910 resultados para more individuals hypothesis


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We examined movement patterns of sportfish that were tagged in the northern Indian River Lagoon, Florida, between 1990 and 1999 to assess the degree of fish exchange between an estuarine no-take zone (NTZ) and surrounding waters. The tagged f ish were from seven species: red drum (Sciaenops ocellatus); black drum (Pogonias cromis); sheepshead (Archosargus probatocephalus); common snook (Centropomus undecimalis); spotted seatrout (Cynoscion nebulosus); bull shark (Carcharhinus leucas); and crevalle jack (Caranx hippos). A total of 403 tagged fish were recaptured during the study period, including 65 individuals that emigrated from the NTZ and 16 individuals that immigrated into the NTZ from surrounding waters of the lagoon. Migration distances between the original tagging location and the sites where emigrating fish were recaptured were from 0 to 150 km, and these migration distances appeared to be influenced by the proximity of the NTZ to spawning areas or other habitats that are important to specific life-history stages of individual species. Fish that immigrated into the NTZ moved distances ranging from approximately 10 to 75 km. Recapture rates for sportfish species that migrated across the NTZ boundary suggested that more individuals may move into the protected habitats than move out. These data demonstrated that although this estuarine no-take reserve can protect species from fishing, it may also serve to extract exploitable individuals from surrounding fisheries; therefore, if the no-take reserve does function to replenish surrounding fisheries, then increased egg production and larval export may be more important mechanisms of replenishment than the spillover of excess adults from the reserve into fishable areas.

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Although subsampling is a common method for describing the composition of large and diverse trawl catches, the accuracy of these techniques is often unknown. We determined the sampling errors generated from estimating the percentage of the total number of species recorded in catches, as well as the abundance of each species, at each increase in the proportion of the sorted catch. We completely partitioned twenty prawn trawl catches from tropical northern Australia into subsamples of about 10 kg each. All subsamples were then sorted, and species numbers recorded. Catch weights ranged from 71 to 445 kg, and the number of fish species in trawls ranged from 60 to 138, and invertebrate species from 18 to 63. Almost 70% of the species recorded in catches were “rare” in subsamples (less than one individual per 10 kg subsample or less than one in every 389 individuals). A matrix was used to show the increase in the total number of species that were recorded in each catch as the percentage of the sorted catch increased. Simulation modelling showed that sorting small subsamples (about 10% of catch weights) identified about 50% of the total number of species caught in a trawl. Larger subsamples (50% of catch weight on average) identified about 80% of the total species caught in a trawl. The accuracy of estimating the abundance of each species also increased with increasing subsample size. For the “rare” species, sampling error was around 80% after sorting 10% of catch weight and was just less than 50% after 40% of catch weight had been sorted. For the “abundant” species (five or more individuals per 10 kg subsample or five or more in every 389 individuals), sampling error was around 25% after sorting 10% of catch weight, but was reduced to around 10% after 40% of catch weight had been sorted.

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All gibbons are monogamous and territorial with the exception of Hylobates concolor. This paper reports the coexistence of monogamy and polygyny in black-crested gibbons. Based on the fact of two adult females and two offspring of the same age category in one group and other reasons, we suppose that the two adult females have bred in a single group, i.e. a polygynous one. The other main reasons are: (1) a large home range makes it possible for more individuals to live in one group; (2) mutual tolerance among two females; and (3) selection pressure favouring polygyny.

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The Yangtze finless porpoise, Neophocaena phocaenoides asiaeorientalis, is all endangered small cetacean that occurs only in the middle and lower reaches of the Yangtze River of China. The establishment of a breeding population of the porpoise in Tian-e-Zhou Baiji National Natural Reserve represents the first attempt at ex situ conservation efforts for a cetacean species. With the goal of effective protection, management, and monitoring of this preserved population, we examined its genetic diversity using 930 bp of mtDNA control region sequences and 13 polymorphic microsatellite loci. A very low level of genetic variation (h = 0.6010 +/- 0.0029 s.d.; pi = 0.0007 +/- 0.0000002 s.d.) in the mtDNA control region sequences and a moderate genetic diversity (Ho = 0.5740 +/- 0.2575 s.d.) in the microsatellites were detected in the population. It is necessary to introduce more individuals with representative genetic variations into the reserve ill order to foml a larger and healthier group structure for long-term survival of the population. Successful establishment of the Yangtze finless porpoise population in the Reserve also provides a useful model for an ex situ conservation programme for other rare and endangered species. (c) 2005 International Council for the Exploration ofthe Sea. Published by Elsevier Ltd. All rights reserved.

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Background: Noroviruses (NoVs) are the most common cause of epidemic gastroenteritis, responsible for at least 50% of all gastroenteritis outbreaks worldwide and were recently identified as a leading cause of travelers' diarrhea (TD) in US and European travelers to Mexico, Guatemala, and India.

Methods: Serum and diarrheic stool samples were collected from 75 US student travelers to Cuernavaca, Mexico, who developed TD. NoV RNA was detected in acute diarrheic stool samples using reverse transcription-polymerase chain reaction (RT-PCR). Serology assays were performed using GI.1 Norwalk virus (NV) and GII.4 Houston virus (HOV) virus-like particles (VLPs) to measure serum levels of immunoglobulin A (IgA) and IgG by dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA); serum IgM was measured by capture enzyme-linked immunosorbent assay (ELISA), and the 50% antibody-blocking titer (BT50 ) was determined by a carbohydrate-blocking assay.

Results: NoV infection was identified in 12 (16%; 9 GI-NoV and 3 GII-NoV) of 75 travelers by either RT-PCR or fourfold or more rise in antibody titer. Significantly more individuals had detectable preexisting IgA antibodies against HOV (62/75, 83%) than against NV (49/75, 65%) (p = 0.025) VLPs. A significant difference was observed between NV- and HOV-specific preexisting IgA antibody levels (p = 0.0037), IgG (p = 0.003), and BT50 (p = <0.0001). None of the NoV-infected TD travelers had BT50  > 200, a level that has been described previously as a possible correlate of protection.

Conclusion: We found that GI-NoVs are commonly associated with TD cases identified in US adults traveling to Mexico, and seroprevalence rates and geometric mean antibody levels to a GI-NoV were lower than to a GII-NoV strain.

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We characterize a class of collective choice rules such that collective preference relations are consistent. Consistency is a weakening of transitivity and a strengthening of acyclicity requiring that there be no cycles with at least one strict preference. The properties used in our characterization are unrestricted domain, strong Pareto, anonymity and neutrality. If there are at most as many individuals as there are alternatives, the axioms provide an alternative characterization of the Pareto rule. If there are more individuals than alternatives, however, further rules become available.

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Altruism and selfishness are 30–50% heritable in man in both Western and non-Western populations. This genetically based variation in altruism and selfishness requires explanation. In non-human animals, altruism is generally directed towards relatives, and satisfies the condition known as Hamilton's rule. This nepotistic altruism evolves under natural selection only if the ratio of the benefit of receiving help to the cost of giving it exceeds a value that depends on the relatedness of the individuals involved. Standard analyses assume that the benefit provided by each individual is the same but it is plausible in some cases that as more individuals contribute, help is subject to diminishing returns. We analyse this situation using a single-locus two-allele model of selection in a diploid population with the altruistic allele dominant to the selfish allele. The analysis requires calculation of the relationship between the fitnesses of the genotypes and the frequencies of the genes. The fitnesses vary not only with the genotype of the individual but also with the distribution of phenotypes amongst the sibs of the individual and this depends on the genotypes of his parents. These calculations are not possible by direct fitness or ESS methods but are possible using population genetics. Our analysis shows that diminishing returns change the operation of natural selection and the outcome can now be a stable equilibrium between altruistic and selfish alleles rather than the elimination of one allele or the other. We thus provide a plausible genetic model of kin selection that leads to the stable coexistence in the same population of both altruistic and selfish individuals. This may explain reported genetic variation in altruism in man.

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Fire is an important factor in several ecosystems, affecting plant population biology. Campos grasslands are under constant influence of disturbance, mostly grazing and fire. However, few studies evaluated the effect of fire on plant population biology of grassland species. Therefore, we aim to analyze the effect of fire on the population biology of four species, from different functional groups and regeneration strategies: Chaptalia runcinata (forb, resprouter, absence of belowground organ), Vernonia flexuosa (forb, resprouter, presence of rhizophore), Eupatorium ligulaefolium (shrub, resprouter, presence of xylopodium) and Heterothalamus psiadioides (shrub, obligate seeder). Seven plots were established in different sites in southern Brazil: frequently burned (FB) and excluded from fire since 6 years (E). All plots were subjected to controlled burns during summer. Before experiments, populations were sampled. Further observations were carried out after 90 and after 360 days of fire experiments. In addition, we counted the number of seedlings and resprouters recruited after fire. Heat shock experiments were conducted with two species (H. psiadioides and V. flexuosa), as well as the study of the bud bank of the following species: E. ligulaefolium and V. flexuosa. The obligate seeder species had all individuals killed by fire and established only after 1 year. Resprouters, however, showed new stems immediately after fire. E. ligulaefolium and V. flexuosa showed only vegetative regeneration from belowground organs and more individuals in excluded sites 1 year after the fire. The bud bank of E. ligulaefolium tended to be larger in excluded sites, whilst V. flexuosa showed an opposite result. High temperatures did not enhance nor kill seeds from both studied species. Vegetative regeneration was the most important strategy for all studied species, except for H. psiadioides, the obligate seeder species. Fire thus, plays an important role on population structure and demography, being also important for plant recruitment.

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Objective: ADHD and learning disabilities (LD) frequently coexist and there are indications that comorbidity may increase the risk of psychopathology.

Method: The current study examined the gender distribution and frequency of comorbidity and its impact on the prevalence of symptoms of anxiety,  depression, and aggression in a clinic sample of 80 adults with ADHD, aged 18 to 58 years. More individuals were diagnosed with ADHD+LD than ADHD only, with no difference in this distribution according to gender.

Results: A factorial multivariate analysis of variance indicated that females with ADHD+LD displayed more cognitive depression than females with ADHD only and than males with ADHD+LD and ADHD only. However,individuals with ADHD only and individuals with ADHD+LD did not differ on overall anxiety, depression or aggression. Likewise, males and females did not differ on measures of psychopathology.

Conclusion
: This study lays the foundation for continued research into the characteristics and comorbidities of adults with ADHD.

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Background: The introduction of the Australia Council's 'Arts in a Multicultural Australia Policy' (AIMAP) (2000) represented a shift in how the arts in multicultural communities were viewed. It has long been recognised that the arts play a significant role in promoting social cohesion, social policy goals, economic growth, and shaping a nation’s sense of identity. However, prior to the introduction of this policy, multicultural arts was typically seen as involving cultural retentive activities which had their roots in expressions of migrant cultural traditions. The introduction of the policy heralded the beginning of an era in which culturally and linguistically diverse (CaLD) Australians were seen as integral to the fabric of the Australian arts sector. Evaluation of the policy in 2005 however, revealed that culturally and linguistically diverse Australians were under-represented in most artistic categories. Western Australia is the most culturally diverse state in Australia. It is therefore of great interest to the State Government to have a comprehensive picture of the situation in that state. Hence, the Office of Multicultural Interests (OMI) commissioned Deakin University to undertake an investigation into the participation rates of CaLD artists in the arts sector in Western Australia.

Scope: The project examined the participation in the arts of CaLD artists in Western Australia. The arts sector comprises many more individuals and organisations than artists. For example, there are arts agency administrators, venue operators, policy officers, curators, and countless others who work together to make up the arts sector. This project focused on the artists, the individuals such as those who make music, visual art, dance and theatre performances. In the past it has been shown that CaLD populations are not well represented in the broader arts sector. This research aimed to discover the current position for CaLD artists in terms of participation in the broader arts sector and what factors influence their situation.

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There are many participants in the tourism network who have vested interests in tourism development. These organizations include hotels, associations of hotels and hotel owners, inbound travel agents, travel wholesalers, tourism industry associations, airlines, cruise lines, tourism promotional agencies, regional and local tourism authorities, SME tourism businesses, conference and convention centres and many more. Individuals in the tourism industry intermittently change employment. They often remain in the industry and can move between types of organizations. Their contacts, associations and personal networks remain useful and indeed are utilized. The Interactive Approach postulated by the IMP Group proposes that both suppliers and manufacturers are often involved in close, long-lasting adaptive relationships. Firms within relationships must work together, share objectives, share information and also communicate clearly and precisely using a common language. Here relationship partners should have a similar point of view on the meaning of marketing strategy and related concepts including market segmentation, differentiation and competitive positioning.

This paper seeks to assess the nature, perspectives and characteristics of interactions in the tourism network in Australia. There are two stages of this research. The first stage obtained the perspectives of network participants on the challenges facing tourism, key growth segments, brand and promotional strategies and customer insights and satisfaction levels. Participants were also asked to provide advice to the national marketing organization on a range of developmental topics. The second stage of this research assesses the interaction patterns among network participants Network picture, network position, resource constellations, interaction, resources and activities, interdependence, adaptation, actor bonds, strategy and change are also assessed. The relationships are political and consultative in nature. There is much interdependence and possible conflict between the network participants. The national tourism body has particular skills in tourism planning and tourism research. They also have significant resources and the ability to influence inbound tourism patterns. This paper seeks to assess and understand the interactions within this network.

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Aim Conservation managers designate significant areas for shorebirds based on imperfect data. Significant wetlands for migratory shorebirds have usually been identified on the basis of whether they exceed certain thresholds, defined either by total abundance (usually 20,000 waterbirds) or percentage of a population (usually 1.0%). We evaluate the performance of existing criteria and determine if lowering thresholds would improve shorebird conservation without adding unreasonable numbers of significant sites.

Location Australia.

Methods We evaluated the best available data, which is used by managers to designate significant areas, to describe the effect of lowering thresholds on the number of significant sites identified and the number of shorebirds these sites support using a range of thresholds in existing criteria. We also investigated factors which may explain interspecific differences evident when lowering thresholds.

Results When the threshold for total abundance was lowered from 20,000 to 2000 shorebirds, an additional 45 shorebird areas, holding 65% more shorebirds, were identified. When thresholds for the percentage of a population criterion were lowered from 1.0 to 0.1%, an additional 86 shorebird areas were identified which held 29% more shorebirds. The proportion of a species population counted within wetlands identified as significant by the application of criteria varied widely between species. The percentage of population criterion always identified a network of areas that included more individuals of each species than the total abundance criterion at all threshold levels tested. The percentage of species populations found in networks of significant areas showed greater increase as thresholds were lowered for species that were abundant, widespread and well represented at existing thresholds.

Main conclusions Our results suggest lowering thresholds will substantially increase the number of shorebirds in identified significant areas. However, some species will remain under-represented, partly because of interspecific differences in distribution and inadequate sampling of some shorebird habitats.

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Despite considerable controversy and speculation regarding sexting behaviour and its associated risks, to date there has been no integration and analysis of empirical literature on this topic. To collect and synthesise findings of the prevalence of sexting, its correlates, and the context in which it occurs, a systematic search of databases was conducted. Thirty-one studies, reporting on sexting prevalence and a diverse range of related variables, met inclusion criteria. The estimated mean prevalence weighted by sample size was calculated, with trends indicating sexting is more prevalent amongst adults than adolescents, older age is predictive of sexting for adolescents but not adults, and more individuals report receiving sexts than sending them. The correlates of sexting behaviour were grouped in terms of demographic variables, sexual and sexual risk behaviours, attitudes towards sexting, perceived outcomes of sexting, motivations for sexting, mental health and well-being variables, and attachment dimensions. Findings are discussed in terms of the trends indicated by the data, which provided substantiation that sexting behaviour is associated with numerous behavioural, psychological, and social factors. Limitations of the current research literature and future directions are also presented.

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Depression afflicts one in four people during their lives. Several studies have shown that for the isolated and mentally ill, the Web and social media provide effective platforms for supports and treatments as well as to acquire scientific, clinical understanding of this mental condition. More and more individuals affected by depression join online communities to seek for information, express themselves, share their concerns and look for supports [12]. For the first time, we collect and study a large online depression community of more than 12,000 active members from Live Journal. We examine the effect of mood, social connectivity and age on the online messages authored by members in an online depression community. The posts are considered in two aspects: what is written (topic) and how it is written (language style). We use statistical and machine learning methods to discriminate the posts made by bloggers in low versus high valence mood, in different age categories and in different degrees of social connectivity. Using statistical tests, language styles are found to be significantly different between low and high valence cohorts, whilst topics are significantly different between people whose different degrees of social connectivity. High performance is achieved for low versus high valence post classification using writing style as features. The finding suggests the potential of using social media in depression screening, especially in online setting.

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Synchronism is the efetivation of the same behavior at the same time by two or more individuals. In cetology only from 2000 we verify an increasing of efforts for studies of synchronic behaviors. The synchronism in cetaceans was reported for a variety of contexts, including feeding, socializing, parental care, while resting, traveling and play, during afilliation, in sexual behaviour and possible while teaching. The synchronism in behavior is influenced by environmental factors and can be modified during stress situations such as the presence of boats. The aim of this study is to explore behavior synchronism presented by the estuarine dolphin (Sotalia guianensis) in Pipa, Rio Grande do Norte state, Northeastern Brazil. A total of 414 hours of observation during the year 2006, using scan sampling method, from a land based sighting was conducted. Analyses were conducted in four steps. Firstly, we determined the pattern of activity of the groups within the bay, testing for the influence of bay configuration before and after rains periods on the activity of animals. Analyses show that forage occurs more frequently after the rainy period, but there was no change in the number of individuals or spatial cohesions between them. Secondly, we analysed the influence of turism boat traffic on the behavior of animals. We verified no changes on the bahavior of animals during the presence of boats. Finally, we tested seven hypotheses regarding the ecological and social dynamics of synchronic behavior. Environmental aspects were considered the main influence for the synchronism, no influences of age, and more selective exihibition of synchronic breathing in feeding and social displays were observed during the study period