Costs and benefits of temporary brood desertion in a Neotropical harvestman (Arachnida: Opiliones)

Brood desertion is a life history strategy that allows parents to minimize costs related to parental care and increase their future fecundity. The harvestman Neosadocus maximus is an interesting model organism to study costs and benefits of temporary brood desertion because females abandon their clutches periodically and keep adding eggs to their clutches for some weeks. In this study, we tested if temporary brood desertion (a) imposes a cost to caring females by increasing the risk of egg predation and (b) offers a benefit to caring females by increasing fecundity as a result of increased foraging opportunities. With intensive field observations followed by a model selection approach, we showed that the proportion of consumed eggs was very low during the day and it was not influenced by the frequency of brood desertion. The proportion of consumed eggs was higher at night and it was negatively related to the frequency of brood desertion. However, frequent brood desertion did not result in higher fecundity, measured both as the number of eggs added to the current clutch and the probability of laying a second clutch over the course of the reproductive season. Considering that harvestmen are sensitive to dehydration, brood desertion during the day may attenuate the physiological stress of remaining exposed on the vegetation. Moreover, since brood desertion is higher during the day, when egg predation pressure is lower, caring females could be adjusting their maternal effort to the temporal variation in predation risk, which is regarded as the main cost of brood desertion in ectotherms.

Soberania: conceito e aplicação para a gestão da água

Domínio sobre um território. Monopólio do uso da força. Possibilidade de indicar representantes em outros países. Promover acordos bilaterais ou com organismos multilaterais. Essas são algumas das definições clássicas de soberania. Elas são válidas atualmente? Teriam perdido significado diante do avanço de organismos multilaterais e de empresas transnacionais? São operacionais na resolução de problemas transfronteiriços, como ocorre em grande parte dos temas ambientais? Esses aspectos são discutidos a partir de autores clássicos e contemporâneos que abordam a soberania. É preciso rever a definição de soberania, sem precisar abandoná-la como defendem neoliberais, para reafirmar seu papel relevante nas relações entre países no mundo contemporâneo. Esse é o objetivo central desse artigo, que trata do conceito tendo como exemplo o acesso à água. Para alcançar esse objetivo, ele foi organizado em quatro partes: revisita aos clássicos, a paz de Westfália, o debate contemporâneo e as considerações finais.