[Extinction of large herbivore mammals: niche characteristics of musk ox Ovibos moschatus and reindeer Rangifer tarandus coexisting in isolation].

The extinction of large northern herbivores is a puzzle for many biologists. It is long debated whether climate change or human activity was the main factor of the extinction. The survival of the weak trophic competitors should reject the climatic hypothesis. Extant species of Pleistocene communities allow testing this explicitly. Up to date, reindeer and musk ox coexist in the Arctic territory. Their island populations provide a unique natural experiment to assess the role of competition. On Wrangel Island, their population sizes show the opposite trends and the same situation recurs on other Arctic islands--the reindeer population size decreases with the muskoxen population increasing. We have shown that the trends are defined by food-web structure. Niche overlap between species is found to .be considerable and cannot be facilitated by habitat partitioning. The number of plant species in the muskoxen diet was higher than in the reindeer. The exclusive part of the muskoxen diet was higher as well. Food webs in all of the habitat types showed the same relation. However, the changes in herbivores distribution during the Pleistocene demonstrate the opposite pattern. Therefore, the competitive advantage could not save the Palaearctic musk ox, and the extinction seems to be a result of selective overkill. Conclusively, the human activity may be considered as the main factor of the Late Pleistocene herbivore extinctions, and the musk ox reintroducing should be coupled with extensive conservational measures.

Shakespeare and sleep disorders.

Shakespeare was a consummate dramatist and profound observer of human behavior. He vividly described many clinical disorders, including those of sleep. His characters suffered from somnambulism, sleep apnea, insomnia, and nightmares. Sleep, to Shakespeare, was a blessing denied to many of his protagonists.

Sleepsex: a variant of sleepwalking.

Sexual acts performed by a sleeping subject have been rarely reported. Two cases are now presented involving sexual behavior performed while asleep. The first case involves the hitherto unreported association of sleepsex with sleepeating. The second case concerns a rarely reported act of sexual battery by a known sleepwalker, and the use of somnambulism as a legal defense. Sexual behavior in sleep may be pleomorphic and more common than realized in both the patient and normal populations.

Delayed diagnosis of voiding dysfunction: occult spinal dysraphism.

The recognition of spinal dysraphism as a potential cause of voiding dysfunction is of the utmost importance if appropriate treatment and followup are to be initiated. We present 2 women with prolonged voiding dysfunction who had spinal dysraphism, intradural lipoma and related urodynamic abnormalities. The importance of initial symptom recognition, physical examination, urodynamic evaluation, appropriate treatment and periodic re-examination to detect progressive neurological impairment is emphasized.