bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pair Bonds in Monogamous Apes: a Comparison of the Siamang Hylobates Syndactylus and the White-Handed Gibbon Hylobates Lar
Authors: Palombit Ryne A. 
Published: April 2008

AbstractDescriptions of the social systems of gibbons (Hylobates, Hylobatidae) have typically emphasized generically uniform attributes such as 'monogamy' and 'territoriality'. This has prevented testing of the hypothesis that pair bonds differ in the siamang (Hylobates syndactylus) and the white-handed gibbon (Hylobates lar) (Chivers, 1972). I replace a description of sociality based on mating system and group size/composition with quantitative measurement of social interactions and spatial relations between wild adult males and females in three heterosexual pairs of siamang and two pairs of white-handed gibbons studied for 2.5 years at the Ketambe Research Station (Sumatra, Indonesia). Siamang pair bonds show greater heterosexual cohesion than those of white-handed gibbon as reflected in higher rates of affinitive interactions such as close proximity, relaxed physical contact, embraces, and communal use of sleep trees. Although males are more responsible than females for the maintenance of close proximity in both species, sex differences in intra-pair allogrooming suggest divergent mechanisms maintaining pair bonds in the two species. In white-handed gibbons, the female rarely initiates grooming and grooms her mate significantly less than he grooms her, partly because she solicits grooming from him at higher rates while simultaneously ignoring more of his 'presents' for grooming. In siamang, the contributions of the sexes to grooming are more equivalent and reciprocal. Taken together, these results suggest that investment of the sexes in maintaining the pair bond is more asymmetrical in white-handed gibbons (i.e. males contribute relatively more than females) and more mutual in siamang. Although mate guarding may have been the selective force behind the origin of pair bonds in both species, greater intra-group feeding competition in the gibbon and substantial paternal care in the siamang may account for the evolution of more reciprocal and stronger pair bonds in the latter. Future research on more groups is necessary to clarify the proposed species differences in light of existing intraspecific variation in social behavior.
The Proximate Mechanisms of Natal Dispersal in Female Horses
Authors: Monard Anne-Marie , Duncan Patrick , Boy Vincent 
Published: April 2008

Abstract
The aim of this study was to investigate proximate mechanisms of natal dispersal by female horses, Equus caballus (i.e. proximate causes and the factors influencing the timing), and to test predictions from two functional hypotheses: the intrasexual competition hypothesis, and inbreeding avoidance. The data concerned 40 individuals born between 1974-1985 in a closely monitored herd which developed a natural social structure during this period. All the females dispersed from their natal groups; none became solitary; 80% transferred to existing harems, the others formed new groups with bachelor stallions. Abduction by stallions affected only a quarter of the females whose transfers were observed. The results of this study do not support the hypothesis that a function of natal dispersal is to reduce intrasexual competition. The young females were not expelled by resident females of their natal groups, and did not, as a rule, experience increased aggression from these females before emigration. Their social bonds with members of their natal groups showed no progressive weakening prior to departure, and there was no gradual strengthening of bonds with individuals in the groups to which they transferred. There was no evidence for reproductive competition between the young females and resident mares of their natal groups, since the young females always refused the sexual approaches by males of these groups. Finally, age at dispersal did not decrease with the number of resident females in the groups they left. In contrast, as predicted by the inbreeding avoidance hypothesis, the primary cause of dispersal appeared to be sexual attraction to unfamiliar males. When in oestrus and before dispersing, the young females accepted matings only with males of other groups in spite of frequent sexual approaches by males of their natal groups (normally close relatives). In addition, none dispersed before first oestrus, and most did so during an oestrous period, at or before the conception of their first foal. The mothers of most young females interposed themselves when close kin males of the natal group approached their daughters sexually; this could contribute to the avoidance of close inbreeding. Among the other factors examined, some did not influence dispersal of the young females : they experienced low levels of aggression by adult stallions of their natal groups, particularly at the time of departure; their weight and body condition had no significant effects on leaving age nor did their mother's rank, the number of siblings, or the birth of another. In contrast, as the number of groups and the breeding sex ratio increased, dispersal age declined, occurring at a median age of 23 months (range 12-42 months) in the later years, when the herd had developed a natural social system.
Response of Male Goby, Padogobius Martensii, To Aggressive Sound Playback Following Pre-Experimental Visual Stimulation
Authors: Lugli Marco 
Published: April 2008

AbstractThree playback experiments with a freshwater goby, Padogobius martensii, examined the effects of recent aggressive experience on the response of the territorial fish to the aggressive sound alone. Experiments 1 and 2 were conducted on a first group of fifteen resident males (i.e. males individually housed within laboratory tanks for at least 5 days). Experiment 1 simply consisted of playing back the sound to the resident male not exposed to social stimulation for at least 48 h. In experiment 2 the same male was exposed to its mirror image before the start of playback. Results showed that in experiment 1 males ignored or even tended to avoid the site of sound stimulation, whereas in experiment 2 they attended the sound site more frequently during the sound playback. In both experiments the mirror and the loudspeaker were placed on the same side of the tank. The third playback experiment was therefore developed to include mirror and loudspeaker on opposite sides of the tank. A different group of sixteen males was used for these experiments. Results showed that the sound playback may be more important than the mirror site in directing the approach response of the male. Furthermore, the magnitude of sound interference was positively correlated with the level of mirror aggressiveness shown by the male before playback. Functional implications of the responses to the aggressive sound alone for the territorial fish are discussed.
Sensitivity To Variability in Food Amount: Risk Aversion Is Seen in Discrete-Choice, But Not in Free-Choice, Trials
Authors: Roche John P. , Timberlake William , Mccloud Christie 
Published: April 2008

Abstract
A number of studies have observed that animals experiencing positive energy budgets tend to prefer alternatives offering constant amounts of food over those offering variable amounts of food, i.e. they tend to be risk averse. This observation, and the related finding that small animals experiencing negative energy budgets have been observed to prefer alternatives variable in food amount (i.e. to be risk prone), has often been explained by the hypothesis that animals choose the alternative with the highest expected utility. The present study examined if short-term differences in expected energy intake created by delays until when food is next available influence risk sensitivity in Norway rats (Rattus norvegicus). Norway rats were presented with choices between two feeding sites, one offering constant amounts of food, one offering variable amounts of food. In one treatment, rats could only sample one feeding site per daily trial (discrete-choice trials), in a second, they could sample both sites within a trial (free-choice trials), and in a third, they could sample the second-choice site after an imposed delay of 30 s. In the free-choice treatment, rats were indifferent to variability in food amount whereas in the discrete-choice treatment rats displayed a significant preference for the constant alternative. Therefore, the sensitivity the rats showed toward variability in food amount was influenced by the rats' expected energy intake in the period after visiting the first-choice patch. Rats in the free-choice with delay treatment displayed risk indifference just as those in the free-choice treatment did, however, indicating that differences in expected energy intake over a 30-s interval did not influence risk sensitivity.
The Organisation of Behaviour in Hermit Crabs: Responses To Variation in Stimulus Strength
Authors: Hazlett Brian A. 
Published: April 2008

AbstractChemical stimuli were presented to individuals of the hermit crab Diogenes avarus to determine the nature of the interactions between stimuli that elicit conflicting responses. The odour of degraded snail flesh (a signal associated with potential empty shells) elicited an increase in both locomotion and the rate of grasping of gastropod shells. The odour of a visual predator (Matuta lunaris) elicited a cessation of locomotion by the hermit crabs. When snail flesh odour was presented in combination with various strengths of the predator odour (5% to 100%), the responses tended to show a step-function relationship to stimulus strength. Predator inhibition of snail-induced grasping dominated until predator strength was just 5% of full strength odour. However, 5% predator odour alone induced a response similar to full strength predator odour. In the case of locomotion, snail-induced increases predominated no matter what the strength of the predator odour. For both behaviours, responses of hermit crabs tended to be hierarchical rather than graded.
Carib Grackles Imitate Conspecific and Zenaida Dove Tutors
Authors: Lefebvre Louis , Templeton Jennifer , Brown Kathleen , Koelle Michelle 
Published: April 2008

Abstract
In Barbados, Carib grackles (Quiscalus lugubris) forage in opportunistic aggregations that include territorial Zenaida doves (Zenaida aurita) and flocks of conspecifics. In searching for and handling food, grackles use complex beak movements and modulate priority of access with a mixture of postural signals and intra- and interspecific scramble (unaggressive) competition. We show in two experiments that wild-caught grackles learn as readily from a Zenaida dove as they do from a conspecific tutor, whether tutors use similar or different food-finding techniques. Grackles also imitate the technical variant that the hetero- and conspecific tutors were shaped to demonstrate: those who observed a Zenaida dove used the dove's closed beak pecking technique, while those who observed a conspecific used the grackle's open beak pulling, probing or prying. Our findings suggest that imitation, like other forms of social learning, is strongly influenced by a species' foraging ecology. In particular, the ability to imitate novel motor skills should be favored in opportunistic species which exhibit scramble competition and which use complex searching and handling techniques to forage on embedded foods.
Behavioural Indicators of Anxiety: an Empirical Test in Chimpanzees
Authors: Baker Kate C. , Aureli Filippo 
Published: April 2008

AbstractBehavioural, pharmacological, and physiological evidence supports an association between displacement activities and anxiety in macaques. Information is scarce in other primate and non-primate species. This study contributes to the understanding of the relation between displacement activities and emotional states by investigating the correspondence between self-directed behaviour and an inherently stressful situation in chimpanzees (Pan troglodytes). Data were collected on 81 captive chimpanzees housed in conditions varying from indoor single caging to indoor/outdoor enclosures containing up to 14 individuals. Observation of gentle and rough scratching, self-grooming, and yawning were used to test predictions concerning the response of individuals to neighbour vocalisation (i.e. the calls and noisy displays produced by neighbouring groups of chimpanzees), which has been previously demonstrated to increase the likelihood of intragroup agonistic behaviour. In socially-housed chimpanzees rough and gentle scratching and yawning were significantly more common after neighbouring individuals vocalised or displayed than before, but the effect lasted longer for rough-scratching. In addition, during periods characterised by higher levels of neighbour vocalisation, socially-housed chimpanzees performed rough scratching at higher rates. Self-grooming was not affected by the level of neighbour vocalisation. Single-caged chimpanzees, for whom neighbour vocalisation carries no risk of aggression by group members, showed no increase in self-directed behaviour when neighbour vocalisation level was high, suggesting that the risk of intra-group aggression, rather than neighbour vocalisation itself, elicits anxiety. While our study suggests that rough scratching is the most reliable indicator of anxiety in chimpanzees in the context of neighbour vocalisation, it also provides evidence that gentle scratching and yawning can be considered displacement activities in this species.
Shoal Choice Behaviour in Fish: the Relationship Between Assessment Time and Assessment Quality
Authors: Krause Jens , Rubenstein Dan , Brown David 
Published: April 2008

Abstract
In this study, we investigated the role of assessment time in group size discrimination and in particular the trade-off between the time cost involved in gathering information and the potential benefits derived from the acquired information. In a first experiment, we presented individual chub, Semotilus atromaculatus, with a choice between 4 vs 4 and 8 vs 8 conspecific stimulus fish. After release we recorded the time taken by test fish to make a choice between the two stimulus shoals in the presence and absence of a fright stimulus. Test fish significantly reduced their response time in the presence of a fright stimulus and larger shoals (8 vs 8) were more quickly approached than smaller ones (4 vs 4). In a control experiment, chub were given a choice between an empty cylinder and a shoal (of 4 or 8 fish). By subtracting the response time in the control treatment from that in the choice treatment, we estimated the time test fish spent choosing between stimulus shoals to be 24-55% of the overall response time. These results indicate that choosing between different groups is associated with a significant time cost. In a second experiment, we presented test fish with stimulus shoals that differed in size: 4 vs 5, 4 vs 6, 4 vs 7 and 4 vs 8, to investigate how the response time of fish and their ability to distinguish between shoals of different size were affected by the magnitude of the shoal size difference and the presence and absence of a fright stimulus. The ability to discriminate between shoals of different size increased with increasing shoal size difference whereas response time decreased. Both response time and discrimination ability were significantly reduced in the presence of a fright stimulus. The latter suggests that the benefits derived from group size discrimination were increasingly outweighed by the time costs of making group size assessments in the presence of potential danger; i.e. making fast assessments became relatively more important than making correct ones.
Mortality Risk of Spatial Positions in Animal Groups: the Danger of Being in the Front
Authors: Bumann Dirk , Krause Jens , Rubenstein Dan 
Published: April 2008

Abstract
We modified Hamilton's (1971) selfish herd model by introducing directional movement to the prey groups and the predators. The consequences of this modification with regards to differential predation risks are compared to Hamilton's original model (using stationary prey groups) and tested against empirical data. In model 1, we replicated Hamilton's original predator-prey system. In models 2 and 3, prey groups were mobile and predators were mobile (model 2) or stationary (model 3). Our results indicate that additional to the positive risk gradient from centre to periphery predicted by Hamilton's model for stationary groups, there might be another positive risk gradient from the rear to the front part in moving groups. Furthermore, models 2 and 3 suggest that moving groups should generally exhibit an elongated shape (longer than wide along the axis of locomotion) if risk minimisation is the only factor concerned. Also smaller inter-individual distances are predicted for front individuals than individuals elsewhere in the group. Empirical data based on the three-dimensional structure of fish shoals (using roach, Rutilus rutilus) were consistent with the above two predictions. A second experiment which involved lake chub, Semotilus atromaculatus, as prey and rock bass, Ambloplites rupestris, as predators, provided direct support for the hypothesis that individuals in front positions of groups incurred a significantly higher predation risk than fish in rear positions. Finally, we discuss the differential risks of different group positions in the context of potential foraging gains which provides the basis for a dynamic model of position preferences in group-living animals.
Experiments On Pair Bond Stability in Domestic Pigeons (Columba Livia Domestica)
Authors: Wosegien Angelika 
Published: April 2008

AbstractMany long-lived birds form long-term pair bonds, but they sometimes divorce. Until now most suggestions concerning factors relevant to the stability of the pair bond in birds were based on correlational data, which do not allow conclusions about causal relationships. Here, the probability of divorce in domestic pigeons (Columba livia) was tested experimentally, and separately for both male and female. Breeding success and pair bond duration of pairs was manipulated. After separation from the mate for up to 60 days the subject (female or male) was allowed to court to a new mate for 4 hours. Then the subject was given a choice between the old and the new mate presented simultaneously on either side of the experimental cage. A further possibility to choose between the two mates was given in later stage in the familiar aviary. Female subjects without breeding success showed little courtship towards the old male, especially when they had nest-cooed a lot to the new male during the four hours exposure. In the latter cases they chose the new male in the experimental choice situation. The preference for the old mate in the choice situation by females with breeding success was positively related to the duration of the previous pair bond. All females that had been paired for at least 200 days (N = 11), chose their old males. On the other hand, 86% of the females that had been paired for less than 152 days, chose the new male. Forty percent of the male subjects with breeding success preferred the new female in the experimental choice situation. This preference was especially shown by males that had performed frequent nest-cooing during the four hours exposure period. In the aviary, however, all males with or without breeding success reoccupied their nest at once and started nest-cooing and finally courted the female which was able to defend access to the nest against other females. This was always the male's former mate. Males preferred to occupy a nest over courting with any particular female. The results are discussed in relation to existing hypotheses of divorce.
The Hamilton and Zuk Hypothesis Revisited: a Meta-Analytical Approach
Authors: Hamilton William J. , Poulin Robert 
Published: April 2008

Abstract
The Hamilton & Zuk (1982) hypothesis of parasite-mediated sexual selection has been the subject of both inter- and intraspecific tests. Past reviews have used vote counting to determine whether this hypothesis is supported by empirical evidence. This study reanalysed 199 separate quantitative assessments of a central prediction of the Hamilton & Zuk hypothesis using meta-analytical techniques. Overall, our meta-analysis showed that there was a significant negative effect of parasites on male showiness as predicted. However the magnitude of this effect varied between host taxa and between endo and ectoparasitic taxa. As a whole intraspecific correlations between parasite load and male showiness provided very little support for the hypothesis with only the effect of parasites on fish morphology matching the Hamilton & Zuk prediction. There was more support for the hypothesis from interspecific studies especially those based upon the original Hamilton & Zuk (1982) data set, although other bird studies provided weaker support. The generality of the Hamilton & Zuk hypothesis in respect to parasite mediated sexual selection across taxa is thrown into doubt by these results. However, in some specific host-parasite systems the role of parasites appears important and future intraspecific tests of parasite-mediated sexual selection should perhaps focus on such systems.
Size and Density Dependent Mating Tactics in the Simultaneously Hermaphroditic Seabass Serranus Subligarius (Cope, 1870)
Authors: Oliver Ann S. 
Published: April 2008

AbstractThis study examines factors within the mating system of Serranus subligarius (belted sandfish) that are likely to maintain simultaneous hermaphroditism as an evolutionarily stable strategy in a highly mobile, high density species. I focus on changes in mating behavior with size. Mating behavior was observed underwater in the northeastern Gulf of Mexico at St. Andrew Bay State Park. Every hermaphrodite can spawn in three roles over the course of the daily spawning period: female pair spawn, male pair spawn, and male streak spawn. Pair spawning fish trade eggs, taking turns fertilizing one another's eggs. Egg trading is not symmetrical; the smaller fish in a pair spawns more often in the female role than the larger fish. Overall, small fish ( 70 mm SL) pair spawn more frequently as females, while large fish ( 80 mm SL) pair spawn more often as males. A size advantage appears to exist for male function. However, large fish usually release at least one egg parcel per spawning
The Barnacle, Balanus Eburneus Gould (Cirripedia) Conditioned To Spawn in the Laboratory 1)
Authors: Landau Matthew , Finney Colin M. , D'Agostino A. 
Published: April 2008

Abstract
In New York waters the barnacle, Balanus eburneus, is found containing embryo masses from May to August. Adults collected from January to early April can be kept at 8° C as long as 12 months without affecting their capacity to reproduce when transferred to 21° C seawater.
Rearing of Petrolisthes Lamarckii (Leach, 1820) Under Laboratory Conditions (Decapoda, Porcellanidae)
Authors: Yaqoob Mohammad 
Published: April 2008

AbstractThe complete larval development under laboratory conditions of the porcellanid crab, Petrolisthes lamarckii is described and illustrated for the first time. There is a pre-zoeal stage of short duration, two zoeal stages, and a megalopal stage. This species is closely related to Petrolisthes rufescens. The larvae of both these species are very similar in many respects but can be distinguished from each other by certain features (table I). Comparison of some important zoeal characters in four Petrolisthes species of Karachi, namely, Petrolisthes rufescens, P. ornatus, P. boscii and P. lamarckii is made to distinguish their larvae in the plankton.
Notes On the Courtship and Mating Behavior in Penaeus Monodon Fabricius (Decapoda, Natantia) 1)
Authors: Primavera Jurgenne H. 
Published: April 2008

AbstractCourtship and mating behavior in the sugpo or giant tiger prawn, Penaeus monodon Fabricius, are described. These are divided into three phases: parallel swimming of male and female; male turns ventral side up to female; and, male turns perpendicular to female, curves body around female and flicks both head and tail. Comparison with observations on P. japonicus and P. stylirostris is made.