Nornica ruda jest leśnym gryzoniem stanowiącym główny rezerwuar bakterii z rodzaju Borrelia, wywołujących boreliozę. Jednocześnie wykształciła odporność na zakażenie bakteryjne przez utrwalenie się pewnych wariantów genu receptora błonowego TLR2 odpowiedzialnego za rozpoznanie patogenu i aktywację odpowiedzi immunologicznej. Różne warianty genu wyewoluowały w wyniku presji selekcyjnej spowodowanej przez krętki z rodzaju Borrelia. U nornic w Szwecji wykazano istnienie trzech odrębnych grup haplotypów w obrębie częściowej sekwencji (1173 pz) tego genu. Dwie wyodrębnione grupy haplotypów (c1 i c2) były bezpośrednio związane z odsetkiem zakażonych nornic. W zależności od posiadanych wariantów genów zakażenie wśród osobników wahała się od 16 do 50%. Ponadto wykazano, że sekwencja ta u nornicy rudej jest pod wpływem selekcji pozytywnej. Osobniki z taką adaptacją mogą uzyskać przewagę ewolucyjną w środowisku o dużym zagęszczeniu zakażonych krętkami z rodzaju Borrelia wektorów, głównie kleszczy.
EN
Bank vole is a highly adaptive forest species of rodent. It is known to be a reservoir of Borrelia sp. spirochetes, the etiological agent of Lyme disease. Bank vole also developed the adaptation in membrane Toll-like receptor 2 (TLR2) gene to avoid disease development. TLR2 is involved in pathogen recognition and initiation of immune response. In Swedish populations of bank vole three different groups of haplotypes of TLR2 gene partial sequence (1173 bp) were found. The frequencies of two of them (c1 and c2) were directly correlated with the incidence of Lyme disease in bank vole populations. Morbidity among vole populations varied from 16 to 50% and depended on gene variants. Higher resistance was found in populations, where c2 TLR2 haplotypes were present. Recent studies have shown that TLR2 sequence in bank vole is under positive selection. Individuals with adaptive variants (c2 group) may have had an evolutionary advantage in environments with high frequency of infected vectors (mainly ticks).
The paper addresses the following issues: (1) does the bank vole response to odours of other rodent species by urine and faeces marking (2) does this reaction depend on the species, (3) does the amount of odour influence the marking, and (4) the response of bank voles to the presence of heterospecifics, and its comparison with the response of marking the odour deposited by these species. The study was conducted in a Ribo nigri-Alnetum swamp located in the Kampinos National Park, central Poland (52 [degrees] 20'N and 27 [degrees] 25'E). To observe scent marking, white paper sheets (15 x 21 cm) supplied with sponges (1 cm[^3]) soaked in odour of particular rodent species were exposed in the forest along a line ca 1200 m long. Odour donors were countryside species: a) phylogenetically close to the bank vole, such as Microtus agrestis (L.) and M. oeconomus (Pallas), b) sympatric, such as Apodemus flavicollis (Melchior) and A. sylvaticus (Melchior), or occupying a different habitat A. agrarius (Pallas), and allopatric species such as Meriones unguiculatus (Milne-Edwards), Mesocricetus auratus (Waterhouse), and Octodon degus (Bennet). Also sheets with the odour of bank vole and control sheets without odour were exposed. Marking was analysed basing on the number of marked sheets (marking extensity), and on the number of urine and faeces marks on sheets (marking intensity). During the three study years, a high marking extensity was observed for the odours of phylogenetically close species. The odours of sympatric species were marked less frequently and with a higher variability in successive years. The lowest marking extensity was found for geographically alien (allopatric) species. The mean number of marks per sheet did not differ significantly between the species. To examine the effect of odour quantity on marking, a line (ca 630 m long) made up of sheets provided with 1, 3, and 5 sponges with M. oeconomus and C. glareolus odour, and of control sheets was established. The increase in the number of sponges with heterospecific odour had no effect on the extensity and intensity of marking. Significant difference in marking extensity, but not in marking intensity, was found in the case of conspecific odour. The response of bank voles to the presence of heterospecifics was examined based on the number of captures in double-traps with a live individual. In the forest, a line of 30 double-traps placed every 10 m was established, containing single M. oeconomus, A. flavicollis, or C. glareolus. Bank voles were more often captured in traps with conspecifics than with heterospecofics. Thus, bank voles avoid encounters with heterospecifics but they do not avoid marking their odour (marking the heterospecific odour was not lower than marking conspecifics and control). It may suggest that under natural conditions, interspecific communication is largely mediated through olfactory cues.
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Social behaviour of the bank vole was video recorded during direct encounters between individuals under natural conditions. The apparatus consisted of miniature video cameras, a system of image processing and recording, and infrared emitters. This device enabled continuous 24-h observations at several sites simultaneously. The study was conducted in an alder swamp Ribonigri-Alnetum located in the Kampinos National Park, central Poland (52 [degrees] 20'N, 20 [degrees] 25'E). Observations were made in the late summers of 2002 and 2003 at six independent baited sites for 10 days and nights per each site. Rodents visiting the sites were individually marked by fur clipping. In sum, 13 053 visits to the sites and 1868 encounters between two marked individuals of C. glareolus were video recorded during 1440 hours of observation. It has been found that under natural conditions, bank voles most often avoided each other (55% of the encounters). In the case of close contacts they were aggressive (30%), rarely tolerant (7%), and during the remaining encounters they showed a mixed behaviour. The voles met mainly in the night (94% of the encounters) despite of 25% of their daily activity ran during the day. The frequency and character of encounters depended on the sex, age, and the origin of individuals. Encounters between males were more aggressive than between females (P <0.01). In encounters between opposite sexes, males were dominants (P <0.001). Individuals with a larger body mass were dominant in access to food (P <0.000). Cases of the dominance of juveniles over adults were interpreted as a result of the site of their origin. Social relations between individuals were characterised by persistence and repeatability in time. The results are compared with the literature describing experiments with animals kept in the laboratory or in enclosures, and field observations based on trapping techniques and telemetry.
Effects of heavy seed crop (mainly oak mast) in year 2003 and 2004 (no seed crops) on small mammal communities in three isolated stands of broad leaved lowland forests (area 60-280 ha) with different management were studied in southern Moravia in three sites: (1) close-to-nature not managed floodplain forest - Ulmeto-Fraxinetum carpineum (FF), (2) managed forest - Carpineto-Quercetum acerosum (MF), (3) pheasantry - Ulmeto-Fraxinetum carpineum, Saliceto-Alnetum and Carpineto-Quercetum acerosum, with a considerable number of biotopes including open areas (PH). We presumed the influence of seed production on mammal species, especially granivorous rodents. In the most numerous species (Apodemus flavicollis (Mel.), A. sylvaticus (L.) and Myodes glareolus (Pallas)) the demographic parameters (abundance, sex ratio), body mass, and body length were compared between popu-lations in 2003 and 2004 in each stand. Animals were trapped in snap mousetraps laid out in lines. In 2003 reproduction of both Apodemus sp. was extended to November in contrast to 2004, when it ceased already in the end of summer. Individual body mass of animals were significantly higher in 2004 vs. 2003 in all three species (A. flavicollis, P = 0.01; A. sylvaticus, P <0.01 and Myodes glareolus, P <0.05) but body length was higher only in case of A. sylvaticus (P <0.01). The forest stands under study in an intensively managed agroecosystem in southern Moravia play an important role as a refuge for small mammals.