125 research outputs found

    Wild Chimpanzees Exchange Meat for Sex on a Long-Term Basis

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    Humans and chimpanzees are unusual among primates in that they frequently perform group hunts of mammalian prey and share meat with conspecifics. Especially interesting are cases in which males give meat to unrelated females. The meat-for-sex hypothesis aims at explaining these cases by proposing that males and females exchange meat for sex, which would result in males increasing their mating success and females increasing their caloric intake without suffering the energetic costs and potential risk of injury related to hunting. Although chimpanzees have been shown to share meat extensively with females, there has not been much direct evidence in this species to support the meat-for-sex hypothesis. Here we show that female wild chimpanzees copulate more frequently with those males who, over a period of 22 months, share meat with them. We excluded other alternative hypotheses to exchanging meat for sex, by statistically controlling for rank of the male, age, rank and gregariousness of the female, association patterns of each male-female dyad and meat begging frequency of each female. Although males were more likely to share meat with estrous than anestrous females given their proportional representation in hunting parties, the relationship between mating success and sharing meat remained significant after excluding from the analysis sharing episodes with estrous females. These results strongly suggest that wild chimpanzees exchange meat for sex, and do so on a long-term basis. Similar studies on humans will determine if the direct nutritional benefits that women receive from hunters in foraging societies could also be driving the relationship between reproductive success and good hunting skills

    Homology Inference of Protein-Protein Interactions via Conserved Binding Sites

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    The coverage and reliability of protein-protein interactions determined by high-throughput experiments still needs to be improved, especially for higher organisms, therefore the question persists, how interactions can be verified and predicted by computational approaches using available data on protein structural complexes. Recently we developed an approach called IBIS (Inferred Biomolecular Interaction Server) to predict and annotate protein-protein binding sites and interaction partners, which is based on the assumption that the structural location and sequence patterns of protein-protein binding sites are conserved between close homologs. In this study first we confirmed high accuracy of our method and found that its accuracy depends critically on the usage of all available data on structures of homologous complexes, compared to the approaches where only a non-redundant set of complexes is employed. Second we showed that there exists a trade-off between specificity and sensitivity if we employ in the prediction only evolutionarily conserved binding site clusters or clusters supported by only one observation (singletons). Finally we addressed the question of identifying the biologically relevant interactions using the homology inference approach and demonstrated that a large majority of crystal packing interactions can be correctly identified and filtered by our algorithm. At the same time, about half of biological interfaces that are not present in the protein crystallographic asymmetric unit can be reconstructed by IBIS from homologous complexes without the prior knowledge of crystal parameters of the query protein

    The prognostic influence of tumour-infiltrating lymphocytes in cancer: a systematic review with meta-analysis

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    Background:Tumour-infiltrating lymphocytes (TILs) are often found in tumours, presumably reflecting an immune response against the tumour. We carried out a systematic review and meta-analysis, aiming to establish pooled estimates for survival outcomes based on the presence of TILs in cancer.Methods:A Pubmed and Embase literature search was designed. Studies were included, in which the prognostic significance of intratumoural CD3+, CD4+, CD8+, and FoxP3+ lymphocytes, as well as ratios between these subsets, were determined in solid tumours.Results:In pooled analysis, CD3+ TILs had a positive effect on survival with a hazard ratio (HR) of 0.58 (95% confidence interval (CI) 0.43-0.78) for death, as did CD8+ TILs with a HR of 0.71 (95% CI 0.62-0.82). FoxP3+ regulatory TILs were not linked to overall survival, with a HR of 1.19 (95% CI 0.84-1.67). The CD8/FoxP3 ratio produced a more impressive HR (risk of death: HR 0.48, 95% CI 0.34-0.68), but was used in relatively few studies. Sample size and follow-up time seemed to influence study outcomes.Conclusion:Any future studies should be carefully designed, to prevent overestimating the effect of TILs on prognosis. In this context, ratios between TIL subsets may be more informative.British Journal of Cancer advance online publication, 31 May 2011; doi:10.1038/bjc.2011.189 www.bjcancer.com

    The global flood protection savings provided by coral reefs

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    Coral reefs can provide significant coastal protection benefits to people and property. Here we show that the annual expected damages from flooding would double, and costs from frequent storms would triple without reefs. For 100-year storm events, flood damages would increase by 91% to US272billionwithoutreefs.ThecountrieswiththemosttogainfromreefmanagementareIndonesia,Philippines,Malaysia,Mexico,andCuba;annualexpectedfloodsavingsexceedUS 272 billion without reefs. The countries with the most to gain from reef management are Indonesia, Philippines, Malaysia, Mexico, and Cuba; annual expected flood savings exceed 400?M for each of these nations. Sea-level rise will increase flood risk, but substantial impacts could happen from reef loss alone without better near-term management. We provide a global, process-based valuation of an ecosystem service across an entire marine biome at (sub)national levels. These spatially explicit benefits inform critical risk and environmental management decisions, and the expected benefits can be directly considered by governments (e.g., national accounts, recovery plans) and businesses (e.g., insurance).We gratefully acknowledge support from the World Bank Wealth Accounting and Valuation of Ecosystems (WAVES) Program, the Lyda Hill Foundation, Science for Nature and People Partnership, Lloyd’s Tercentenary Research Foundation, a Pew Fellowship in Marine Conservation to MWB, the German International Climate Initiative (IKI) of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and the Spanish Ministry of Economy and Innovation (BIA2014-59718- R)

    Trading or coercion? Variation in male mating strategies between two communities of East African chimpanzees

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    Across taxa, males employ a variety of mating strategies, including sexual coercion and the provision, or trading, of resources. Biological Market theory (BMT) predicts that trading of commodities for mating opportunities should exist only when males cannot monopolise access to females and/or obtain mating by force, in situations where power differentials between males are low; both coercion and trading have been reported for chimpanzees (Pan troglodytes). Here, we investigate whether the choice of strategy depends on the variation in male power differentials, using data from two wild communities of East African chimpanzees (P.t. schweinfurthii): the structurally despotic Sonso community (Budongo, Uganda) and the structurally egalitarian M-group (Mahale, Tanzania). We found evidence of sexual coercion by male Sonso chimpanzees, and of trading—of grooming for mating—by M-group males; females traded sex for neither meat nor protection from male aggression. Our results suggest that the despotism–egalitarian axis influences strategy choice: male chimpanzees appear to pursue sexual coercion when power differentials are large and trading when power differentials are small and coercion consequently ineffective. Our findings demonstrate that trading and coercive strategies are not restricted to particular chimpanzee subspecies; instead, their occurrence is consistent with BMT predictions. Our study raises interesting, and as yet unanswered, questions regarding female chimpanzees’ willingness to trade sex for grooming, if doing so represents a compromise to their fundamentally promiscuous mating strategy. It highlights the importance of within-species cross-group comparisons and the need for further study of the relationship between mating strategy and dominance steepness

    Adaptive Developmental Delay in Chagas Disease Vectors: An Evolutionary Ecology Approach

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    The developmental time of vector insects is important to their population dynamics, evolutionary biology, epidemiology of the diseases they transmit, and to their responses to global climatic change. In various triatomine species vectors of Chagas disease (Triatominae, Reduviidae), a delay in the molt of a small proportion of individuals has been observed, and from an evolutionary ecology approach, we propose the hypothesis that the developmental delay is an adaptation to environmental stochasticity through a spreading of risk (bet-hedging) diapause strategy. We confirmed, by means of a survey among specialists, the existence of the developmental delay in triatomines. Statistical descriptions of the developmental time of 11 species of triatomines showed some degree of bi-modality in nine of them. We predicted by means of an optimization model which genotype, coding for a given frequency of developmental diapause, is expected to evolve. We identified a series of parameters that can be measured in the field and in the laboratory to test the hypothesis of an optimal diapause frequency. We also discuss the importance of these findings for triatomines in terms of global climatic change and epidemiological consequences such as their resistance to insecticides
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