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Background: The emergence and re-emergence of zoonotic and vector-borne diseases are increasing in Europe. Prominent rodent-borne zoonotic viruses include Puumala hantavirus (PUUV; the causative agent of nephropathia epidemica, NE), lymphocytic choriomeningitis virus (LCMV), and orthopoxviruses (OPV). In addition, Ljungan virus (LV) is considered a potentially zoonotic virus. Objective: The aim of this study was to compare clinical picture between acute PUUV patients with and without additional rodent-borne viral infections, to investigate if concurrent infections influence disease severity. Study design: We evaluated seroprevalence of and seroconversions to LCMV, LV and OPV in 116 patients hospitalized for NE. Clinical and laboratory variables were closely monitored during hospital care. Results: A total of five LCMV, 15 LV, and one OPV seroconversions occurred. NE patients with LCMV seroconversions were younger, and had lower plasma creatinine concentrations and platelet counts than patients without LCMV seroconversions. No differences occurred in clinical or laboratory findings between patients with and without seroconversions to LV and OPV. We report, for the first time, LCMV seroprevalence in Finland, with 8.5% of NE patients seropositive for this virus. Seroprevalences for LV and OPV were 47.8% and 32.4%, respectively. Conclusion: Cases with LCMV seroconversions were statistically younger, had milder acute kidney injury and more severe thrombocytopenia than patients without LCMV. However, the low number of seroconversion cases precludes firm conclusions. Concurrent LV or OPV infections do not appear to influence clinical picture for NE patients. (C) 2016 Elsevier B.V. All rights reserved.

Mitsainas, George/0000-0003-4976-8275; Lindholm, Anna K/0000-0001-8460-9769; Mathias, Maria da Luz/0000-0003-3876-958X; Foerster, Daniel/0000-0002-6934-0404; Hauffe, Heidi Christine C/0000-0003-3098-8964; Threadgill, David W/0000-0003-3538-1635; Gabriel, Sofia I/0000-0003-3702-4631; Chesler, Elissa/0000-0002-5642-5062; Didion, John/0000-0002-8111-6261; solano, emanuela/0000-0001-8482-9243; Weinstock, George/0000-0002-2997-4592; McMullan, Rachel/0000-0003-0297-4549; Holt, James/0000-0001-6411-9236; Rehermann, Barbara/0000-0001-6832-9951 WOS: 000376170300001 PubMed: 26882987 A selective sweep is the result of strong positive selection driving newly occurring or standing genetic variants to fixation, and can dramatically alter the pattern and distribution of allelic diversity in a population. Population-level sequencing data have enabled discoveries of selective sweeps associated with genes involved in recent adaptations in many species. In contrast, much debate but little evidence addresses whether "selfish" genes are capable of fixation-thereby leaving signatures identical to classical selective sweeps-despite being neutral or deleterious to organismal fitness. We previously described R2d2, a large copy-number variant that causes nonrandom segregation of mouse Chromosome 2 in females due to meiotic drive. Here we show population-genetic data consistent with a selfish sweep driven by alleles of R2d2 with high copy number (R2d2(HC)) in natural populations. We replicate this finding inmultiple closed breeding populations from six outbred backgrounds segregating for R2d2 alleles. We find that R2d2(HC) rapidly increases in frequency, and in most cases becomes fixed in significantly fewer generations than can be explained by genetic drift. R2d2(HC) is also associated with significantly reduced litter sizes in heterozygous mothers, making it a true selfish allele. Our data provide direct evidence of populations actively undergoing selfish sweeps, and demonstrate that meiotic drive can rapidly alter the genomic landscape in favor of mutations with neutral or even negative effects on overall Darwinian fitness. Further study will reveal the incidence of selfish sweeps, and will elucidate the relative contributions of selfish genes, adaptation and genetic drift to evolution. National Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [T32GM067553, F30MH103925, P50GM076468, K01MH094406, DK-076050, DK-056350, AG038070]; National Science FoundationNational Science Foundation (NSF) [IOS-1121273]; Vaadia-BARD Postdoctoral Fellowship AwardUS-Israel Binational Science Foundation [FI-478-13]; U.S. Army Medical Research and Materiel CommandU.S. Army Medical Research & Materiel Command (USAMRMC) [W81XWH-11-1-0762]; Jackson Laboratory new investigator funds; National Center for Scientific Research, France [ISEM 2016-002]; University of Rome "La Sapienza"; Claraz-Stiftung; Natural Environment Research Council (UK)NERC Natural Environment Research Council; EU Human Capital and Mobility Programme [CHRX-CT93-0192]; Foundation for Science and Technology, PortugalPortuguese Foundation for Science and Technology [PTDC/BIA-EVF/116884/2010, UID/AMB/50017/2013]; Spanish "Ministerio de Ciencia y Tecnologia"Spanish Government [CGL2007-62111]; "Ministerio de Economia y Competitividad"Spanish Government [CGL2010-15243]; School of Medicine at University of North Carolina We wish to thank all the scientists and research personnel who collected and processed the samples used in this study. In particular we acknowledge Luanne Peters and Alex Hong-Tsen Yu for providing critical samples; Ryan Buus and T. Justin Gooch for isolating DNA for high-density genotyping of wild-caught mice; and Vicki Cappa, A. Cerveira, Guila Ganem, Ron and Annabelle Lesher, K. Said, Toni Schelts, Dan Small, and J. Tapisso for aiding in mouse trapping. We thank Muriel Davisson at the Jackson Laboratory for maintaining, for several decades, tissue samples from breeding colonies used to generate wild-derived inbred strains. We also thank Francis Collins, Jim Evans, Matthew Hahn, and Corbin Jones for comments on an earlier version of this manuscript. This work was supported by the National Institutes of Health T32GM067553 to J.P.D. and A.P.M., F30MH103925 to A.P.M., P50GM076468 to E.J.C., G.A.C., and F.P.M.V., K01MH094406 to J.J.C., DK-076050 and DK-056350 to D.P., AG038070 to G.A.C, and the intramural research program to B.R. and S.P.R.; National Science Foundation IOS-1121273 to T.G.; Vaadia-BARD Postdoctoral Fellowship Award FI-478-13 to L.Y.; U.S. Army Medical Research and Materiel Command W81XWH-11-1-0762 to C.J.B.; The Jackson Laboratory new investigator funds to E.J.C.; The National Center for Scientific Research, France to J.B.D. (this is contribution no ISEM 2016-002); the University of Rome "La Sapienza" to R.C. and E.S.; Claraz-Stiftung to S.G. and A.L.; Natural Environment Research Council (UK) to M.D.G., H.C.H., and J.B.S.; EU Human Capital and Mobility Programme (CHRX-CT93-0192) to H.C.H. and J.B.S.; Foundation for Science and Technology, Portugal PTDC/BIA-EVF/116884/2010 and UID/AMB/50017/2013 to S.I.G., M.L.M., and J.B.S.; Spanish "Ministerio de Ciencia y Tecnologia" CGL2007-62111 and "Ministerio de Economia y Competitividad" CGL2010-15243 to J.V.;and the Oliver Smithies Investigator funds provided by the School of Medicine at University of North Carolina to F.P.M.V. All data are made available at http://csbio.unc.edu/r2d2/. The authors declare no competing financial interests. Correspondence and requests for materials should be addressed to F.P.M.V. (fernando@med.unc.edu).

The aim of the present study was to investigate the genetic structure of the Valais shrew (Sorex antinorii) by a combined phylogeographical and landscape genetic approach, and thereby to infer the locations of glacial refugia and establish the influence of geographical barriers. We sequenced part of the mitochondrial cytochrome b (cyt b) gene of 179 individuals of S. antinorii sampled across the entire species' range. Six specimens attributed to S. arunchi were included in the analysis. The phylogeographical pattern was assessed by Bayesian molecular phylogenetic reconstruction, population genetic analyses, and a species distribution modelling (SDM)-based hindcasting approach. We also used landscape genetics (including isolation-by-resistance) to infer the determinants of current intra-specific genetic structure. The phylogeographical analysis revealed shallow divergence among haplotypes and no clear substructure within S. antinorii. The starlike structure of the median-joining network is consistent with population expansion from a single refugium, probably located in the Apennines. Long branches observed on the same network also suggest that another refugium may have existed in the north-eastern part of Italy. This result is consistent with SDM, which also suggests several habitable areas for S. antinorii in the Italian peninsula during the LGM. Therefore S. antinorii appears to have occupied disconnected glacial refugia in the Italian peninsula, supporting previous data for other species showing multiple refugia within southern refugial areas. By coupling genetic analyses and SDM, we were able to infer how past climatic suitability contributed to genetic divergence of populations. The genetic differentiation shown in the present study does not support the specific status of S. arunchi.

The wood tick Ixodes ricinus, one of the most common arthropod-borne disease vectors, is of increasing relevance for human and animal health in Europe. The aim of this study was to determine the relative contribution of several abiotic and biotic factors potentially affecting questing activity and local abundance of I. ricinus in Italy, considering the scale at which these factors interact with the host-seeking ticks. Within EDEN, a large-scale EU collaborative project on eco-epidemiology of vector-borne diseases, we collected questing ticks for three consecutive years using a standard protocol at eleven sites in the Italian Alps and Apennines. A total of 25 447 I. ricinus were collected. All sites showed the same annual pattern of tick activity (bimodal for nymphs and unimodal for larvae and adults), although the abundance of nymphs was statistically different between sites and years. A Generalized Linear Mixed Model and a Linear Mixed Model fitted to data for nymphs, showed that while the principal variables affecting the local abundance of questing ticks were saturation deficit (an index combining temperature and relative humidity) and red deer density, the most important variable affecting questing nymph activity was saturation deficit. As for the timing of seasonal emergence, we confirmed that the threshold temperature at this latitude for larvae is 10°C (mean maximum) while that for nymphs is 8°C.

Here we provide the first detailed description of the hybrid zone between the Cremona chromosomal race of house mouse (ICRE; 2n = 22) and the standard all-telocentric race (40ST; 2n = 40), with full karyotypes of 106 individuals from 17 localities along a transect between the 2 races to the west of Lake Garda in Northern Italy. The ICRE race is characterised by 9 pairs of metacentric chromosomes in a homozygous state and we use the metacentric frequency data along the transect to fit tanh metacentric clines. The clines are narrow (5–8 km, standardised width) suggesting low hybrid fitness. However, the lack of occurrence of ICRE × 40ST F1 hybrids and presence of other hybrid types suggests that the F1 hybrids initially produced in this hybrid zone were at least partially fertile, despite having 9 meiotic trivalent configurations. We apply the same cline-fitting methodology to 3 previously studied hybrid zones between metacentric races and the 40ST race. Taken together with published clinal data on 4 further metacentric-40ST hybrid zones, we are able to make objective generalisations on the characteristics of such zones in the house mouse. Zones involving 22-chromosome races are narrower, on average, than other metacentric-40ST hybrid zones and do not show a tendency towards the generation of new races as found with zones where the metacentric race has a higher 2n. It appears that metacentric-40ST zones are unlikely to be sites of speciation (even when a 22-chromosome race is involved), although a mosaic structure to the hybrid zone may enhance this possibility. We make a comparison between metacentric-40ST zones and contacts between 2 metacentric races, for a comprehensive perspective of chromosomal hybrid zones in the house mouse.

To the Editor: The tick-borne pathogen Anaplasma phagocytophilum is an increasing potential public health threat across Europe. Its intraspecific genetic variability is associated with different reservoir host and vector tick species (1–4); however, the roles of various vertebrates as competent reservoirs of A. phagocytophilum in Europe need clarification (1). During March 2011–June 2013, we studied the prevalence and genetic variability of A. phagocytophilum in 821 questing Ixodes ricinus ticks (155 adults [A], 666 nymphs [N] collected by standard blanket dragging) and 284 engorged ixodid ticks (61A, 191N, 21 larvae [L]) collected from humans, dogs, sheep, hunted wild ungulates, live-trapped birds, and rodents. Blood samples from 1,295 rodents (yellow-necked mice [Apodemus flavicollis]), bank voles [Myodes glareolus], and harvest mice [Moscardinus avellanarius]) were also analyzed. All animal-handling procedures and ethical issues were approved by the Provincial Wildlife Management Committee (authorization n. 595 issued on 04.05.2011). The study site, Valle dei Laghi (northeastern Italian Alps), is a well-studied focus of emerging tick-borne pathogens in northern Italy (4).

Although the standard karyotype of the western house mouse (Mus musculus domesticus) consists entirely of telocentric chromosomes, there are over 100 populations across western Europe and North Africa characterized by different sets of metacentrics formed by Robertsonian fusions and whole-arm reciprocal translocations. Here we report the discovery of a new metacentric population from Valchiavenna, northern Italy, that we have named the ‘Lower Valchiavenna population’ (abbreviated as ILVC). This metacentric population is found in villages and on farms over a 10-kilometer stretch comprising the southern half of Valchiavenna. ILVC is characterized by the metacentrics 1.18, 2.4, 3.8, 5.15, 6.7, 9.14, 10.12, 11.13 and 16.17, and appears to be closely related to the Chiasso population (CHCH), which possesses the same set of metacentrics except 1.18. We discuss the evolutionary origin of ILVC in relation to human occupation of the region. We also suggest that the geographical position of ILVC between 2 other metacentric populations with entirely different sets of metacentrics (Chiavenna, ICHI, and lower Valtellina, ILVA) may provide 2 additional chromosomal hybrid zones for the study of speciation.

There are at least 24 different karyotypic races of house mouse in the central Alps, each characterized by a different complement of ancestral acrocentric and derived metacentric chromosomes; altogether 55 different metacentric chromosomes have been described from the region. We argue that this chromosome variation largely arose in situ. If these races were to make contact, in most cases they would produce F1 hybrids with substantial infertility (sometimes complete sterility), due to nondisjunction and germ cell death associated with the formation of long-chain and/or ring configurations at meiosis. We present fertility estimates to confirm this for two particular hybrid types, one of which demonstrates male-limited sterility (in accordance with Haldane's Rule). As well as a model for speciation in allopatry, the Alpine mouse populations are of interest with regards speciation in parapatry: we discuss a possible reinforcement event. Raciation of house mice appears to have happened on numerous occasions within the central Alps. To investigate one possible source of new karyotypic races, we use a two-dimensional stepping stone model to examine the generation of recombinant races within chromosomal hybrid zones. Using field-derived ecological data and laboratory-derived fertility estimates, we show that hybrid karyotypic races can be generated at a reasonable frequency in simulations. Our model complements others developed for flowering plants that also emphasize the potential of chromosomal hybrid zones in generating new stable karyotypic forms.

A substantial portion of today's biodiversity is attributed to the climatic oscillations of the Pleistocene Ice Ages. Gradual but dramatic climate changes were accompanied by expansion, contraction, and isolation of populations, promoting the accumulation of genome differences and adaptations in refugial populations and resulting in allopatric differentiation in a variety of taxa. In the present study, partial mitochondrial DNA sequences of the widely distributed European brown hare (Lepus europaeus) were analyzed to test whether the species' present genetic structure is the result of postglacial re-colonization of Europe from Asia Minor (clade A) and the Balkans (clade B) only, as suggested previously, or if additional refugia are likely. Analyses indicated the presence of an additional refugium (Italy, clade I). The genealogic network of Italian hares displayed the tree-like structure expected from refugial populations, whereas central European brown hare haplotypes revealed a clear star-phylogeny indicative of past-bottleneck population growth. This population size expansion, which was confirmed by mismatch analysis, was estimated to have occurred ∼50-55 thousand years ago (kya). The divergence of clade A* from the remaining matrilines is estimated at 239 kya, whereas the divergence of the ancestors of clades B* and I from A*occurred about 128 kya. © 2008 Springer-Verlag.

A selective sweep is the result of strong positive selection rapidly driving newly occurring or standing genetic variants to fixation, and can dramatically alter the pattern and distribution of allelic diversity in a population or species. Population-level sequencing data have enabled discoveries of selective sweeps associated with genes involved in recent adaptations in many species. In contrast, much debate but little empirical evidence addresses whether "selfish" genes are capable of fixation -- thereby leaving signatures identical to classical selective sweeps -- despite being neutral or deleterious to organismal fitness. We previously reported the discovery of R2d2, a large copy-number variant that causes non-random segregation of mouse Chromosome 2 in females due to meiotic drive. Here we show population-genetic data consistent with a "selfish" sweep driven by alleles of R2d2 with high copy number (R2d2HC) in natural populations of mice. We replicate this finding in multiple closed breeding populations from six outbred backgrounds segregating for R2d2 alleles. We find that R2d2HC rapidly increases in frequency, and in most cases becomes fixed in significantly fewer generations than can be explained by genetic drift. R2d2HC is also associated with significantly reduced litter sizes in heterozygosity, making it a true selfish allele. Our data provide direct evidence of populations actively undergoing selfish sweeps, and demonstrate that meiotic drive can rapidly alter the genomic landscape in favor of mutations with neutral or even negative effects on overall Darwinian fitness. Further study will reveal the incidence of selfish sweeps, and will elucidate the relative contributions of selfish genes, adaptation and genetic drift to evolution.

The expansion of agriculture is shrinking pristine forest areas worldwide, jeopardizing the persistence of their wild inhabitants. The Udzungwa red colobus monkey (Procolobus gordonorum) is among the most threatened primate species in Africa. Primarily arboreal and highly sensitive to hunting and habitat destruction, they provide a critical model to understanding whether anthropogenic disturbance impacts gut microbiota diversity. We sampled seven social groups inhabiting two forests (disturbed vs. undisturbed) in the Udzungwa Mountains of Tanzania. While Ruminococcaceae and Lachnospiraceae dominated in all individuals, reflecting their role in extracting energy from folivorous diets, analysis of genus composition showed a marked diversification across habitats, with gut microbiota α-diversity significantly higher in the undisturbed forest. Functional analysis suggests that such variation may be associated with food plant diversity in natural versus human-modified habitats, requiring metabolic pathways to digest xenobiotics. Thus, the effects of changes in gut microbiota should not be ignored to conserve endangered populations.

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich. This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. Understanding the causes and effects of species invasions is a priority in ecology and conservation biology. One of the crucial steps in evaluating the impact of invasive species is to map changes in their actual and potential distribution and relative abundance across a wide region over an appropriate time span. While direct and indirect remote sensing approaches have long been used to assess the invasion of plant species, the distribution of invasive animals is mainly based on indirect methods that rely on environmental proxies of conditions suitable for colonization by a particular species. The aim of this article is to review recent efforts in the predictive modelling of the spread of both plant and animal invasive species using remote sensing, and to stimulate debate on the potential use of remote sensing in biological invasion monitoring and forecasting. Specifically, the challenges and drawbacks of remote sensing techniques are discussed in relation to: i) developing species distribution models, and ii) studying life cycle changes and phenological variations. Finally, the paper addresses the open challenges and pitfalls of remote sensing for biological invasion studies including sensor characteristics, upscaling and downscaling in species distribution models, and uncertainty of results.

This review evaluates direct (live-trapping) and indirect (genetic) methods to study dispersal in wild house mice (Mus musculus) and summarizes field and experimental data to examine the causes and consequences of dispersal. Commensal house mice (associated with human habitations, farms, food stores and other anthropogenic habitats) typically show lower rates of dispersal than feral house mice (living in crops, natural and semi-natural habitats). However, early claims of long-term fine-scale genetic structure in commensal house mice (due to low rates of dispersal) are not supported by recent data. Dispersal becomes obligatory when habitat conditions deteriorate, but most dispersal occurs below the local environmental carrying capacity and is due to social interactions with conspecifics. Excursions are relatively frequent and probably allow mice to assess the quality of habitats before dispersing. Young males have the greatest tendency to disperse, apparently prompted mainly by aggressive interactions with dominant males. If they do disperse, females integrate into new groups more easily than do males. Dispersing house mice risk loss of condition or death, but may gain reproductive opportunities on arrival in a new location. House mice can be transported passively as stowaways with humans; this contributes to population persistence and genetic structure at regional scales and has allowed house mice to spread world-wide.

Although the standard karyotype of the western house mouse, Mus musculus domesticus, consists entirely of acrocentric chromosomes, there are 97 distinct 'populations' that are characterized by various combinations of metacentric chromosomes that have arisen by Robertsonian (Rb) fusions and whole-arm reciprocal translocations (WARTs). In this review we discuss the processes behind the origin and fixation of these rearrangements and then present a unified list of all known metacentric populations and evaluate their phylogenetic relationships. Eleven independent phylogeographical 'systems', each consisting of 2-25 metacentric populations, were identified in Scotland, Denmark, Northern Europe-Northern Switzerland, Southern Switzerland, Northern Italy, Croatia, Spain, Central-Southern Italy, Peloponnesus, Mainland Greece and Madeira. There are six isolated metacentric populations that do not belong to any of these systems. To generate phylogenies of the metacentric populations within each system, we determined those outcomes with the fewest steps regarding accumulation of metacentrics by Rb fusions, WARTs and zonal raciation and taking into account geographical proximity. These phylogenies should be viewed as working hypotheses that will be refined with further chromosomal and molecular data and improvements in methods of phylogenetic reconstruction. The list of metacentric populations and our phylogenies are also published electronically and can be accessed at http://www.studenec.ivb.cz/Projects/RobertsonianMice/.

Red squirrels (Sciurus vulgaris) are widely distributed throughout Eurasia, occurring in many types of coniferous and mixed-deciduous forests. In fragmented landscapes, small and partly isolated populations with low immigration rates show reduced genetic diversity, but reforestation can increase gene flow and restore levels of genetic variation in a few decades. No studies have so far investigated the genetic structure of red squirrel in large, continuous forests. The Italian Alps are presently characterized by almost continuous, recently reconnected forest habitats, that were affected by deep landscape changes during last glaciations but remained mostly unchanged between 10 000 and 200 years bp, when forest cover was heavily reduced. In this study we analyse patterns of genetic variability of red squirrels in and between seven sites distributed over 250 km of Alpine habitat, using mitochondrial DNA (mtDNA) and microsatellites. We use isolation-by-distance (IBD) models to investigate the relative importance that past (Pleistocene glaciations) and recent (fragmentation, bottlenecks) events had on the present genetic situation. Both nuclear and mtDNA data indicate a significant differentiation among study sites and a significant correlation between genetic and geographical distance only over a large scale. No recent bottlenecks are recorded through microsatellites and demographic models strongly support equilibrium between gene flow and drift; however, mtDNA suggests that there may have been local demographic crashes, probably in correspondence with the 19th-century forest fragmentation. These findings indicate that local landscape factors other than geographical distance per se, such as barriers of unsuitable habitat, affect gene flow and determine differentiation.

The reintroduction of wild boar from central Europe after World War II has contributed substantially to the range expansion of this species in Italy, where indiscriminate hunting in earlier times resulted in extreme demographic reduction. However, the genetic impact of such processes is not well-understood. In this study, 105 individuals from Italian and Hungarian wild boar populations were characterized for nine autosomal microsatellite loci. The Hungarian samples, and two central Italian samples from protected areas (parks) where reintroduction is not documented, were assumed to be representative of the genetic composition of the source and the target populations in the reintroduction process, respectively. Animals hunted in the wild in the Florence area of Tuscany (Italy) were then studied to identify the effects of reintroduction. The results we obtained can be summarized as follows: (i) none of the populations analysed shows genetic evidence of demographic decline; (ii) the three parental populations from Italy and Hungary are genetically distinct; however, the low level of divergence appears in conflict with the naming of the Italian and the European subspecies (Sus scrofa majori and Sus scrofa scrofa, respectively); in addition, the Italian groups appear to be as divergent from each other as they are from the Hungarian population; (iii) most of the individuals hunted near Florence are genetically intermediate between the parental groups, suggesting that hybridization has occurred in this area, the average introgression of Hungarian genotypes is 13%, but approximately 45% of the genetic pool of these individuals can not be directly attributed to any of the parental populations we analysed; (iv) analysis of microsatellite loci, though in a limited number, is an important tool for estimating the genetic effect of reintroduction in the wild boar, and therefore for the development of conservation and management strategies for this species.

PCR diagnostics detected 100% prevalence of Helicobacter in 425 wild house mice ( Mus musculus ) from across central Europe. Of seven species identified, the five most frequent were Helicobacter rodentium (78%), H. typhlonius (53%), H. hepaticus (41%), H. bilis (30%), and H. muridarum (1%). Double infections were more common (42%) than single (30%) and triple (21%) infections. Wild house mice could be considered potential reservoirs of Helicobacter strains for both humans and other vertebrates.

We describe Stammericaris destillans sp. nov., and re-describe Stammericaris trinacriae (Pesce, Galassi and Cottarelli 1988) based on new material. The two species were collected from epikarstic drips and pools on the floor of two different caves: a karstic (Molara Cave) and a gypsum (Entella Cave) cave, respectively, both located in Sicily, Italy. We also report the presence of previously undescribed structures for Stammericaris amyclaea (Cottarelli 1969) and Stammericaris orcina (Chappuis 1938). Phylogenetic analyses of the mitochondrial COI and ribosomal 18S genes attributed the new species to Stammericaris Jakobi 1972, therefore the structure of the male P4 endopod of S. destillans is interpreted as an autapomorphy; other morphological features (structure of male antennule and P3, of female P3; inner ornamentation of P1 basis, armature of caudal rami and shape and armature of P5 of both sexes) correspond to those typical of the genus. Hence, we slithgly amended the generic diagnosis. [zoobank.org:pub:4CC84A0C-C511-4388-9728-41647E58097A]

Ljungan virus (LV) is a picornavirus originally isolated from Swedish bank voles (Myodes glareolus) in 1998. The association of LV with human disease has been debated ever since, but fundamental data on the ecology of the virus are still lacking. Here we present results of the first intensive study on the prevalence of LV in bank voles trapped in Fennoscandia (Sweden and Finland) from 2009–12 as determined by PCR. Using an LV-specific real-time reverse transcriptase PCR, LV was detected in the liver of 73 out of 452 (16.2%) individuals and in 13 out of 17 sampling sites across Sweden and Finland (mean per site prevalence 16%, SE 3%, range 0–50%). We found more infected animals in autumn compared to spring, and lighter and heavier individuals had a higher prevalence than those with intermediate body masses. The result that LV prevalence is also lower in heavier (i.e., older) animals suggests for the first time that LV infection is not persistent in rodents.

We report Ljungan virus infection in Eurasian red squirrels (Sciurus vulgaris) for the first time, and extend the known distribution of adenoviruses in both native red squirrels and alien gray squirrels (Sciurus carolinensis) to southern Europe.

Following the discovery of over 40 Robertsonian (Rb) races of Mus musculus domesticus in Europe and North Africa, the house mouse has been studied extensively as an ideal model to determine the chromosomal changes that may cause or accompany speciation. Current models of chromosomal speciation are based on the assumption that heterozygous individuals have a particularly low fertility, although recent studies indicate otherwise. Despite their importance, fertility estimates for the house mouse are incomplete because traditional measurements, such as anaphase I nondisjunction and germ cell death, are rarely estimated in conjunction with litter size. In an attempt to bridge this gap, we have taken advantage of the house mouse hybrid zone in Upper Valtellina (Lombardy, Italy) in which five Rb races interbreed. We present data on the fertility of naturally occurring (“wild-caught”) hybrids and of offspring from laboratory crosses of wild-caught mice (“laboratory-reared”), using various measurements. Wild-caught mice heterozygous for one fusion were more infertile than predicted from past studies, possibly due to genic hybridity; laboratory-reared heterozygotes carrying seven or eight trivalents at meiosis I and heterozygotes carrying one pentavalent also had low fertilities. These low fertilities are especially significant given the probable occurrence of a reinforcement event in Upper Valtellina.

Speciation may be promoted in hybrid zones if there is an interruption to gene flow between the hybridizing forms. For hybridizing chromosome races of the house mouse in Valtellina (Italy), distinguished by whole-arm chromosomal rearrangements, previous studies have shown that there is greater interruption to gene flow at the centromeres of chromosomes that differ between the races than at distal regions of the same chromosome or at the centromeres of other chromosomes. Here, by increasing the number of markers along race-specific chromosomes, we reveal a decay in between-race genetic differentiation from the centromere to the distal telomere. For the first time, we use simulation models to investigate the possible role of recombination suppression and hybrid breakdown in generating this pattern. We also consider epistasis and selective sweeps as explanations for isolated chromosomal regions away from the centromere showing differentiation between the races. Hybrid breakdown alone is the simplest explanation for the decay in genetic differentiation with distance from the centromere. Robertsonian fusions/whole-arm reciprocal translocations are common chromosomal rearrangements characterizing both closely related species and races within species, and this fine-scale empirical analysis suggests that the unfitness associated with these rearrangements in the heterozygous state may contribute to the speciation process.

Policy makers and managers are increasingly called upon to assess the state of biodiversity, and make decisions regarding potential interventions. Genetic tools are well-recognised in the research community as a powerful approach to evaluate species and population status, reveal ecological and demographic processes, and inform nature conservation decisions. The wealth of genetic data and power of genetic methods are rapidly growing, but the consideration of genetic information and concerns in policy and management is limited by the currently low capacity of decision-makers to access and apply genetic resources. Here we describe a freely available, user-friendly online resource for decision-makers at local and national levels (http://congressgenetics.eu), which increases access to current knowledge, facilitates implementation of studies and interpretation of available data, and fosters collaboration between researchers and practitioners. This resource was created in partnership with conservation practitioners across the European Union, and includes a spectrum of taxa, ecosystems and conservation issues. Our goals here are to (1) introduce the rationale and context, (2) describe the specific tools (knowledge summaries, publications database, decision making tool, project planning tool, forum, community directory), and the challenges they help solve, and (3) summarise lessons learned. This article provides an outlook and model for similar efforts to build policy and management capacity

Ljungan virus (LV, genus Parechovirus, family Picornaviridae) is considered currently to be a rodent-borne virus. Despite suggested human disease associations, its zoonotic potential remains unclear. To date, LV antibody prevalence in both humans and rodents has not been studied. In this study, two different LV immunofluorescence assays (LV IFAs) were developed with LV genotypes 1 (LV strain 87-012G) and 2 (LV strain 145SLG), and cross-neutralization and -reaction studies were carried out with LV strain 145SLG. Finally, a panel of 37 Finnish sera was screened for anti-LV antibodies using two different LV IFAs (LV 145SLG and LV 87-012G) and a neutralization (NT) assay (LV 145SLG), and 50 samples from Myodes glareolus by LV IFA (LV 145SLG). The LV seroprevalence study showed 38% and 18% positivity in humans and M. glareolus, respectively. LV IFAs and NT assays were compared, and the results were in good agreement. The data are the first evidence of humans and rodents coming into contact with LV in Finland. Additional studies are required in order to acquire a better understanding of the prevalence, epidemiological patterns and possible disease association of LV infections.

Speciation may be promoted in hybrid zones if there is an interruption to gene flow between the hybridizing forms. For hybridizing chromosome races of the house mouse in Valtellina (Italy), distinguished by whole-arm chromosomal rearrangements, previous studies have shown that there is greater interruption to gene flow at the centromeres of chromosomes that differ between the races than at distal regions of the same chromosome or at the centromeres of other chromosomes. Here, by increasing the number of markers along race-specific chromosomes, we reveal a decay in between-race genetic differentiation from the centromere to the distal telomere. For the first time, we use simulation models to investigate the possible role of recombination suppression and hybrid breakdown in generating this pattern. We also consider epistasis and selective sweeps as explanations for isolated chromosomal regions away from the centromere showing differentiation between the races. Hybrid breakdown alone is the simplest explanation for the decay in genetic differentiation with distance from the centromere. Robertsonian fusions/whole-arm reciprocal translocations are common chromosomal rearrangements characterizing both closely related species and races within species, and this fine-scale empirical analysis suggests that the unfitness associated with these rearrangements in the heterozygous state may contribute to the speciation process.

The causal relationship between species diversity and environmental (landscape) heterogeneity has been a long-lasting interest among ecologists. In fact, environmental heterogeneity is considered to be one of the main factors associated with biodiversity given that areas with higher environmental heterogeneity can host more species due to their higher number of available niches. In particular, entropy (also referred to as “heterogeneity”) measured by the spatial variation of remotely sensed spectral signals has been proposed as a proxy for species diversity. The aim of this book chapter is to review the main spatial algorithms for measuring landscape heterogeneity based on remote sensing.

Tick borne encephalitis (TBE) is endemic to eastern and central Europe with broad temporal and spatial variation in infection risk. Although many studies have focused on understanding the environmental and socio-economic factors affecting exposure of humans to TBE, comparatively little research has been devoted to assessing the underlying ecological mechanisms of TBE occurrence in enzootic cycles, and therefore TBE hazard. The aim of this study was to evaluate the effect of the main ungulate tick hosts on the pattern of tick infestation in rodents and TBE occurrence in rodents and questing adult ticks. In this empirical study, we considered three areas where endemic human TBE occurs and three control sites having no reported human TBE cases. In these six sites located in Italy and Slovakia, we assessed deer density using the pellet group count-plot sampling technique, collected questing ticks, live-trapped rodents (primarily Apodemus flavicollis and Myodes glareolus) and counted ticks feeding on rodents. Both rodents and questing ticks were screened for TBE infection. TBE infection in ticks and rodents was positively associated with the number of co-feeding ticks on rodents and negatively correlated with deer density. We hypothesise that the negative relationship between deer density and TBE occurrence on a local scale (defined by the minimum overlapping area of host species) could be attributed to deer (incompetent hosts) diverting questing ticks from rodents (competent hosts), know as the 'dilution effect hypothesis'. We observed that, after an initial increase, the number of ticks feeding on rodents reached a peak for an intermediate value of estimated deer density and then decreased. Therefore, while at a regional scale, tick host availability has already been shown to be directly correlated with TBE distribution, our results suggest that the interactions between deer, rodents and ticks are much more complex on a local scale, supporting the possibility of a dilution effect for TBE.

Onymacris rugatipennis, a tenebrionid from the Namib Desert, is currently classified as having two subspecies distinguishable in the adult phase (Penrith, 1975). However, other authors have suggested species status for the ‘waxy’ and ‘non-waxy’ types on the basis of larval characteristics and the apparent lack of introgression of adult morphology in areas of overlap (Koch, 1962; Schulze, 1962, 1964; Osberg, Hanrahan & Seely, 1986). In a previous paper (Hauffe & Seely, In press) we took the view that waxiness in O. rugatipennis is a continuously varying character that does not define major taxonomic subdivisions. Behavioural observations reported here support this idea; daily activity patterns and precopulatory behaviour of waxy and non-waxy adult O. rugatipennis is very similar under the same environmental conditions. In addition, allozyme analysis indicates that there is little genetic divergence between populations across the range of this species.

International audience; Despite improvements in prevention, diagnosis and treatment, Lyme borreliosis (LB) is still the most common arthropod-borne disease in temperate regions of the northern hemisphere, with risk of infection associated with occupation (e.g. forestry work) and certain outdoor recreational activities (e.g. mushroom collecting). In Europe, LB is caused by infection with one or more pathogenic European genospecies of the spirochaete Borrelia burgdorferi sensu lato, mainly transmitted by the tick Ixodes ricinus. Recent surveys show that the overall prevalence of LB may be stabilising, but its geographical distribution is increasing. In addition, much remains to be discovered about the factors affecting genospecific prevalence, transmission and virulence, although avoidance of tick bite still appears to be the most efficient preventive measure. Uniform, European-wide surveillance programmes (particularly on a local scale) and standardisation of diagnostic tests and treatments are still urgently needed, especially in the light of climate change scenarios and land-use and socio-economic changes. Improved epidemiological knowledge will also aid development of more accurate risk prediction models for LB. Studies on the effects of biodiversity loss and ecosystem changes on LB emergence may identify new paradigms for the prevention and control of LB and other tick-borne diseases.

The Robertsonian fusion is a common chromosomal mutation among mammal species and is especially prevalent in the West European house mouse, Mus musculus domesticus. More than 40 races of the house mouse exist in Europe, including the famous "tobacco mouse" (Poschiavo race) of Val Poschiavo, Switzerland. Documented here is the discovery of an extreme case of karyotypic variation in the neighboring Upper Valtellina, Italy. In a 20-km stretch of the valley, 32 karyotypes were observed, including five chromosomal races and 27 hybrid types. One previously unknown race is reported, the "Mid Valtellina" race, with a diploid number of 2n = 24 and the Robertsonian fusions Rb(1.3), Rb(4.6), Rb(5.15), Rb(7.18), Rb(8.12), Rb(9.14), Rb(1 1.13), and Rb(1 6.17). The Poschiavo race (2n = 26), Upper Valtellina race (2n = 24), Lower Valtellina race (2n = 22) and all-acrocentric race (2n = 40) were also present. The races form a patchy distribution, which we term a "mottled hybrid zone." Geographical position, isolation, extinction, recoloni- zation, and selection against hybrids are all believed to be instrumental in the origin and evolution of this complex system. Previous studies of house mice from Upper Valtellina indicated that two of the races in the valley (the Upper Valtellina and Poschiavo races) may have speciated in the village of Migiondo. We discuss the possibility that there may have been a reinforcement event in this village.

Identified in 1998, Ljungan virus (LV; Picornaviridae) causes type 1 diabetes–like symptoms and myocarditis in bank voles (Myodes glareolus) from Sweden and Denmark, and may be a zoonotic agent of several important diseases (e.g., intrauterine fetal death, type 1 diabetes, Guillain-Barre syndrome, and myocarditis). Using a real-time reverse transcriptase–polymerase chain reaction assay and sequence analysis, we detected LV in bank voles, and for the first time, in yellow-necked mice (Apodemus flavicollis) collected during 2006 from a site in northern Italy. The global distribution of LV and its role as a mammalian pathogen deserve further attention.

Laboratory house mice (Mus musculus) with the XXY condition can be generated with ease and have been used as a biomedical model. However, although the XXY constitution has been described in humans and many domestic and wild mammal species, and a very large number of wild house mice have been karyotyped previously, no wild individuals of M. musculus with an XXY karyotype have ever been reported. Therefore, it is rather extraordinary that two wild XXY house mice were caught by us on two different farms in northern Italy in 2008. Except for the extra X chromosome, one male had a standard karyotype (2n = 40) and the other, the karyotype of the Cremona metacentric population (2n = 22). In this paper, the phenotype of these two individuals is described. Observations for both of these wild males agree with those of laboratory XXY mice, i.e., they had a normal body mass and appearance, but significantly smaller testes than normal, and no visible germ cells. The incidence of the XXY chromosome anomaly in wild mice (two among 5,123 wild mice surveyed by us and our colleagues, i.e., approximately 0.08% among wild-caught males) is intermediate between that found in male laboratory mice (approximately 0.04%) and that found in male humans (0.2%).

The work reported here was funded by the Turkish government (to İ.G.), the Natural Environment Research Council, UK (to C.L.P., M.D.G., D.W.F., H.C.H. and J.B.S.), the Programme Alßan of the European Union (to M.D.G.), the British Council (to J.V., M.J.L.-F. and J.B.S.) and the Spanish Ministerio de Ciencia y Tecnología (to M.A.S.-F.). In the house mouse there are numerous chromosomal races distinguished by different combinations of metacentric chromosomes. These may come into contact with each other and with the ancestral all-acrocentric race, and form hybrid zones. The chromosomal clines that make up these hybrid zones may be coincident or separated from each other (staggered). Such staggered hybrid zones are interesting because they may include populations of individuals homozygous for a mix of features of the hybridising races. We review the characteristics of four staggered hybrid zones in the house mouse and discuss whether they are examples of primary or secondary contact and whether they represent reticulate evolution or not. However, the most important aspect of staggered hybrid zones is that the homozygous populations within the zones have the potential to expand their distributions and become new races (a process termed 'zonal raciation'). In this way they can add to the total 'stock' of chromosomal races in the species concerned. Speciation is an infrequent phenomenon that may involve an unusual set of circumstances. Each one of the products of zonal raciation has the potential to become a new species and by having more races increases the chance of a speciation event.

The chamois is a useful species with which to investigate the combined genetic impact of habitat fragmentation, over hunting, and translocations. Genetic variation within and between chamois (genus Rupicapra) populations was analyzed in 259 individuals from 16 sampling sites located in Italy, Spain, Slovakia, and the Czech Republic. Two mitochondrial DNA markers (control region and cytochrome b) and 11 nuclear microsatellites were typed. The principal results of this study can be summarized as follows: 1) high and significant differentiation between almost all chamois populations is observed even on a microgeographical scale, probably caused by the patchy distribution of this species, sharp geographical barriers to gene flow, and drift effects related to recent bottlenecks; 2) historical translocation events have left a clear genetic signature, including interspecific hybridization in some Alpine localities; 3) the Apennine subspecies of chamois, Rupicapra pyrenaica ornata, shows a high and similar level of divergence (about 1.5 My) from the Pyrenean (Rupicapra pyrenaica pyrenaica) and the Alpine (Rupicapra rupicapra) chamois; therefore, the specific status of these taxa should be revised. These results confirm the potential of population genetic analyses to dissect and interpret complex patterns of diversity in order to define factors important to conservation and management.

Background The Western Tick-borne encephalitis (TBE) virus often causes devastating or lethal disease. In Europe, the number of human TBE cases has increased dramatically over the last decade, risk areas are expanding and new foci are being discovered every year. The early localisation of new TBE foci and the identification of the main risk factors associated with disease emergence represent a priority for the public health community. Although a number of socio-economic parameters have been suggested to explain TBE upsurges in eastern Europe, the principal driving factors in relatively stable western European countries have not been identified. Methodology/Principal Findings In this paper, we analyse the correlation between the upsurge of TBE in 17 alpine provinces in northern Italy from 1992 to 2006 with climatic variables, forest structure (as a proxy for small mammal reservoir host abundance), and abundance of the principal large vertebrate tick host (roe deer), using datasets available for the last 40 years. No significant differences between the pattern of changes in climatic variables in provinces where TBE has emerged compared to provinces were no clinical TBE cases have been observed to date. Instead, the best model for explaining the increase in TBE incidence in humans in this area include changes in forest structure, in particular the ratio of coppice to high stand forest, and the density of roe deer. Conclusion/Significance Substantial changes in vegetation structure that improve habitat suitability for the main TBE reservoir hosts (small mammals), as well as an increase in roe deer abundance due to changes in land and wildlife management practices, are likely to be among the most crucial factors affecting the circulation potential of Western TBE virus and, consequently, the risk of TBE emergence in humans in western Europe. We believe our approach will be useful in predicting TBE risk on a wider scale.

Two house mouse subspecies, Mus musculus domesticus and Mus musculus musculus, form a hybrid zone in Europe and represent a suitable model for inferring the genes contributing to isolation barriers between parental taxa. Despite long-term intensive studies of this hybrid zone, we still know relatively little about the causes and mechanisms maintaining the 2 taxa as separate subspecies; therefore, to gain insight into this process, we developed 8 wild-derived inbred house mouse strains. In order to produce strains as pure domesticus or musculus genomes as possible, the individuals used to establish the breeding colony for the 3 domesticus and 2 of the musculus strains were captured in the Czech Republic from wild populations at extreme western and eastern edges of the subspecific contact zone, respectively. The remaining 3 musculus strains were bred from mice captured about 250 km east of the hybrid zone. Genetic analysis based on 361 microsatellite loci showed that 82% of these markers are diagnostic for either the musculus or the domesticus strains. In order to demonstrate the potential utility of this genetic differentiation in such strains, phenotypic variation was scored for 2 strains from opposite edges of the hybrid zone and significant differences in morphology, reproductive performance, in vitro immune responses, mate choice based on urinary signals, and aggressiveness were found. In addition, the 3 strains derived from musculus populations far from the hybrid zone display significant differences in polymorphism in hybrid male sterility when crossed with the laboratory strains C57BL/6 or C57BL/10, which have a predominantly domesticus genome. Although further studies will be necessary to demonstrate intersubspecific differences, all analyses presented here indicate that these newly developed house mouse strains represent a powerful tool for elucidating the genetic basis of isolation barriers in hybrid zones and for studying speciation in general.

The gut microbiota is vital to host health and, as such, it is important to elucidate the mechanisms altering its composition and diversity. Intestinal helminths are host immunomodulators and have evolved both temporally and spatially in close association with the gut microbiota, resulting in potential mechanistic interplay. Host–helminth and host–microbiota interactions are comparatively well-examined, unlike microbiota–helminth relationships, which typically focus on experimental infection with a single helminth species in laboratory animals. Here, in addition to a review of the literature on helminth–microbiota interactions, we examined empirically the association between microbiota diversity and composition and natural infection of multiple helminth species in wild mice ( Apodemus flavicollis ), using 16S rRNA gene catalogues (metataxonomics). In general, helminth presence is linked with high microbiota diversity, which may confer health benefits to the host. Within our wild rodent system variation in the composition and abundance of gut microbial taxa associated with helminths was specific to each helminth species and occurred both up- and downstream of a given helminth's niche (gut position). The most pronounced helminth–microbiota association was between the presence of tapeworms in the small intestine and increased S24–7 (Bacteroidetes) family in the stomach. Helminths clearly have the potential to alter gut homeostasis. Free-living rodents with a diverse helminth community offer a useful model system that enables both correlative (this study) and manipulative inference to elucidate helminth–microbiota interactions.

Sequences of the variable intergenic spacer region 5S (rrfA) 23S (rrlB) rRNA were used to identify Borrelia genospecies present in Ixodes ricinus nymphs collected from the Lamar Lakes area of the Province of Trento, Italy (overall prevalence=6.3%). Four genospecies were identified, one for the first time in this Province (B. valaisiana), and three which have been noted previously (B. afzelii, B. garinii, and B. burgdorferi s.s.). In order to compare the genetic variability of these genospecies in Trento with that at a European level, our 21 sequences (15 new haplotypes) and all appropriate European Borrelia sequences registered in GenBank (up to the end of 2004) were subjected to a phylogenetic analysis (for a total of 73 sequences and 43 haplotypes). Clusters of sequences representing the five main European genospecies (afzelii, garinii, burgdorferi s.s., valaisiana, lusitaniae) are well-supported. At least two other groups of haplotypes (genospecies) are suggested by our analysis; moreover, divergent evolution may be occurring in several genospecies. The maximum uncorrected pairwise differences between sequences within genospecies ranges from 1.5% (B. burgdorferi s.s.), to 2.3% (B. garinii and B. valaisiana) to 4.7% (B. afzelii), and are not correlated with geographical distribution. Within the Province of Trento, these values for the same genospecies are 1.5%, 2.3%, 0.9%, 1.9%, respectively. These high mutation rates within genospecies suggest that the sequencing of haplotypes should continue if we are to fully understand and monitor the evolution and epidemiology of Borrelia.

In the alpine valley of Valtellina there are two Robertsonian chromosomal races of house mouse, the Poschiavo (POS: 2n = 24-26) characterized by metacentric 8.12 and acrocentrics 2 and 10 and the Upper Valtellina (UV: 2n = 22-24) characterized by metacentrics 2.8 and 10.12. The races inhabit separate villages in the valley except in Sommacologna and Sondalo, where they both occur together with hybrids. A total of 179 mice from 16 villages were typed at 13 microsatellite loci. Seven of these loci were localized close to the centromeres of chromosomes 10 and 12, with the prediction that these regions on the race-specific chromosomes would be the most likely to experience a barrier to gene flow. The remaining six loci were localized at the telomeres of chromosomes 10 and 12 and at the centromeres of chromosomes that do not differ between the races. Substantial differences in allelic frequencies were found between the villages with POS and UV races at five of the loci at the centromeres of chromosomes 10 and 12 but at none of the other loci. These differences were not found to distinguish the two races in Sommacologna and Sondalo. Therefore, the centromeric regions of race-specific chromosomes do appear to experience a barrier to gene flow, although this can break down under intense interbreeding between the races. These results are considered in the context of Harrison's (1990) concept of the semipermeability of hybrid zones to gene exchange and in relation to parapatric speciation.

Gündüz, İslam (Balikesir Author), The article reviews over 30 years' study of the chromosomal variation of the western house mice (Mus musculus domesticus) from the neighboring valleys of Poschiavo and Valtellina on the Swiss-Italian border. This is done in the context of the social and political history of this area, on the grounds that mice, as commensals, are influenced by human history. The chromosomal study of mice in this area was initiated because their unusual black coat color led a 19th century naturalist to describe the "tobacco mice" from Val Poschiavo as a separate species ( Mus poschiavinus). The special coloration of the Val Poschiavo mice is matched by their chromosomes: they have 26 chromosomes instead of the usual 40. The Val Poschiavo mice are not a separate species according to the Biological Species Concept; instead they constitute a chromosome race ( the "Poschiavo", POS) that is related to other races with reduced chromosome numbers that occur in N Italy ( of which only those races in Val Poschiavo and Upper Valtellina have black coats). A phylogenetic analysis of mitochondrial DNA sequences suggests that the lineage of chromosome races found in N Italy was not formed during an extreme population bottleneck, although such bottlenecks have apparently occurred during the origin of individual races and certainly have influenced single populations. In one small, isolated population in Valtellina (Migiondo), two chromosome races ( the POS and the "Upper Valtellina", UV, 2n = 24) became reproductively isolated from each other. In another small population (Sernio) bottlenecking led to fixation of a hybrid form with the UV karyotype and coat color, but with allozyme and microsatellite alleles characteristic of mice with the standard 40-chromosome karyotype. Two of the chromosome races in Valtellina ( the UV and the "Mid Valtellina", MV, 2n = 24) also appear to be the product of hybridization. The dynamic history and patchy distribution of the house mouse chromosome races in Val Poschiavo and Valtellina in part reflects extinction-recolonization events; the formation of the UV and MV races and the introduction of the pale brown Standard race mice are believed to reflect such events. Dynamism in the chromosomal constitution of single populations is also evident from 25 years of data on the population in Migiondo. Due to change in agricultural practices, house mice in Valtellina and Val Poschiavo are becoming rarer, which is likely to have further impacts on the distribution and characteristics of the chromosome races in this area. Copyright

An unusual chromosomal hybrid zone of the house mouse, Mus musculus domesticus, exists in Upper Valtellina, Northern Italy, consisting of four Robertsonian (Rb) races and the standard (all-acrocentric, or 2n = 40) race, all hybridizing freely within 10 km2. The hybrid zone in Valtellina provides an excellent opportunity to study the role of Rb fusions in reproductive isolation and speciation. This hybrid zone has already been well studied for the distribution of Rb fusions and the fertility of hybrids, but in order to understand the dynamics of the zone, a basic understanding of the origin and genetic similarity of the chromosomal races is necessary. This paper presents the results of three different methods of measuring genetic differentiation: multivariate analysis of morphological traits and analyses of allozyme variation and mitochondrial DNA sequences. The standard race is clearly distinguishable from the three Rb races by all three methods, but the Rb races are not distinguishable from one another. This provides strong evidence for our previous suggestions that the well-established Rb races in Valtellina are closely related, and that the standard race was introduced into the valley more recently from a distant source. The fact that the Rb races are indistinguishable is also consistent with our hypothesis that a within-village speciation event involving two of the races (Hauffe & Searle, 1992) was a recent occurrence. The low level of allozyme heterozygosity among the Rb races suggests that these populations are the products of at least one bottleneck. The present article substantially extends earlier studies and provides the first detailed morphological and molecular analysis of this complex hybrid zone.

A population of house mice, Mus musculus domesticus, from the village of Migiondo was found to be genetically distinct from nearby populations in Upper Valtellina (Italian Alps). At the supernatant malic enzyme locus, Mod1, the only alleles found in Migiondo (c and n2) were virtually absent from the other populations in the valley, which were characterized by allele a. The extraordinary genetic distinctiveness of the Migiondo population is apparently the result of genetic drift, perhaps coupled with a founder event, and attests to the existence of nearly impenetrable geographic barriers around the village isolating it from other settlements only a few hundred metres away. The Mod1 features of the house mice in Migiondo are reminiscent of the characteristics of house mice on maritime islands. The genetic confirmation of the geographic isolation of Migiondo is of interest because there is evidence that this village may have been the site of recent speciation and extinction events. The data are also of significance given the phenomenal chromosomal variation in house mice from the vicinity of the Alps. It has frequently been proposed that genetic drift/founder events are of importance in the fixation of chromosomal rearrangements; this study provides the first direct evidence for their occurrence in alpine mouse populations.