Beryl

lovely milf Kyleigh
Chat now

Information

  • Age:
  • 21

About

The video has been added to your member zone favourites. Tags: Indian Desi X. The field is required. Thank you!

Description

If the address matches an existing you will receive an with instructions to reset your password. If the address matches an existing you will receive an with instructions to retrieve your username. Google Scholar. Find this author on PubMed.

cutie moms Oakleigh

Search for more papers by this author. Territorial social species, including humans, compete between groups over key resources. This between-group competition has evolutionary implications on adaptations like in-group cooperation even with non-kin. An emergent property of between-group competition is group dominance. Mechanisms of group dominance in wild animal populations are difficult to study, as they require long-term data on several groups within a population.

Here, using long-term data on four neighbouring groups of wild western chimpanzees, we test the hypothesis that group dominance impacts the costs and benefits of between-group competition, measured by territory size and the pressure exerted by neighbouring groups.

Related penetration with chimp woman a

Larger groups had larger territories and suffered less neighbour pressure compared with smaller groups. Within-group increase in the of males led to territory increase, suggesting the role of males in territory acquisition. However, variation in territory sizes and neighbour pressure was better explained by group size.

This suggests that the bisexually-bonded social system of western chimpanzees, where females participate in territorial behaviour, confers a competitive advantage to larger groups and that group dominance acts through group size in this population. Considering variation in social systems offers new insights on how group dominance acts in territorial species and its evolutionary implications on within-group cooperation.

Related videos

Many social species compete for resources between groups of conspecifics [ 1 — 3 ]. This between-group competition BGC has evolutionary implications, especially for humans, resulting in forms of territoriality and probably shaping aspects of sociality, such as within-group cooperative skills [ 45 ]. Consequently, understanding the mechanisms and effects of BGC in social species is of key importance but requires long-term studies on several groups within a population [ 6 ]. The inter-group dominance hypothesis [ 7 ] is a theoretical framework attempting to integrate BGC into an evolutionary canvas and proposes that neighbouring groups compete for space and that competition in a population-scale group hierarchy.

Dominant groups could then benefit from larger territories and therefore increased access to food resources. This would regulate within-group feeding competition, which in turn would benefit individuals through nutritional benefits causing improved fitness [ 78 ]. Other benefits, such as mate-attraction and infant-defence [ 9 ], might also be associated with a high group dominance status. A variety of social species show evidence of group dominance effects: i African lionesses Panthera leo that live in larger prides face lower levels of BGC, have access to better quality habitats and show lower mortality [ 8 ]; ii large group sizes in spotted hyenas Crocuta crocuta have positive effects on hunting success and reproduction [ 10 ]; and iii larger packs of wolves Canis lupus are more successful than smaller packs in preying upon large prey [ 11 ] and larger packs outcompete smaller packs of neighbouring conspecifics [ 12 ], potentially resulting in fitness benefits.

Among primates, effects of group dominance through large group sizes have also been found: i larger groups of vervet monkeys Chlorocebus pygerythrus inhabit higher quality habitats and have lower infant and juvenile mortality [ 13 ]; ii larger groups of Japanese macaques Macaca fuscata occupy better quality habitats which entail lower travelling costs associated with BGC [ 14 ]; iii larger groups of black and white colobus Colobus guereza seem dominant and access better quality feeding areas [ 15 ]; and iv larger groups of wedge-capped capuchins Cebus olivaceus benefit from improved reproductive success than smaller groups [ 16 ].

Chimpanzees Pan troglodytes are one of the most territorial primate species, with intense BGC [ 17 ], which can lead to inter-group killings [ 18 — 21 ]. Chimpanzees live in a fission—fusion system, where individuals roam within their territory in parties of fluctuating sizes and composition [ 2223 ].

gorgeous girl Coraline

This system can create strong, but temporary, power imbalances between neighbouring groups, resulting in low between-group aggression costs from the outing parties in cases of strong imbalance [ 24 ]. In chimpanzees, adult males seem to play an important role in group dominance: inter-group aggression is more likely to occur when the of males in a group is high [ 21 ]; in Ngogo Ugandainter-group killings by males seemed specifically targeted toward a small neighbouring group, leading across time to a territorial expansion [ 25 ], suggesting that the Ngogo group dominated the smaller one.

In another eastern chimpanzee Pan t. Even if territorial expansion in Ngogo chimpanzees seems caused by the of males [ 25 ], the relationship between territory size and demographic competitive ability in chimpanzees remains unclear, with inconsistent evidence across populations.

Videos for: monkey ape

In Gombe eastern chimpanzees Tanzaniano relationship between the of males and territory size was detected [ 27 ], but instead the of females was positively associated with territory size. In the North group of western chimpanzees Pan t. Although inter-group killings are more frequent in eastern chimpanzees [ 21 ], they also occur in western chimpanzees [ 20 ].

lovely women Journee

These differences may come from population density differences [ 21 ], larger s of adult males in eastern populations [ 21 ], but also from differences in grouping patterns [ 29 ]. Chimpanzee populations differ in their social grouping patterns summarized in [ 30 ] : most eastern chimpanzee populations are characterized by a male-bonded community system [ 273132 ], where males have a much larger territory than females.

These differences in social structures may imply different mechanisms of group dominance. While adult males in male-bonded populations play an essential role in territorial behaviour and therefore in territorial expansion and neighbours' repulsion, in bisexually-bonded populations, group size may matter more than the of males for the group's competitive ability.

Given the importance of inter-group interactions and BGC in human evolution [ 37 — 40 ], understanding the mechanisms of group dominance in our closest living relatives and how their social structures relate to their competitive ability would shed light on the mechanisms by which BGC acted as a selective pressure on territoriality and cooperation with non-kin in the hominoid lineage. In order to test the mechanisms of group dominance, extensive long-term data on several groups of differing demography are necessary.

Using these long-term data, we tested the hypothesis whether or not group dominance effects are reflected in the costs and benefits of BGC measured using territory size and perceived neighbour pressure measured by a composite index considering the rate of inter-group encounters IGEsthe degree of neighbour intrusion of these IGEs, and the salience of the location of IGEs in term of past usage [ 42 ].

Larger territory sizes and lower neighbour pressure are considered beneficial, while smaller territories and higher neighbour pressure are considered costly for the individuals [ 4344 ]. As potential proxies for group dominance, determined by the competitive ability of a group, we used the of adult individuals of the dominant sex of the group malesthe of adults and adolescent males and females of mature individuals and group size of independent individuals. First, we tested how annual territory sizes are influenced by a group's competitive ability of males, of mature individuals and group size separately and by food availability, two variables known to determine territory sizes in a variety of species [ 43 ].

Second, we analysed how perceived neighbour pressure, which reflects potential threat of intrusion by neighbours into one's territory [ 42 ], is influenced by a group's competitive ability, food availability and presence of attractive females.

Search options

The rationale behind this approach is that BGC in chimpanzees is potentially driven by i the males' need to attract more fertile females, and ii by the group's need to ensure safe feeding grounds to support their energetic requirements. More dominant groups should be better at competing for these resources than less dominant ones, but variation in resource availability may change the intensity of competition between the groups.

Despite the availability of several neighbouring groups, we could not include the relative power of each group in relation to the response variables, since all groups are also neighboured by unhabituated groups from which no information is available regarding their competitive ability.

However, we modelled in our analysis potential patterns of group dominance via group differences, by disentangling the demographic within- and between-group effects [ 46 ]. We are not looking specifically at interactions between these groups, as each of these groups have more neighbouring non-habituated groups, even if some of the inter-group encounters considered in this study involve these groups. The neighbour pressure index NPI [ 42 ] enables captures of the level of threat represented by the intrusion of any neighbours, without having the information about their or relative power see below.

From towe used nest-to-nest continuous focal follows on individual chimpanzees [ 47 ], to record information on behaviour, party compositions, vocalizations, activity and social interactions involving the focal individual [ 41 ].

Yearly plan

Each day, we reported the presence of all individuals observed. We individually checked the GPS tracks to match them with the daily observation periods. We defined observation time as the time human observers followed individual chimpanzees of different parties, keeping only one set of the data whenever different focal individuals were simultaneously followed within the same party.

The observation time was calculated in hours and log-transformed, reflecting the cumulative effect of observation on ranging data in particular, expected to reach a plateau after a certain amount of observation time. We chose yearly intervals January 1 to December 31 as the temporal scale to calculate territory size, as a full year enables inclusion of the majority of food types consumed by chimpanzees, and takes into intra-annual productivity differences [ 4950 ].

We processed spatial datasets in R v. Areas were assessed with self-made functions. A summary of spatial parameters is provided in electronic supplementary material, table S1. We considered demographic parameters to determine the competitive ability of a given group. Therefore, in concordance with other studies [ 353655 — 57 ] we considered here males as adult when the have reached 12 years of age.

Monthly plan

We considered females as adult as soon as they presented exaggerated sexual swellings minimum age: 9. Adolescent males and females included those aged between 10 and 12 years old, excluding females already presenting exaggerated sexual swellings [ 23 ].

Group size was defined as the total of within-group weaned individuals, that is all individuals that travel and feed independently from their mothers. s of males, of mature individuals adult and adolescent males and females and group sizes were measured monthly and averaged across the year. All groups experienced demographic variation due to deaths, births, female emigrations and immigrations electronic supplementary material, table S1. The first measure considers that, even if pluriparous females are unlikely to emigrate under the pressure of neighbours, they may nonetheless constitute a factor of attraction, as extra-group forced copulations have been observed, even if rare [ 20 ].

The second measure considers that neighbouring groups may be attracted by females that could potentially emigrate to their group. However, reporting just the ratio of these two values would not for the fact that several females could have swellings the same day, so we adjusted the of females presenting fully tumescent swellings to the of days where a certain of females had swellings.

This conservative measure of the of fully tumescent females allows circumventing the issue of not observing females for some days and so not being able to assess the complete fully tumescent period. Nulliparous females are those from the age of 10 years old including the one female already showing swellings at age 9. We used the NPI proposed in Lemoine et al. Physical IGE included those where individuals from opposing groups are in close visual contact, with or without direct physical aggression.

Vocal IGE include those where individuals from opposing groups were not in visual contact. We distinguished vocalizations and drums emitted by neighbours from those emitted by the same group's members, either because the entire group was present with the observer, or based on the direction of the emitted vocalizations relative to the group's location, and the vocal response and reaction of fear and excitement displayed by the followed group.

lovely singles Sienna

The usage of the territory is not homogeneous, meaning that the successive layers of kernel distributions are not concentric. Some areas in the periphery are more used than others. Thus, the kernel values are poorly correlated with the degree of intrusion [ 42 ]. Including the past usage of the location in the NPI resides in the fact that the level of threat from neighbours may be higher in areas preferentially used by the resident chimpanzees, as it may impair future usage of this area, and that residents may then be more inclined to respond strongly in these areas of importance, as seen in various primate species [ 6061 ] and as predicted by theoretical models [ 4462 ].

A large NPI value reflects a stronger neighbour pressure. The NPI considers all the intrusions and interactions from all neighbouring groups, even from those which are not habituated to human observers, and from which information regarding their relative power is not available.

Instead of reflecting the power of neighbouring groups, it reflects how dangerous their intrusions are.

cute latina Ariyah

We used a food availability index FAI established in studies in this population [ 4950 ].

Recent members

Maire

Log in through your institution.
More

Callie

When you enter pakistaniporn2.
More

Camile

Try out PMC Labs and tell us what you think.
More

Brittaney

With a personal , you can read up to articles each month for free.
More