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Evolutionary explanations of cooperative breeding based on kin selection have predicted that the individual contributions made by different helpers to rearing young should be correlated with their degree of kinship to the litter or brood they are raising. In the cooperative mongoose or meerkat, Suricata suricatta, helpers babysit pups at the natal burrow for the first month of pup life and frequent babysitters suffer substantial weight losses over the period of babysitting. Large differences in contributions exist between helpers, which are correlated with their age, sex and weight but not with their kinship to the young they are raising. Provision of food to some group members raises the contributions of individuals to babysitting. We discuss the implications of these results for evolutionary explanations of cooperative behaviour.
1. Land & People 2. The Prehistory of South-East Asia 3. South-East Asia's Middle Ages' c. 400-c. 1500 4. South-East Asia in the 'Age of Commerce' 5. European Imperialism c. 1800-1941 6. World War, Nationalism & Decolonisation 1941-65 7. Problems of Independence 8. The Future Includes historical gazetter, lists of rulers, chronology of major events.
Cooperative breeders are animals where parents are assisted in protecting and provisioning their young by helpers that seldom or never breed themselves. Systems of this kind occur in birds, mammals and some fish, and have usually evolved from ancestors with monogamous breeding systems. Helpers are often previous offspring of breeders and are usually closely related to the young they help to raise though, in some systems, they can also be unrelated immigrants. Their contributions commonly enhance the growth and survival of juveniles and reduce the workload of their parents, increasing their fecundity. Cooperative breeding systems appear to have evolved where the costs of dispersal are high, helping provides substantial fitness benefits to related recipients or to helpers themselves and the fitness costs of helping are low.
Although malaria has been largely eradicated from temperate countries, it is on the increase in the tropics. Infection with Plasmodium falciparum affects a vast number of people and kills over a million annually. Severe malaria is a multisystem disease affecting particularly the central nervous system (causing coma and convulsions), the kidneys (resulting in acute tubular necrosis), and the liver (contributing to lactic acidosis and hypoglycaemia). Acute pulmonary oedema (acute respiratory distress syndrome) may occur in adults particularly in association with renal impairment. In children these symptoms are rare, whereas hypoglycaemia, lactic acidosis and severe anaemia are more common. Malaria should be suspected in any febrile patient living in or returning from the tropics, and a blood smear examined. Chloroquine has been the mainstay of antimalarial treatment for the past 40 years, but resistance in P. falciparum is now widespread throughout the tropics and has recently been recognised in P. vivax from Oceania. Sulfadoxine-pyrimethamine resistance is also common. Fortunately, quinine, and the newly introduced compounds, halofantrine and mefloquine, can be relied upon nearly everywhere. The most rapidly acting and effective of all antimalarial drugs, artemisinin and its derivatives, have come from China. They offer a genuine prospect of reducing mortality from malaria in the tropics.
In many mammals, the energetic costs of lactation double a female's daily energy requirements on her activity budgets, food choice and ranging behaviour–but the effects of lactation have rarely been documented. In this paper, the ecological consequences of lactation in free‐ranging Red deer ( Cervus elaphus ) hinds on the lsle of Rhum is examined by comparing the feeding behaviour, habitat use and ranging behaviour of hinds that were supporting calves (milk hinds) with hinds that did not have calves (yeld hinds). In summer, milk hinds graze for approximately two hours longer per day then yeld hinds. This difference has disappeared by the latter half of the winter, when the grazing budgets of milk and yeld hinds are similar. Both in summer and winter milk hinds spend more time grazing on the most strongly selected plant communities (short, herb‐rich greens) where standing crops are low but food quality is comparatively high. Inter‐year variation in habitat use by milk hinds is also closely related to variation in rainfall—while this is not the case among yeld hinds. Both in summer and winter, yeld hinds range more widely than milk hinds.
