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No description available.

One of the major costs of group living is increased competition due to social information. Social information allows foragers to gain information about the location and the quality of food patches from observing other group members. Ultimately, this allows social foragers to use resources more efficiently. However, the distribution and quality of food varies both spatially and temporally and social information may result in aggregations of foragers around favourable food patches when they are available. This results in individuals of various dominance ranks aggregating around food resources and competing for food. In order to understand how dominance and patch quality interact to determine foraging behaviour, various foraging models have been created. In particular, producer-scrounger social foraging models are used to understand foraging behaviour and patch choice under competitive conditions. In producer scrounger games, individuals can either find their own food patches (produce) or join other individuals at food patches (scrounge). This study focused on how the combination of patch holder dominance status and patch quality interacts to influence patch joining decisions by scroungers. According to producer-scrounger models scroungers only join patches held by subordinate individuals. However, I found that a scrounger will join any patch as long as the patch holder is not within the top five most ranked individuals in the herd. However, as patch quality increased, fewer of the top ranked patch holders were avoided at each patch quality. This suggests that foraging is a trade-off between the costs of an aggressive interaction and the benefits gained from each patch. Behavioural titrations found that the initial density of food at a patch needs to be 2.3 times greater for a scrounger to feed from the next dominant patch holder. At high patch qualities there was a threshold point where patch quality became the driving force behind patch joining decisions and no patch holders were avoided, no matter their dominance status. Scroungers that fed from the top ranked patch holders had the same intake rate when compared with feeding with subordinate patch holders. This could be due to an increased level of vigilance by the scrounger in order to avoid an aggressive interaction with the dominant patch holder. However, scrounger’s intake rate increased when they fed from dominant patch holders that were not the top ranked herd members. This suggests that only the top ranked herd members are aggressive enough to prevent scrounging attempts. A novel discovery of this study was that although the goats formed a linear dominance hierarchy, they did not forage in accordance with it, with lower ranking individuals avoiding dominant patch holders. This suggest that in social herbivores dominance hierarchies are not maintained to determine who has priority access to food. This study shows that even large differences in dominance are not sufficient enough to prevent scrounging decisions and only the top ranked patch holders have the ability to prevent joining attempts. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

In order to study sperm competition and mating dynamics in the snow crab Chionoecetes opilio, a genomic library was established with the goal of identifying highly polymorphic microsatellite markers. Six pairs of DNA primers were designed to amplify markers Cop3-4, Cop4-1, Cop5, Cop10, Cop24-3 and Cop111 by the polymerase chain reaction (PCR). All markers produced patterns as expected from single loci inherited in a mendelian fashion, except for Cop5 which revealed a multi-locus banding pattern. The cross-amplification of the six loci in seven additional crabs species revealed DNA polymorphisms at one or more loci for each species. Markers Cop3-4 and Cop24-3 were used to determine paternity of larvae of primiparous females both from the wild and from multiple mating experiments under laboratory settings. The two markers were also used to genotype the contents of female spermathecae in order to determine the number of number of male genotypes present. Spermathecal contents of wild-caught females were cut into several cross-sections and each section genotyped individually. Histological analysis of spermathecae was carried out to complement genetic data in order to elucidate patterns of sperm competition. Single paternity was observed for the progeny of all females. The analysis of laboratory females showed displacement was the mechanism by which single paternity was obtained by the last males to mate. The analysis of wild females revealed that their spermathecae contained on average the sperm of at least 3.7 males. Larvae appeared to be sired by males whose genotypes were found in the spermathecal cross-sections toward the blind-end of the spermathecae. This suggested that they were the first males to mate with females they guarded until oviposition, and females remated with other males thereafter. Also, a comprehensive account of the mating dynamics was carried out in a wild population of the Northwest Gulf of Saint Lawrence (Eastern Canada) and demonstrated the e

Macaques (Macaca) are the most geographically widespread and behaviourally diverse primate genus, and although macaque species share the same basic social structure, they display broad interspecific variation in patterns of social behaviour. Based on these patterns, macaque species have been arranged along a 4-grade scale for social style. At one end of the scale, there are grade 1 species (e.g., Japanese macaques) that have highly hierarchical and despotic social systems, and at the other end, grade 4 species (e.g., Tonkean macaques), that have more relaxed and egalitarian social systems. In this study, the play fighting of juvenile Tonkean and Japanese macaques was compared to determine whether or not play behaviour co-varies in a manner similar to that of adult social behaviour. As predicted, Tonkean macaques exhibit a relatively cooperative style of play fighting, whereas Japanese macaques exhibit a relatively competitive style of play fighting. / x, 174 leaves : ill. ; 29 cm. --

Niche and life-history differences in five species of Trithemis were investigated to determine the extent of interspecific competition. Interspecific competition was mostly avoided because species favoured different habitats and microhabitats. There was the possibility of competition between larvae under conditions of lowered food concentration, where they occurred in the same habitat and microhabitat. Larvae of different species preferred specific prey taxa, but chose to feed on a different prey taxon once it was more readily available. Because species were restricted more by food size than taxon, competition for food was unlikely. Interspecific competition may have occurred between adults because the niche breadth of some species became contracted as the density of other species increased. Interspecific competition among larvae was unlikely because individuals of different sizes were present together, allowing for food partitioning. Asynchronous development therefore ensured that competition for food of the same size was reduced. Competition was also reduced by species showing peaks in abundance at different times of the year. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.

Previous work on feral pigeons (Columba livia) and zenaida doves (Zenaida aurita) suggests that both individual and social learning varies with type of competition: rapid non-aggressive feeding is associated with rapid individual learning as well as rapid social learning from the tutor types a bird usually feeds with in the field. Comparative learning tests, however, may be influenced by intervening variables like neophobia and tameness: tests are always run on captive animals by human experimenters using novel stimuli. / This thesis compares pigeons to territorial and group-feeding zenaida doves on their response to novel stimuli in the field and in captivity, in the presence or absence of humans. In single cages, tameness and neophobia co-vary with learning: pigeons are more rapid than doves at learning, at interacting with a novel apparatus and at feeding in the absence of the human; territorial zenaida doves are slower than group-feeding doves on all three tests. Multiple regressions show that neophobia and tameness explain an important part of the variance in learning. These results are confirmed by a re-analysis of data previously obtained on finches (Whittle, 1996), where neophobia predicts individual learning which in turn predicts social learning. / In the field, however, neophobia has opposite effects: territorial zenaida doves now show the smallest effect of novel stimuli on feeding latency. Experiments that test evolutionary predictions about learning using captive animals are thus open to questions of internal and external validity: when we measure comparative performance on a captive learning test, is it really learning we are measuring and does it mirror, as it should, adjustment to environmental novelty in the field?

Great tits (Aves: Passeriformes; Parus major) and blue tits (Parus caeruleus) nested in boxes in Wytham Woods near Oxford. The breeding densities of both species were limited by the availability of nest sites. The larger great tits were dominant in obtaining nest boxes. This was most important where breeding sites were scarce. The two species did not maintain interspecific territories or interfere with interspecific nest site spacing beyond the immediate vicinity of the nest. Blue and great tit numbers fluctuated in parallel where nest sites were not limiting resources. Annual changes in breeding numbers of great tits were negatively related to blue tit breeding density but great tit density did not seem to affect changes in the blue tit population. Overlap in the feeding sites of blue and great tits was greatest during the summer and interference competition was lowest at this time. The nestling diets of the two species were very similar. Despite an apparent abundance of food for nestlings, adults were pressed to feed large broods. Food for nestlings was probably a limiting and depletable resource. The date of clutch initiation of great tits, but not blue tits, was retarded at high densities of blue or great tits. The clutch sizes of both species were probably negatively affected by high breeding densities of congeners but the results were not clear cut. Heavy great tit fledglings are most likely to survive to breed. Great tit fledglings were heavier at low densities of blue tits. An experiment in which blue tit young were removed from a section of the Woods, showed that great tit nestlings were heavier and developed faster, and that female condition was better, than in a control section or section where blue tit broods were supplemented. In terms of resource competition, blue tits were the better scramble competitors and great tits the better interference competitors.