Том 7, № 1 (2017)

To date, more than a quarter of tropical coral reefs of the World Ocean are believed to be totally destroyed. Given the present rate of reef degradation, this value may double in the nearest 30 years. For a significant part of the coastal population of the planet, the destruction of coral ecosystems implies the loss of a major food resource, natural protection from storms, and significant (if not the only) revenues from exploitation of reefs, especially in the tourist industry. Finally, the disappearance of populated low-laying coral islands may threaten the local communities by depriving them of living space. Global negative effects include temperature anomalies of the sea surface waters and an increase in CO₂ concentration in the atmosphere, which leads to acidification of the World Ocean. The local negative effects include an increase in sedimentation and eutrophication, cyclone and storm passages, coral diseases, chemical pollutions, mechanical destruction of corals by humans, and anthropogenic depletion of functional groups of fish and invertebrates. The entire range of responses of coral ecosystems to these stressful factors is reviewed both at the level of separate taxa and at the level of the ecosystem in general. An analysis of literature data suggests with high probability that, in the middle of this century, more than 50% of tropical coral communities will suffer a collapse stage, especially in areas with a high human population density. According to the most optimistic scenario, the integrated effect of the reviewed negative factors will result in the survival of coral ecosystems in some areas. However, after global transformations, these ecosystems will be dominated by the most resistant taxa, mainly massive and encrusting growth forms of long-lived species with low growth rates and high competitive ability. Among such taxa, Poritidae show the highest adaptive capability. According to the most pessimistic scenario, scleractinian communities will be replaced by alternative communities of macroalgae or noncalcareous anthozoans everywhere.

The interspecies distinctions were determined in two artiodactyl communities from geographically distant populations by means of discriminant analysis of four traits: altitude, mean body mass, mean group size, and territorialism. These communities inhabit similar landscapes of the Altai and Himalayas. They are formed by species with different territorial systems (year-round and seasonal), and also by species without such systems. By this attribute, the species ratio was 1 : 1 : 2 in the community of Altai and 1 : 3 : 3 in the Himalayan community. Territorial system diversity is a natural character of the communities under study; it provides the basis for essential distinctions in the structure of specific biological signal fields. An inhibiting role of year-round territorialism in population separation was demonstrated. In it, species are characterized by a seasonal pattern of scent marking by dermal gland secretion. Based on the results, a principle was formulated for the separation of species with active biological signal fields in Cetartiodactyla communities. According to this principle, two species with year-round territorialism, the basic element of which is intensive scent marking, cannot occupy the same habitat. The mechanism of olfactory exclusion of mammalian species with specific functioning of the olfactory system is discussed.

The stresses faced by animals in nature are reflected in the adrenal cortex functional activity. It is possible to expect that the basal concentrations of glucocorticoid hormones will be increased in animals inhabiting unfavorable conditions (and correspondingly the value of the adrenocortical reaction to acute stress will be decreased). Since mobilization of the organism resources for the compensation of environmental challenges is the main function of the stress reaction, its weakening should result in a decrease in the reserve capabilities of metabolism. To check this assumption, the basal and maximal metabolic rates, body temperature, and corticosterone concentration in plasma measured before and after acute cooling in a helium–oxygen mixture were compared in northern red-backed voles (Myodes rutilus) from two populations differing in their relative abundance. It was found that, despite higher basal levels of corticosterone and decreased stress reaction values, individuals from the population of the forest park zone of Novosibirsk Science Center with a low relative abundance demonstrated a higher maximal metabolic rate than individuals from the mountain–taiga population with a high abundance. The results demonstrated that habitation in unfavorable conditions leads to elaboration of physiological adaptations that increase resistance to acute stress but increase the risk of the development of the chronic stress, which negatively influences adaptability.