Species composition, host association and niche differentiation in fleas of small mammals in the Ilmen-Volkhov lowland

Species composition, abundance, annual cycles, and host association of fleas parasitizing small mammals were investigated. The problem of niche differentiation in these insects is considered on the base of the comparative analysis of their annual cycles. The annual cycles of the fleas are revealed to be similar in the case of few number of flea species in parasite community. Thus, two species parasitizing Sorex araneus (Doratopsylla dasycnema and Palaeopsylla soricis), as well as three species associated with Apodemus uralensis (Megabothris turbidus, Ctenophthalmus agyrtes, and Ct. uncinatus) have equal phenology of parasitizing. The fleas community of Clethrionomys glareolus is characterized by a large species number and high diversity of the annual cycles. The differentiation by the seasons of parasitizing is observed most clearly in the dominant flea species, namely Amalaraeus penicilliger, Ct. uncinatus, and Peromyscopsylla bidentata. The periods of imaginal life are overlapped significanly in these species, but they are differed by the season of dominance. Ct. uncinatus predominates in spring and summer, while P. bidentata predominates in autumn, and A. penicilliger predominates in winter and early spring. It may be noted also, that niche partitioning was not observed in the fleas having wide range of hosts. The imaginal life of such fleas usually does not go beyond the warm season.     

Phylogeny of the genus Apodemus with a special emphasis on the subgenus Sylvaemus using the nuclear IRBP gene and two mitochondrial markers: cytochrome b and 12S rRNA

Phylogenetic relationships among 17 extant species of Murinae, with special reference to the genus Apodemus, were investigated using sequence data from the nuclear protein-coding gene IRBP (15 species) and the two mitochondrial genes cytochrome b and 12S rRNA (17 species). The analysis of the three genes does not resolve the relationships between Mus, Apodemus, and Rattus but separates Micromys from these three genera. The analysis of the two mitochondrial regions supported an association between Apodemus and Tokudaia and indicated that these two genera are more closely related to Mus than to Rattus or Micromys. Within Apodemus, the mitochondrial data sets indicated that 8 of the 9 species analyzed can be sorted into two main groups: an Apodemus group, with A. agrarius, semotus, and peninsulae, and a Sylvaemus group, with uralensis, flavicollis, alpicola, sylvaticus, and hermonensis. The position of Apodemus mystacinus is ambiguous and might be either included in Sylvaemus or considered a distinct subgenus, Karstomys, more closely related to Sylvaemus than to Apodemus. Estimation of the divergence time for these taxa suggests a separation between 7 and 8 My ago for the three groups (mystacinus and the two subgenera Apodemus and Sylvaemus). Within each subgenus, divergence times are between 5.4 and 6 My for Apodemus and between 2.2 and 3.5 My for Sylvaemus and mystacinus.     

Molecular phylogeny and taxonomy of wood mice (genus Apodemus Kaup, 1829) based on complete mtDNA cytochrome b sequences, with emphasis on Chinese species

Phylogenetic relationships among 15 species of wood mice (genus Apodemus) were reconstructed to explore some long-standing taxonomic problems. The results provided support for the monophyly of the genus Apodemus, but could not reject the hypothesis of paraphyly for this genus. Our data divided the 15 species into four major groups: (1) the Sylvaemus group (A. sylvaticus, A. flavicollis, A. alpicola, and A. uralensis), (2) the Apodemus group (A. peninsulae, A. chevreri, A. agrarius, A. speciosus, A. draco, A. ilex, A. semotus, A. latronum, and A. mystacinus), (3) A. argenteus, and (4) A. gurkha. Our results also suggested that orestes should be a valid subspecies of A. draco rather than an independent species; in contrast, A. ilex from Yunnan may be regarded as a separate species rather than a synonym of orestes or draco. The species level status of A. latronum, tscherga as synonyms of A. uralensis, and A. chevrieri as a valid species and the closest sibling species of A. agrarius were further corroborated by our data. Applying a molecular clock with the divergences of Mus and Rattus set at 12 million years ago (Mya) as a calibration point, it was estimated that five old lineages (A. mystacinus and four major groups above) diverged in the late Miocene (7.82-12.74 Mya). Then the Apodemus group (excluding A. mystacinus) split into two subgroups: agrarius and draco, at about 7.17-9.95 Mya. Four species of the Sylvaemus group were estimated to diverge at about 2.92-5.21 Mya. The Hengduan Mountains Region was hypothesized to have played important roles in Apodemus evolutionary histories since the Pleistocene.     

PCR identification of DNA of hosts of the taiga tick nymphs (Ixodes persulcatus: Ixodinae) in St. Petersburg and its suburbs

PCR identification of host DNA in unfed females and males of taiga tick Ixodes persulcatus was performed. Amplification of each sample was done using primers species-specific by 12S rDNA mitochondrial gene. Four species of small mammals (Apodemus uralensis, Clethrionomys glareolus, Microtus arvalis, and Sorex araneus) and two passeriform bird species (Fringilla coelebs and Parus major) were analysed. For one third of tick samples, hosts of previous stages were established using this method. In five cases, feeding on more than one host species was detected.     

A phylogenetic study of the genus Apodemus by sequencing the mitochondrial DNA control region

The sequences of the mitochondrial DNA control region (D-loop) and flanking tRNA genes (about 1000 bp) of 20 samples of wood mice (genus Apodemus ) were analyzed in order to clarify the relationships between different species belonging to the genus. The phylogenetic trees obtained using different methods showed similar topologies with distinct Karstomys ( Apodemus epimelas and Apodemus mystacinus ) and Sylvaemus ( Apodemus alpicola , Apodemus flavicollis , Apodemus hermonensis , Apodemus sylvaticus and Apodemus uralensis ) subtrees. Within Sylvaemus all species appeared to be closely related to each other, probably as result of a bush-like radiation event. Nevertheless, A. hermonensis seemed to be the first diverging branch followed by A. sylvaticus ; A. alpicola and A. flavicollis appeared to be very closely related. Three individuals of uncertain taxonomical status were included in the analysis: hypotheses as to their status are discussed. Further phylogenetic analysis was carried out combining the D-loop sequences of part of the samples of certain taxonomical status with 12S rRNA and cytochrome b sequences obtained by other researchers. Furthermore, I present a structure analysis of the D-loop in Apodemus as compared other rodent species.     

Wild small mammals are the reservoir hosts of the Bartonella genus bacteria in the south of Moscow region

A total of 103 blood samples collected from wild small mammals captured in the Prioksko-Terrasny Reserve on the south of Moscow region were studied to determine the bartonellae prevalence. The examined species were the yellow-necked mice Apodemus flavicollis (35 samples), the European wood mouse Apodemus uralensis (10 samples), the bank vole Clethrionomys glareolus (51 samples), the house mouse Mus musculus (3 samples), the common vole Microtus arvalis (2 samples), and the shrew Sorex araneus (2 samples). Initially, we obtained 76 bacterial Bartonella-like isolates after plating onto the surface of the solid nutrient media. 66 of them were PCR-positive at least for three of four targets, gltA, ftsZ, ribC and 16S RNA. Thus, the percentage of the infection in the studied community was 64%. Subsequent RFLP assay showed that obtained isolates belonged to the Bartonella grahamii and/or B. taylorii species. In 7 cases we found both bartonellae species in one animal. These data were confirmed by direct sequencing of four ftsZ, four ribC and two gltA amplicons. According to our data, there is no any marked host specificity for these bartonellae species. Now we have laid the bartonellae strain collection consisting of 31 isolates. To our knowledge, this is the first investigation of the bartonellae prevalence in wild small mammals performed in Russia. The comparison of our data with those obtained by European researchers and issues of coinfection by different bartonellae species and host specificity are discussed.     

Genetic variation and evolution in the genus Apodemus (Muridae: Rodentia)

Genetic variation was studied using protein electrophoresis of 28–38 gene loci in 1347 specimens of Apodemus agrar-ius, A. peninsulae, A. flavicollis, A. sylvaticus, A. alpicola, A. uralensis, A . cf. hyrcanicus, A. hermonensis, A. m. mystacinus and A. m. epimelas , representing 121 populations from Europe, the Middle East, and North Africa. Mean values of heterozygosity per locus for each species ranged from 0.02 to 0.04. Mean values of Nel's genetic distance ( D ) between the taxa ranged from 0.06 (between A. flavicollis and A. alpicola) to 1.34 (between A. uralensis and A. agrarius ). The highest values of D were found between A. agrarius and other Apodemus species (0.62-1.34). These values correspond to those generally observed between genera in small mammals. Our data show that A. agrarius and A. peninsulae are sister species, well-differentiated from other taxa. High genetic distance between A. m. mystacinus and A. m. epimelas leads us to consider them distinct species and sister taxa to other Western Palaearctic species of the subgenus Sylvaemus . The data also suggest a recent separation of members of the latter group from a common ancestor, and subsequent rapid radiation, making it difficult to infer phylogenetic relationships. Some taxonomic implications of the results are discussed further.© 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 395–419.     

The cytogenetic consequences of chronic irradiation in rodent populations inhabiting the Eastern Urals Radioactive Trace zone

In bone marrow cells of rodents (Apodemus (Sylvaemus) uralensis Pall., 1811, Apodemus agrarius Pall., 1771) inhabiting the Eastern Urals Radioactive Trace (EURT) zone (Kyshtym radiation accident 1957) and adjacent areas of Urals, the chromosome instability and 90Sr accumulation in bones were investigated. Intensive mutagenic process in both species from impact plots (the soil pollution by 90Sr 2322-16690 kBq/m2) was found. Significant positive correlation of aberrant cells frequencies and 90Sr was shown. Possible causes of the lack of resistance to long-term mutagenic factor (over 100 generations since 50 years from the accident) such as migration of animals and specific configuration of the EURT zone (narrow extended territory with sharply falling gradient of radionuclide pollution), which considerably decrease the probability that certain changes will be fixed and inherited in a series of generations of rodents, are discussed.     

六种鼠乳酸脱氢酶和超氧化物歧化酶位点变异的研究

用电泳比较分析了鼠科动物６个种的组织ＬＤＨ同工酶的Ａ、Ｂ、Ｃ亚基和ＳＯＤ同工酶位点的种属差异。结果表明,ＬＤＨ的Ａ和Ｂ亚基在进化上的可变性程度不同。在被分析的２个属共６种鼠中,首次发现Ｂ亚基的结构具有属的特征,同属的鼠种Ｂ亚基泳动度相同,在垂直凝胶电泳板上处于同一泳动线上。不同属的鼠其Ｂ亚基泳动度不同,家鼠属的鼠Ｂ亚基比姬鼠属的泳动快;Ａ亚基的结构既有属的特性,更具有种的特征,同属不同种的鼠Ａ亚基泳动速度不同,表现为ＬＤＨ同工酶带的间距不同。ＬＤＨ的Ｃ亚基结构因鼠种不同而异,由Ｃ亚基组成的ＬＤＨ－Ｘ带黄毛鼠位于自身的ＬＤＨ－３和ＬＤＨ－４之间,社鼠和褐家鼠此带位于自身的ＬＤＨ－４和ＬＤＨ－５之间,白腹巨鼠此带位于自身的ＬＤＨ－５以外的阴极端,与黑线姬鼠此带的位置特征相同。ＳＯＤ同工酶带只表现种的差异,其３条带泳动速度的改变具有协同而变的共同特点。被分析的鼠种经配对法比较生化特征的相同程度,初步表明黄毛鼠亲缘上与褐家鼠比较近,白腹巨鼠亲缘上又比其余３种鼠更近于姬鼠属。     

Sex chromosomes at early meiosis in three wood mice species of the genus Apodemus (Rodentia, Muridae)

The prophase of the first meiotic division was studied in field mice of the species Apodemus (Sylvaemus) flavicollis, A. (S.) ponticus, and A. (S.) uralensis by light and electron microscopy. The karyotypes of the species were described on the base of electron microscopy of synaptonemal complexes in spermatocytes I. The axial elements of the sex chromosomes at early-middle pachytene can synapse along the major portion of the Y axis; at late pachytene-early diplotene, the synapsis region shrinks; and at diakinesis-metaphase I, X and Y chromosomes associate tail-to-tail in all species studied. The behavior of sex chromosomes in the synapsis in the species studied was quite uniform. The results are discussed in the context of earlier data on the behavior of sex chromosomes in various rodent species in meiosis prophase I and their banding.     

PCR identification of the host DNA in the taiga tick (Ixodinae: <Emphasis Type="Italic">Ixodes persulcatus</Emphasis>) nymphs in St. Petersburg and its environs

Host DNA from hungry males and females of Ixodes persulcatus (a total of 143 specimens) collected in the wild in April–May 2008 and 2009 was identified by means of the PCR method. Amplification of each sample was performed using a primer species-specific by the 12S rRNA mitochondrial gene. Four species of small mammals (Apodemus uralensis, Clethrionomys glareolus, Microtus arvalis, and Sorex araneus) and two species of passerine birds (Fringilla coelebs and Parus major) were analyzed. Hosts were established for 44 samples (30.8% of the material); in five cases (3.5%), feeding on more than one host was revealed.     

Skin lesions in small mammals parasitized by Psorergates apodemi and P. dissimilis (Gheyletoidea: Psorergatidae)

Histopathology in the sites of localization and parasiting of the mites Psorergates apodemi Fain et al., 1966 and P. dissimilis Fain et al., 1966 on the Ural field mouse Apodemus uralensis (Pallas) and the bank vole Clethrionomys glareolus (Schreber) is described. The mites affected all epidermis cell layers down to the cambium layer and caused hyperkeratosis.     

Allozyme variation of the pygmy wood mouse Sylvaemus uralensis (Rodentia, Muridae) and estimation of the divergence of its chromosome forms

The genetic divergence between the eastern European, southern European, and Asian chromosome forms of the pygmy wood mouse Sylvaemus uralensis, whose karyotypes differ from one another in the amount of pericentromeric heterochromatin, has been reevaluated using allozyme analysis. In general, Asian S. uralensis living in eastern Kazakhstan, eastern Turkmenistan (the Kugitang Ridge), and Uzbekistan are more monomorphic than European populations of this species. However, the allozyme differences between all chromosome forms of the pygmy wood mouse is comparable with the interpopulation differences within each form and are an order of magnitude smaller than those between "good" species of the genus Sylvaemus. Thus, the chromosome forms of S. uralensis cannot be considered to be separate species. The concept of races as large population groups that have not diverged enough to regard them as species but differ from one another in some genetic characters is used to describe the differentiation of S. uralensis forms more adequately. The currently available evidence suggests the existence of two S. uralensis races, the Asian and the European ones, and two chromosome forms (eastern and western) of the European race. The possible historical factors that have determined the formation of the races of the pygmy wood mouse are considered. According to the most plausible hypothesis, the shift and fragmentation of the broad-leaved forest zone during the most recent glacial period (late Pleistocene) were the crucial factors of the formation of these races, because they resulted in a prolonged isolation of the European and Asian population groups of S. uralensis from each other.     

六种鼠组织中过氧化物酶和酯酶变异的比较

本文研究姬鼠属（Ａｐｏｄｅｍｕｓ）２种鼠和鼠属（Ｒａｔｕｓ）４种鼠的心组织过氧化物酶和肝组织酯酶同工酶等位基因的变异。结果表明,６种鼠心组织过氧化物酶皆为４条区带,其中社鼠和白腹巨鼠的酶带泳动速度略快于褐家鼠和黄毛鼠的酶带;鼠属４种鼠的酶带间距大致相同,而姬鼠属的酶带间距略大于鼠属,这种谱型的区别就所分析的６种鼠而言,可以认为是该同工酶表现的属间区别。肝组织酯酶区带较多,其酶带数和泳动速度的差异具有明显的种间特征;泳动最快的酶带在姬鼠中是２条,在鼠属中是１条,可以认为是属间特征的区别。从９项生化指标的异同作动物配对比较,表明褐家鼠与黄毛鼠亲缘上较近,社鼠与白腹巨鼠亲缘上也较近,而且白腹巨鼠在进化上可能要比其余３种鼠属动物更接近于姬鼠属     

Structure of parasitic arthropod communities in forest small mammals

Species composition and structure of ectoparasite arthropod communities were examined all year round six years in the bank vole Clethrionomys glareolus, Ural wood mouse Apodemus uralensis and the common shrew Sorex araneus in forests of the Ilmen'-Volkhov depression. In total, 4500 host samples have been examined and all ectoparasites have been collected. The species composition of ectoparasite community in small mammal species are as follows: the bank vole--29 insect, tick and mite species, the common shrew--23 species, the Ural wood mouse--16 species. In forest biotopes, many temporary ectoparasitic species occur on several host species living in the same habitats under a forest canopy and contacting each other. A parasitic supracommunity in the ecosystem examined has a pool of temporary ectoparasites, which is available for all the community of small mammals. A role of different rodent and shrew species are hosts of insects and ticks changes depending on a density of potential host populations and numerous other environment factors.     

Structure of populations and ecological nishes of ectoparasites in the parasite communities of small forest mammals

The paper reports the results of eight-year investigations on the ectoparasites of rodents and insectivores carried out in southern taiga of the Ilmen-Volkhov lowland (Novgorod Region) and Kurgolovsky reserve (Leningrad Region). Twelve species of small mammals were captured including three dominate species--bank vole Clethrionomys glareolus (2722 specimens), common shrew Sorex araneus (1658 specimens), and wood mouse Apodemus uralensis (367 specimens). Parasite community of the bank vole comprises 34 species of mites, ticks, and insects, the community of common shrew comprises 25 species, and the community of A. uralensis includes 28 species. Taxonomic diversity of the ectoparasite communities was shown to be based on the diversity of types of parasitism and ecological nishes of the host body. Permanent ectoparasites are found to be represented by 2 species of lie and 14 species of acariform mites. The group of temporary parasites includes 13 species of fleas, 10 species of gamasid mites. 3 ixodid species and 1 Trombiculidae. There is a common pool of temporary parasites of small mammals in the ecological system of taiga. Significance of different shrew and rodent species as hosts were found to be dependent on the population density in possible hosts and many other factors. Species diversity in the parasite communities of different small mammal species is dependent on the number of possible ecological nishes in the host body. Actual infill of these nishes by ectoparasites is usually lesser than potential one. Species composition of temporary parasites, their occurrence and abundance changes according to season. Interspecific competition in the temporary parasite species can decrease because of the seasonal disjunction of their population peaks. Diversification of the ecological niches of ectoparasites allow simultaneous feeding of more parasite individuals on one host, than in the case of parasitising of single species or several species with similar ecological nishes. The distribution of parasites on their hosts was also studied. The aggregative distribution has been found in ixodid larvae only, and the distribution of fleas was close to the Poisson distribution. Deviations from the aggregative distribution can be an effect of several independent factors, including limited ability of small mammals for providing numerous parasites with food. On the most part of hosts simultaneous parasitizing of no more than 1-3 individuals of each tick, mite, and flea species was registered. Excessive infestation by ectoparasites may probably be limited by effective reactions of self-purification in the mammal hosts.     

On the problem of radioadaptation in small mammals (ecological specialization of species, radioresistance, hemopoiesis, immunity)

The data illustrating ambivalent nature of radioresistance of rodents having different ecological specialization: wood mice (Apodemus uralensis Pallas 1811) and mole-voles (Ellobius talpinus Pallas 1770) to acute (laboratory experiment) and chronic (long-term inhabiting the East Ural Radioactive Trace - EURT) radiation action are presented. These species are greatly distinguished by a way of life, a migratory activity, an average life span etc. Numerous immunological, hematological disturbances were found in more radioresistant wood mice inhabiting in radioactively-polluted biogeocenosis (density of pollution 90Sr - 18.5 MBq/m2 = 500 Ci/km2). On the contrary there are no pathological shifts in more radiosensitive mole-voles from the EURT zone (density of pollution 90Sr - 37 MBq/m2 = 1000 Ci/km2). Comparative analysis of the hematological and immunological parameters and absorbed dose loads in rodents from radiocontaminated environment testify about the possibility of radioadaptation in a series of generations in Ellobius talpinus Pall. The leading role in development of radioadaptation of mole-voles belongs to ecophysiological peculiarities of the species.     

新疆加依尔山发现草原鼠兔

2008年9月4日,我们在进行鼠类调查时于新疆克拉玛依区加依尔山克孜勒乌赞一带的新疆圆柏灌丛中捕获2只鼠兔标本,经鉴定为草原鼠兔(Ochotona pusilla)。     

Effects of acorn masting on population dynamics of three forest-dwelling rodent species in Hokkaido,Japan

The effects of the abundance of acorns of the oak, Quercus crispula, on the population dynamics of three rodent species (Apodemus speciosus, A. argenteus, and Clethrionomys rufocanus) were analyzed using time series data (1992–2006). The data were obtained in a forest in northern Hokkaido, Japan, by live trapping rodents and directly counting acorns on the ground. Apodemus speciosus generally increased in abundance following acorn masting. However, the clear effect of acorn abundance was not detected for the other two rodent species. Acorns of Q. crispula contain tannins, which potentially have detrimental effects on herbivores. Apodemus speciosus may reduce the damage caused by acorn tannins with tannin-binding salivary proteins and tannase-producing bacteria, whereas such physiological tolerance to tannins is not known in the other two rodent species. The differences in the effects of acorns between the three species may be due to differences in their physiological tolerance to tannins.     

How many species of Apodemus and Rattus occur in China? A survey based on mitochondrial cyt b and morphological analyses

Apodemus(mice) and Rattus(rats) are the top rodent reservoirs for zoonoses in China, yet little is known about their diversity. We reexamined the alpha diversity of these two genera based on a new collection of specimens from China and their cyt b sequences in Gen Bank. We also tested whether species could be identified using external and craniodental measurements exclusively. Measurements from 147 specimens of Apodemus and 233 specimens of Rattus were used for morphological comparisons. We analysed 74 cyt b sequences of Apodemus and 100 cyt b sequences of Rattus to facilitate phylogenetic estimations. Results demonstrated that nine species of Apodemus and seven species of Rattus, plus a new subspecies of Rattus nitidus, are distributed in China. Principal component analysis using external and craniodental measurements revealed that measurements alone could not separate the recognized species. The occurrence of Rattus pyctoris in China remains uncertain.