Sex chromosomes are useful in elucidating the evolutionary factors affecting diversity and divergence. In particular, Y chromosome analyses may complement studies using mitochondrial DNA for inferring sex-specific population genetic processes. Y chromosome studies have been scarce due to limited access to genetic markers and the dynamic evolution of Y. Conserved Y-specific primers that could amplify a diverse set of mammalian species were developed from comparison of gametologous X and Y sequences. Y-specific sequence, generally more than one kb, was amplified for all 20 species examined. Intraspecific diversity on mammalian Y was found to be reduced even when male-biased mutation rate and effective population size were corrected for. A number of factors can cause this low variation on Y of which selection on a haploid chromosome seems most important. The field vole (Microtus agrestis), a common and well-studied small mammal in Eurasia, was examined for X and Y variability. Earlier studies on mtDNA had shown that the field vole is separated in two distinct lineages in Europe. The X and Y chromosome sequences confirmed the deep split and suggested that the two lineages of field vole should be reclassified as two separate species. Two distinct Y chromosome haplogroups were found in modern European cattle, distributed among breeds according to a north-south gradient. Ancient DNA analysis of European aurochsen showed the northern haplogroup to be the most common, possibly indicating local hybridization between domestic cows and wild aurochs bulls in Europe.

The bank vole (Microtus arvalis) develops glucose intolerance both when kept in captivity and in the wild state. Glucose intolerant bank voles kept in captivity exhibited polydipsia, polyuria, hyperglycemia, hyperinsulinemia, islet autoantibodies and a markedly changed islet structure resembling so–called hydropic degeneration. Islets showing hydropic degeneration have reduced β–cell mass. However, the relative islet size to total pancreas area was not changed. Pancreatic islet isolated from glucose intolerant bank voles had an altered islet function showing signs of being exposed to an increased functional demand on their β–cells. Also, islets from male bank voles seem more affected than the islets from females. Islets isolated from glucose tolerant male bank voles cultured for 5 days at 28 mM glucose did not reveal any change in insulin gene expression or insulin biosynthesis rate. However, islets from female bank voles displayed a glucose concentration dependent response. This suggests that there is gender difference in that, islets of female more easily than islets of males adapt to elevated glucose concentration. Furthermore, islets isolated from glucose tolerant males had reduced insulin gene expression after exposure to proinflammatory cytokines for 48 hrs. This effect seemed to be NO-independent since only a minor elevation of nitrite accumulation in the medium was seen, and the use of iNOS inhibitor could not counteract the cytokine effect. The observed response seen in bank vole islets upon exposure to various glucose concentrations or proinflammatory cytokines is similar to those seen in studies of human islets. The bank vole may therefore represent a novel animal model for the study of diabetes. An unresolved issue is the role of the Ljungan virus which is found in the bank vole colony. Bank voles developing glucose intolerance display features of both human type 1 and type 2 diabetes, where environmental factors seems to play an important role as determinant. Our findings suggest that bank voles bred in the laboratory may develop more of a type 2 diabetes. However, bank voles caught in nature instead may rather develop a type 1 form of the disease.

The background to the large-scale planting of Pinus contorta in northern Sweden is reviewed with an account of the distribution and characteristics ofPi nus contorta within its natural range in western North America. The threatsto successful planting of exotics are discussed in relation to the historicalbackground. Attention is also drawn to parasitic fungi which are infectingPi nus contorta in western Canada, and to the potential threat they representto the indigenous Pi nus sylvestris in Sweden.During a seven-year-period 100 provenances of Pi nus contorta have been investigatedannually with respect to different kinds of damage, primarilythose by parasitic fungi. The study indicates that damage to Pi nus contortaprimarily occurs during the first ten years after planting. Northern provenancesof Pi nus contorta are generally more resistant to pathogens than southernprovenances. Weather damage occurs almost every year among trees ofsouthern and coastal provenance. Even trees of northern provenance have sufferedfrom weather damage due to temperature oscillations during shoot elongation.Severe weather damage is a predisposing factor to infection by secondarypathogens primarily.Gremmeniella abietina. There is a minor correlation betweensevere weather damage and Phacidium infestans. Even northern provenancesof Pinus contorta are infected by Phacidi um infestans in high altitude standsin northern Sweden. Snow b light infection is, however, of a minor importanceto lodgepole pine than to Scots pine due to the rapid early growth of the former.The most productive plants of both Pinus contorta and Pinus sylvestrisare attacked by Phacidi um infestans. Plants not infected by snow b light havea lower height growth than those infected.Severe infection by Gremmeniella abietina has been recorded after voleattack, even among northern provenances of lodgepole pine. So far Pinus contortahas mainly been infected by the same fungi as Pinus sylvestris, with the |exception of Melampsora pinitorqua and Lophodermella sul ci gena. Pinus contorta iis, however more susceptible to infection by Gremmeniella abietina in connec- !tion with vole damage, depending on the more severe injuries to lodgepole pinethan to Scots pine.So far vole damage has been the most severe threat to Pinus contorta innorthern Sweden. Voles prefer lodgepole pine to Scots pine providing vole populationis moderate. At times of high vole populations even Scots pine suffersdamage. Voles attack Pinus contorta even 14 years after planting. The differencein frequency of vole damage among provenances strongly decreased with increasedvole population and repeated attacks from year to year.Tree tilting was first noted five to eight years after planting on sites exposedto strong winds and severe icing.In the central parts of northern Sweden most provenances of Pinus contortaare less attacked by pathogens than the indigenous Pinus sylvestris, and inorthern provenances of lodgepole pine are remarkably productive in thenorthernmost site, despite a relatively high frequency of Phacidium infestar^.Later investigations indicate, however, more severe damage to Pinuscontorta with increasing latitude and altitude in northern Sweden. / digitalisering@umu

SMULKIŲJŲ ŽINDUOLIŲ RŪŠINĖ SUDĖTIS IR MIGRACIJA NEMUNO DELTOS REGIONINIO PARKO UŽLIEJAMOSE PIEVOSE Agnė Janonytė Nemuno deltos regioninis parkas – vienintelis gamtinis kompleksas Lietuvoje ir visame Baltijos jūros regione, pasižymintis didele biotopų įvairove gana nedidelėje teritorijoje. Europinės svarbos buveinės – tai šiame parke esančios užliejamos pievos, turinčios unikalių biotos ir kraštovaizdžio elementų. Per Nemuno deltą eina Arktikos-Europos-Rytų Afrikos paukščių migracijos kelias, todėl didelė paukščių įvairovė patraukia ornitologų dėmesį, o smulkieji žinduoliai šiame regione mažai ištirti. Tyrimai buvo vykdomi nuo 2004 m. iki 2006 m. Rusnės saloje ir Žalgirių miške. Iš viso sugautas 621 individas, priklausantis 10 rūšių. Absoliutus dominantas buvo pelkinis pelėnas (M. oeconomus) kuris sudarė 55% visų individų. 2006 m. pelkinių pelėnų (M. oeconomus) bendras vados dydis buvo didesnis neužliejamose pievose – 6.20±0.38 (3–10) embrionai, palyginus su užliejamomis – 5.87±1.10 (2–11) embrionai. Jis priklausė nuo sezono. Pavasarį (gegužės mėn.) buvo didesnis užliejamose pievose, nei neužliejamose, atitinkamai: 10.0±1.0 ir 7.75±0.63 embrionai. Kiekvienais metais dalis Rusnės salos pievų užliejamos, o vandeniui atslūgus rekolonizuojamos. Rekolonizacija – laipsniškas procesas. Be to, smulkieji žinduoliai pasižymi skirtingomis šlapios pievos rekolonizacijos strategijomis. Pirmieji į šlapią pievą migruoja pelkiniai pelėnai (M. oeconomus) – tipiški drėgnų pievų gyventojai... [toliau žr. visą tekstą] / THE SPECIFIC STRUCTURE AND MIGRATION OF SMALL MAMMALS IN THE FLOODED MEADOWS OF THE NEMUNAS DELTA Agnė Janonytė The Nemunas Delta Regional Park (W. Lithuania) is characterized by exceptional habitat diversity. Flooded meadows on Rusnė Island border with non-flooded meadows and are separated by channels and dikes. Birds are well known in the area, as the site is enlisted as a habitat of the European importance and Ramsar site, but small mammals were scarcely investigated to date. Small mammals were trapped from June 2004 to October 2006. The total catch in both flooded and non-flooded meadows was 621 specimens. They belong to 10 species. The absolute dominant was root vole (M. oeconomus), with the share of 55% in the whole area. For the first time in Lithuania, the data on breeding of M. oeconomus were collected (32 cases). We found litter size differences according to the season and habitat. Totally, litter size of M. oeconomus in flooded meadows was 5.87±1.10 (2–11), while that in non-flooded meadows – 6.20±0.38 (3–10) embryo. In May, litter size was higher in flooded meadows – 10.0±1.0 vs. 7.75±0.63 embryo. Each year a part of the meadows is flooded and re-colonized. Migration is an inevitable process in small mammal ecology. Recolonization was found to be a progressive process, resulting in heterogeneous distribution of small mammals in the floodplain. From summer to autumn densities increased and specimens could be observed on larger distances from the non-flooded areas... [to full text]

Thesis (M.S.)--University of North Carolina at Wilmington, 2006. / Includes bibliographical references (leaves: 31-35)

The aim of the study was to find out the character of abundance fluctuations in a field vole population on immission clearings in the Krušné (Ore) Mountains during a 25 year series of trapping. Another aim was to find out the influence of climaticconditions on these cycles, concretely the influence of local climatic condition and the influence of North-Atlantic oscillation

This master thesis contains detailed description of the elements of Günthers?s vole social behaviour, from agonistic, investigative, and amicable, to reproductive behaviour. Each of the observed behavioural elements is put into context, interpreted, and compared with behaviour reported from other vole or rodent species. The resulting ethogram will be helpful in future ethological studies of this species.

Two crucial issues related to personality in non-human animals have been identified: firstly, the underlying 'causes' of personality and,secondly, the stability of behavioural repertoires (essentially the defining feature of personality) have both been the subject of long-standing debate. This thesis is focused on investigating stable inter- and intra- individual differences in the behaviour of wildcaught bank voles, Myodes glareolus (that varied according to mtDNA type), and in common voles, Microtus arvalis. The first study, using wild voles, revealed empirical evidence about the effects of sex and mtDNA type on individual differences in basal metabolic rate and in behaviour in the open field which provides measures of approach and avoidance (here, generically termed 'proactivity') and which relate to several theoretical conceptualisations of animal personality. The second study demonstrated the presence of stable individual differences in reactions to exposure to open field test and radial maze in common voles, which were shaped by the social environment and in turn, related to cognitive efficiency. The same species was used in the third study documenting the distinct temporal patterns of behavioural plasticity that manifested over repeated exposures to the open field test. We suggest that this distinct temporal patterning in habituation, whilst it varied over time, was predictable in nature and therefore a reflection of a stable underlying personality. To conclude, this body of thesis work draws together a number of influencing factors, and considers their contribution to animal personality.

The study investigated the effect of non-genetic social factors (represented by litter size, litter sex composition, and affinity to age cohort) on the development of consistent inter-specific differences in reaction to novelty in common voles (Microtus arvalis). The voles were tested in three behavioural experiments ? Forced Open Filed test (FOF), Unforced Open Field test (UFOF), and Radial-arm maze (RAM). A siginificant impact of compontents of social environment was detected.

No description available.