Showing papers in "Behaviour in 1995"
TL;DR: It is argued that for both males and females, a temporal concentration of female fertility (breeding synchrony) increases the net benefits of seeking EPFs, and one implication of this finding is that tropical songbirds are predicted to have low levels of extra-pair matings.
Abstract: Extra-pair mating systems are now considered to be typical of songbirds because DNA fingerprinting has revealed high rates of extra-pair fertilizations (EPFs) in so many species previously thought to be monogamous. However, there is no general framework to explain the tremendous variability among songbirds in EPF rate. Here, in a comparison of EPF rates and temporal patterns of nesting among songbirds, we show that EPFs are most common in species where females breed synchronously. We argue that for both males and females, a temporal concentration of female fertility (breeding synchrony) increases the net benefits of seeking EPFs. One implication of this finding is that tropical songbirds, most of which breed asynchronously, are predicted to have low levels of extra-pair matings. Testes size is positively correlated with frequency of EPFs, and as predicted, tropical songbirds had small testes size relative to temperate zone species. The few DNA fingerprinting studies that exist for socially monogamous tropical songbirds support the correlation between breeding synchrony and EPFs. We believe that breeding synchrony is the most important factor promoting the evolution of extra-pair mating systems.
310 citations
TL;DR: In this paper, the temporal placement of bows relative to actions that are also used in other contexts (dominance or predatory encounters) such as biting accompanied by rapid side-to-side shaking of the head was analyzed to determine if bows performed during ongoing social play are used to communicate the message "I want to play despite what I am going to do or just did".
Abstract: Actions called play signals have evolved in many species in which social play has been observed. Despite there being only few empirical demonstrations, it generally is accepted that play signals are important in the initiation ("I want to play") and maintenance ("I still want to play") of ongoing social play. In this study I consider whether a specific and highly stereotyped signal, the bow, is used to maintain social play in adult and infant domestic dogs, infant wolves, and infant coyotes. To answer this question the temporal placement of bows relative to actions that are also used in other contexts (dominance or predatory encounters) such as biting accompanied by rapid side-to-side shaking of the head was analyzed to determine if bows performed during ongoing social play are used to communicate the message "I want to play despite what I am going to do or just did - I still want to play". The non-random occurrence of bows supports the hypothesis that bows are used to maintain social play in these canids when actions borrowed from other contexts, especially biting accompanied by rapid side-to-side shaking of the head, are likely to be misinterpreted.
239 citations
TL;DR: It is concluded that after a period of tuition chimpanzees can go on to imitate arbitrary actions, providing evidence of a basic cognitive capacity for perspective-taking and cross-modal matching.
Abstract: Contrary to recent scepticism, systematic use of an experimental approach suggested by HAYES & HAYES (1952) shows that chimpanzees can imitate novel actions. Two chimpanzees imitated 13 and 17 novel arbitrary gestures, respectively. They were first taught to reproduce 15 gestures on the command, "Do this!", and then presented with 48 novel items. Using a rigourous coding system, two independent observers correctly identified a significant number of the chimpanzees' imitations (p < 0.0001). We conclude that after a period of tuition chimpanzees can go on to imitate arbitrary actions, providing evidence of a basic cognitive capacity for perspective-taking and cross-modal matching.
237 citations
TL;DR: Demographic constraints, such as length of time to male maturation, coupled with intense male-male competition for mates may limit the number and duration of groups with a multimale structure.
Abstract: Twenty-five years of demographic data on free-ranging mountain gorillas (Gorilla gorilla beringei) from the Karisoke Research Center, Rwanda were used to assess male life histories and the variation within the age-graded social structure. Group types include lone silver-backs, one-male, multimale, and all-male groups. Although 60% of gorilla groups in the Virunga population are one-male, a multimale structure may increase chances of survival and future reproductive success for males at three stages of their lives. Infants born in one-male groups appear more likely to die from infanticide than those in multimale groups. Immature males in one-male groups may face decreased future reproductive opportunities compared to males in multimale groups. Adult males in one-male groups lack possible partners for coalition formation during intergroup encounters. Demographic constraints, such as length of time to male maturation, coupled with intense male-male competition for mates may limit the number and duration of groups with a multimale structure. Individuals are not restricted to one group type for their entire adult lives and males that attain maturity in each group type may eventually reproduce. Variation in male reproductive success is based both on length of reproductive tenure and on the number of mates.
182 citations
TL;DR: This paper found that women tend to become less demanding as they age, whereas males become more demanding (probably because resources increase with age), that women (but not men) offering cues of physical attractiveness make higher demands than those that do not, that men with few resources to offer attempt to offset this disadvantage by offering cues, and that men and women with dependent offspring make lower demands than others without.
Abstract: Advertisements from 'Lonely Hearts' columns in four US newspapers are used to test hypotheses about mate preferences by male and female humans. We first confirm conventional findings that, in general, men prefer young women whose reproductive value is high while women prefer men who are slightly older than themselves, that women seek resources while men seek physical attractiveness and that women are more choosy than men. We then go on to test a series of predictions derived from the hypothesis that an individual's preferences in these respects are likely to be contingent on what he/she has to offer. We show that women tend to become less demanding as they age (probably because reproductive value declines with age), whereas males become more demanding (probably because resources increase with age), that women (but not men) offering cues of physical attractiveness make higher demands than those that do not, that men (but not women) offering resources make higher demands than those that do not, that men with few resources to offer attempt to offset this disadvantage by offering cues of family commitment, that men and women with dependent offspring make lower demands than those without and that individuals from higher socio-economic groups (who are likely to have more resources to offer) make more demands than those from lower socio-economic groups.
176 citations
TL;DR: The white-faced capuchin, Cebus capucinus, employed a specialized vocalization, the trill, to coordinate troop movement at La Selva, an Atlantic wet-forest study site in Costa Rica as mentioned in this paper.
Abstract: The white-faced capuchin, Cebus capucinus, employed a specialized vocalization, the trill, to coordinate troop movement at La Selva, an Atlantic wet-forest study site in Costa Rica. We analyse the contexts in which this intra-group vocalization was emitted, including responses elicited from other group members. A cumulative 26.6 hours of continuous samples and 3,314 spectrograms (including 1,295 trills) were analysed from a study troop with 16 focal subjects. These results generally corroboratc the conclusions of a comparable field study of white-faced capuchins at Santa Rosa, a Pacific coast dry-forest site in Costa Rica (BOINSKI, 1993, Amer. J. Primatol. 30, p. 85-100). At both sites, (I) trills were closely associated with the initiation of movement by a stationary troop in a specific direction. (2) Trills were emitted at a much higher rate in the leading edge of a travelling troop than in following positions. (3) Individuals often reinforced the efforts of other troop members to coordinate troop movement. (4) Lack of consensus among troop members over the travel route was evident. (5) In rare instances trills were employed in tactical maneuvers suggestive of intentionality and the ability to anticipate behavioural effects. Differences in the usage of trills at these two sites were also detected. (1) At La Selva all troop members, with the exception of infants, used trills in the coordination of troop movement, whereas at Santa Rosa marked age, sex and rank distinctions in the extent of participation were apparent. (2) Capuchins at Santa Rosa altered the trajectory of travelling troops with trills, even reversing directions, but not at La Selva. These disparities may follow from differences between the sites in the extent of visual and auditory contact typical among troop members, social structure, susceptibility to predation, and possible genetic variation.
97 citations
TL;DR: The present results provide the first empirical demonstration, with appropriate non-maternal controls, of maternal aggression in decapod crustaceans, and the direct relation between reproductive status and contest outcome in both ovigerous and post-hatch P. clarkii are the first such data reported in crustacean research in general.
Abstract: A series of experiments investigated intraspecific aggression by maternal (carrying eggs and/or hatched young) and non-maternal female red swamp crayfish (Procambarus clarkii) residents against intrusions by non-maternal female and Form I (reproductively active) male conspecifics. Each resident occupied an aquarium containing a shelter for 24 hours prior to the initial intrusion. The winner of each encounter was determined, as well as the pair member that initiated the aggressive interaction, and the relation between the initiation of aggression and contest outcome. The results showed that: (1) Maternal female residents were winners in 92% of the encounters with male intruders, and initiated aggression in a significantly higher proportion of encounters than the male intruders. (2) Maternal female residents were the winners in 75% of the encounters with non-maternal female intruders. The maternal residents also initiated aggression in a significantly higher proportion of the encounters than the non-maternal intruders. (3) Non-maternal female residents lost 77% of the encounters with non-maternal intruders. Also, the non-maternal intruders initiated aggression in a significantly higher proportion of the encounters than did the non-maternal residents. (4) Non-maternal female residents lost all of their encounters with male intruders. However, there was no significant difference in the proportion of the encounters in which aggression was initiated by residents or intruders. (5) For all experiments combined, maternal residents won a significantly higher proportion of their encounters than did non-maternal residents, regardless of whether the intruders were males or non-maternal females. (6) For the three experiments combined, the initiation of aggression reliably predicted contest outcome (i.e. the initiator of aggression ultimately won). The present results provide the first empirical demonstration, with appropriate non-maternal controls, of maternal aggression in decapod crustaceans. Also, the direct relation between reproductive status and contest outcome in both ovigerous and post-hatch P. clarkii are the first such data reported in crustaceans, in general. Finally, the findings of these experiments bear notable similarities to the results of maternal aggression research in other taxonomic groups.
90 citations
TL;DR: The large difference between the freshwater and two marine populations is interpreted as an adaptive response to the stability of arrays of prey, characteristic of their respective habitats.
Abstract: Individuals were collected from a residential marine population of Spinachia spinachia, an anadromous population of Gasterosteus aculeatus forma trachura and a residential freshwater population of G. aculeatus forma leiura. After maintenance for 2 months on a diet of mysid, individuals were subjected to ten, consecutive daily trials on a diet of amphipods or oligochaetes. During this period, individuals learned to handle the prey more effectively, as measured by attack efficiency, handling efficiency and handling time. Learning was similar among populations but differed between diets, being more pronounced for amphipods, which are more difficult to catch and handle than oligochaetes. Once trained to these diets, fish were tested for foraging efficiency after successively longer periods of stimulus deprivation, when they were fed a maintenance diet of mysid. All three measures of foraging efficiency with the amphipod diet, but only that based on handling time with the oligochacte diet, declined to naive levels in the residential marine and anadromous populations. No decrease in foraging efficiency with either diet occurred in the residential freshwater population. Memory window was 8 d, 10 d and > 25 d in the residential marine, anadromous and residential freshwater populations respectively. The large difference between the freshwater and two marine populations is interpreted as an adaptive response to the stability of arrays of prey, characteristic of their respective habitats.
88 citations
TL;DR: Small size appears potentially to limit male provisioning of the brood, and is unlikely to be an adaptation for division oflabour in parental care, which casts doubt on the relevance of the division-of-labour hypothesis for adult size dimorphism.
Abstract: Reversed sexual size dimorphism in avian species (females larger than males) may be an adaptive consequence of different roles of males and females in parental care. We examined the alleged division of labour in two-chick broods of the blue-footed booby, using behavioural observation and frequent weighing of chicks. In the first week of parental care, males and females fed broods at similar frequencies and provided similar masses of food, but females brooded more than males when broods were 5-10 d old. Subsequently, females provided a greater mass of food and frequency of feeds than males until chicks were at least 35 d old (mass) and 60 d old (frequency), while attending the brood for just as much time as males until chicks were at least 35 d old. Males and females did not differ in the tendency to feed (frequency and mass) the first-hatched chick differentially. In nearly all components of parental care examined here, and in other studies, the female's contribution is equal to or greater than the male's. Only in clutch attendance and nest defence does the male contribute more than the female, but his small size seems unlikely to enhance performance in these activities. Overall, small size appears potentially to limit male provisioning of the brood, and is unlikely to be an adaptation for division oflabour in parental care. This result casts doubt on the relevance of the division-of-labour hypothesis for adult size dimorphism.
84 citations
TL;DR: In this paper, the influence of maternal reproductive condition on moth-infant contact, maternal rejection and infant mortality was evaluated using data from 160 vervet monkey dyads living in captive social groups and the authors concluded that mothers in marginal condition limited maternal care to restore their own health, often at the expense of infant mortality.
Abstract: Seemingly contradictory results on the relationship between maternal condition and the quality of maternal care can be resolved by the hypothesis that maternal rejection is a U-shaped function of maternal condition. Data from 160 vervet monkey (Cercopithecus aethiops sabaeus) mother-infant dyads living in captive social groups were used to evaluate the influence of maternal reproductive condition on mothcr-infant contact, maternal rejection and infant mortality. Reproductive condition was defined as Marginal, Prime and Average based on age, weight, and dominance rank. Marginal mothers were at the extremes of the reproductive age distribution (3 years old or over 14) or were below a critical body weight (3.9 kg), characteristics that are associated with low rates of fertility in the study population. Prime mothers were in the top third of the female dominance hierarchy and of prime age (5-13), characteristics associated with higher than average fertility. Both marginal mothers and prime mothers had similar high rates of maternal rejection and low rates of ventral contact and proximity with their infants. Compared to mothers in the two extreme groups, mothers in average reproductive condition were significantly less rejecting and played a larger role in maintaining contact with their infants. Rates of maternal rejection, mother-infant contact, responsibility for contact, and the percentage time that infants spent on nonmaternal caretakers were all significantly related to maternal condition in U-shaped or inverted U-shaped functions. The infant mortality due to maternal abandonment or neglect was highest in the marginal group and was related to low body weight of the mother. We conclude that mothers in marginal condition limited maternal care to restore their own health, often at the expense of infant mortality, whereas mothers in prime condition used rejection to shorten the interval to the ncxt conception, without suffering higher rates of infant mortality than average mothers.
83 citations
TL;DR: Chimpanzees in the Ndoki forest seem to be able to obtain termitcs from the deep subterranean nest throughout the year by using their tool-set, and this newly described behavior shows that chimpanzees habitually manipulate a tool on an object which they previously modified with another type of tool.
Abstract: Observations strongly indicate chimpanzees (Pan troglodytes troglodytes) of the Ndoki forest use two types of tools, 'perforating sticks' and 'fishing probes' in combination for termite (Macrotermes muelleri) fishing. Perforating sticks were always made of small, stout branches or young saplings of Thomandersia laurifolia (Acanthaceae), about 10 mm in diameter, with lengths of about 50 cm. Fishing probes were made from the flexible stems of Marantaceae species, and were about five mm in diameter, with lengths of about 50 cm. Approximately 15 cm of one end of the tool was usually shaped into a brush. It is likely that chimpanzees make small holes in the termite mound wall to attain access into the termite nest inside, then they insert the probe into the holes and eat the major and minor soldier termites which bite the brush-like end. Of 214 chimpanzee feces collected, 50% contained termite remains of this species, and this fecal analysis shows that termite-eating behavior occurred all the year around, and did not correspond to the seasonality of rainfall or termite activity on the ground. Chimpanzees in the Ndoki forest seem to be able to obtain termitcs from the deep subterranean nest throughout the year by using their tool-set. Such a tool-set might be responsible for the higher frequency of termite-eating in Ndoki chimpanzees than those of chimpanzees in other sites who fish for termites using only probes. This newly described behavior shows that chimpanzees habitually manipulate a tool on an object which they previously modified with another type of tool.
TL;DR: In this paper, the dynamics of dominance between 20 adult male wild rats were investigated in a multi-generational, free-breeding colony in a large outdoor enclosure, and age was the most reliable indicator of adult dominance, with the higher ranking males being older but not necessarily heavier.
Abstract: One way of understanding the evolution of social dominance is to establish which factors determine an animal's ability to dominate conspecifics. The dynamics of dominance between 20 adult male wild rats were investigated in a multi-generational, free-breeding colony in a large outdoor enclosure. Dominance relations between the adult males were stable and organised in a near-linear hierarchy. Dyadic interactions not fitting the social hierarchy, as well as challenges by subordinates and overt aggression by dominants were rare (< 5%) and principally occurred between animals of similar social rank. The correlates of social status within the colony show, for the first time in adult small mammals, that despite the significant role of body weight on the probability of winning contests, age was the most reliable indicator of adult dominance, with the higher ranking males being older but not necessarily heavier. Age also explained the outcome of 85% of agonistic encounters between dyads, compared with 65% for weights. The proximate mechanisms of age-related dominance fit better the 'previous outcome' hypothesis than the alternative 'fighting skill' or 'site dominance' hypotheses. The stability of dominance relations and the role of age, which in stable groups is equivalent with time spent in the colony, suggest that rats remain dominant over individuals that they have beaten in the past, long after initial body weight asymmetries have disappeared. The functional significance of the acceptance of subordinate social status is consistent with the fact that dominant individuals generally could not monopolize food resources or mates.
TL;DR: There is a behavioural continuum on migration between the feeding and breeding grounds which is not governed solely by spatial proximity to the terminus, and the pod characteristics of humpback whales on their return migration to the feeding grounds showed greatest similarity to those observed on breeding grounds elsewhere.
Abstract: The size and sex composition of migrating humpback whale pods were investigated off the east Australian coast. Two hundred and thirty one singletons, 257 pairs, 63 trios, 7 quads and 4 pods containing more than 5 individuals were observed during two land-based surveys carried out throughout the northward migration in 1991 and 1993. Generally humpback whales migrated northward towards the breeding area in pods of I or 2 individuals. In 1992, a biopsy study was carried out throughout the northward and southward migrations. Pods migrating southward (mean = 2.59, SE = 0.19) towards the feeding areas were significantly larger than those travelling north (mean = 1.75, SE = 0.03). The sex of 134 individuals in 63 complete pods was determined by molecular analysis of skin biopsies. Male humpback whales were found in larger pods than females. The most common pod type observed was the male-female pair, which is suggestive of either mating on migration and/or mate-guarding. Males were found associated together frequently. Competitive behaviour was observed during both the northward and southward migrations. The sexing of all individuals within 8 competitive pods indicated that not all contained a female. Although competitive behaviour was observed during the migration, most male-male associations were charactcrised by non-agonistic and occasionally cooperative interactions. We suggest there is a behavioural continuum on migration between the feeding and breeding grounds which is not governed solely by spatial proximity to the terminus. The pod characteristics of humpback whales on their return migration to the feeding grounds showed greatest similarity to those observed on breeding grounds elsewhere. In conclusion, our study showed that the migration of humpback whales is more
TL;DR: Divergent selection pressures, which are probably common in natural populations, would account for the presence of multiple phenotypes and allow for rapid shifts in defensive morphology among different populations where predation regime differs.
Abstract: This study investigates ecological aspects to intrapopulation variability in the lateral plates of threespine stickleback (Gasterosteus aculeatus) at a coastal lake in western Canada. The frequency distribution of the plates, which was slightly skewed to the right and leptokurtic, varied spatially and seasonally. Cyclical frequency changes in plates were most pronounced on sub-adult size classes and these closely tracked (multiple r = 0.77) seasonal differences in the relative proportion of the two major predator groups, trout and diving birds. Trout predation was correlated with an increase in plate number while bird predation was correlated with a reduction in plate number. Such divergent selection pressures, which are probably common in natural populations, would account for the presence of multiple phenotypes and allow for rapid shifts in defensive morphology among different populations where predation regime differs.
TL;DR: Results demonstrate that fathead minnows recognize and avoid areas where darter alarm pheromone is detected and that this is a learned response, and suggest that less experienced fish do not avoid darter skin extract to the same extent as do older more experienced fish.
Abstract: Detection of an alarm pheromone may allow conspecifics to lower their risk of predation if they avoid areas where alarm pheromones are detected Similarly, individuals that learn to recognize and avoid alarm signals produced by heterospecifics of their prcy guild (ie those with which they share common predators) will likely receive similar benefits In two separate field studies we tested whether fathead minnows (Pimephales promelas) avoid areas labelled with Iowa darter (Etheostoma exile) skin extract (which contains an alarm pheromone) One population of minnows tested was sympatric with darters while thc other was allopatric from darters Swordtails (Xiphophorus helleri) are allopatric from fathead minnows in both of the populations tested Swordtail skin lacks ostariophysan and darter alarm pheromones, and was used to control for a general response to damaged skin of an unfamiliar fish In the darter-sympatric population we captured significantly fewer and smaller minnows in traps marked with darter skin extract (experimental traps) than traps marked with a control of swordtail skin extract Given the correlation between age and size, and therefore experience, these data suggest that less experienced fish do not avoid darter skin extract to the same extent as do older more experienced fish In the darter-allopatric population there was no difference in the number of minnows or the size of minnows captured in control versus experimental traps Taken together, these results demonstrate that fathead minnows recognize and avoid areas where darter alarm pheromone is detected and that this is a learned response Use of heterospecific alarm pheromones to assess predation risk may be a widespread phenomenon within communities of small fishes
TL;DR: In this paper, it was shown that Barbary macaque mothers can recognize their offspring by more than one signal cue, and such a strategy may improve the recognition system's robustness against possible distortions caused by the environment.
Abstract: It had been shown that Barbary macaque (Macaca sylvanus) mothers are able to individually recognise their offspring by its vocal signals, but it remained unclear which acoustical cues may account for such an ability. In order to address this issue from a basic perspective, about 1800 calls of infants and yearlings (N = 10) were investigated. The investigation applied a method of signal analysis which allowed to determine a large number of parameters (N = 84) for each vocal signal. The application of discriminant and cluster analyses provided the following results: (1) Animals differed in almost all call parameters. However, individuals were best identified by specific parameters which formed an individually characteristic parameter set. (2) Those parameters that facilitated the assignment of vocal patterns to a given individual usually were different among individuals. (3) Infants and yearlings achieved the same maximum value of correct assignment. However, infants achieved a reasonable assignment at a much smaller number of call parameters. (4) Cluster analysis of vocalisations revealed that Barbary macaques uttered individual versions of common call types. (5) When the discriminant analysis was rerun on the call clusters, the correct assignment could be improved from 81 % to 94% for infants and from 80.5% to 96% for yearlings. Our findings suggest that Barbary macaque mothers can recognise their offspring by more than one signal cue, and such a strategy may improve the recognition system's robustness against possible distortions caused by the environment. The pronounced differences in vocal patterns of young Barbary macaques may help mothers or other group members to readily learn and recognise the individually specific signal features. The methodological procedures described in this paper provide a powerful tool for an assessment of signal parameters also in other areas of vocal interactions.
TL;DR: In this paper, the authors examined whether prenatal chemosensory experience influenced chemoencensory-based orientation behavior in newly-born lambs and found that lambs showed a clear attraction to amniotic fluid (AF) and distilled water in a double-choice test.
Abstract: The present study examined whether prenatal chemosensory experience influenced chemosensory-based orientation behaviour in newly-born lambs. Two experimental strategies were developed in order: (i) to analyse the responsiveness of lambs to odours extracted from the prenatal environment (experiments 1 and 4) and to odours their were never exposed to (experiment 2), and (ii) to analyse the neonatal consequences of a prenatal exposure to a novel odorant (experiment 3). In experiment 1, when simultaneously presented with amniotic fluid (AF) and distilled water in a double-choice test, lambs displayed a clear attraction to AF. In experiment 3, two groups of lambs received differing exposure to citral in utero: group I lambs were born to ewes fed a citral diet and group 2 lambs were born to ewes never exposed to citral (CI). They were assessed in a double-choice test contrasting CI and AF (experiment 2 indicates that CI was neither attractive nor aversive in naive lambs). Although control lambs showed a clear preference for AF over CI, those exposed to CI prenatally did not orient discriminately to either stimulus, suggesting that prenatal experience with CI may alter postnatal responsiveness to it. Experiment 4 tested the ability of lambs to discriminate between the chemosensory qualities of samples of own vs alien AF; lambs oriented preferentially to their own AF. These findings suggest that prenatal chemosensory experience may be stored by lambs for some time after birth and influence their search behaviour.
TL;DR: Observations of freely moving birds suddenly confronted with another hen showed that even when the object bird was familiar, it was in all cases initially scrutinized from a close distance, which is consistent with the hypothesis that hens are unable to recognize other birds except when close enough to view them with the myopic lower frontal field.
Abstract: When shown familiar and unfamiliar birds at different distances, hens viewed birds 0.7 m or 1.4 m away with modal head angles between 54° and 72° from the midline, using the lateral visual field but viewed birds closer (less than 20 cm) binocularly, with the head within 18° either side of the midline (Expt. 1 When faced with a choice between a familiar and an unfamiliar bird at different distances, hens chose the familiar bird if the choice could be made 8 cm away but their choices were random if they had to chose 66 or 124 cm away (Expt. 2). This suggests that hens may be unable to discriminate familiar from unfamiliar birds except when they are very close to them. Observations of freely moving birds suddenly confronted with another hen (Expt. 3) showed that even when the object bird was familiar, it was in all cases initially scrutinized from a close distance (26 cm or less), which is consistent with the hypothesis that hens are unable to recognize other birds except when close enough to view them with the myopic lower frontal field. Reasons for this constraint on social recognition are discussed.
TL;DR: Subjects were more attracted to zigzag dancing ♂ displaying at normal to slightly faster tempo than to ♂♂ displaying outside that range, suggesting stabilizing selection that such effects might impose on animals could contribute to the typical intensity that characterizes much of their display behaviour.
Abstract: [Reproductive ♂ and ♀ threespine stickleback Gasterosteus aculeatus were presented with a videotaped sequence of a zigzag dancing ♂ played back at normal (T), half (0.5T), one-and-a-half (1.5T), double (2T) and triple (3T) tempo. Playbacks were displayed pairwise (T/0.5T; T/ 1.5T; T/2T; T/3T) on monitors placed at opposite ends of the test tank. Each playback pair was displayed to subjects for 4 min, with display locations switched to opposite ends of the test tank at 2 min to control for position preference. Both ♂ and ♀ subjects responded to playback images much like they do to live ♂♂, ∏demonstrating the potential of video playback for analysing visual communication in stickleback. Male and ♀ subjects contacted 1.5T and 2T images as much as images moving at normal tempo but they contacted 0.5T and 3T images less. Thus, subjects were more attracted to ♂♂ displaying at normal to slightly faster tempo than to ♂♂ displaying outside that range. The stabilizing selection that such effects might impose on animals could contribute to the typical intensity that characterizes much of their display behaviour., Reproductive ♂ and ♀ threespine stickleback Gasterosteus aculeatus were presented with a videotaped sequence of a zigzag dancing ♂ played back at normal (T), half (0.5T), one-and-a-half (1.5T), double (2T) and triple (3T) tempo. Playbacks were displayed pairwise (T/0.5T; T/ 1.5T; T/2T; T/3T) on monitors placed at opposite ends of the test tank. Each playback pair was displayed to subjects for 4 min, with display locations switched to opposite ends of the test tank at 2 min to control for position preference. Both ♂ and ♀ subjects responded to playback images much like they do to live ♂♂, ∏demonstrating the potential of video playback for analysing visual communication in stickleback. Male and ♀ subjects contacted 1.5T and 2T images as much as images moving at normal tempo but they contacted 0.5T and 3T images less. Thus, subjects were more attracted to ♂♂ displaying at normal to slightly faster tempo than to ♂♂ displaying outside that range. The stabilizing selection that such effects might impose on animals could contribute to the typical intensity that characterizes much of their display behaviour.]
TL;DR: The data suggest that vigilance costs occur in wild blue monkeys engaged in allogrooming, and they may accrue to the recipient ofgrooming as well as the groomer, and may be compensated for both partners by long- or short-term benefits.
Abstract: Although allogrooming in Catarrhine primates is often interpreted as if it were a costly behavior for the groomer, such costs have not been convincingly documented. This paper presents data on rates of vigilance for aerial predators, measured as looking up toward the sky, in wild blue monkeys engaged in allogrooming, and compares these vigilance rates to those occurring when the same individuals engaged in other activities, namely feeding and resting. Grooming individuals have much lower vigilance rates than resting or feeding individuals, suggesting that grooming individuals are more likely to be at risk of being preyed upon. These results are not caused by a systematic relationship in the sample between activity and either foliage density or time of day, two factors potentially related to levels of safety from predation. Nor was there evidence that blue monkeys avoid the vigilance costs of grooming by engaging in this behavior primarily at safe times or in safe locations. Although the data suggest that vigilance costs occur, they may accrue to the recipient ofgrooming as well as the groomer, and may be compensated for both partners by long- or short-term benefits.
TL;DR: The authors summarizes the research into the social abnormalities in autism, and reviews the empirical support for two behavioural hypotheses on autism, i.e., that autism results from impaired attachment, or from intense and prolonged approach-avoidance conflicts.
Abstract: Autism is characterized by an impaired development in social interaction and communication and a markedly restricted repertoire of activities and interests. This paper summarizes the research into the social abnormalities in autism, and reviews the empirical support for two behavioural hypotheses on autism, i.e. that autism results from impaired attachment, or from intense and prolonged approach-avoidance conflicts. The core social impairment of autistic subjects seems to be a deficit in attunement and timing of actions and reactions rather than a difference in frequencies of behaviours. Attachment behaviour of most, if not all autistic children tends to be disorganized; nevertheless, they do form attachment relationships in terms of preferential proximity seeking or reunion behaviour in the Strange Situation Test. Attachment studies performed sofar however have methodological limitations ; particularly the study of maternal-infant attunement and reciprocity has been neglected. Empirical evidence fails to support the presence of approach-avoidance conflicts in autistic subjects, and is further at variance with the predicted consequences of such conflicts. Insufficient attention has hitherto been paid to the clinical heterogeneity of autism in behavioural studies. A promising approach to deepen our understanding of the development of the autistic symptomatology is the early detection and subsequent behavioural study of 1-2 year old children at high-risk for autism. Finally, behaviour observation studies in autistic subjects are likely to benefit from the concurrent assessment of physiological indices of arousal, and from the integrated measurement of social-cognitive processes.
TL;DR: In the sex-role reversed pipefish Syngnathus typhle males search for mates, and prefer to mate with large rather than small females.
Abstract: In the sex-role reversed pipefish Syngnathus typhle males search for mates, and prefer to mate with large rather than small females. When mate density was experimentally manipulated, males exerted ...
TL;DR: Juvenile and adult Psammodromus algirus lizards were slower than adult lizards, and escaped during less time and to shorter distances, even when removing the effect of body size.
Abstract: We compared the escape behaviour of juvenile and adult Psammodromus algirus lizards, by using data of escape performance in the laboratory and field observations of escape behaviour. We specifically examined whether a differential escape response is a constraint of body size, or whether juveniles behave differently in order to maximize their escape possibilities taking into account their size-related speed limitations. In the laboratory, juvenile lizards were slower than adult lizards, and escaped during less time and to shorter distances, even when removing the effect of body size. In the field, juveniles allowed closer approaches and after a short flight usually did not hide immediately, but did so after successive short runs if the attack persists. Approach distance of juveniles was not affected by habitat, but initial and total flight distances were shorter in covered microhabitats. There was no significant effect of environmental temperature on approach and initial flight distances of juveniles. However, the total flight distances were significantly correlated with air temperatures.
TL;DR: Current selection on sexual size dimorphism was studied in a widely foraging non-territorial lizard, Ameiva plei, and it appears that natural selection has favored different trade-offs between growth and reproduction in males and females.
Abstract: Current selection on sexual size dimorphism was studied in a widely foraging non-territorial lizard, Ameiva plei. Males were significantly larger than females. Large males won intrasexual agonistic encounters and guarded females during their entire receptive period (1-4 days). Guarding males spent significantly less time foraging than males who were alone. Only males that guarded females were observed to mate. Mating success was highly skewed with only six of 21 mature males in the study site observed mating. All six males who mated were 141 mm SVL (males mature at 62 mm SVL). The four largest males obtained 84% of all observed matings and were estimated to have fertilized 88% of the eggs. Sexual selection appears to favor large size in males due to competition among males to guard females. Large females on Anguilla also had higher reproductive success bccause SVL was positively correlated with clutch size and number of clutches in a season. It appears that natural selection has favored different trade-offs between growth and reproduction in males and females.
TL;DR: The results suggest that the ancestral condition was intermediate and that both cannibalistic and non-cannibalistic freshwater populations display some derived elements in their reproductive repertoires, which can provide insights into the patterns and causes of adaptive diversification.
Abstract: The endemic radiation of the threespine stickleback in North America possesses features that will permit us to gain unique insights into evolutionary pattern and process Already, comparison of populations has demonstrated a remarkable level of adaptive differentiation in reproductive behavior across populations in both southern British Columbia, Canada, and the Cook Inlet Region of Alaska, USA In small, shallow lakes, threespine stickleback feed predominantly on benthic invertebrates in the shallow littoral zone They form large groups that attack nests defended by males, and consume all of the young within In contrast, in larger, more oligotrophic lakes, adult stickleback feed primarily on plankton in large open-water foraging groups They do not form groups that cannibalize young in nests In these non-cannibalistic populations, males perform more conspicuous courtship behavior than do those in cannibalistic populations, apparently because risk of attack by visually hunting conspecifics is low Courtship in these lakes more often includes the conspicuous zig-zag dance, and less often, meandering and dorsal pricking Anadromous populations tend to be cannibalistic, but also are often behaviorally intermediate They incorporate the zig-zag dance in courtship more often than do males in cannibalistic freshwater populations, but also usually incorporate the less conspicuous dorsal pricking behavior These results suggest that the ancestral condition was intermediate and that both cannibalistic and non-cannibalistic freshwater populations display some derived elements in their reproductive repertoires This kind of comparison among populations thought to have been independently derived from the marine form can provide insights into the patterns and causes of adaptive diversification For populations such as these, carefully chosen from disparate geographic locations so as to preclude common evolutionary history after colonization of freshwater,
TL;DR: All aspects of male reproductive behaviour can be restored in castrated males with 11KA capsules, and 11-androgens are more effective than other androgens in stimulating secondary sexual characters, notably kidney hypertrophy.
Abstract: In vitro incubations showed 11-ketoandrostenedione (11KA) to be the main androgen produced by the testes of the breeding stickleback. In breeding males the plasma levels of 11-ketotestosterone (11KT) are higher than those of other measured androgens, and display a clear peak in the breeding season. 11 KA can be converted extra-testicularily to 11KT. In breeding females the plasma levels of 11KT are lower than in breeding males, whereas the opposite is the case for testosterone. Castration leads to the disappearence of male reproductive behaviour and secondary sexual characters. 11-androgens are more effective than other androgens in stimulating secondary sexual characters, notably kidney hypertrophy. All aspects of male reproductive behaviour can be restored in castrated males with 11KA capsules. 11KA was more effective than other tested androgens in this respect. The effcctiveness of 11KA on nesting is not influenced by photoperiod.
TL;DR: Threespine stickleback vary greatly in male nuptial display, from full red expression between the throat and pelvis to total melanism without any traces of red, which suggests that preference for an epigamic optical signal is likely a function of its efficacy in generating visual contrast rather than its intrinsic spectral characteristics.
Abstract: Threespine stickleback vary greatly in male nuptial display, from full red expression between the throat and pelvis to total melanism without any traces of red. The dominant expression for any population is correlated with the underwater spectral irradiance and many populations with melanistic nuptial colour occur in bog habitats where the aquatic spectrum is shifted to long wavelengths. Field observations indicate that in these bog habitats, the typical red nuptial signal is 'spectrally masked' and this might reduce the effectiveness of display during male-male and male-female interactions. We used video imaging techniques to test whether the spectral composition of the visual background influences female preference for nuptial colouration in male threespine sticklebacks. Throat colour preference tests were carried out in which females chose between video images of red and black-throated males superimposed on either a blue or a red background. Despite belonging to a red-throated population, females were found to respond preferentially to the black-throated male image viewed against a red background, indicating that preference was not determined by throat patch hue. This suggests that preference for an epigamic optical signal is likely a function of its efficacy in generating visual contrast rather than its intrinsic spectral characteristics.
TL;DR: The results shows that female preference may impose directional sexual selection upon a static acoustic character that is correlated with male size in Alytes obstetricans and A. cisternasii.
Abstract: A previous study reported that large males had greater mating success than small males in two species of midwife toads. A behavioural mechanism that would explain such a pattern is sought. Dominant frequency is inversely correlated with male size in Alytes obstetricans and A. cisternasii. In both cases, two-speaker playback tests with synthetic calls show that females have a significant preference for calls with low frequencies. The results shows that female preference may impose directional sexual selection upon a static acoustic character that is correlated with male size. Male Alytes tend their eggs on land, but male size is not correlated with hatching success. Therefore female preference for larger males does not appear to directly increase female fitness.
TL;DR: In this paper, the authors studied dominance relations among females in a small, well-habituated troop of Yakushima macaques (Macaca fuscata yakuz) in southern Japan.
Abstract: Dominance relations among females were studied in a small, well-habituated troop of Yakushima macaques (Macaca fuscata yakuz) in southernjapan. Data were collected using focal animal sampling over a 20-month period. Although the frequency of aggression was much lower than that reported for provisioned groups, and support in agonistic interactions was rare, a clear linear dominance hierarchy was apparent. In each of the four pairs of sisters in the troop the older was dominant to the younger. This is contrary to the pattern commonly reported for provisioned groups of Japanese and rhesus macaques, in which dominance among sexually mature sisters tends to be inversely correlated with age. For each pair of sisters in the study troop the mother was alive and healthy when the younger daughter became sexually active, but no cases were seen of a mother aiding one daughter against another. We therefore conclude a) that the absence of youngest ascendancy was due to a lack of support, rather than a lack of potential allies, and b) that both frequent agonistic support and youngest ascendancy are most likely to occur under conditions where concentrated food resources result in frequent and intense aggression.
TL;DR: The results of mathematical models of colour opponent and luminosity processing suggest that female preferences are influenced by a male's belly colour contrast and not by merely its brightness contrast.
Abstract: We investigated the importance of male nuptial colouration as a cue for female mate choice in the threespine stickleback Gasterosteus aculeatus L. In courtship preference tests, sexually receptive females were presented with pairs of dummies that differed in the hue, extent or distribution of colouration. Females preferred to court i) a red-bellied dummy over a green-bellied dummy, a uniformly tan dummy, and an all-red dummy and ii) a yellow-bellied dummy over a red-bellied dummy. Females showed no preferences when presented with i) an all-red and uniformly tan dummy and ii) two dummies that differed only in the location of red colouration (belly versus dorsum). In the three experiments in which females preferred a 25% red dummy, the proportion of courtship directed to this dummy increased with overall female responsiveness. The results of mathematical models of colour opponent and luminosity processing suggest that female preferences are influenced by a male's belly colour contrast and not by merely its brightness contrast.