, and high: 30 °C). We found that: (1) the critical body temperatures of these two skinks increased with an increase in acclimation temperatures, and (2) under the same acclimation temperature regime, the critical body temperature of S. taiwanensis was lower than that of S. incognitus as expected. 3. We also recorded the 6-month survival rates of S. taiwanensis under three temperature settings (10, 20, and 30 °C). The survival rate of S. taiwanensis at 30 °C dropped to 0% in 186 days accompanied with significant reduction in body weight over time. S. taiwanensis kept at 10 °C had a survival rate of 100% with no significant change in body weight. Individuals of S. taiwanensis kept at 20 °C had a survival rate of 84.6% and a significant increase in body weight. 4. We concluded that the thermal tolerances of S. taiwanensis and S. incognitus corresponded to their altitudinal distributions and that environmental temperature might be a limiting factor for their current altitudinal distributions.

Lipoproteins and vascular factors may play roles in the development of Alzheimer's disease (AD) and/or vascular dementia (VaD). In this study, odd ratios (ORs) and 95% confidence intervals (CIs) for apolipoprotein E (APOE), angiotensin-converting enzyme (ACE), and kallikrein (KLK1) polymorphisms were computed to test their association with the disease by a case-control study. The risk of AD was significantly increased for individuals with APOE varepsilon4 allele (OR = 3.73, 95% CI = 2.38-5.98). The risk of AD was also significant for people with ACE DD genotype, D allele, or T-D haplotype [OR (95% CI) = 4.29 (1.96-10.23), 1.90 (1.35-2.70), or 2.91 (1.71-5.10), respectively]. The above association between ACE-VaD was also strong (p = 0.0012, 0.0050, 0.0007, respectively). Reporter constructs containing the -240 A or T allele displayed similar transcriptional activity in both HEK-293 and IMR-32 cells. Thus, another putative pathogenic marker that is linked with the Alu D allele might affect the risk of AD and VaD in Taiwan.

In a previous study of canine temperament (Hsu and Serpell 2003), a distinct “trainability” factor was identified, characterized by a dog's willingness to attend to its owner and obey simple comman...

Parkinson's disease (PD) involves several genetic and environmental components. Heat-shock protein 70, a chaperone that is up-regulated in stress responses and that refolds protein, may be involved in the pathogenesis of PD. We have investigated the association of polymorphisms -110 A/C, +190 G/C, +1267 A/G, +2074 G/C, and +2437 G/C in the 5' and coding regions of the HSP70-1, HSP70-2, and HSP70-hom genes with the risk of PD by screening DNA samples from 274 PD patients and 183 controls in assays based on the polymerase chain reaction. There was no statistically significant difference in genotype distribution between patients and controls for the three coding-region polymorphisms in HSP70-2 and HSP70-hom. However, for HSP70-1, the overall genotype distribution was significantly different at the -110 site (P=0.004) and tended to be different at the +190 site (P=0.012) between patients and controls. The frequencies of the -110 CC and +190 CC genotypes were significantly higher in PD patients than in controls (P=0.001 and 0.006, respectively). Both -110 CC (odds ratio: 2.91; 95% CI: 1.51-5.96; P=0.002) and +190 CC (odds ratio: 3.59; 95% CI: 1.53-9.88; P=0.006) genotypes were significantly associated with PD. Reporter constructs containing the -110 A allele cloned into a luciferase reporter plasmid drove marginally higher transcriptional activity of HSP70-1 compared with the -110 C allele in both control and heat-shocked IMR32 and 293 cells. Therefore, -110 A/C may be a functional polymorphism in the 5' promoter region of HSP70-1 and may affect susceptibility to PD.

Introduction Individual recognition and winner/loser effects both play important roles in animal contests, but how their influences are integrated to affect an individual’s contest decisions in combination remains unclear. Individual recognition provides an animal with relatively precise information about its ability to defeat conspecifics that it has fought previously. Winner/loser effects, conversely, rely on sampling information about how an animal’s ability to win compares with those of others in the population. The less precise information causing winner/loser effects should therefore be more useful to an individual facing an unfamiliar opponent. In this study, we used Kryptolebias marmoratus, a hermaphroditic mangrove killifish, to test whether winner/loser effects do depend on opponent familiarity. In addition, as previous studies have shown that subordinates that behave aggressively sometimes suffer post-retreat retaliation from contest winners, we also explored this aspect of contest interaction in K. marmoratus. Results In the early stages of a contest, subordinates facing an unfamiliar dominant were more likely to signal their aggressiveness with either gill displays or attacks rather than retreating immediately. A winning experience then increased the likelihood that the most aggressive behavioral pattern the subordinates exhibited would be attacks rather than gill displays, irrespective of their opponents’ familiarity. Dominants that received a losing experience and faced an unfamiliar opponent were less likely than others to launch attacks directly. And subordinates that challenged dominants with more aggressive tactics but still lost received more post-retreat attacks from their dominant opponents. Conclusions Subordinates’ contest decisions were influenced by both their contest experience and the familiarity of their opponents, but these influences appeared at different stages of a contest and did not interact significantly with each other. The influence of a losing experience on dominants’ contest decisions, however, did depend on their subordinate opponents’ familiarity. Subordinates and dominants thus appeared to integrate information from the familiarity of their opponents and the outcome of previous contests differently, which warrants further investigation. The higher costs that dominants imposed on subordinates that behaved more aggressively toward them may have been to deter them from either fighting back or challenging them in the future.

Contest decisions are influenced by the outcomes of recent fights (winner–loser effects). Steroid hormones and serotonin are closely associated with aggression and therefore probably also play important roles in mediating winner–loser effects. In mangrove rivulus fish, Kryptolebias marmoratus , individuals with higher testosterone (T), 11-ketotestosterone and cortisol levels are more capable of winning, but titres of these hormones do not directly mediate winner–loser effects. In this study, we investigated the effects of winning/losing experiences on brain expression levels of the receptor genes for androgen (AR), oestrogen α/β (ER α/β ), glucocorticoid (GR) and serotonin (5-HT 1A R). The effect of contest experience on AR gene expression depended on T levels: repeated losses decreased, whereas repeated wins increased AR gene expression in individuals with low T but not in individuals with medium or high T levels. These results lend strong support for AR being involved in mediating winner–loser effects, which, in previous studies, were more detectable in individuals with lower T. Furthermore, the expression levels of ER α/β , 5-HT 1A R and GR genes were higher in individuals that initiated contests against larger opponents than in those that did not. Overall, contest experience, underlying endocrine state and hormone and serotonin receptor expression patterns interacted to modulate contest decisions jointly.

Most guide and service dog organizations would benefit from the development of accurate methods for the early evaluation of canine temperament traits. This paper describes the development and validation of a novel questionnaire method for assessing behavior and temperament in 1-year-old guide dogs. Volunteer puppy-raisers scored a total of 1097 prospective guide dogs on a series of 40 semantic differential-type, behavioral rating scales. Principle components factor analysis of these scores extracted eight stable and interpretable common factors: stranger-directed fear/aggression, non-social fear, energy level, owner-directed aggression, chasing, trainability, attachment, and dog-directed fear/aggression. Three of these eight factors exhibited moderate internal consistency (Cronbach’s α≥0.72), while the reliabilities of the remaining factors were relatively low (Cronbach’s α=0.53–0.61). The eight factors were then validated against the guide dog school’s own criteria for rejecting dogs for behavioral reasons. The results of this analysis confirmed the construct validity of the puppy raisers’ questionnaire assessments of their dogs, and suggested that such methods can provide a useful and accurate means of predicting the suitability of dogs for guiding work. Various modifications to the original questionnaire are proposed in order to enhance its overall reliability.

We examined the effect of prior winning and losing experiences on the initiating and responding strategies of contestants in contests between individuals of Rivulus marmoratus (Cyprinodontidae). Each contestant was given a penultimate and a recent fighting experience approximately 48 and 24 h prior to the dyadic contests, respectively, through randomly selected procedures. Winning and losing experience appeared to influence different types of fighting behaviours. Losing experiences decreased the probability of an individual initiating a confrontation and thus increased its tendency to retreat immediately when challenged. Winning experiences did not affect the probability of initiation, but significantly increased the likelihood of an individual initiating with attacks that effectively deterred its opponents. A substantial proportion (59/153) of individuals retreated immediately when challenged and reduced the number of fights available for examining experience effects on responding strategies at later stages of a contest. None the less, winning experiences consistently increased the likelihood of an individual retaliating by attacking its opponent at various stages of a contest, and eventually increased its probability of escalating a confrontation into physical fights. However, the effects of losing experiences on these responding strategies were undetectable. Recent experiences significantly affected all fighting behaviours examined, but penultimate experiences significantly affected only the tendency to initiate a confrontation with attacks and the likelihood of escalation. These results indicated that prior experiences had the longest lasting effect on the potentially most costly fighting behaviour. Prior experiences influenced the outcome of nonescalated contests as well as the probability of escalation, but did not significantly affect the outcome of escalated contests. These results are consistent with the hypothesis that prior experiences modify the information that an individual has about its fighting ability but do not alter its actual fighting ability and that actual fighting ability becomes the more important influence on outcomes of escalated contests.

Aggression plays an important role in animal contests, but the extent to which aggression correlates with dominance has been a topic of much debate. The relationship between aggression and dominance ability in the hermaphroditic fish, Rivulus marmoratus, was investigated using three standard protocols, the mirror test (Mi), model test (Mo), and standard opponent test (So). In each, display latency, attack latency, and biting frequency were quantified for a test individual towards its opponent. The general rank-order for eliciting strength of the three different stimuli was Mi > So > Mo. The relationships between the individual indices from the standard tests and three dyadic contest variables, initiator of display, initiator of attack, and winner, were analysed in contests between previously tested pairs to ascertain how well the standard protocols predicted dyadic contest behaviour/outcome. Display and attack latencies in the standard tests did not predict the level of analogous combat behaviour. Biting frequency differences between individuals in a pair in the So and Mo tests as well as display latency differences in the Mi test contributed to predictions of contest outcome. The individual that scored higher, relative to its opponent, won a significantly greater proportion of the bouts. These findings demonstrate the importance of relative differences in aggression in determining dominance. However, the predictive value of standard test behaviour is test-specific and, based on the available literature, depends on both the species used and the context in which they are employed.

Forty-nine dogs showing signs of separation-related problems were randomly assigned to one of three groups: group A (15 dogs) received a placebo twice daily; group B (17 dogs) received clomipramine at 0.5 to 1.0 mg/kg twice daily; and group C (17 dogs) received clomipramine at 1.0 to 2.0 mg/kg twice daily. All the dogs also received behavioural therapy. Their owners were required to complete questionnaires about their dog's behaviour initially, and one, four and eight weeks after the treatment with clomipramine began. Bipolar ratings scales were used to monitor the frequencies of 'general', 'attachment-related' and 'separation-related' behaviours. Kruskal-Wallis tests and Kendall Rank correlations were used to determine any initial differences between the treatment groups, and the association between the initial scores and behavioural changes after one week of treatment with clomipramine. Extended Mantel-Haenszel statistics were used to evaluate the effects of clomipramine treatment versus the placebo, and Page's test was used to assess the effectiveness of behavioural therapy on its own. There were no significant differences in the demographic characteristics of the owners of the dogs assigned to the three groups. The dogs differed slightly in age between groups, and the dogs in the two clomipramine-treated groups were reported as showing problems at a significantly earlier age than those in the placebo group. Clomipramine treatment had a sustained suppressive effect on the dogs' general activity levels, and a more modest suppressive effect on their attachment-related tendency to want much physical contact with their owners. The typical signs of separation-related behaviour problems were not significantly affected by treatment with clomipramine, but behavioural therapy on its own was highly effective in reducing behavioural problems.

An important question in state-dependent behaviour is how multiple influences on state are integrated to determine current behaviour. Aggressive behaviour is known to be affected by a prior contest experience. Nevertheless, whether and how multiple prior fighting experiences are integrated into a fighting decision remain unexplored. In this study, individuals of Rivulus marmoratus (Cyprinodontidae), a hermaphroditic fish, were given different combinations of two prior fighting experiences to investigate: (1) the effect of penultimate experiences on the probability of winning a subsequent contest; (2) the relative effect of a recent win and loss; and (3) whether the effect of a winning experience was as short lived as observed in other species. Penultimate and recent fighting experiences were given to the test fish approximately 48 and 24 h prior to the dyadic contests, respectively. From the results of the five types of contests staged, we conclude that: (1) penultimate fighting experiences had a significant effect on the probability of winning a subsequent contest; (2) a more recent experience had a more pronounced effect than an earlier experience, which suggested that the effect of a fighting experience would decay and/or the effect of a recent experience would interfere with the effect of an earlier experience; (3) no asymmetric effect between a winning experience and a losing experience was detected; and (4) the effect of both a winning and a losing experience lasted for at least 48 h in R. marmoratus which was the maximum time tested in these experiments. The possible reasons for the differences in results among studies of experience effects on contest outcomes are discussed. Copyright 1999 The Association for the Study of Animal Behaviour.

Summary Fishes have been central to our understanding of many of the major aspects of contest behaviour, extending from Tinbergen's early work on social releasers to some of the initial tests of assessment models and now to the neuroendocrine and genomic regulation of aggression and dominance. In this chapter, we focus on some exciting areas of research in fish contest behaviour that promise to shed light on the multidimensionality of resource holding potential (RHP), sex- and size-related differences in decision-making during contests, whole-organism performance and fight outcomes, selection and potential constraints on contest behaviour; and the role of developmental plasticity in driving RHP-related phenotypic variation. We have developed this chapter more as a prospectus than a review, using the concrete foundation laid down by numerous researchers to highlight areas that could be of great import in the years to come. This approach, of course, leaves us with many unanswered questions that we hope will serve as a springboard for rigorous hypothesis testing using an integrative framework for fish contest behaviour. Introduction The formal study of fish aggression has a long and prolific history dating back at least 70 years to a curious observation of three-spined sticklebacks, Gasterosteus aculeatus , responding intensely to a red postal truck that would occasionally pass the window of Niko Tinbergen's laboratory (Kruuk 2003, p. 87). What triggered aggression in the sticklebacks, of course, was not the truck but rather the colour red, a trait that males boast on their throat and ventral surface during the breeding season (ter Pelwijk & Tinbergen 1937), and that might indicate an imminent threat to a resident male's territory (Bolyard & Rowland 1996). Tinbergen and his contemporaries subsequently made significant efforts to identify behavioural, morphological and chromatic ‘releasers’ of aggression (e.g. Seitz 1940, Tinbergen 1948 and references in Earley et al . 2000).

Many animals modify behavioural decisions based on information they have previously acquired. Contest behaviour is often affected by previous contest experiences: individuals behave more and less aggressively after a victory and defeat, respectively (winner/loser effect). Individuals in the field sometimes encounter multiple competitors in quick succession, but whether these experiences interact to influence each other’s importance is unclear. We tested five hypotheses for experience interaction (no interaction, retroactive interference, proactive interaction, reinforcement and diminishing returns) using Kryptolebias marmoratus. Focal individuals were paired up with opponents having the same 1-month contest outcome (1 month before the experiment), as this difference in actual or perceived fighting ability has been shown to affect the fish’s response to new experiences. We gave the focal individual of a pair a winning or losing experience on day 1. Then both fish of the pair received the same winning, losing or no-contest experience on day 2. Then we organised fights between the two. The effect of a day-1 losing experience did depend on the fish’s actual or perceived fighting ability: one-month losers readily showed loser effects from the day-1 losing experience, irrespective of the day-2 experience (i.e. no interaction between day-1 and day-2 experiences). One-month winners, however, only showed loser effects from a day-1 losing experience when the day-2 experience was also a loss (i.e. reinforcement). Day-1 winning experiences did not interact with day-2 experiences in 1-month losers or winners. Therefore, multiple experiences sometimes reinforce each other, but how they combine to influence behaviour depends on an individual’s actual or perceived fighting ability.

Introduction Animals are capable of using information from recent experiences to modify subsequent behavioral responses. Animals' ability or propensity to modify their behavior in the light of new information has repeatedly been shown to correlate with, or be influenced by, either their intrinsic competitive ability or their dominance experience - an influence which can be long-lasting. Using a mangrove killifish, Kryptolebias marmoratus, as the study organism, we investigated whether and if so how the effect of a winning or a losing experience one day prior to a dyadic contest was modulated by both competitive ability measured two months previously and a winning or losing experience forced on the contestants one month previously. Results Winning/losing experience forced on the fish one month previously affected how they utilized information from their winning/losing experience one day before Test Day: Individuals that were randomly assigned a losing experience one month previously were more susceptible to the influence of their 1-day winning/losing experience than those assigned a winning experience. Competitive ability measured two months previously, winning/losing experience from one month previously and the winning/losing experience received one day previously all significantly influenced the fish's contest behaviors on Test Day, although only 2-month competitive ability significantly influenced escalation duration, indicating that it was still a good index for the fish's competitive ability two months later. Conclusions These results suggest that the value to the fish of information from a recent win or loss depends on the outcome of their past contests and show that contest experience has a long-term effect on contest behavior.

PPP2R2B, a protein widely expressed in neurons throughout the brain, regulates the protein phosphatase 2A (PP2A) activity for the microtubule-associated protein tau and other substrates. Altered PP2A activity has been implicated in spinocerebellar ataxia 12, Alzheimer's disease (AD), and other tauopathies. Through a case-control study and a reporter assay, we investigated the association of PPP2R2B CAG repeat polymorphism with Taiwanese AD, essential tremor (ET), Parkinson's disease (PD), and schizophrenia and clarified the functional implication of this polymorphism. The distribution of the alleles was not significantly different between patients and controls, with 68.6-76.1% alleles at lengths of 10, 13, and 16 triplets. No expanded alleles were detected in either group. However, the frequency of the individuals carrying the short 5-, 6-, and 7-triplet alleles was notably higher in patients with AD (5/180 [2.8%], Fisher's exact test, P = 0.003; including 2 homozygotes) and ET (4/132 [3.0%], Fisher's exact test, P < 0.001) than in the controls (1/625 [0.2%]). The PPP2R2B transcriptional activity was significantly lower in the luciferase reporter constructs containing the (CAG)(5-7) allele than in those containing the common 10-, 13-, and 16-triplet alleles in both neuroblastoma and embryonic kidney cells. Therefore, our preliminary results suggest that the PPP2R2B gene CAG repeat polymorphism may be functional and may, in part, play a role in conferring susceptibility to AD and ET in Taiwan.

This study was to determine whether polymorphisms of heat shock protein 70-1 (HSP70-1) and tumor necrosis factor α (TNF-α) are associated with the risk of Alzheimer’s disease (AD) and vascular dementia (VaD). Using the criteria of the NINCDS-ADRDA and NINDS-AIREN, 125 AD patients, 57 VaD patients and 109 ethnically matched nondemented controls were enrolled. The HSP70-1 –110 A/C and TNF-α –1031 T/C, –863 C/A and –857 C/T polymorphisms were analyzed by means of genotype or haplotype association methods. None of the four genotypes examined showed a statistically significant difference in genotype distribution between the AD cases and controls. However, the HSP70-1 –110 CC genotype occurred more frequently among AD cases (p = 0.0821; odds ratio: 2.08; 95% confidence interval, CI: 0.92–4.98). The overall genotype distribution among the VaD cases tended to be different at the HSP70-1 –110 and TNF-α –1031 sites (p = 0.0604 and 0.0316, respectively). The HSP70-1 –110 CC genotype was more frequent (p = 0.0459), and the association of the –110 CC genotype with VaD was evident (p = 0.0207; odds ratio: 3.22; 95% CI: 1.20–8.87). The more frequent TNF-α –1031 TC genotype (p = 0.0614) was also evidently associated with VaD (p = 0.0209; odds ratio: 2.32; 95% CI: 1.14–4.78). Multivariate analysis demonstrated the synergistic effect of the HSP70-1 –110 CC and TNF-α –1031 TC/CC genotypes on VaD (p = 0.0091; odds ratio: 10.09; 95% CI: 2.01–75.97). Haplotype analysis among TNF-α –1031, –863, –857 sites revealed that –1031C–857C may act as a risk haplotype among VaD cases (p = 0.0132, odds ratio: 2.26; 95% CI: 1.19–4.33). Our results suggest a potential protective role for HSP70 in both VaD and AD, whereas TNF-α may act as a risk factor only for VaD, and not for AD.

Experience in aggressive contests often affects behaviour during, and the outcome of, later contests. This review discusses evidence for, variations in, and consequences of such effects. Generally, prior winning experiences increase, and prior losing experiences decrease, the probability of winning in later contests, reflecting modifications of expected fighting ability. We examine differences in the methodologies used to study experience effects, and the relative importance and persistence of winning and losing experiences within and across taxa. We review the voluminous, but somewhat disconnected, literature on the neuroendocrine mechanisms that mediate experience effects. Most studies focus on only one of a number of possible mechanisms without providing a comprehensive view of how these mechanisms are integrated into overt behaviour. More carefully controlled work on the mechanisms underlying experience effects is needed before firm conclusions can be drawn. Behavioural changes during contests that relate to prior experience fall into two general categories. Losing experiences decrease willingness to engage in a contest while winning experiences increase willingness to escalate a contest. As expected from the sequential assessment model of contest behaviour, experiences become less important to outcomes of contests that escalate to physical fighting. A limited number of studies indicate that integration of multiple experiences can influence current contest behaviour. Details of multiple experience integration for any species are virtually unknown. We propose a simple additive model for this integration of multiple experiences into an individual's expected fighting ability. The model accounts for different magnitudes of experience effects and the possible decline in experience effects over time. Predicting contest outcomes based on prior experiences requires an algorithm that translates experience differences into contest outcomes. We propose two general types of model, one based solely on individual differences in integrated multiple experiences and the other based on the probability contests reach the escalated phase. The difference models include four algorithms reflecting possible decision rules that convert the perceived fighting abilities of two rivals into their probabilities of winning. The second type of algorithm focuses on how experience influences the probability that a subsequent contest will escalate and the fact that escalated contests may not be influenced by prior experience. Neither type of algorithm has been systematically investigated. Finally, we review models for the formation of dominance hierarchies that assume that prior experience influences contest outcome. Numerous models have reached varied conclusions depending on which factors examined in this review are included. We know relatively little about the importance of and variation in experience effects in nature and how they influence the dynamics of aggressive interactions in social groups and random assemblages of individuals. Researchers should be very active in this area in the next decade. The role of experience must be integrated with other influences on contest outcome, such as prior residency, to arrive at a more complete picture of variations in contest outcomes. We expect that this integrated view will be important in understanding other types of interactions between individuals, such as mating and predator-prey interactions, that also are affected significantly by prior experiences.

Objective—To develop and validate a questionnaire to assess behavior and temperament traits of pet dogs. Design—Cross-sectional survey of dog owners. Animals—1,851 dogs belonging to clients of a veterinary teaching hospital or members of national breed clubs and 203 dogs examined by canine behavior practitioners because of behavior problems. Procedure—Owners were asked to complete a questionnaire consisting of 152 items eliciting information on how dogs responded to specific events and situations in their usual environment. Data from completed questionnaires were subjected to factor analysis, and the resulting factors were tested for reliability and validity. Results—Factor analysis yielded 11 factors from 68 of the original questionnaire items that together accounted for 57% of the common variance in questionnaire item scores. Reliability was acceptable for all but 1 of these factors. Behavior problems in 200 of the 203 dogs with behavior problems could be assigned to 7 diagnostic categories that matched 7 of the factors identified during factor analysis of questionnaire responses. Dogs assigned to particular diagnostic categories had significantly higher scores for corresponding questionnaire factors than did those assigned to unrelated diagnostic categories, indicating that the factors were valid .Validity of the remaining 4 factors could not be examined because of a lack of information on dogs with behavior problems related to these factors. Conclusions and Clinical Relevance—Findings suggest that the resulting 68-item questionnaire is a reliable and valid method of assessing behavior and temperament traits in dogs. The questionnaire may be useful in screening dogs for behavior problems and in evaluating the clinical effects of various treatments for behavior problems. (J Am Vet Med Assoc 2003;223: 1293–1300)

This study conducted a quantitative ethnographic analysis of the influence of demographic factors and early experience (childhood exposure to dogs) on Taiwanese dog-keeping practices and behavior. A telephone survey of a randomly selected sample of 2001 Taiwan residents determined their dog ownership histories, current patterns of dog ownership and disposal, and other dog-related activities. The results suggest that low rates of neutering, easy availability of low- or no-cost puppies, a tendency to allow owned dogs free access to the outdoors, unrealistic expectations of dog ownership, canine behavioral problems, and religious and cultural taboos against euthanasia and shelter relinquishment have contributed to the recent increase in the numbers of free-roaming dogs in Taiwan. Logistic regression analyses determined that a relatively small number of demographic and experiential variables predicted dog ownership and disposal patterns. The most important of these was childhood experience of living with household dogs. In light of these findings, future efforts to reduce the stray dog problem should focus on enforcing registration fees, particularly for unsterilized animals; low-cost neutering schemes; and educational programs designed to promote neutering, improve knowledge of canine behavior and behavior problems, and develop more realistic expectations and attitudes toward dog ownership. Marked Taiwanese resistance to canine euthanasia and shelter relinquishment suggests a need for alternative methods of managing the existing free-roaming dog population.