800 resultados para Conspicuous donation behaviour
Resumo:
A major challenge in studying social behaviour stems from the need to disentangle the behaviour of each individual from the resulting collective. One way to overcome this problem is to construct a model of the behaviour of an individual, and observe whether combining many such individuals leads to the predicted outcome. This can be achieved by using robots. In this review we discuss the strengths and weaknesses of such an approach for studies of social behaviour. We find that robots-whether studied in groups of simulated or physical robots, or used to infiltrate and manipulate groups of living organisms-have important advantages over conventional individual-based models and have contributed greatly to the study of social behaviour. In particular, robots have increased our understanding of self-organization and the evolution of cooperative behaviour and communication. However, the resulting findings have not had the desired impact on the biological community. We suggest reasons for why this may be the case, and how the benefits of using robots can be maximized in future research on social behaviour.
Resumo:
In recent years much progress has been made towards understanding the selective forces involved in the evolution of social behaviour including conflicts over reproduction among group members. Here, I argue that an important additional step necessary for advancing our understanding of the resolution of potential conflicts within insect societies is to consider the genetics of the behaviours involved. First, I discuss how epigenetic modifications of behaviour may affect conflict resolution within groups. Second, I review known natural polymorphisms of social organization to demonstrate that a lack of consideration of the genetic mechanisms involved may lead to erroneous explanations of the adaptive significance of behaviour. Third, I suggest that, on the basis of recent genetic studies of sexual conflict in Drosophila, it is necessary to reconsider the possibility of within-group manipulation by means of chemical substances (i.e. pheromones). Fourth, I address the issue of direct versus indirect genetic effects, which is of particular importance for the study of behaviour in social groups. Fifth, I discuss the issue of how a genetic influence on dominance hierarchies and reproductive division of labour can have secondary effects, for example in the evolution of promiscuity. Finally, because the same sets of genes (e.g. those implicated in chemical signalling and the responses that are triggered) may be used even in species as divergent as ants, cooperative breeding birds and primates, an integration of genetic mechanisms into the field of social evolution may also provide unifying ideas.
Resumo:
We survey the population genetic basis of social evolution, using a logically consistent set of arguments to cover a wide range of biological scenarios. We start by reconsidering Hamilton's (Hamilton 1964 J. Theoret. Biol. 7, 1-16 (doi:10.1016/0022-5193(64)90038-4)) results for selection on a social trait under the assumptions of additive gene action, weak selection and constant environment and demography. This yields a prediction for the direction of allele frequency change in terms of phenotypic costs and benefits and genealogical concepts of relatedness, which holds for any frequency of the trait in the population, and provides the foundation for further developments and extensions. We then allow for any type of gene interaction within and between individuals, strong selection and fluctuating environments and demography, which may depend on the evolving trait itself. We reach three conclusions pertaining to selection on social behaviours under broad conditions. (i) Selection can be understood by focusing on a one-generation change in mean allele frequency, a computation which underpins the utility of reproductive value weights; (ii) in large populations under the assumptions of additive gene action and weak selection, this change is of constant sign for any allele frequency and is predicted by a phenotypic selection gradient; (iii) under the assumptions of trait substitution sequences, such phenotypic selection gradients suffice to characterize long-term multi-dimensional stochastic evolution, with almost no knowledge about the genetic details underlying the coevolving traits. Having such simple results about the effect of selection regardless of population structure and type of social interactions can help to delineate the common features of distinct biological processes. Finally, we clarify some persistent divergences within social evolution theory, with respect to exactness, synergies, maximization, dynamic sufficiency and the role of genetic arguments.
Resumo:
The oviposition behaviour of the braconid parasitoid, Compsobracon mirabilis ( Szépligeti, 1901) is described. Observations were conducted in a cerrado region located in Três Marias, Minas Gerais, Brazil. The oviposition occurred in a branch of Alibertia concolor (Cham.) K. Schum. 1889 (Rubiaceae), inside of which there were thirteen larvae of an unidentified species of Lepidoptera.
Resumo:
The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: Donation Scams in the Wake of a Storm or Disaster
Resumo:
The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: Donation Scams in the Wake of a Storm or Disaster
Resumo:
The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: Donation Scams in the Wake of a Storm or Disaster
Resumo:
Consider the density of the solution $X(t,x)$ of a stochastic heat equation with small noise at a fixed $t\in [0,T]$, $x \in [0,1]$.In the paper we study the asymptotics of this density as the noise is vanishing. A kind of Taylor expansion in powers of the noiseparameter is obtained. The coefficients and the residue of the expansion are explicitly calculated.In order to obtain this result some type of exponential estimates of tail probabilities of the difference between the approximatingprocess and the limit one is proved. Also a suitable local integration by parts formula is developped.
Resumo:
BACKGROUND AND OBJECTIVE: Restless legs syndrome (RLS) is a frequent condition with a prevalence of 5-15% in the general population. Clinical and genetic observations have shown that iron deficiency, highly prevalent among blood donors, can be related to RLS. The objective of this study was to assess the prevalence of RLS in female blood donors 1 week after blood donation. METHODS: One week after blood donation, 291 female blood donors, aged <50 years, self-responded to all four RLS questions defined by the 1995 International RLS study group. Blood donation rate, fatigue, aerobic capacity, menstruation, mood disorder and quality of life were also assessed along with haemoglobin and ferritin blood concentrations. RESULTS: Prevalence of RLS in female blood donors 1 week after blood donation was 6·9% (CI 95% 4·2-10·4%). Female blood donors with RLS had a higher prevalence of hyper-menorrhaea (P = 0·033) and were significantly more tired (P = 0·001). We observed no associations between RLS and number of previous donations (P = 0·409), aerobic capacity (P = 0·476), mood disorder (P = 0·169), quality of life (P = 0·356), haemoglobin (P = 0·087), and serum ferritin level (P = 0·446). CONCLUSION: Restless legs syndrome prevalence in female blood donors is not as important as described in some other studies, which could reassure blood donors. The prevalence of hypermenorrhaea and fatigue is higher in RLS blood donors. Therefore, screening for fatigue and hypermenorrhaea could be considered as these symptoms are associated with RLS in female blood donors.
Resumo:
Isolates of the Trichophyton mentagrophytes complex vary phenotypically. Whether the closely related zoophilic and anthropophilic anamorphs currently associated with Arthroderma vanbreuseghemii have to be considered as members of the same biological species remains an open question. In order to better delineate species in the T. mentagrophytes complex, we performed a mating analysis of freshly collected isolates from humans and animals with A. benhamiae and A. vanbreuseghemii reference strains, in comparison to internal transcribed spacer (ITS) and 28S rDNA sequencing. Mating experiments as well as ITS and 28S sequencing unambiguously allowed the distinction of A. benhamiae and A. vanbreuseghemii. We have also shown that all the isolates from tinea pedis and tinea unguium identified as T. interdigitale based on ITS sequences mated with A. vanbreuseghemii tester strains, but had lost their ability to give fertile cleistothecia. Therefore, T. interdigitale has to be considered as a humanized species derived from the sexual relative A. vanbreuseghemii.
Resumo:
BACKGROUND: Little is known about smoking, unhealthy use of alcohol, and risk behaviours for sexually transmitted diseases (STDs) in immigrants from developed and developing countries. METHOD: We performed a cross-sectional study of 400 patients who consulted an academic emergency care centre at a Swiss university hospital. The odds ratios for having one or more risk behaviours were adjusted for age, gender, and education level. RESULTS: Immigrants from developing countries were less likely to use alcohol in an unhealthy manner (OR = 0.35, 95% CI 0.22-0.57) or practise risk behaviours for STDs (OR = 0.31, 95% CI 0.13-0.74). They were also less likely to have any of the three studied risk behaviours (OR = 2.5, 95% CI 1.5-4.3). DISCUSSION: In addition to the usual determinants, health behaviours are also associated with origin; distinguishing between immigrants from developing and developed countries is useful in clinical settings. Surprisingly, patients from developing countries tend to possess several protective characteristics.