5,286 research outputs found

    Modeling the emergence of modular leadership hierarchy during the collective motion of herds made of harems

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    Gregarious animals need to make collective decisions in order to keep their cohesiveness. Several species of them live in multilevel societies, and form herds composed of smaller communities. We present a model for the development of a leadership hierarchy in a herd consisting of loosely connected sub-groups (e.g. harems) by combining self organization and social dynamics. It starts from unfamiliar individuals without relationships and reproduces the emergence of a hierarchical and modular leadership network that promotes an effective spreading of the decisions from more capable individuals to the others, and thus gives rise to a beneficial collective decision. Our results stemming from the model are in a good agreement with our observations of a Przewalski horse herd (Hortob\'agy, Hungary). We find that the harem-leader to harem-member ratio observed in Przewalski horses corresponds to an optimal network in this approach regarding common success, and that the observed and modeled harem size distributions are close to a lognormal.Comment: 18 pages, 7 figures, J. Stat. Phys. (2014

    Graph Models of Harems and Tournaments in Sports Clubs

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    By looking at the extension of Hall's marriage theorem to harems, where some people are allowed to have more than one partner, Traditionally in harems any man can have multiple wives but no woman can have more than one husband. then consider the different types of matches by looking at 'round robin tournaments' in sports clubs. An unexpected connection between the two worlds emerged when we were able to use our harem results to deduce theorems about the tournament

    Sex- and season-dependent behaviour in a flightless insect, the Auckland tree weta (Hemideina thoracica)

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    In a polygynous mating system, males frequently compete by locating and defending sites with resources essential to female survival and reproduction. We investigated seasonal changes in site occupancy in a sexually dimorphic, harem-forming insect, the Auckland tree weta (Hemideina thoracica). First we established artificial cavities as diurnal refuge cavities and potential harem guarding sites. We then examined cavity occupancy changes, and, based on our knowledge of prior occupants, determined sex-specific patterns of arrival, departure, and aggregation at a population level throughout the year. Both season and the sex of prior occupants influenced weta occupancy patterns. Most observations were of single females. However, both males and females moved into cavities previously occupied by a weta of the opposite sex more often than expected by chance alone. Females avoided cavities where other females were present, except during summer when most harems formed. In early summer, male and female tree weta previously living apart began co-habiting. Generally there was little relationship between the number and sex of the weta inside cavities and female departure rates from cavities. Males who were sharing with other males departed cavities more frequently than single males, as might be expected in a polygynous species with male-male combat. Males were less likely to depart if they were sharing a cavity with a harem of more than two females during the summer-autumn period. Analysis of departure rates from artificial cavities indicates males are more mobile than females only in winter and spring. Based on our arrival and departure data, and high occupancy of artificial cavities, we suggest that female weta at this site are mobile and may search for mates during the summer. The data are consistent with a polygynandrous mating system as inferred for other tree weta species (Hemideina spp.)

    Social structure of a polygynous tent-making bat, \u3ci\u3eCynopterus sphinx\u3c/i\u3e (Megachiroptera)

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    The social structure of an Old World tent-making bat Cynopterus sphinx (Megachiroptera), was investigated in western India. A combination of census and mark–recapture data over 2 years (1996–98) was used to infer the form of the mating system, compositional stability of social groups and mode of new social group formation. The breeding population of C. sphinx was subdivided into diurnal roosting colonies, each of which contained one to five discrete roosting groups and often one or more solitary bats in adjacent roosts. Bats most frequently roosted in stem tents constructed in the flower/fruit clusters of the kitul palm Caryota urens. Temporal variation in social structure was assessed using visual census data for a subset of the study population over 3 years (1995– 98) spanning six consecutive reproductive periods. The sex and age composition of diurnal roosting groups indicated a polygynous harem-forming mode of social organization, as groups invariably contained a single adult male, 1–37 reproductive females and their dependent young (n = 33 harems). Harem size averaged 6.1 adults in the wet season (n = 19, SD = 3.5) and 13.6 adults in the dry season (n = 14, SD = 8.5). The same harem social configuration was maintained year-round, despite a high degree of synchrony and seasonality in the timing of reproduction. Juveniles of both sexes dispersed after weaning and sexually immature bats were never present in harems at the time of parturition. Adult females often remained associated as roostmates from one parturition period to the next, and group cohesion was unaffected by turnover of harem males. Adult females frequently transferred among roosts within the same colony, and harems underwent periodic fissions and fusions. The founding of new harems most often resulted from the fissioning of previously cohesive harems within the same colony. However, some harems contained disproportionate numbers of yearling females, indicating that new groups are also founded by nulliparous females of the same age cohort. A significant degree of heterogeneity in age composition among harems was revealed in the 1998 dry season, but was unrelated to age-stratification of tent roosts. Although formation of new harems may be non-random with respect to age composition of the founders, founding events are not restricted to newly created tents and often involve recolonization of previously occupied roosts

    The Female Captivity Narrative: Blood, Water, and Orientalism

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    The story of how Europeans institutionalized, commodified, and controlled their anxious projections about Muslim Others is a long, complex, and ultimately tragic saga that the term Orientalism only partially conveys. Historians as well as literary, religious, political, and cultural critics have attempted for close to four hundred years to come to terms with the meaning of Islam and more broadly with the challenges that the Eastern world presents to the West. More importantly for the purposes of this essay, it is necessary to recognize that the binary model (Self/Other) adopted by Edward Said to define Orientalism has been challenged and modified by recent feminist literary critics as both gender and class-blind

    The Harem: Looking Behind the Veil

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    European travel writing about Middle Eastern countries became a popular genre in the 1700s and into the early 1900s. When European male writers were not permitted access into the part of Eastern households known as harems, they became suspicious and wrote sexualized descriptions of harems in their travelogues, based on Western hegemonic views and male fantasy. These claims refuted by European women who were permitted into the harems and wrote their own, more accurate observations. Their writings evolved into harem literature and became a women-dominated genre. However, while dispelling the male sexualized fantasy of harems, the women’s writings had a tendency to promote other concepts of Western constructed Orientalism, centering on the perceived repression of Eastern women. European women focused on perceived repressions of Eastern women by their men, and ironically seemed unable (or unwilling) to see their own repression and the hypocrisy constructed by the men of their own Western culture. European women also infused their own fantasies back into Eastern travel literature, which originated from the stories from Arabian Nights. These fantasies of the magical Orient were the bridge between travel/harem literature and what was to become the desert romance novel in the early 20th century. These novels, while entertaining and sexually liberating to women at that time, continued to promote stereotypes of latent Orientalism and objectify Western women as well

    Demographics by depth: spatially explicit life-history dynamics of a protogynous reef fish

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    Distribution and demographics of the hogfish (Lachnolaimus maximus) were investigated by using a combined approach of in situ observations and life history analyses. Presence, density, size, age, and size and age at sex change all varied with depth in the eastern Gulf of Mexico. Hogfish (64–774 mm fork length and 0–19 years old) were observed year-round and were most common over complex, natural hard bottom habitat. As depth increased, the presence and density of hogfish decreased, but mean size and age increased. Size at age was smaller nearshore (<30 m). Length and age at sex change of nearshore hogfish were half those of offshore hogfish and were coincident with the minimum legal size limit. Fishing pressure is presumably greater nearshore and presents a confounding source of increased mortality; however, a strong red tide occurred the year before this study began and likely also affected nearshore demographics. Nevertheless, these data indicate ontogenetic migration and escapement of fast-growing fish to offshore habitat, both of which should reduce the likelihood of fishing-induced evolution. Data regarding the hogfish fishery are limited and regionally dependent, which has confounded previous stock assessments; however, the spatially explicit vital rates reported herein can be applied to future monitoring efforts

    The Barbarians of Hollywood : The Exploitation of Aurora Mardiganian by the American Film Industry

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    As the first genocide of the 20th century tore through Ottoman Turkey, advances within the film industry opened new doors for humanitarian aid. The story of Aurora Mardiganian, a teenage Armenian survivor, provided Americans with a visual representation of what mass atrocity looked like through the film Ravished Armenia. However, the means to which the film and accompanying autobiography were created exemplify a violation of ethics. Anthony Slide’s edited edition of the narrative titled Ravished Armenia and the Story of Aurora Mardiganian offers an insightful account of Mardiganian’s plight, and gives evidence to the claim that she was exploited physically, psychologically, and financially, in order to yield the maximum profit. Mardiganian’s legacy highlights the need for remembrance over apathy, and active awareness over indifference

    Seasonal Movements and Behavior of Ring-Necked Pheasants in Eastern South Dakota

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    Information was gathered on mobility, behavior, and related activities of pheasants from July 1966 to July 1968 by banding and/or marking 160 birds with backtags and radio transmitters. Food was readily available since the winters were mild with little snow. Birds moved less than 1/4 mile from roosting areas to cornfields and weed patches to feed. Numbers of birds dispersing from the study area in spring varied each of the years, but 60 to 70 remained there during the two reproductive seasons. Adult cocks traveled less than 1/4 mile when dispersing-and adult hens moved less than 1/2 mile. Movements by two juvenile cocks averaged over 1/2 mile and one juvenile hen traveled two miles. Adult and juvenile cocks moved less than ¼ and 1/2 mile, respectively, from capture sites according to hunting recoveries. Home ranges of hens and breeding cocks overlapped during early nesting periods. Hens sometimes nested within the territories of their chosen cocks. Following nest destruction hens sought other crowing cocks up to one mile away. Home ranges for five hens in harems averaged 69 acres while two hens not in harems averaged 25 acres. Home ranges for six cocks with harems averaged nine acres while those without harems (five) averaged 15 acres. Two radio-equipped juvenile cocks occupied 60-acre areas during hunting season

    Causes and possible consequences of hybridisation in angelfishes at Christmas Island

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    The angelfishes (family Pomacanthidae) have the greatest proportion (~30%) of hybridising species, compared to other families of reef fishes, with 26 species implicated in hybridisation. However, very little is known about hybridisation in angelfish, especially in terms of fitness of the hybrids and possible ecological consequences. Hybrids between three species (C. flavissima, C. eibli and C. vroliki) in the genus Centropyge have previously been reported from Christmas island, where these have been observed in heterospecific harems and interbreeding. This provides the unique opportunity to examine the breakdown in assortative mating in marine fishes. The broad aim of this study was to determine causes and consequences of hybridisation in angelfish at Christmas Island (Western Australia). To achieve this, the abundances, habitat and fitness of the three angelfish parent species and their hybrids have been investigated. Based on 14 years of surveys, C. flavissima was abundant (4.53 per 250 m2 +/- 0.66), whereas C. eibli, C. vrolikii, and all hybrid combinations were consistently low in abundance or rare (average abundance \u3c 0.3 per 250 m2 +/- 0.03). Parent species and their hybrids displayed high niche overlap, with all being more abundant at 20 m depth compared to 5 m, and showing similar diets that comprised a mix of green, red, and brown algae. Thus, rarity of parent species and niche overlap would help to promote hybridisation in angelfishes at Christmas Island. The relative fitness of angelfish hybrids against the parent species was evaluated by comparing key life history traits. Both the von Bertalanffy growth coefficient (k) and the asymptotic length (L∞) of the hybrid C. flavissima × C. eibli did not differ from the parent species C. flavissima. In comparison, C. eibli tended to grow at a slightly faster rate but reached a smaller size than the hybrid and C. flavissima, potentially increasing its reproductive success. Both females and males of the hybrid C. flavissima × C. eibli presented similarly developed gonads and showed all stages of oocytes and spermatocytes development to the parent species. The presence of post-ovulatory follicles indicated possible spawning activity (and fertility) of the hybrid. The level of fitness of the hybrids at Christmas Island was similar to their parent species, and could explain their persistence at this location. Angelfish hybrids formed harems with all parent species and the species composition of the harems reflected the underlying patterns of abundance for the parent species. The total number of fish and number of males did not differ between different types of harems (mixed and pure). Harems comprised an average of ~4 fishes, generally with one male, but some harems had 2 males, which were found in each type of harem. Almost one third of the dominant males in the mixed harems were hybrids, while ranks two to six were occupied by similar percentages of hybrids. The ability of the angelfish hybrids reaching similar ranks as both males and females of parent species and being in similar sized harems in mixed harems, combined with them displaying similar growth and size, indicates that their reproductive output would be similar to the parent species C. eibli and C. vrolikii. However, since C. flavissima was far more abundant and was the only species to form mono-specific harems, its reproductive output would be larger than the other two species and its hybrid. This study provides empirical evidence that hybridisation in reef fishes conforms to terrestrial-based theories, and thus advances our understanding of the processes underlying hybridisation in coral-reef systems. Given the variable changes in environmental conditions occurring in the ocean, hybridisation and introgression could prove beneficial if it can provide new genotypes that increase the adaptive capacity of hybrids and/or parent species
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