No abstract

In many birds and mammals, the size and sex composition of litters can have important downstream effects for individual offspring. Primates are model organisms for questions of cooperation and conflict, but the factors shaping interactions among same-age siblings have been less-studied in primates because most species bear single young. However, callitrichines (marmosets, tamarins, and lion tamarins) frequently bear litters of two or more, thereby providing the opportunity to ask whether variation in the size and sex composition of litters affects development, survival, and reproduction. To investigate these questions, we compiled a large dataset of nine species of callitrichines (n = 27,080 individuals; Callithrix geoffroyi,

Summary Life history theory predicts a trade-off between the quantity and quality of offspring. Short interbirth intervals—the time between successive births—may increase the quantity of offspring but harm offspring quality. In contrast, long interbirth intervals may bolster offspring quality while reducing overall reproductive output. Further research is needed to determine whether this relationship holds among primates, which have intensive parental investment. Using Cox proportional hazards models, we examined the effects of interbirth intervals (short, normal, or long) on infant survivorship using a large demographic dataset (n = 15,852) of captive callitrichine monkeys (marmosets, tamarins, and lion tamarins). In seven of the nine species studied, infants born after short interbirth intervals had significantly higher risks of mortality than infants born after longer interbirth intervals. These results suggest that reproduction in callitrichine primates may be limited by physiologic constraints, such that short birth spacing drives higher infant mortality.

This article describes the hand‐rearing of a ♀ Two‐toed sloth Choloepus didactylus from birth to its death at the age of 10 months. Developmental issues are discussed in detail, including diet, health, growth and weaning. The infant was successfully introduced to an adult ♀ in preparation for long‐term pairing with a young 3. Socialization, integration and imprinting issues are also discussed. Retrospective analysis concluded that this was a worthwhile hand‐rearing exercise that may he of benefit to others maintaining the species.

Generations of geographers attuned themselves to the view that a very large part of their subject was inevitably concerned with the distribution of the energy sources which had been influential in determining the location of manufacturing industry. As a consequence, innumerable historical and contemporary research topics focused upon energy as a locational factor and this became a basic and recurrent theme in courses on 'economic' and 'regional' geography. The relevance and validity of such an emphasis were inescapable provided one was concerned with patterns arising from earlier stages of the industrial revolution when, for obvious reasons, industry was overwhelmingly dependent on coal and water wheels for its power. But these obvious relationships were rapidly diminished as the extraction of petroleum and the generation of electricity, with their associated pipe lines and transmission cables, loosened the shackles. It began to seem as though, over large areas of the earth, political considerations and capital availability were rapidly becoming the only really important locational factors.The advent of electricity from nuclear power stations in 1954 seemed finally to set the seal on industrial dispersal; henceforth it was going to be possible to site an economically viable generating device almost anywhere -even in a submarine. Relatively tiny quantities of nuclear fuel can produce vast quantities of energy, so that sophisticated study of the relative costs of the different ways of bringing together the energy and the material for fabrication is rendered virtually academic.Proliferation of nuclear installations seems to suggest that this era of potentially foot-loose industry has already arrived. By the beginning of 1973, 22 countries (USA,