bluuebunny/crossref_metadata_2025 huggingface dataset:
HIV-1 evolution: frustrating therapies, but disclosing molecular mechanisms
Authors: Das Atze T. , Berkhout Ben
Published: May 2010

Replication of HIV-1 under selective pressure frequently results in the evolution of virus variants that replicate more efficiently under the applied conditions. For example, in patients on antiretroviral therapy, such evolution can result in variants that are resistant to the HIV-1 inhibitors, thus frustrating the therapy. On the other hand, virus evolution can help us to understand the molecular mechanisms that underlie HIV-1 replication. For example, evolution of a defective virus mutant can result in variants that overcome the introduced defect by restoration of the original sequence or by the introduction of additional mutations in the viral genome. Analysis of the evolution pathway can reveal the requirements of the element under study and help to understand its function. Analysis of the escape routes may generate new insight in the viral life cycle and result in the identification of unexpected biological mechanisms. We have developed
in vitro
HIV-1 evolution into a systematic research tool that allows the study of different aspects of the viral replication cycle. We will briefly review this method of forced virus evolution and provide several examples that illustrate the power of this approach.
Combining mathematics and empirical data to predict emergence of RNA viruses that differ in reservoir use
Authors: Ogbunugafor C. Brandon , Basu Sanjay , Morales Nadya M. , Turner Paul E.
Published: May 2010

RNA viruses may be particularly capable of contributing to the increasing biomedical problem of infectious disease emergence. Empirical studies and epidemiological models are informative for the understanding of evolutionary processes that promote pathogen emergence, but rarely are these approaches combined in the same study. Here, we used an epidemiology model containing observations of pathogen productivity in reservoirs, as a means to predict which pathogens should be most prone to emerge in a primary host such as humans. We employed as a model system a collection of vesicular stomatitis virus populations that had previously diverged in host-use strategy: specialists, directly selected generalists and indirectly selected (fortuitous) generalists. Using data from experiments where these viral strategists were challenged to grow on unencountered novel hostsin vitro, logistic growth models determined that the directly selected generalist viruses tended to grow best on model reservoirs. Furthermore, when we used the growth data to estimate average reproductive rate across secondary reservoirs, we showed that the combined approach could be used to estimate relative success of the differing virus strategists when encountering a primary host. Our study suggests that synergistic approaches combining epidemiological modelling with empirical data from experimental evolution may be useful for developing efforts to predict which types of pathogens pose the greatest probability of emerging in the future.
Memories of lost enhancers: Figure 1.
Authors: Sen Ranjan , Grosschedl Rudolf
Published: May 2010

Transcriptional enhancers are key determinants of developmentally regulated gene expression. Models of enhancer function must distinguish between analog or digital control of transcription, as well as their requirement to initiate or maintain transcriptional activity of a gene. In light of a recent study by Chong and colleagues (pp. 659–669) providing evidence of a transient requirement of an enhancer associated with the CD4 gene, we discuss possible mechanisms by which transcriptional memory can be propagated in the absence of enhancers.
The influence of parasitism on fish population success
Authors: LONGSHAW M. , FREAR P. A. , NUNN A. D. , COWX I. G. , FEIST S. W.
Published: May 2010

Abstract  The influence of parasitism on first‐year growth and recruitment success of two cyprinid species in the Yorkshire Ouse catchment, England, was investigated using a 14‐year dataset. This study demonstrated a significant role of parasitism in growth and recruitment success of roach, Rutilus rutilus (L.), and European chub, Squalius cephalus (L.) populations. Muscle infections by Bucephalus polymorphus Baer (Digenea), Myxobolus pseudodispar Gorbunova (Myxozoa) and Myxobolus pfeifferi Thélohan were considered important, with significant relationships between these parasites and year‐class strength and age‐0 fish length. Other parasites, such as Phyllodistomum sp. and Goussia sp., were implicated in host success to a lesser extent. Parasitism may be a major factor in recruitment and account for a high proportion of the variation in year‐class strength, although this varied among locations.
Comparing naturalized alien plants and recipient habitats across an east–west gradient in the Mediterranean Basin
Authors: Arianoutsou Margarita , Delipetrou Pinelopi , Celesti‐Grapow Laura , Basnou Corina , Bazos Ioannis , Kokkoris Yannis , Blasi Carlo , Vilà Montserrat
Published: May 2010

Aim  To investigate alien plant species invasion levels in different habitats and alien species traits by comparing the naturalized flora in different areas of the same biogeographical region.

Location  Spain, Italy, Greece and Cyprus.

Methods  Comparison of floristic composition, species traits and recipient habitats of naturalized alien neophytes across an east–west gradient comprising four countries in the European Mediterranean basin.

Results  A total of 782 naturalized neophytes were recorded; only 30 species were present in all four countries. Although floristic similarity is low, the four alien floras share the same patterns of growth form (mostly herbs), life cycle (mostly perennials) and life form (mostly therophytes, hemicryptophytes and phanerophytes). The majority of the recipient habitats were artificial. Wetlands were the natural habitats, with the highest numbers of naturalized species. Floristic similarity analyses revealed: (1) the highest floristic similarity between Italy and Spain, both of which were more similar to Greece than to Cyprus; (2) two groups of floristic similarity between habitat categories in each country (Greece–Cyprus and Italy–Spain); (3) a higher degree of homogenization in the plant assemblages in different habitats in Greece and Cyprus and a lower degree of homogenization in those in Italy and Spain; and (4) a higher degree of homogenization in artificial and natural fresh‐water habitats than in the other natural habitats.

Main conclusions  The floristic similarity of naturalized neophytes between the four countries is low, although the overall analysis indicates that the western group (Italy–Spain) is separated from the eastern group (Greece–Cyprus). Similar patterns emerged regarding the life‐history traits and recipient habitats. The artificial habitats and the natural wet habitats are those that are invaded most and display the greatest homogenization in all four countries. Coastal habitats display a lower degree of homogenization but a high frequency of aliens. Dry shrubs and rocky habitats display a lower degree of homogenization and a low frequency of aliens.
Degree of Behavioral Neoteny Differentiates Canid Polymorphs
Authors: Coppinger R. , Glendinning J. , Torop E. , Matthay C. , Sutherland M. , Smith C.
Published: May 2010

As with juvenile wolves or coyotes, adult livestock conducting dogs displayed the first‐half segment of a functional predatory system of motor patterns and did not express play or social bonding toward sheep; whereas, like wolf or coyote pups, adult livestock protecting dogs displayed sequences of mixed social, submissive, play and investigatory motor patterns and rarely expressed during ontogeny (even when fully adult) predatory behaviors. The most parsimonious explanation of our findings is that behavioral differences in the two types of livestock dogs are a case of selected differential retardation (neoteny) of ancestral motor pattern development.
Behavioural Responses to Crowding Modification and Home Intrusion in Acanthopleura gemmata (Mollusca, Polyplacophora)
Authors: Chelazzi Guido , Parpagnoli Daniele
Published: May 2010

The intertidal chiton Acanthopleura gemmata (Blainville) is a central place forager which rests in a dug scar and moves at nocturnal low tide. The fraction of chitons abandoning the home during each potential foraging phase is reduced after experimental overcrowding. On the contrary, reduced crowding in the natural population increases number of active chitons. Feeding excursions after increasing or reducing crowding are shorter than in control chitons. Also the orientation of migration is scattered after manipulation. Animals sharing their home with a conspecific suppress migrations, but local overcrowding when body‐contact is lacking also reduces activity. Rest zonation in overcrowded areas shifts upward, and most imported chitons fail to home. Induced home co‐ownership is followed by overt aggressive patterns and by a “waiting war”. Conflicts are resolved according to size ratio between contestants.
Aspects of the Social Organisation of the European Wild Rabbit (Oryctolagus cuniculus)
Authors: Cowan David P.
Published: May 2010

The social organisation of a free‐living population of wild rabbits was examined. Discrete breeding groups were recognised which consisted of individuals who shared access to underground refuges. Males attempted to maximise their access to females by a) occupying large home ranges; b) defending female access indirectly through territorial defence; c) defending female access directly within groups. Females defended nest site access within groups. Intergroup interactions between females were rare because of limited home range overlap. Interruption of female‐female aggression by males was observed suggesting that conflicts of interest arose between the sexes. Adult‐juvenile aggression was primarily intra‐sexual; females initiated more interactions than males who adopted a protective role in some cases.
The Behavioral Ecology of Libellula luctuosa (Burmeister) (Anisoptera: Libellulidae): I. Temporal Changes in the Population Density and the Effects on Male Territorial Behavior
Authors: Moore Allen J.
Published: May 2010

A single population of a common pond dragonfly, Libellula luctuosa, was studied at a site where the density of males increased dramatically during the breeding season. Early in the summer one active male was found on each territory on the pond. Satellite males were only occasionally found on the territories. Later in the season the number of males per territory increased so that two or more males simultaneously defended on many of the territories, and several satellite males occupied each of the territories. The number and rate of female visitations per day did not change over the summer. These factors resulted in a change in the operational sex ratio with variations in male density. Male behavior was also altered with increasing population density. As male density increased, males were less likely to be seen perching on their territories and more likely to be seen performing aggressive acts such as chasing nearby territorial males and chasing intruders. At high male density, the duration of territorial behaviors was shorter than at low male density. Thus, the percent of a time budget spent in any one activity did not change despite the change in number of males present. Male activity in L. luctuosa is not strictly determined by the opportunity for aggression. Costs of aggression associated with territoriality are minimized by maintaining flexible territorial behaviors.
Social Status and Circulating Levels of Hormones in Flocks of House Sparrows, Passer domesticus
Authors: Hegner Robert E. , Wingfield John C.
Published: May 2010

Captive groups of house sparrows Passer domesticus formed stable social hierarchies during a two‐week test period. Higher‐ranking individuals were more aggressive during the first week of testing and had higher plasma levels of luteinizing hormone (LH) and testosterone (T) at the end of that week. Higher‐ranking individuals continued to be more aggressive during the second week of testing, but concentrations of LH and T in blood no longer were related to social status. Higher‐ranking individuals also did not have higher levels of these hormones on the day the tournament began. Circulating titers of dihydrotestosterone and corticosterone were random with respect to social status. These results support the hypothesis that social rank and aggressiveness are related to circulating levels of T, but this relationship is expressed only when social status is being established or is actively ‘challenged’.
The Perception of Sex‐specificity in Long Calls of the Tamarin (Saguinus labiatus labiatus)
Authors: Masataka Nobuo
Published: May 2010

Long calls given by red‐chested moustached tamarins (Saguinus l. labiatus), typically 1–2 s in duration and made up of individual syllables, reveal distinctive sex‐specificity as well as population and individual differences in their acoustic structure. Distributions of male calls and female vocalizations are discrete with regard to two acoustic parameters, i.e. number of syllables and mean inter‐syllable intervals. Mean number of syllables produced in a given time is much greater in male than in female calls. I played back synthetic versions of the long calls varying in mean inter‐syllable intervals to captive tamarins and found that the sex differences were encoded in a relatively simple acoustic form. The tamarin is able to identify the sex of unfamiliar calling conspecifics by voice alone.
Slides of Group Members as Representations of the Real Animals (Macaca fascicularis)
Authors: Dasser Verena
Published: May 2010

Three long‐tailed macaques (Macaca fascicularis) apparently recognized the identity of group members presented by means of colour slides. After training on a minimum of examples, the subjects correctly identified in unique transfer trials novel views of the stimulus animals used in training. In first trials, one subject matched different face views, and face views with other body parts, of the same animal significantly more often than by chance when the animals were group members. Slides of group members can therefore be used as representations of monkeys individually known to the subjects.
Quantitative Analysis of Animal Vocal Phonology: an Application to Swamp Sparrow Song
Authors: Clark Christopher W. , Marler Peter , Beeman Kim
Published: May 2010

Sound spectrograms have been a traditional method for comparing animal vocalizations and demonstrating their similarities or differences, but quantification of the comparative process has been difficult. This lack of quantification has hindered progress in documenting the timing and degree of song development in song birds. With this in mind, computer‐based methods for sound comparison and sound averaging were developed. These methods utilize a numerical representation of a sound's frequency‐time structure to compute a similarity value between any two sounds and an average sound spectrogram for a set of sounds. These analytical techniques were applied to an analysis of song notes of the swamp sparrow (Melospiza georgiana). The results demonstrate the usefulness of the methods and reveal new details in the description of the swamp sparrow's set of species‐universal note types and in the decrease of note variability during the course of developmental transitions from subsong, through plastic song to song crystallization.
Nestmate Recognition in Leptothoracine Ants: Testing Fielde's Progressive Odor Hypothesis
Authors: Stuart Robin J.
Published: May 2010

Fielde's progressive odor hypothesis postulates that certain hereditary nestmate recognition odors in adult ants change progressively with age such that workers will often not accept older siblings that differ from them in age by as little as 40–60 days unless they eclosed among siblings of that age class and learned their recognition cues. Fielde's hypothesis was based on extensive but unsystematic experimental studies which fail to provide unequivocal evidence for this phenomenon. The present study tested this hypothesis for three closely‐related ant species, Leptothorax ambiguus, L. curvispinosus, and L. longispinosus, by introducing workers between groups with known age structures and a minimum age difference of eight months. The results invalidate Fielde's hypothesis for these ants. However, progressive odors may yet be found in other species and may be associated with age polyethism.
Yawning: Relation to Sleeping and Stretching in Humans
Authors: Provine Robert R. , Hamernik Heidi B. , Curchack Barbara C.
Published: May 2010

The temporal relations among yawning, sleeping, and stretching were investigated by having undergraduate college students record the occurrences of these behaviors during a one‐week period. Yawning was most frequent during the hour before sleeping and after waking. In contrast, stretching was common only during the hour after waking. Concurrent yawning and stretching were common but stretching was accompanied more often by yawning than vice‐versa. The temporal proximity of yawning to sleep and waking times is probably the basis for yawning as a paralinguistic signal for drowsiness. The role of contagious yawning in synchronizing the behavior and physiological state of a group is considered.
Foraging Rules for Group Feeders: Area Copying Depends upon Food Density in Shoaling Goldfish
Authors: Pitcher T. J. , House A. C.
Published: May 2010

The decision rules governing forage area copying behaviour were investigated in shoaling fish. Shoaling goldfish were offered two equal food patches, one of which was adjacent to an equal‐sized shoal feeding behind a transparent barrier. When food was low, goldfish foraged according to an area copying rule, but under high and zero food area copying disappeared. Only under high food density did equal numbers of fish feed at both sites as predicted by foraging theory. Under zero food the fish were less certain about where to forage. Precise visual cues from feeding fish were required: non‐feeders did not attract area copiers. Furthermore, area copying was task‐dependent since it reappeared strongly if fish were not able to forage on patches like their fellows. Control experiments eliminated an increase in group size for anti‐predator advantage as an explanation. Two sequential decisions: to stay or move, and to join or leave may explain the results, which are not accommodated by simple optimality models. These decisions may be based on a comparison of current food intake with the anticipation of a higher reward by foraging socially.
Resource Defense and Alternative Mating Tactics in the Banksia Bee, Hylaeus alcyoneus (Erichson)
Authors: Alcock John , Houston Terry F.
Published: May 2010

Some males of the Australian colletid bee Hylaeus alcyoneus defend single flowering spikes of various species of Banksia, selecting spikes in the maturational state most attractive to foraging females. Other males do not engage in food resource defense but instead nonaggressively patrol a circuit that takes them to many spikes, some occupied, others not held by territorial males. When territory owners are experimentally removed, replacement males quickly claim the vacated spikes. Some of these males have been patrolling previously, showing that patrolling and territoriality are alternative tactics in a conditional strategy. Territorial males are larger on average than patrolling males, replacement territory holders, and females. Male territoriality at flowers appears in several other Hylaeus, and in these and other bees, resource defense tactics are often associated with specialized foraging requirements of females and a patchily distributed resource.
Spacing in Colonial Spiders: Effects of Environment and Experience
Authors: Cangialosi Karen R. , Uetz George W.
Published: May 2010

Colonial orb‐weaving spiders from Mexico (Metepeira spp.), show considerable geographic variation and temporal flexibility in group size and social spacing. A series of laboratory studies was conducted to test whether the variation observed in the field is the result of behavioral plasticity, or the result of genetic mechanisms inherent in different populations. Spiders from source populations in desert and moist tropical habitats were collected as eggs and raised in the laboratory under identical controlled conditions. To test for the effect of experience on conspecific tolerance, experiments were conducted rearing tropical and desert spiderlings in isolation and in communal groups. Measurements of spacing in laboratory colonies and observations of web building behavior show significant differences between populations, suggesting genetic differences between them. Desert spiders show an initial effect of isolation on tolerance of conspecifics — greater inter‐individual distance that is eventually modified by communal adult experience. Tropical spiders put together after isolation show spacing patterns opposite those observed for desert spiders, and nearest neighbor distances similar to those seen in the communally reared (tropical) groups. These findings support the hypothesis that these populations represent separate species that differ with respect to their level of sociality.
Effects of Carrion‐Independent Pheromone Emission by Male Burying Beetles (Silphidae: Necrophorus)
Authors: Müller J. K. , Eggert A. K.
Published: May 2010

All former publications on the reproductive biology of burying beetles (genus Necrophorus) state that in these species copulations take place on carcasses only, this being the only place for the sexes to meet. Our laboratory investigations have shown that males emit pheromones if no carrion is around. We now present data from a field investigation showing the effects of pheromone emission by males that have not secured a carcass. Such males are successful in attracting conspecific females. But conspecific males and individuals of other species are also attracted by the scent. Possible benefits for attracted individuals of different species and sex are discussed.

Pheromone emission and attraction of conspecifics are restricted to a distinct species‐specific period of the day in at least two of the common species.
Ethogram of the Australian Magpie (Gymnorhina tibicen) in Comparison to Other Cracticidae and Corvus Species
Authors: Brown Eleanor D. , Veltman Clare J.
Published: May 2010

This study is a descriptive catalogue of the behavior patterns of the Australian magpie (Gymnorhina tibicen, Cracticidae), a member of the Australian corvid assemblage (SlBLEY & AHLQUIST 1985) and a group‐living species that maintains year‐round territories. The ethogram is constructed with comparisons to the cracticid genera Strepera and Cracticus and the closely related genus Corvus. In comparison with Corvus species, Australian magpies have few close‐range social communication patterns, and there are few interactions among members of the same territorial social group. Conversely, Australian magpies exhibit many behavior patterns used in long‐distance communication related to territorial aggression and defense. The foraging and food item manipulation patterns of the magpie are more limited than in currawongs (Strepera) or in Corvus. These differences may be due to the Australian magpie's highly specialized territorial way of life and relatively narrowly defined diet. Corvus and Strepera species are generalists that exhibit flocking, partial migration, and a lesser degree of territoriality. Territoriality in Gymnorhina may be an evolutionary response to environmental factors, interspecific competition with other cracticids and Corvus, or both.
Status Signalling by Parus major: An Experiment in Deception
Authors: Jäurvi Torbjörn , Walsø Øyvind , Barken Morten
Published: May 2010

The ‘social control’ and ‘incongruence’ hypotheses, first put forward by ROHWER (1977) to explain how attempted ‘deceit’ status signalling is kept in check among winter‐flocking birds, were tested under semi‐natural conditions for Parus major. This species signals its social status by the width of its breast stripe. The lowest‐ranked male in experimental flocks, each made up of four individuals, was manipulated in one of three ways: 1) the status signal was altered by painting the breast stripe to make it broader; 2) agonistic behaviour was altered by injecting testosterone; 3) both status signal and behaviour were manipulated. A study of the outcome of subsequent agonistic encounters by these birds revealed that the status of the manipulated individuals only rose when both their behaviour and status signal were altered. This indicates that the ‘social control’ hypothesis must be rejected, but not the ‘incongruence’ hypothesis.
The Role of “Outward‐Journey Information” in Homing Experiments with Pigeons: New Data on Ontogeny of Navigation and General Survey
Authors: Wallraff Hans G. , Sinsch Ulrich
Published: May 2010

Potentially, homing from distant areas can be based on two different principles of navigation: (1) A path‐integration mechanism records and integrates an animal's motions during the outward trip; it is independent of location‐specific stimuli. (2) Site localization, by contrast, is performed by deducing the animal's position in relation to home from such stimuli. Hence the first mechanism entirely depends on an uninterrupted flow of “outward‐journey information”. The second mechanism may but need not be independent of stimuli recorded during the outward journey.

Homing of pigeons is evidently based on site localization. Empirical findings do not support the idea that in experiments using passive displacement path integration is involved in addition or alternatively. Also, there is no reason to assume that very young pigeons transitionally, for only few weeks, apply such a method (as has been concluded by Wiltschko & Wiltschko 1982, 1985, etc.).

It is shown that very young pigeons require local olfactory signals for initial homeward orientation as do older birds (Fig. 1). They are not generally better at homeward orientation than older inexperienced pigeons and show similar deviations from home and preferences for a particular compass direction (Table 1, Fig. 2).

Olfactory signals appear to be gathered, as good as conditions allow, during any stage of a homing experiment. No fundamental difference can be recognized between olfactory “outward‐journey information”, “release‐site information”, etc. Signals received at different times and sites before release may contribute by varying proportions to the initial‐orientation patterns observed under varying circumstances.
The Effect of Density and Temperature on the Swimming and Aggregating Behaviour of the Backswimmer, Anisops deanei (Heteroptera: Notonectidae) and Subsequent Encounter Rate with a Sit‐and‐Wait Predator
Authors: Bailey Paul C. E.
Published: May 2010

Four different swimming behaviours of the backswimmer, Anisops deanei, each characterized by a different angular position of the metathoracic legs and speed, are described along with the effect of water temperature and density on (1) the number of each behaviour exhibited and (2) total time spent swimming, per unit time. Generally, as density increased the swimming activity in each behaviour decreased while as temperature increased swimming activity increased. The direction of the effects were the same when total time spent swimming per unit time was examined. Nearest neighbour analysis showed that A. deanei form obvious aggregations in laboratory tanks as density increases, and this effect remains significant at least to the third neighbour. Density had a significant effect on neighbour distances whereas temperature did not. It was hypothesized that the primary function of these aggregations, which are also commonly observed in the field, is an anti‐predator behaviour. Laboratory experiments using models of a common sit‐and‐wait predator of A. deanei, showed that although the encounter rate increased with both water temperature and density the observed encounter rate at the higher densities was significantly less than expected with a random distribution of prey. It is suggested that this defence effect would also exist with more mobile predators like fish.
Interindividual Variability and Idiosyncrasy in Social Behaviours in the Ant Camponotus vagus Scop
Authors: Bonavita‐Cougourdan Annie , Morel Laurence
Published: May 2010

Large intraspecific variability was found in interactive ant behaviours. However, a time study of callow and mature Camponotus vagus workers showed some stability in relationships within pairs of workers or in given individuals. Individual idiosyncrasies were observed as tendencies to simultaneously display a single level of activity for several behaviours. Thus some mature workers reverse the food flow during trophallactic exchanges, spend more time exchanging food and are more aggressive toward intruders. The time spent by callows in their main activity, brood‐tending, allows discrimination on two activity levels. Moreover, callows deprived of any relationship with older nestmates show different levels of activity in the duration and intensity of aggressive and non‐aggressive behaviours. The causality of these behavioural idiosyncrasies could possibly be explained in part by the social experience of each individual.
A Universal Time Constant Operating in Human Short‐term Behaviour Repetitions
Authors: Schleidt Margret
Published: May 2010

In repetitive movement patterns of everyday behaviour in humans a time constant of about 3 s could be shown to prevail. This time constant was found in four independent cultures (Europeans, Trobriand Islanders, Yanomami Indians and Kalahari Bushmen) and structures behaviour into units. As Pöppel (1978, 1985) has already found such a time constant in recited verse and optical illusions, it seems that we are dealing here with a universal central nervous mechanism structuring time. Its function could be seen in creating a subjective present and in facilitating communication and synchronisation between interactants.

Only 15% of patterns in the investigated behaviour repetitions do not obey the 3‐s time span. These are stereotyped behaviour patterns of longer duration which seem to have a special function.
Communal Nesting among Genetically Similar House Mice
Authors: Wilkinson Gerald S. , Baker Ann Eileen Miller
Published: May 2010

From March to October 1986, 35 house mice, Mus domesticus, were fitted with radio‐transmitters and tracked in and around a Colorado feed shed for an average of 5 (range 2 to 17) days. 5 of 36 simultaneously tracked pairs of lactating females used identical nesting sites. Genotypic similarity at 5 enzyme loci, assayed from biopsies of blood and toes, indicated that these females were more genetically alike than would be expected if pairing occurred randomly among females. We posit that female house mice recognize and preferentially form communal nests with close relatives. Aside from the communally nesting females, minimal overlap occurred among home ranges of lactating females. Only 4 of 10 adult male home ranges appreciably overlapped female home ranges. The home ranges of these 4 males overlapped less than the other adult male home ranges suggesting that males defend one or more females for access to mating. The possibility that communally nesting females are nursing each other's pups is discussed.
Foraging, Delayed Maturation, and Advantages of Cooperative Breeding in White‐winged Choughs, Corcorax melanorhamphos
Authors: Heinsohn Robert G. , Cockbu Andrew , Cunningham R. B.
Published: May 2010

White‐winged choughs live in groups which cooperate in all aspects of rearing young, affording an opportunity to examine the influence of cooperation on foraging behavior. The amount of food choughs forage for themselves and feed to young increases with age, supporting the idea that individuals which dispersed to breed would have difficulty in rearing young. When feeding nestlings, individuals in the two larger groups returned to the nest less often and with larger loads than the individuals in the smallest group. Choughs in the smallest group also consumed less food at the beginning of each trip from the nest than those in the larger groups. We suggest that these measures indicate the greater efficiency allowed to individuals in larger groups when foraging from the nest. In all groups, individuals returning to the nest simultaneously with other group members carried smaller loads than those returning alone. We propose that returning in groups enables all nestlings of asynchronously hatched broods to obtain sufficient food.
Wie klassifizieren Javaneraffen (Macaca fascicularis) natürliche Muster?
Authors: Dittrich Winand
Published: May 2010

How do Crab‐eating Monkeys (Macaca fascicularis) Perceive and Classify Realistic Visual Patterns?

The process by which crab‐eating monkeys perceive and classify stimuli functionally relevant to their feeding behaviour was investigated. The visual patterns consisted of realistic drawings of insects and parts of plants.

A new experimental approach was conceived: During the experimental sessions social interactions within the group were permitted while the learning behaviour of individual monkeys was analysed. The procedure consisted of the simultaneous discrimination tasks of four visual patterns and motoric responses (continuous reinforcement).

To prepare the functional analysis of their ability to classify environmental objects, tests were conducted in which the animals successively learned to answer visual stimuli with motoric responses. The monkeys learned not only to discriminate geometrical patterns from contrast and form cues but also to build specific associations between visual patterns and special motoric coordinations. When shown similar geometrical stimuli, the animals were able to generalise their recognition of invariant features (‘angularity’).

The monkeys learned very quickly to discriminate insects from parts of plants. This discrimination ability could be transferred immediately to other insect pictures. This learning process was linked with a memorized classification system of natural objects induced by environmental experience. A preference test for single cues resulted in a graded estimation of particular pattern components. Numerous variations of the insect pattern were shown to the animals. From the different choice frequency for single cues, a gradual continuum of cue relevance could be established (e. g. contrast and form were the most relevant cues). A direct dependence between the completeness of the insect ‘gestalt’ and its choice frequency was shown.
Homing in Harvester Termites: Evidence of Magnetic Orientation
Authors: Rickli M. , Leuthold R. H.
Published: May 2010

Colonies of Trinervitermes geminatus (Wasman) build a network of forked foraging trails. Homing workers choose, with few exceptions, those tracks at the forks of the pheromone trail network that lead direct to the nest. Assessments show that these workers are also able to distinguish between the homeward and outward direction along an unbranched trail. Experiments involving the alteration of the local natural magnetic field by means of a weak permanent magnet provide evidence that the termites recognise the home direction by means of magnetoreception.
Aggression and Nearest Neighbour Distances in Female Reindeer during the Rut
Authors: Kojola Ilpo , Nieminen Mauri
Published: May 2010

Data on nearest neighbours and aggressive behaviour were collected within rutting groups of semi‐domesticated reindeer (Rangifer t. tarandus L.) in a 1300‐ha pasture in Finnish Lapland, and wild forest reindeer (Rangifer t. fennicus Lönnb.) in a 15‐ha enclosure in Central Finland. Adult cows of forest reindeer charged yearling males, yearling females and calves in that order of decreasing frequency. Semi‐domesticated reindeer cows rushed yearling females more often than they did one another. One suggested influence of antagonism by cows were the observed intragroup associations of yearling females. Cows were tolerant toward their own yearling females, but not toward their own yearling males. Although no maternal aggression toward calves was found, male calves moved away more often from their mothers than did female calves during the post‐rut period.
Initiation and Resolution of Fights between Swimming Crabs (Liocarcinus depurator)
Authors: Glass C. W. , Huntingford F. A.
Published: May 2010

Fights between male swimming crabs (Liocarcinus depurator) were studied in the laboratory and in the field. These crabs fight readily in the laboratory, interactions being initiated equally often by the larger and the smaller of the two opponents, but usually being won by the larger. Many different combinations of cheliped and swimming leg postures are seen during fights, which fell into 4 categories: 13% involved only stationary display, 38% were resolved by a single approach and retreat by displaying crabs, 9% were resolved by multiple approaches and retreats and 39% involved physical contact between the crabs. Fight length was variable, and depended both on the absolute size and on the relative size of the participants. During the course of the fights, few behavioural differences were observed between the eventual winners and losers. Fights were less common in the field, but the same rules determined their initiation, content and outcome. The results are discussed in the context of game theory.
Development of Antipredator Responses in Snakes
Authors: Herzog Harold A. , Burghardt Gordon M.
Published: May 2010

Individual and litter differences in the number of attacks directed by Mexican garter snakes (Thamnophis melanogaster) at a threatening stimulus were studied over the first year of life. Newborn snakes born to wildcaught females from the same population were tested the day after they were born and at 7, 16, 31, and 54 weeks of age on reactivity to a potent nonmoving and moving stimulus (a human finger). There were significant individual and interlitter differences in number of strikes directed at both stimuli but no significant effect of sex. Intercorrelations among the strike scores of individuals across test days averaged .54 for the nonmoving stimulus presentations and .63 for trials with the moving stimulus. Strike scores to the moving and nonmoving stimuli were significantly correlated at each age, however, attack responses to the moving stimulus declined over the year while those to the nonmoving stimulus remained constant. Measures of concordance showed that both individual strike scores and litter means were highly consistent, whereas consistency within litters was reduced. The results indicate that litter and individual differences among newborn snakes in the tendency to engage in antipredator behavior (“defensive temperament”) remain relatively stable from the first day after birth throughout the first year of life.
Aggressive Behavior and Courtship Rejection in Brightly and Plainly Colored Female Keeled Earless Lizards (Holbrookia propinqua)
Authors: Cooper William E.
Published: May 2010

Relationships between bright secondary sexual coloration and behavior were studied in female Holbrookia propinqua, which develop striking orange and yellow colors during the breeding season. In tethered introduction studies, brightly colored females performed aggressive courtship rejection behaviors toward conspecific males; plainly colored females were not aggressive toward males, but attempted to avoid them. Responses of females of the two color patterns toward conspecific females of both color phases were not detectably different. Experimental introductions of lizards with coloration modified by paint showed that females of both color patterns recognize any other lizard bearing the bright female colors as female, regardless of actual sex. Both the orange and yellow components were shown to contribute to sex recognition. The yellow component alone allowed accurate sex identification, but only half the females responded to males painted with only the orange female component as if they were females. Because females did not behave differently toward other females on the basis of coloration, the hypothesis that bright coloration evolved as an adaptive signal between females is rejected. The dark ventrolateral stripes of male and plainly colored females did not appear to affect intraspecific social responses by females.
Auditory Processing of Temporal Information in a Neotropical Frog is Independent of Signal Intensity
Authors: Rose Gary J. , Zelick Randy , Rand A. Stanley
Published: May 2010

Animals often encounter the problem of identifying the temporal structure of their species‐specific communication sounds amidst heterospecific signals that are more intense. Little information is available, however, concerning the effects of intensity on these discriminative capacities. Here we report that male frogs,Physalaemus pustulosus, are able to discriminate between sounds that differ only in their direction of frequency modulation and that this discrimination remains intact over their entire response range; more than a 10,000‐fold range in sound intensity in some cases.
Repertoires and Countersinging in Western Meadowlarks (Sturnella neglecta)
Authors: Horn Andrew G. , Falls J. Bruce
Published: May 2010

Countersinging in territorial birds has been viewed as a form of vocal contest. We studied the role of song repertoires in countersinging by western meadowlarks,Sturnella neglecta, by simultaneous observations of neighboring males. Neighbors tended to switch song types synchronously, but tendency to lead or follow in such switches did not correlate with orientation, subsequent behaviour, tendency to interact (as measured by the number of repetitions of each song type), or breeding stage. Males did not match song types, but were more likely to sing if their neighbour sang a song type that they shared. We suggest that synchronous switching is not a vocal contest in this species, but may be a form of competitive advertisement.
Temporal Features of Social Play in the Laboratory Rat
Authors: Hole Graham
Published: May 2010

Longitudinal observational studies were made of social play (wrestling) in laboratory‐housed Rattus norveguus, between 21–60 days of age. Particular attention was paid to the temporal features of this behaviour. Data are presented on the duration of play bouts, the percentage of time spent by each participant in the “on‐top” position, and the number of role reversals occurring during play.

Play bouts were found to be very brief events, in which very little reciprocity was shown; the initiator of a bout tended to remain on top of his partner for most of the bout. Males initiated more play than did females, but there were relatively few age or sex differences in the temporal measures of play. However, bouts involving females did tend to be shorter than those between males. Females initiating mixed‐sex play were less likely to remain on top for prolonged periods than was the case in play bouts initiated by males with females or in bouts between same‐sex pairs.

The duration of play bouts appeared to be randomly determined. This fact, together with the absence of age‐changes in bout duration, is held to represent evidence against the hypothesis that play's primary function is to provide physical training for the participants, at least for social play in this particular species.

The implications of these results for the use of “reciprocity” as a defining characteristic of play are discussed.
Mating Systems and Reproductive Strategies in Three Australian Gryllid Crickets: Bobilla victoriae Otte, Balamara gidya Otte and Teleogryllus commodus (Walker) (Orthoptera: Gryllidae: Nemobiinae; Trigonidiinae; Gryllinae)
Authors: Evans A. R.
Published: May 2010

The behaviour of B. victoriae and B. gidya in simulated natural habitats is described. Regular predictable sequences of behaviour are represented by ethograms.

The mating systems of B. victoriae and B. gidya are compared with that of T. commodus which shows a sedentary call‐and‐reside strategy. B. victoriae shows an elaborated male call‐search strategy while in B. gidya the male strategy is one purely of searching rather than advertising for mates. Males of B. victoriae and B. gidya were less territorial and less aggressive than males of T. commodus.

Males of B. victoriae attracted females and monopolized them for repeated matings by providing what might be a nutritional resource in the form of multiple spermatophores which females were allowed to eat soon after copulation. Males of B. gidya produced fewer but much larger spermatophores than males of B. victoriae or T. commodus and females of B. gidya became unreceptive after mating.

The reproductive strategies of the three species are analyzed in terms of environmental variables.
Pillar Function in the Fiddler Crab Uca beebei (I): Effects on Male Spacing and Aggression
Authors: Christy John H.
Published: May 2010

Males of 14 species of fiddler crabs (genus Uca) are known to build structures out of mud or sand at the entrances to burrows they court from and defend. A study of spacing, space use and aggression between courting male Uca musica (Zucker 1974, 1981) suggested that the hoods males build reduce territorial overlap and rates of aggression between neighboring males. Thus, each male may have more time to court females during limited lunar, diurnal and tidal mating periods.

I studied the courtship and aggressive behavior of male Uca beebei in the field to determine if the pillars males of this species build affect male behavior as do the hoods of U. musica. U. beebei occurs sympatrically with U. musica on the Pacific coast of Panama and is broadly similar in its ecology and mating behavior. Unlike the hoods of U. musica, pillars did not focus a male's activity space away from its closest neighbor nor did they reduce either overlap with neighbors' activity spaces or rates of aggressive interaction among neighbors. Pillar builders courted more but also fought their neighbors more than did males that did not build pillars. The pillars of U. beebei and the hoods of U. musica affect male behavior differently and probably have different functions.
Comparison of the Reconciliation Behavior of Stumptail and Rhesus Macaques
Authors: Waal Frans B. M. de , Ren RenMei
Published: May 2010

Observations were made following spontaneous aggressive incidents in a breeding group of captive stumptail macaques (Macaca arctoides). Participants were observed both during the first 10 min following the aggressive incident, and during matched‐control observations. Data on 670 pairs of former opponents were collected, and compared with a sample of 573 such pairs of rhesus macaques (M. mulatta), which had been observed with identical methods in a previous study. Selective attraction between opponents was confirmed for the stumptail monkeys, i.e. both the absolute and the relative rate of nonagonistic body contact between individuals increased after aggression between them. The species was found to be considerably more conciliatory than rhesus monkeys, and to have a remarkably rich repertoire of reassurance gestures. The most characteristic conciliatory behavior is the hold‐bottom ritual, in which one individual (usually the subordinate) presents its hindquarters, and the other (usually the dominant) clasps the other's haunches. The high rate of reconciliation among stumptail monkeys extended to all relationship classes, and a correlation with the closeness of social bonds (measured as time spent in association) could not be demonstrated. Because of the generality of the species' high peacemaking tendencies it is assumed that group cohesiveness is of great survival value in the wild.