卷 481, 编号 1 (2018)

We evaluated individual risk factors of the development of alcohol preference in a model of voluntary alcohol consumption. Drinking behavior was estimated in the two-bottle test, and other behavioral features were studied in the open field test, test for social interaction, and marble burying test. The low adaptive capacity of an animal, which was manifested in a shorter time spent in the center of the open field, and low consumption of ethanol when the animal first tasted it were the leading factors of the subsequent preference of alcohol under the conditions of free choice.

The frequency resolving power of hearing (FRP) of the beluga whale Delphinapterus leucas was studied as dependent on influence of lasting low-intensity sounds (of the ultrasonic range from –20 to +10 dB). Testing of the spectrum ripple-phase reversal was used in conjunction with a noninvasive recording of auditory evoked potentials. FRP parameters were found to depend nonmonotonically on the intensity of the background noise. The resultant adaptation effects can be explained by the fact that, in response to the high-intensity signals, the auditory system sensitivity is reduced to the level optimal for analysis of these signals.

The waveform and some characteristics of the electric organ discharges have been studied in 11 individuals of Cyphomyrus petherici, the only representative of the genus in the Nilotic fauna. The discharge is characterized by three to five phases with a prevalence of the second phase in terms of the relative amplitude and a wide variability of the total duration of discharge (from 212 to 558 μs). The comparison of the discharges of the species under study with those in the congeneric species and representatives of the genus Pollimyrus (which previously encompassed C. petherici) demonstrates a general similarity of the C. petherici discharges with those of Cyphomyrus, but not Pollimyrus. This is in agreement with the correspondence of the discharge characteristics observed in other mormyrids to the phylogenetic position and taxonomic status of the species.

The structure of the papillomatous junction between epidermis and dermis (papillomatous netting, PN) in the skin of cetaceans (white whales, bowhead, and gray whales) and sirens (American manatee, dugong) was studied and compared using histophysiological and morphogeometric methods. The relative extent of PN development proved to be similar in members of both orders, but significant differences were found in PN configuration, the volume of “free area of grille”, the degree of skin vertical compression, and skin density, which influence buoyancy. The differences are discussed from the viewpoint of species biology.

The study deals with a new sample of the mammalian fossils from the Pleistocene deposits of the Ignatievskaya Cave in Southern Urals (54°53' N, 57°46' E). Among the rodent fossils, the teeth of red squirrel (Sciurus vulgaris) and forest dormouse (Dryomys nitedula) have been identified. The enamel differentiation quotient (SDQ) of the water vole teeth matches the Arvicola terrestris species from locations of the end of Middle and Late Pleistocene (oxygen isotope stages, OIS 6 and OIS 5–2, respectively). The high SDQ value for the water vole and the presence of the squirrel and dormouse in the fauna allow dating the finding near the end of the Middle Pleistocene and beginning of the Late Pleistocene (OIS 6 and OIS 5e, respectively). The widespread open and forest landscapes were inhabited by this fauna.