scholarly journals Effects of body size and prior residence on dominance hierarchies in female Asian particolored bats

2020 ◽  
Vol 101 (2) ◽  
pp. 526-534 ◽  
Author(s):  
Heng Liu ◽  
Xin Zhao ◽  
Yuze Wang ◽  
Ying Liu ◽  
Jiang Feng ◽  
...  

Abstract Social animals may cooperate to gain resources such as food and territory. However, unavoidable conflicts over limited resources frequently occur between group members. Social rank may effectively decrease conflicts within animal social groups, thereby reducing energy consumption and maintaining group stability. In this study, we tested the two factors most often proposed to influence winning a conflict: body size and prior residence. Our results showed that female Asian particolored bats (Vespertilio sinensis) formed near-linear dominance hierarchies. Forearm length was significantly positively correlated with dominance rank in three replicate experiments. In addition, prior residents had significantly higher dominance ranks than intruders of similar body size. These results suggested that both body size and prior residence might affect dominance ranks in female Asian particolored bats.

2021 ◽  
Author(s):  
Taylor Lynne Rystrom ◽  
Romy C. Prawitt ◽  
S. Helene Richter ◽  
Norbert Sachser ◽  
Sylvia Kaiser

Social interactions among group members often lead to the formation of stable dominance hierarchies. Glucocorticoids (i.e. cortisol) have been proposed as an endocrine mechanism underlying social behavior, and previous studies have linked baseline as well as challenge glucocorticoid concentrations to dominance rank. Since the importance of rank on fitness differs between males and females, selection pressures acting on the underlying endocrine mechanisms may differ between the sexes. In male guinea pigs, for example, it is known that cortisol responsiveness mediates social behavior and that dominance rank and cortisol responsiveness are stable within individuals over time. It is unclear whether this is also the case for female guinea pigs. Thus the aim of this study was to investigate whether cortisol concentrations are repeatable in female guinea pigs and whether female rank is correlated to baseline cortisol concentrations or cortisol responsiveness. We show that cortisol responsiveness and dominance rank were significantly repeatable but not correlated in female guinea pigs. Furthermore, baseline cortisol was not repeatable and also did not correlate to dominance rank. Our results demonstrate that baseline cortisol and cortisol responsiveness represent different biological processes; cortisol responsiveness reflects a stable trait while baseline cortisol likely fluctuates with current state. Furthermore, cortisol responsiveness as a mediator of aggressive behavior and dominance acquisition might not be important for maintaining dominance hierarchies in stable groups of females displaying minimal aggression. Overall, this study reveals the remarkable stability of cortisol responsiveness and dominance rank in an adult female rodent and lays the groundwork for future investigations into the causes and consequences of this individual variation.


2019 ◽  
Author(s):  
Atul Pandey ◽  
Uzi Motro ◽  
Guy Bloch

AbstractJuvenile hormone (JH) is a key regulator of insect development and reproduction. Given that JH commonly affects adult insect fertility, it has been hypothesized to also regulate behaviors such as dominance and aggression that are associated with reproduction. We tested this hypothesis in the bumble bee Bombus terrestris for which JH has been shown to be the major gonadotropin. We used the allatoxin Precocene-I (P-I) to reduce hemolymph JH titers and replacement therapy with the natural JH to revert this effect. In small orphan groups of workers with similar body size but mixed treatment, P-I treated bees showed lower aggressiveness, oogenesis, and dominance rank compared with control and replacement therapy treated bees. In similar groups in which all bees were treated similarly, there was a clear dominance hierarchy, even in P-I and replacement therapy treatment groups in which the bees showed similar levels of ovarian activation. In a similar experiment in which bees differed in body size, larger bees were more likely to be dominant despite their similar JH treatment and ovarian state. In the last experiment, we show that JH manipulation does not affect dominance rank in groups that had already established a stable dominance hierarchy. These findings solve previous ambiguities concerning whether or not JH affects dominance in bumble bees. JH positively affects dominance, but bees with similar levels of JH can nevertheless establish dominance hierarchies. Thus, multiple factors including JH, body size, and previous experience affect dominance and aggression in social bumble bees.


2021 ◽  
Author(s):  
T Rueger ◽  
SJ Heatwole ◽  
MY Wong

AbstractMany animal groups consist of individuals organised in dominance hierarchies, based on age, size or fighting ability. Lower ranked individuals often do not reproduce themselves but perform cooperative behaviours to help the reproductive output of dominant individuals or the group as a whole. Theoretical models suggest that individuals of higher rank should show increased amounts of aggressive behaviours, such as aggressions towards other group members, but should decrease the amount of cooperative behaviours, such as brood care or territory maintenance. Most empirical tests of these models focus on insect or mammalian systems where kin selection plays a large role, rather than animals that live in groups of unrelated individuals. Here we use two anemonefish species to test hypotheses of variation in cooperation and aggression with respect to social rank and species, for social systems where group members are unrelated. We assessed the behaviours of each rank in 20 groups of Amphiprion percula and 12 groups of A. perideraion in Kimbe Bay, Papua New Guinea. We also performed a removal experiment to test if cooperative and aggressive behaviours are likely adaptive, i.e., if they change as an individual ascends in rank. Our results show differences between the two species, with A. percula showing more cooperative behaviours and A. perideraion showing more aggressive behaviours, despite them being closely related and sharing a very similar ecology. With respect to both cooperation and aggression we found consistent differences between ranks in both species, with higher ranks performing more aggressive as well as more cooperative behaviours. When we experimentally provided lower ranked individuals (rank 4) an opportunity to ascend in the hierarchy, they showed more aggression and more cooperation in line with our observations for rank 3 individuals. Thus, we show that rank specific behavioural patterns are likely adaptive in anemonefishes and that some model predictions do not hold in systems where kin selection benefits are absent. Rather, future fitness benefits through territory inheritance and group augmentation likely motivate cooperative and aggressive behaviours by subordinates in groups of unrelated vertebrates.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Edward Wright ◽  
Sven Grawunder ◽  
Eric Ndayishimiye ◽  
Jordi Galbany ◽  
Shannon C. McFarlin ◽  
...  

AbstractAcoustic signals that reliably indicate body size, which usually determines competitive ability, are of particular interest for understanding how animals assess rivals and choose mates. Whereas body size tends to be negatively associated with formant dispersion in animal vocalizations, non-vocal signals have received little attention. Among the most emblematic sounds in the animal kingdom is the chest beat of gorillas, a non-vocal signal that is thought to be important in intra and inter-sexual competition, yet it is unclear whether it reliably indicates body size. We examined the relationship among body size (back breadth), peak frequency, and three temporal characteristics of the chest beat: duration, number of beats and beat rate from sound recordings of wild adult male mountain gorillas. Using linear mixed models, we found that larger males had significantly lower peak frequencies than smaller ones, but we found no consistent relationship between body size and the temporal characteristics measured. Taken together with earlier findings of positive correlations among male body size, dominance rank and reproductive success, we conclude that the gorilla chest beat is an honest signal of competitive ability. These results emphasize the potential of non-vocal signals to convey important information in mammal communication.


2021 ◽  
Vol 1 (11) ◽  
pp. 6-15
Author(s):  
Sergey V. Posyabin ◽  
◽  
Elena N. Borkhunova ◽  
Vladislav V. Belogurov ◽  
Mikhail D. Kachalin ◽  
...  

The article presents the results of studies of anatomical, histological and morphometric characteristics of bovine ungulates aimed at identifying signs of structural adaptation of the distal part of the limb to anthropogenically modeled content conditions. The factors that the hoof experiences are the predominance of static load, the high weight of the animal, and the support on solid soil. As a morphological control, elk is considered as a parrotfish animal with similar body size and weight, located in the conditions of natural biotsenose and moving on forest soils. It is shown that constant presence of cattle in conditions of hypokinesia on hard floors leads to change of limb setting and change of hoof shape, which is reflected in change of hoof shape, increase of hoof angle, ratio of plantar and dorsal hoof surfaces length. At the same time, the biomechanical load is redistributed between parts of the hoof so that the load on the wall increases and on the ball decreases. This may be a factor predisposing the hoof to the appearance of microtraumas, later manifested by laminites.


2018 ◽  
Vol 41 ◽  
pp. 13-18
Author(s):  
Olav Hogstad ◽  
Tore Slagsvold

The Willow Tit Poecile montanus is highly sedentary and breeding pairs remain in their exclusive areas throughout the year. During the winter, these areas are defended by small, non-kin flocks, formed as the roaming yearlings become sedentary and join adults during late summer and autumn. Once established, stable social hierarchies are maintained in these flocks during the winter. The winter flocks consist normally of the socially dominant adult mated pair and two mated juvenile pairs, one higher-ranked and one lower-ranked. Individually colour-ringed juvenile Willow Tits were followed over years in subalpine forest in Norway from ringing in the autumn till they disappeared. None of the lower ranked birds survived their first winter, whereas only 4 of 71 higher-ranked juvenile pairs disappeared during this time. Half of the 71 pairs survived their first winter, about 25 % survived two winters, 8.5% survived three winters, and 5.6% survived four winters. Survival was similar for males and females. Alpha pairs remained mated and defended their common territory across years. Maximum age as revealed by ringing showed one female became six years old and two males ringed as adults were at least nine years old when last observed. The main factor associated with survival was early flock establishment that led to a high rank position among the juvenile flock members. Body size seemed insignificant. Birds that survived their first winter either succeeded to establish as territory owners or they were forced into the role as floaters and probably perished.


PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5370 ◽  
Author(s):  
Caterina Penone ◽  
Christian Kerbiriou ◽  
Jean-François Julien ◽  
Julie Marmet ◽  
Isabelle Le Viol

Background Citizen monitoring programs using acoustic data have been useful for detecting population and community patterns. However, they have rarely been used to study broad scale patterns of species traits. We assessed the potential of acoustic data to detect broad scale patterns in body size. We compared geographical patterns in body size with acoustic signals in the bat species Pipistrellus pipistrellus. Given the correlation between body size and acoustic characteristics, we expected to see similar results when analyzing the relationships of body size and acoustic signals with climatic variables. Methods We assessed body size using forearm length measurements of 1,359 bats, captured by mist nets in France. For acoustic analyses, we used an extensive dataset collected through the French citizen bat survey. We isolated each bat echolocation call (n = 4,783) and performed automatic measures of signals, including the frequency of the flattest part of the calls (characteristic frequency). We then examined the relationship between forearm length, characteristic frequencies, and two components resulting from principal component analysis for geographic (latitude, longitude) and climatic variables. Results Forearm length was positively correlated with higher precipitation, lower seasonality, and lower temperatures. Lower characteristic frequencies (i.e., larger body size) were mostly related to lower temperatures and northern latitudes. While conducted on different datasets, the two analyses provided congruent results. Discussion Acoustic data from citizen science programs can thus be useful for the detection of large-scale patterns in body size. This first analysis offers a new perspective for the use of large acoustic databases to explore biological patterns and to address both theoretical and applied questions.


Author(s):  
Elizabeth A. Tibbetts ◽  
Juanita Pardo-Sanchez ◽  
Chloe Weise

Animal groups are often organized hierarchically, with dominant individuals gaining priority access to resources and reproduction over subordinate individuals. Initial dominance hierarchy formation may be influenced by multiple interacting factors, including an animal's individual attributes, conventions and self-organizing social dynamics. After establishment, hierarchies are typically maintained over the long-term because individuals save time, energy and reduce the risk of injury by recognizing and abiding by established dominance relationships. A separate set of behaviours are used to maintain dominance relationships within groups, including behaviours that stabilize ranks (punishment, threats, behavioural asymmetry), as well as signals that provide information about dominance rank (individual identity signals, signals of dominance). In this review, we describe the behaviours used to establish and maintain dominance hierarchies across different taxa and types of societies. We also review opportunities for future research including: testing how self-organizing behavioural dynamics interact with other factors to mediate dominance hierarchy formation, measuring the long-term stability of social hierarchies and the factors that disrupt hierarchy stability, incorporating phenotypic plasticity into our understanding of the behavioural dynamics of hierarchies and considering how cognition coevolves with the behaviours used to establish and maintain hierarchies. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.


Ranking ◽  
2019 ◽  
pp. 42-64
Author(s):  
Péter Érdi

This chapter studies how social ranking in humans emerged as the result of an evolutionary process. It starts with the story of the discovery of pecking order among chickens by a Norwegian boy. Both animals and humans need a healthy balance between cooperation and competition to ensure evolutionarily efficient strategies. The biological machinery behind social ranking is discussed. There are two distinct mechanisms for navigating the social ladder: dominance and prestige. Dominance, an evolutionarily older strategy, is based on the ability to intimidate other members in the group by physical size and strength. The group members don’t accept dominance-based social rank freely, only by coercion. Members of a colony fight, and the winners of these fights will be accepted as “dominants” and the losers as “subordinates.” The naturally formed hierarchy serves as a way to prevent superfluous fighting and injuries within a colony. Prestige, as a strategy, is evolutionarily younger and is based on skills and knowledge as appraised by the community. Prestige hierarchies are maintained by the consent of the community, without pressure being applied by particular members. The mechanisms of forming and maintaining social hierarchies are described. Social structures, both hierarchies and network organizations, are reviewed. Discussion of these structures is carried over to social and political history and the tension between democracy and authoritarianism.


2020 ◽  
Vol 16 (8) ◽  
pp. 20200468
Author(s):  
Steven J. Portugal ◽  
James R. Usherwood ◽  
Craig R. White ◽  
Daniel W. E. Sankey ◽  
Alan M. Wilson

Dominance hierarchies confer benefits to group members by decreasing the incidences of physical conflict, but may result in certain lower ranked individuals consistently missing out on access to resources. Here, we report a linear dominance hierarchy remaining stable over time in a closed population of birds. We show that this stability can be disrupted, however, by the artificial mass loading of birds that typically comprise the bottom 50% of the hierarchy. Mass loading causes these low-ranked birds to immediately become more aggressive and rise-up the dominance hierarchy; however, this effect was only evident in males and was absent in females. Removal of the artificial mass causes the hierarchy to return to its previous structure. This interruption of a stable hierarchy implies a strong direct link between body mass and social behaviour and suggests that an individual's personality can be altered by the artificial manipulation of body mass.


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