Within-group spatial position in Saiga tatarica (Bovidae) in the Stepnoi State Nature Sanctuary, Astrakhan Region, Russia

In group-living animals, the social structure and organisation play a significant role in survival and reproduction. Understanding the social aspects of animal lives in the wild may be crucially important for effective conservation of threatened species. The fitness costs and benefits of living in a group are related to particular spatial positions individuals take within their groups. Age and sex of the individual is a major factor determining intra-group spatial position. In the present study, we investigated the within-group spatial positioning of individuals in the Critically Endangered Saiga tatarica (hereinafter – saiga). In saigas living under natural predation pressure in the Stepnoi State Nature Sanctuary (Astrakhan Region, Russia), we investigated the sex-age category of the first individual in the group, the inter-individual distance in the front individuals and the individuals following them, and the distribution of individuals of each sex-age category between various parts of the group. Three (summer) or four (autumn) sex-age categories of the individuals in the moving groups were recognised by direct observations in the field. In summer, adult females, accompanied by their calves, were the very first individuals in most saiga groups observed. This result agrees with the previous notion that experienced females often lead the saiga groups. However, further investigation is needed to confirm whether adult females do indeed take the role of a leader during long-distance group movements. In line with the results on other mammals, the majority of adult females moved in the central third of the group. Spatial preferences of adult females seem to be based on the risk minimisation as the central positions are likely the safest in the group. In autumn, juvenile males were moving first in the majority of the investigated groups probably because they were the most active and fast-moving sex-age category during this season. In addition, juvenile males and females were significantly more often observed in the first third of the group than in the central and the rear thirds. We suggest that despite the fact that the front edge of the group could be the most dangerous spatial position, foraging benefits may outweigh the increased risk for juvenile saigas. In contrast to some other mammals, adult males did not tend to move at the front edge and were equally often observed in the front, central and rear parts of saiga groups. Finally, our results showed that saigas closer to the front edge of the group maintained shorter inter-individual distances than the individuals positioned behind them. The tighter spacing could be used by front individuals to compensate for the increased risks associated with their within-group spatial position

Visual Laterality of Calf–Mother Interactions in Wild Whales

Behavioral laterality is known for a variety of vertebrate and invertebrate animals. Laterality in social interactions has been described for a wide range of species including humans. Although evidence and theoretical predictions indicate that in social species the degree of population level laterality is greater than in solitary ones, the origin of these unilateral biases is not fully understood. It is especially poorly studied in the wild animals. Little is known about the role, which laterality in social interactions plays in natural populations. A number of brain characteristics make cetaceans most suitable for investigation of lateralization in social contacts.) in the greatest breeding aggregation in the White Sea. Here we show that young calves (in 29 individually identified and in over a hundred of individually not recognized mother-calf pairs) swim and rest significantly longer on a mother's right side. Further observations along with the data from other cetaceans indicate that found laterality is a result of the calves' preference to observe their mothers with the left eye, i.e., to analyze the information on a socially significant object in the right brain hemisphere.Data from our and previous work on cetacean laterality suggest that basic brain lateralizations are expressed in the same way in cetaceans and other vertebrates. While the information on social partners and novel objects is analyzed in the right brain hemisphere, the control of feeding behavior is performed by the left brain hemisphere. Continuous unilateral visual contacts of calves to mothers with the left eye may influence social development of the young by activation of the contralateral (right) brain hemisphere, indicating a possible mechanism on how behavioral lateralization may influence species life and welfare. This hypothesis is supported by evidence from other vertebrates

Does bipedality predict the group-level manual laterality in mammals?

BACKGROUND: Factors determining patterns of laterality manifestation in mammals remain unclear. In primates, the upright posture favours the expression of manual laterality across species, but may have little influence within a species. Whether the bipedalism acts the same in non-primate mammals is unknown. Our recent findings in bipedal and quadrupedal marsupials suggested that differences in laterality pattern, as well as emergence of manual specialization in evolution might depend on species-specific body posture. Here, we evaluated the hypothesis that the postural characteristics are the key variable shaping the manual laterality expression across mammalian species. METHODOLOGY/PRINCIPAL FINDINGS: We studied forelimb preferences in a most bipedal marsupial, brush-tailed bettong, Bettongia penicillata in four different types of unimanual behavior. The significant left-forelimb preference at the group level was found in all behaviours studied. In unimanual feeding on non-living food, catching live prey and nest-material collecting, all or most subjects were lateralized, and among lateralized bettongs a significant majority displayed left-forelimb bias. Only in unimanual supporting of the body in the tripedal stance the distribution of lateralized and non-lateralized individuals did not differ from chance. Individual preferences were consistent across all types of behaviour. The direction or the strength of forelimb preferences were not affected by the animals' sex. CONCLUSIONS/SIGNIFICANCE: Our findings support the hypothesis that the expression of manual laterality depends on the species-typical postural habit. The interspecies comparison illustrates that in marsupials the increase of bipedality corresponds with the increase of the degree of group-level forelimb preference in a species. Thus, bipedalism can predict pronounced manual laterality at both intra- and interspecific levels in mammals. We also conclude that quadrupedal position in biped species can slightly hinder the expression of manual laterality, but the evoked biped position in quadrupedal species does not necessarily lead to the enhanced manifestation of manual laterality

Percentage of lateralized individuals in marsupial species characterized by different degree of bipedality.

<p>The bars represent the percent of the subjects showed significant forelimb preferences for unimanual feeding on non-living food in grey short-tailed opossums, <i>Monodelphis domestica</i> (<i>n</i> = 26) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov1" target="_blank">[13]</a>, sugar gliders, <i>Petaurus breviceps</i> (<i>n</i> = 23) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov1" target="_blank">[13]</a>, red-necked wallabies, <i>Macropus rufogriseus</i> (<i>n</i> = 27) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov3" target="_blank">[49]</a>, and brush-tailed bettongs, <i>Bettongia penicillata</i> (<i>n</i> = 12) (the present study). The arrow indicates the increase of relative degree of bipedality and body verticality from grey short-tailed opossums – terrestrial quadrupeds rarely observed in a bipedal position and sugar gliders – arboreal quadrupeds frequently feeding in a bipedal position <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov1" target="_blank">[13]</a> to red-necked wallabies – bipedal saltators, but moving quadrupedally at slow speeds and brush-tailed bettongs, which prefer bipedal hopping even at the slow speed (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#s3" target="_blank">Discussion</a> for a more detailed comparison).</p

L'Avenir de Luchon : journal scientifique, littéraire, annonces et réclames : guide général des baigneurs et des touristes aux eaux thermales, bains de mer de la France et de l'étranger

23 avril 19331933/04/23 (N585)-1933/04/23.Appartient à l’ensemble documentaire : MidiPyren

Comparative degrees of forelimb preferences at the group level in marsupial species characterized by different degree of bipedality.

<p>The bars represent mean HI scores ±SEM for unimanual feeding on non-living food in grey short-tailed opossums, <i>Monodelphis domestica</i> (<i>n</i> = 26) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov1" target="_blank">[13]</a>, sugar gliders, <i>Petaurus breviceps</i> (<i>n</i> = 23) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov1" target="_blank">[13]</a>, red-necked wallabies, <i>Macropus rufogriseus</i> (<i>n</i> = 27) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone.0051583-Giljov3" target="_blank">[49]</a>, and brush-tailed bettongs, <i>Bettongia penicillata</i> (<i>n</i> = 12) (the present study). Asterisks indicate that the mean HI score differed significantly from zero, *<i>p</i><0.05. The arrow indicates the increase of relative degree of bipedality and body verticality across marsupial species (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051583#pone-0051583-g003" target="_blank">Fig.3</a> caption). The increase of bipedality across species corresponds with the increase of the degree of group-level preference.</p