The effect of water on the ground nesting habits of the giant tropical ant, Paraponera clavata
Abstract The large predatory ant, Paraponera clavata, exerts measurable top-down effects in wet and moist Neotropical forests, and therefore its distribution has potential ecological implications. To determine how water affects the presence of this important predator, the ground nesting ecology of P. clavata was examined with respect to various habitat characteristics. Four hectares of disturbed Costa Rican lowland rain forest were surveyed for ant colonies to determine nest distribution patterns in wet and dry habitat; significantly more colonies were found in dry habitat. Seventeen of 19 nests built on slopes of > 5° inclination were positioned on the downward side of the tree, possibly using the trunk as a shield against runoff during rain showers. Moisture and pH inside nests were significantly different from adjacent soil. These results suggest that water influences the ground nesting habits of P. clavata, thus ecological differences between comparatively wet and dry portions of tropical forests may arise from the relative abundance of this ant species.
Influences of temperature and humidity on oxygen consumption of five Chihuahuan desert ants.
Abstract 1. Oxygen consumption in five sympatric species of Chihuahuan desert ants was measured at three relative humidities at 15, 25 and 35°C. 2. The rate of oxygen consumption (QO2) exhibited non-linear increase in Formica perpilosa, Pogonomyrex desertorum, Novomessor cockerelli and Trachymyrmex smithi neomexicanus, but was linear in Pogonomyrmex californicus. 3. Vapor pressure deficit had a significant effect on QO2 of P. desertorum, T. s. neomexicanus and F. perpilosa but not on the other two species. 4. Activity increased at higher vapor pressure deficits in P. desertorum, N. cockerelli and T. s. neomexicanus. 5. The highest vapor pressure deficits at 35°C resulted in deaths of all species except P. californicus and T. s. neomexicanus died at intermediate and high vapor pressure deficits at all temperatures.
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.