Содержание: Том 8 (1) 2009 (отпечатан 11 November 2009)
Gambaryan P.P., Zherebtsova O.V., Perepelova A.A., Platonov V.V.
The pes myology of the giant anteater Myrmecophaga tridactyla has been studied in detail to understand its adaptive properties. The morphofunctional features of these muscles have been compared to the respective muscles of the brown bear (Ursus arctos), in which the locomotor role of the foot is similar to that in the giant anteater. M. tridactyla has a complete set of short pes muscles and their structure is generally the same as in the brown bear and some other plantigrade mammals. In spite of some differences, the work of the pes muscles in the giant anteater and brown bear is basically similar, which is consistent with the similar anatomy of these muscles in these two mammals. This similarity suggests that the pes myology in the animals studied reflects the adaptation to the run, which in the giant anteater is however less pronounced than in the brown bear.
Abramov A.V., Puzachenko A.Yu.
Spatial variation in sexual size dimorphism was assessed for the Siberian weasel (Mustela sibirica) across localities in Western, Central and Eastern Siberia. Twenty-three cranial measurements from 192 adult specimens were studied using univariate morphometric and non-metric multidimensional scaling techniques. Males found to be larger than females for all characters. Significant spatial variation in degree of SSD was found. The larger degree of sexual dimorphism was found in M. sibirica from Far East and smaller degree of SSD in samples from Western and Central Siberia. Results were interpreted to support the resource partitioning hypothesis.
Five pathologically modified last generation lower teeth of the wooly mammoth Mammuthus primigenius from Alazeya River basin (Yakutia) and Maly Anyui River basin (Chukotka) are studied. The described aberrations represent variants of the same pathology of tooth germ. The studied several tens of last molars of Yakutian mammoths show three main types of deviations appeared during tooth formation, during formation of tooth elements (plates, external cement), and in the process of functioning.
The history of fauna of the East Coast of the Gulf of Finland and its state under increasing anthropogenic pressure are described in this study. Short characteristics of the current coastal ecosystems of the Gulf of Finland were done. The list of mammal species inhabited the Russian coastal territories of the gulf and adjacent islands is provided. The obtained data demonstrated, that despite of high pressure, which has been brought upon the eastern part of the Gulf of Finland by anthropogenic factor, the main body of the coastal and island mammal fauna, which is inherent for southern taiga forests, has not been lost yet. However, the quota of accidental and rare species is reducing within the major part of the territory. So, the increasing building activity and recreational pressure upon this area call for a close attention to the situation.
Weinert D., Schöttner K., Surov A.V., Fritzsche P., Feoktistova N.Yu., Ushakova M.V., Ryurikov G.B.
The hamsters of the genus Phodopus (P. campbelli, P. sungorus, P. roborovskii) inhabit different ecosystems facing them with different environmental challenges. This should have behavioural and physiological consequences, manifested genetically. Therefore, the present paper compares the daily activity rhythm of the three Phodopus species under various conditions, from highly standardized laboratory to semi-natural ones. Motor activity was recorded by the mean of passive infrared sensors (PIR), running wheels (RW) and ring-shaped sensors (RSS) placed on the burrow entrances.
Under standardized laboratory conditions with artificial light-dark cycles (L:D=14:10h or 18:06h), all hamsters were active almost exclusively during the dark time. The amount of general activity (PIR method) per day was not different between males and females or between species. The onset of activity (RSS) was significantly later in P. campbelli than in the two other species, the activity offset was earliest in P. roborovskii. The latter had also the shortest duration of dark-time activity. Running wheels were used mainly during the dark time (on average 97%). P. sungorus did run significantly more than the other two species. On average they realized 9000 revolutions per day (ca. 3.5 km).
The rhythm stability was lowest in P. sungorus. In some hamsters of this species, the activity onset was delayed by several hours, and the activity period was strongly compressed. Also, a free-running rhythm despite the presences of a light-dark cycle or arrhythmicity was observed in those animals. Differences between the species were also found during the last weeks of life. Whereas P. campbelli and P. roborovskii revealed clear activity rhythms until the last decade, in P. sungorus the activity rhythm disappeared from the last 100 days of life.
First studies under semi-natural conditions were performed at the Biological Station of the A.N. Severtsov Institute of Ecology and Evolution in Tchernogolovka. These included experiments in a laboratory though with natural lighting and temperature conditions and in outdoor enclosures. In one of them (75 m2) artificial nest boxes were provided, in the other two (400 m2 each) the animals could dig their own burrows. The observed activity patterns are similar to those obtained under constant, standardized conditions. Moreover, the animals did clearly respond to the changing photoperiod.
The activity patterns of each species described in the present paper are rather similar under semi-natural and artificial environmental conditions. This can be taken as evidence that the obtained species-specific patterns have a genetic basis and are not caused by the different environmental conditions.