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Malygin V.M., Rosmiarek M.
The male reproductive tract (accessory glands, glans ad os penis) is described in 39 specimens of five species -Calomys callosus, Graomys griseoflavus, Akodon simulator, Akodon sp. and Holochilus sp. of the tribes Phyllotini, Akodontini, and Sigmodontini. Quantitative (3 indices based on 6 measurements) and qualitative (13 phenes divided into 4 groups) characteristics of bacula in these hamsters and their individual and age variability are considered. The comparison of the authors’ and literary data allowed one to give taxonomic estimates of the structures composing the male reproductive tract in hamsters from the Neotropics. The number and shape of accessory glands may be used for taxonomy of tribes and Sigmodontinae subfamily. However, specific features of the glans penis are weakly suitable for the diagnostics of species and genera. The species specificity of baculum is displayed only in its size, proportions and form (combination of several phenes). The revealed uniformity in the structure of the male reproductive tract in South American hamsters appears to reflect their phylogenetic relationship and common origin.
The cases of evolutionary stasis of species (species' phenotypic constancy during long time periods) are traditionally attributed to the effect of a stabilizing mode of natural selection. However, the stabilizing selection can act effectively only if the adaptive value of features being subject to natural selection is constant. This is possible for several individual features, but unreal for the whole organism, taking into account that species exist hundreds of thousands of years and the environment changed considerably during this time. The counterbalance of vectors in the directional selection is formed when few factors of natural selection block each other trying to change the same feature in different directions. This is the main factor providing evolutionary stasis under varying environmental conditions. For instance, the species Rana temporaria has maintained the phenotypic constancy from the late Pliocene. At least six differently directed vectors of natural selection act in populations of this species providing the steadiness of species-environmental interactions that causes the stability of the species in time and space (within its habitat). The intraspecies diversity (balanced polymorphism, ecological races and, probably, semi-species) is the second factor underlying the evolutionary stasis. Some ecological groups score an advantage due to environmental changes, the others depopulate and even become extinct, but species exist if at least one of the ecological groups still survives. These two factors act independently of the reorganization of ecosystems. Climatic or geological changes of abiotic conditions lead to the transformation of ecosystems and displacement of species' natural habitat, while the main characteristics of their ecological niches are preserved. As a result, intraspecies diversity, as well as counterbalance of natural selection vectors, are preserved and continue to provide the species stability under new environmental conditions. The counterbalance can be disturbed only by the appearance of a new unbalanced vector of natural selection or by noncompensated changes in the intensity of one of the existing vectors. In this case, species is transformed in order to adapt to the new environment until the new system of balanced vectors in natural selection is established.
Dzerzhinsky F. Ya., Ladygin A.V.
The feeding apparatus in Accipiter gentilis (a representative of Accipitridae family) is mainly generalized and includes the three-condylar quadrato-mandibular joint, a full set of ligaments, and a typical locking mechanism of the joint. The high strength of the hooked upper jaw allows these birds to use the feeding habit which is likely inherited from their scavenging ancestors. Accipitrids tear up their prey by means of muscles of hind limbs, the role of the jaw musculature being moderate. There is a minor exception for the superficial pseudotemporalis muscle, which shows a deviation usual for gallinaceous birds feeding on anchored items. Falconids actively chew their prey with bill tips equipped with additional teeth, perhaps a legacy of ancestral adaptation to feeding on relatively large insects. Such an ability is facilitated by an increased and somewhat complicated jaw muscles, shorter and more robust jaws, clinorhynchy, and the unique structure of quadrato-mandibular joint, in which the locking mechanism is eliminated, the ligament usually effective as the meniscus was lost. However, resistance of the joint increased considerably due to additional differentiation of the lateral condyle.
The following types of chromosomal mutations were found in parasitic Hymenoptera: deletions and duplications, inversions, translocations, centric and tandem fusions and fissions, polyploids, aneuploidy, and numerical variation in B-chromosomes. Evolution of chromosomal numbers of parasitic Hymenoptera is shown to be asymmetric in its mechanisms: the decrease in the numbers was possible due to chromosomal fusions, whereas their increase took place usually due to the production of aneuploids and subsequent restoration of even chromosome numbers. Two main trends in the karyotype evolution of parasitic Hymenoptera were described: the decrease in chromosome numbers (from n = 14-17 to 10-11 and then to n = 4-6) and dissymmetrization of the karyotype (due to an increase in dimensional differentiation of chromosomes or/and in the share of acrocentrics in the chromosome set).
Panov E.N., Tsellarius A. Yu., Nepomnyashchikh V.A.
Temporal organization of adult males’ behavior was studied by means of observations of focal animals with fixation of data on a videotape. The total time of video-recordings made up 10.5 hs, including more than 6 hs of 9 lengthy fixations of the 6 different males’ behavior. The aim of the study was to analyze temporal distribution of elaborated tail movements, which turned out to be standard element of male behavior even outside the social contexts. The single ensemble of such a fixed action pattern is a sequence of a number of similar “series” of tail movements. The series as such can be divided into several (2-30) “cycles”, each of them being a stereotype pattern. The latter consists usually of 3 alternating tail curling and a final tail wagging. The duration of a single cycle is ca. 7 s. The intensity of these movements is shown to decrease in successive cycles within series, while the very series become more and more short. On the contrary, the duration of pauses separating series progressively increases. The intensity of tail movements decreases not only in consecutive cycles of the given series, but also as performance of series is progressed. The recurrence of the series performance under stationary conditions permits us to suppose that these movements are under constant endogenous control. This conclusion calls in question a widely accepted view of the primarily communicative function of the stereotype tail movements in the toad agamas.
Borkin L. Ya., Litvinchuk S.N., Rozanov Yu. M., Skorinov D.V.
The main concepts of species and the relationships between them are considered using different statistical methods. The problem of cryptic species is analyzed in historical aspect. The use of biochemical (molecular) methods and the evolutionary concept of species resulted in a greater number of cryptic species in different groups of animals. Based on allied relations, three categories of morphologically similar species (siblings species, dual species, and ancestor-descendant) were distinguished. The existence of sym-, para-, and allopatric cryptic species was noted. A brief analysis of methods for the discovery of cryptic species is given from the example of amphibians. Some cases of cryptic species formation are described in four groups of the Anura and Urodela orders in the fauna of Russia and adjacent countries. Underestimation of the importance of cryptic species may lead to the lower values of biodiversity and erroneous strategy of species conservation.
The analysis of the basic diagnostic features in bighorn sheep (Pachyceros subgenus) of the Yakutian, Okhotsk, Koryak, and Kamchatka populations and comparison with those in Alaska sheep populations confirmed the specific level of differences between the Palearctic and Nearctic populations (Ovis nivicola - O. dalli) on the subspecific level of differences between the East-Siberian populations (O. n. lydekkeri - O. n. koriakorum -O. n. nivicola). The history of settlement of bighorn sheep over Beringia is discussed. The bighorn branch is suggested to separate from the ancestor form in the Mid- or Late Pliocene. It is not directly related to argali ancestors. The hypothesis that American bighorns have Siberian ancestors entering through the Beringian land bridge as a result of the single eastern migration in the Late - Early Pliocene is confirmed. The chromosome polymorphism found in Asian O. nivicola populations might have Paleartctic origin but not be a consequence of return migration of bighorns from North America to Asia.
Potapova E.G., Vorontsov N.N.
The studies of skull and dental system were carried out to determine the position of Tachyoryctes genus and Rhyzomyidae family in the system of rodents. The morphological data obtained attest to the belonging of Tachyoryctes to the family Rhyzomyidae, where this genus occupies an isolated position. Probably, the developmental routes resulted in the formation of Tachyoryctes, on the one hand, and Rhysomys and Cannomys, on the other, have been dispersed at the early stages of the divergence of the group and were related with different directions in the development of the dental system. The genus Tachyoryctes has preserved the generalized (morphologically advanced) structure of the zygomasseter construction characteristic of Rhyzomyidae. However, this genus has acquired more specialized teeth. The available data on morphology do not confirm absolutely the monophyleticism of Spalacidae and Rhyzomyidae in relation to other Muroidea. Nevertheless, they do not fully refute it. Some similarity in the structure of molar teeth and acoustic system has developed in these groups independently. Such a similarity in the acoustic capsule is determined by the adaptation of animals to the digging way of life, and the structure of the tooth system is related to the similar variants of the masticatory surface in the process of transforming the same kind of tooth corona. These groups represent two independent families (with respect to their taxonomy) similar to other Muroidea families.
Formozov N.A., Baklushinskaya I. Yu., Ma Young
Ochotona argentata (Howell 1928) from the Helan-Shan Ridge was described as a subspecies of the Alpine pika, Ochotona alpina. This form differs from the Alpine pika in its karyotype (2n = 38), plumage color, some features of the skull’s structure, and vocalization. Therefore, it should be described as a separate species. Ochotona helanshanensis Zheng 1990 is the youngest synonym of Ochotona argentata. The types of these forms are identical in size and color of fur; their type localities are only 5-10 km apart. The range of Ocotona argentata has shrunk dramatically as a result of catastrophic deforestation of the Helan-Shan Ridge at the turn of the 20
Korobitsyna K.V., Yakimenko L.V.
The morphological analysis was made based on 182 specimens of the house mouse Mus musculus L. from 34 commensal and indigenous populations in the territory of the former USSR. The distribution of pericentiromeric heterochromatin (H) in karyotypes of 174 animals was also investigated. The variation of the C-heterochromatin content and distribution was revealed using C- and Q-H-banding techniques. Mice of the musculus subspecies group had high morphological and ecological characteristics. Two subgroups representing longtailed and short-tailed forms were distinguished. Animals of the latter were mainly characterized by semi-commensal way of life. Four subspecies (M. m. wagneri, M. m. gansuensis, M. m. manchu, and M. musculus ssp. 2) within the subgroup of short-tailed forms were defined in the faunas of Russia, Kazakhstan, and Central Asia using cytogenetic analysis.
Ecology of mammals and applied theriology develop in our country during the pre-Soviet period. On the contrary, faunistics, systematics, and paleontology have long history. The collections gathered for the nearly 200
Nikol'skii A.A., Rumyantsev V. Yu.
The variability of alarm calls in ground squirrels of the major group was analyzed. Parameters of polynomial equations were used as variables for characterizing the frequency modulation of signals. The range of the populations discussed is from the Volga River to the Gobi Altai. Four main clusters of the populations were distinguished based on the results of multivariate analysis. They correspond with four species of ground squirrels: (1) Spermophilus carruthersi (Thomas 1912); (2) S. brevicauda (Brandt 1843); (3) S. erythrogenis (Brandt 1841); and (4) S. major (Pallas 1778). Brakes in the variability between the population groups (main clusters) are clearly marked by four geographical barriers: (1) Turgai; (2) Balkhash-Alakol; (3) Irtysh-Zaisan; and (4) Tarbagatai. Three of these barriers separating populations of the major group are in southeastern Kazakhstan. The results obtained correspond to the concept of geographical species formation (Meyr 1944).