Desenvolvimento do dimorfismo sexual nos macacos-de-cheiro (Saimiri VOIGT, 1831)

Os macacos-de-cheiro, Saimiri Voigt, 1831 são primatas arbóreos e ágeis, com um corpo relativamente pequeno, se comparado a outros primatas do Novo Mundo. Distribuem-se por toda a Amazônia e parte da América Central. Vários estudos foram realizados com a finalidade de estabelecer grupos taxonômicos em Saimiri. No entanto, os resultados desses estudos mostraram uma série de divergências quanto à classificação, tanto em relação à validade dos táxons, como ao status taxonômico dos mesmos. Neste gênero, observa-se a existência de diferenças sexuais no padrão de coloração da pelagem, no tamanho e forma dos dentes caninos e, ainda, um ciclo espermatogênico anual nos machos, caracterizado pela aquisição de gordura subcutânea, denominada de "condição de engorda". Durante este período, os machos apresentam um aumento de peso variando de 15 a 20%. O presente estudo teve como objetivo investigar o dimorfismo sexual em Saimiri sciureus, comparando os resultados com os de cinco outras espécies de Saimiri (S. cassiquiarensis, S. juruanus, S. ustus, S. boliviensis e S. vanzolinii). Para tanto, foram analisados 610 espécimes pertencentes às coleções do Museu Paraense Emílio Goeldi (MPEG), Museu Nacional, Universidade Federal do Rio de Janeiro (MNRJ) e Museu de Zoologia da Universidade de São Paulo (MZUSP). As classes etárias foram determinadas de acordo com a morfologia da arcada, descrita com base na seqüência eruptiva dos dentes de leite e permanentes. Foram coletados dados sobre caracteres cromáticos, onde se analisou a coloração da mancha pré-auricular de fêmeas em relação ao processo de erupção dentária, morfologia craniana para verificação de diferenciação etária e sexual, além de vinte e uma medidas cranianas, analisadas através do Teste "t" de Student. A partir dos resultados obtidos, constatou-se que não existem diferenças na coloração da pelagem entre classes sexuais anteriores à idade adulta em nenhum dos sexos. Não foram observadas diferenças na coloração da pelagem entre classes de idade em machos. A mancha pré-auricular enegrecida é um caráter exclusivo de fêmeas adultas, mas não está estritamente relacionada à ontogenia. O aparecimento do dicromatismo sexual na pelagem não é sincronizado com o aparecimento do dimorfismo na morfologia do crânio, especialmente dos dentes. Diferenças sexuais visíveis macroscopicamente, como tamanho e forma da caixa craniana, forma da face, distância bi-zigomática e forma da mandíbula podem ser evidenciadas a partir da idade subadulta. Observou-se também que o dimorfismo sexual, para todas as espécies, é melhor evidenciado em variáveis relacionadas ao aparato mastigatório. Além disso, diferenças sexuais na morfologia dos ossos do crânio podem ser claramente observadas entre os indivíduos subadultos de qualquer táxon. Os machos se tornam maiores do que as fêmeas a partir da idade subadulta, e o caráter mais conspícuo do dimorfismo sexual é o comprimento do canino. Cada espécie difere das demais por apresentar exclusividade em alguma variável (ou conjunto de variáveis) morfométricas, evidenciando dimorfismo sexual.

Observations on the biology of Nothobranchius guentheri (Pfeffer) (Cyprinodontidae), an annual fish from the coastal region of East Africa

Nothobranchius guntheri is found in seasonal pools and streams in the coastal region of Tanzania. A population recurring annually in a pond near Kilosa has been studied. Growth in length was rapid and maximum mean lengths were attained within 11-12 and 7-8 weeks of hatching by males and females respectively. Males grew larger and exhibited wider variation in length than females. N. guentheri shows clear sexual dichromatism. No significant inequality in the sex ratio was found. Females with ripe eggs were found 7-8 weeks after hatching. Spawning continued throughout adult life and fecundity increased markedly with increasing length. In laboratory aquaria, aggressiveness between adult males was noted and females were actively driven on to the substratum preparatory to spawning. The diet of the fish pond consisted chiefly of aquatic and terrestrial insects, of which midge larvae and pupae were the most common. N. guentheri is exploited by man in the aquarist trade and for the biological control of mosquitoes. An extended redescription of the species is appended which includes N. melanospilus (Pfeffer) as a synonym.

Interspecific variation in the use of carotenoid-based coloration in birds: diet, life history and phylogeny

Birds show striking interspecific variation in their use of carotenoid-based coloration. Theory predicts that the use of carotenoids for coloration is closely associated with the availability of carotenoids in the diet but, although this prediction has been supported in single-species studies and those using small numbers of closely related species, there have been no broad-scale quantitative tests of the link between carotenoid coloration and diet. Here we test for such a link using modern comparative methods, a database on 140 families of birds and two alternative avian phylogenies. We show that carotenoid pigmentation is more common in the bare parts (legs, bill and skin) than in plumage, and that yellow coloration is more common than red. We also show that there is no simple, general association between the availability of carotenoids in the diet and the overall use of carotenoid-based coloration. However, when we look at plumage coloration separately from bare part coloration, we find there is a robust and significant association between diet and plumage coloration, but not between diet and bare part coloration. Similarly, when we look at yellow and red plumage colours separately, we find that the association between diet and coloration is typically stronger for red coloration than it is for yellow coloration. Finally, when we build multivariate models to explain variation in each type of carotenoid-based coloration we find that a variety of life history and ecological factors are associated with different aspects of coloration, with dietary carotenoids only being a consistent significant factor in the case of variation in plumage. All of these results remain qualitatively unchanged irrespective of the phylogeny used in the analyses, although in some cases the precise life history and ecological variables included in the multivariate models do vary. Taken together, these results indicate that the predicted link between carotenoid coloration and diet is idiosyncratic rather than general, being strongest with respect to plumage colours and weakest for bare part coloration. We therefore suggest that, although the carotenoid-based bird plumage may a good model for diet-mediated signalling, the use of carotenoids in bare part pigmentation may have a very different functional basis and may be more strongly influenced by genetic and physiological mechanisms, which currently remain relatively understudied.

Estimating nutrient intake in comparative studies of animals: an example using dietary carotenoid content in birds

Many different methods of reporting animal diets have been used in ecological research. These vary greatly in level of accuracy and precision and therefore complicate attempts to measure and compare diets, and quantitites of nutrients in those diets, across a wide range of taxa. For most birds, the carotenoid content of the diet has not been directly measured. Here, therefore, I use an avian example to show how different methods of measuring the quantities of various foods in the diet affect the relative rankings of higher taxa (families, subfamilies, and tribes), and species within these taxa, with regard to the carotenoid contents of their diets. This is a timely example, as much recent avian literature has focused on the way dietary carotenoids may be traded off among aspects of survival, fitness and signalling. I assessed the mean dietary carotenoid contents of representatives of thirty higher taxa of birds using four different carotenoid intake indices varying in precision, including trophic levels, a coarse-scale and a fine-scale categorical index, and quantitative estimates of dietary carotenoids. This last method was used as the benchmark. For comparisons among taxa, all but the trophic level index were significantly correlated with each other. However, for comparisons of species within taxa, the fine-scale index outperformed the coarse-scale index, which in turn outperformed the trophic level index. In addition, each method has advantages and disadvantages, as well as underlying assumptions that must be considered. Examination and comparison of several possible methods of diet assessment appears to highlight these so that the best possible index is used given available data, and it is recommended that such a step be taken prior to the inclusion of estimated nutrient intake in any statistical analysis. Although applied to avian carotenoids here, this method could readily be applied to other taxa and types of nutrients.

Sexual selection in a tropical fruit fly : role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field-cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME-fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME-fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field-cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant-derived chemicals.

Multi-victim sexual assault : a case study in rural Australia

Objective: There is a paucity of information regarding cases of multi-victim sexual assault of children. The reported incidence suggests that these cases are rare. The aim of this paper is to provide practitioners with information about effective intervention strategies arising out of the direct experience of managing a case of multi-victim sexual assault in an Australian rural community. --------- Method: A descriptive, case-report methodology summarizing the investigation and intervention in a case of multi-victim sexual assault is reported. A community based intervention arising out of the disclosures of 21 male children is described. The intervention occurred at an individual, group, and community level using a coordinated multi-disciplinary team and natural helping networks. ---------- Results: The coordination of police and welfare services increased the communication flow to victims, their families, and the community. The case also demonstrated the utility in regularly briefing political and bureaucratic authorities as well as local officials about emergent issues. Coordinating political and bureaucratic responses was essential in obtaining ongoing support and sufficient researching to enable the effective delivery of services. ---------- Conclusions: Interventions were focused at an individual, group, and community level using a coordinated multi-disciplinary team and natural helping networks. This provided a choice of services which were sensitive to the case setting. Recommendations are offered for practitioners who are confronted with similar events. While this paper describes an approach for intervening in a case of multi-victim sexual assault, further empirical research is needed to enable service deliverers to efficaciously target interventions which offer choice to victims and their families.

Inhibiting outrage: tactics and counter-tactics in legal cases of sexual harassment

Sexual harassment can be conceptualised as an interaction between harassers and targets. Utilising 23 detailed legal transcripts, this study explored evidence of a range of perpetrator tactics and target counter-tactics. These tactics can be readily fitted into the backfire framework, which proposes that powerful perpetrators of perceived unjust acts are likely to cover up the actions, devalue the target, reinterpret the events, use official channels to give an appearance of justice, and intimidate or bribe people involved. Targets can respond using counter-tactics of exposure, validation, reframing, mobilisation of support, and resistance. The findings have implications for raising awareness of harassing tactics and recommendations for effective informal responses in organisations.

Differences between journalistic and academic accounts of child sexual abuse in Australia

The paper uses qualitative textual analysis to compare journalistic and academic accounts of child sexual abuse. There are seven main differences. Academic accounts suggest higher levels of neglect, emotional abuse, and physical abuse than sexual abuse in Australia, by contrast, journalistic accounts highlight sexual abuse. Academic accounts suggest that child sexual abuse in Australia is decreasing; journalistic accounts suggest that it is increasing. Academic accounts suggest that the majority of cases of child sexual abuse are perpetrated by family members; journalistic accounts focus on abuse by institutional figures (teachers, priests) or by strangers. Academic accounts have shown that innocent sexual play is a normal part of childhood development; journalistic accounts suggest that any sexual play is either a sign of abuse, or in itself constitutes sexual abuse. Academic accounts suggest that one of the best ways to prevent sexual abuse is for children to receive sex education; journalistic accounts suggest that children finding out about sex leads to sexual abuse. Academic accounts can gather data from the victims; journalistic accounts are excluded from doing so. Academic researchers talk to abusers in order to understand how child sexual abuse can be prevented; journalistic accounts exclude the voices of child sexual abusers.

Teachers reporting suspected child sexual abuse : results of a three-state study

Over 3000 cases of child sexual abuse are identified every year in Australia, but the real incidence is higher still. As a strategy to identify child sexual abuse, Australian States and Territories have enacted legislation requiring members of selected professions, including teachers, to report suspected cases. In addition, policy-based reporting obligations have been developed by professions, including the teaching profession. These legislative and industry-based developments have occurred in a context of growing awareness of the incidence and consequences of child sexual abuse. Teachers have frequent contact and close relationships with children, and possess expertise in monitoring changes in children’s behaviour. Accordingly, teachers are seen as being well-placed to detect and report suspected child sexual abuse. To date, however, there has been little empirical research into the operation of these reporting duties. The extent of teachers’ awareness of their duties to report child sexual abuse is unknown. Further, there is little evidence about teachers’ past reporting practice. Teachers’ duties to report sexual abuse, especially those in legislation, differ between States, and it is not known whether or how these differences affect reporting practice. This article presents results from the first large-scale Australian survey of teachers in three States with different reporting laws: New South Wales, Queensland, and Western Australia. The results indicate levels of teacher knowledge of reporting duties, reveal evidence about past reporting practice, and provide insights into anticipated future reporting practice and legal compliance. The findings have implications for reform of legislation and policy, training of teachers about the reporting of child sexual abuse, and enhancement of child protection.