Vocal communication in the bicoloured white-toothed shrew<Emphasis Type="Italic">Crocidura leucodon</Emphasis>

Vocal sounds of 15 individuals ofCrocidura leucodon (Hermann, 1780) emitted during agonistic and amicable interactions in male-male, female-female and male-female dyadic encounters, and intraspecific cage groups, were studied. An analysis of spectral properties, along with an examination of context and function, were performed. The sounds registered during agonistic interactions showed an increase, then a decrease in frequency, often followed a complex undulating curve. The dominant frequency (DF) was 10.7±0.05 kHz, and duration (DU) was 104.2±4.4 ms. The calls emitted by shrews at investigation and grooming often ended with chirping notes (DF=4.8±0.2 kHz, DU=23.5±1.1 ms). While clustering and huddling up to the partner, the animals produced calls consisting of short notes with a very low intensity (DF=1.0±0.07 kHz, DU=35.2±0.8 ms). Based on these finding, it can be assumed that threatening sounds, emitted in agonistic encounters, allow shrews to avoid conflicts, while those, emitted when clustering and huddling up to the partner, contribute to maintenance of group cohesiveness. The variability of frequency ranges and intensity of sounds probably reflects the territorial and gregarious behaviour ofC. leucodon and adaptation to communication in variable acoustic environments.     

Phenotypic flexibility in the energetic strategy of the greater white-toothed shrew,Crocidura russula

The balance between energetic acquisition and expenditure depends on the amount of energy allocated to biological functions such as thermoregulation, growth, reproduction and behavior. Ambient temperature has a profound effect on this balance, with species inhabiting colder climates often needing to invest more energy in thermoregulation to maintain body temperature. This leads to local behavioral and physiological adaptations that increase energetic efficiency. In this study, we investigated the role of activity, behavior and thermogenic capacity in the ability of the greater white-toothed shrew, Crocidura russula, to cope with seasonal changes. Individuals were captured in the Sintra-Cascais Natural Park, a Mediterranean region, and separated into three experimental groups: a control group, acclimated to a 12L:12D photoperiod and temperature of 18–20 °C; a winter group, acclimatized to natural winter fluctuations of light and temperature; and a summer group, acclimatized to natural summer fluctuations of light and temperature. No differences were found in resting metabolic rate and nonshivering thermogenesis between the three groups. However, winter shrews significantly reduced their activity, particularly at night, compared to the control and summer groups. Differences in torpor use were also found between groups, with winter shrews entering torpor more frequently and during shorter periods of time than summer and control shrews. Our results indicate C. russula from Sintra relies on the flexibility of energy saving mechanisms, namely daily activity level and torpor use, to cope with seasonal changes in a Mediterranean climate, rather than mechanisms involving body heat production.     

Flooding ecology of voles, mice and shrews: the importance of geomorphological and vegetational heterogeneity in river floodplains

Since voles, mice and shrews are important animals in food chains of river floodplains, there is a need for data on their spatial and temporal distribution in periodically flooded areas. During a live trapping study between two successive floods in an embanked river floodplain, the ’Afferdensche en Deestsche Waarden (ADW)’, six species were frequently observed, viz,Microtus arvalis (Pallas, 1778),Clethrionomys glareolus (Schreber, 1780),Sorex araneus (Linnaeus, 1758),Crocidura russula (Hermann, 1780),Micromys minutus (Pallas, 1771) andApodemus sylvaticus (Linnaeus, 1758). Ungrazed rough herbaceous vegetation appeared to be rich in numbers and species, whereas no spoors of small mammals were observed in large parts of the ADW floodplain (eg bare substrates and maize fields). Vegetation structure seemed to be very important in guiding the recolonisation process after flood events. Throughout the year the highest numbers of small mammals were captured on and near the non-flooded elevated parts functioning as refugia during inundation. Poor habitat connectivity, sparseness of non-flooded recolonisation sources and small numbers of survivors led to slow recolonisation. The time between two successive floods (eight months) was not long enough for entire recolonisation of ADW. Small mammal densities at more than 30 m from the non-flooded areas were always lower than in non-flooded areas.     

Comparative study of Spanish and Italian terrestrial small mammal coenoses from different biotopes in Mediterranean peninsular tip regions

A comparison of terrestrial small mammal coenoses belonging to nine different biotopes in the tips of the Iberian and Italian peninsulas was carried out using the pitfall trapping method. The influence of both habitat type and peninsular effect on composition of small mammal coenoses was analysed. In Southern Italy, 203 specimens belonging to seven species were trapped: Suncus etruscus (Savi, 1822), Crocidura suaveolens (Pallas, 1811), C. leucodon (Hermann, 1780), Microtus savii (de Sélys-Longchamps, 1838), Apodemus sylvaticus (L., 1758), A. flavicollis (Melchior, 1834) and Mus musculus domesticus Schwarz & Schwarz, 1943. In Southern Spain 428 specimens belonging to five species were trapped: Suncus etruscus, Crocidura russula (Hermann, 1780), Microtus duodecimcostatus (de Sélys-Longchamps, 1839), Apodemus sylvaticus and Mus spretus Lataste, 1883. The relative density of small mammals occurring in the nine Spanish sampling stations was twice that recorded in the Italian stations; however the number of species recorded in the different biotopes show similar mean values, ranging from three to five in Andalusia and from three to six in Calabria. Apodemus sylvaticus was the dominant species in the Calabrian stations, whereas Crocidura russula prevailed in Andalusia. The biotic diversity values are very similar in the Calabrian and Andalusian biotopes. By contrast, the Insectivora/Rodentia ratio was always higher in Andalusia. The more xerophytic biotopes showed greater similarities between the communities in Southern Spain and Southern Italy, while the cooler biotopes differed between these two peninsulas.     

Additive effects of climate and vegetation structure on the altitudinal distribution of greater white-toothed shrews Crocidura russula in a Mediterranean mountain range

Environmental variation along geographic gradients determines the distribution of animals and plants trough both direct and indirect effects. We analyze the relative contribution of climate and vegetation structure variations along a Mediterranean altitude gradient on the patterns of abundance and occurrence of the greater white-toothed shrew Crocidura russula, a generalist small mammal whose distribution is constrained by cold conditions. Sampling was performed from February 1995 to July 1997 on nine plots covering a wide altitudinal gradient (540–1550 m?a.s.l.). Structural equation models for the direct and indirect effects of climate and vegetation on shrew density and occupancy rates showed a stronger effect of vegetation structure (53 %) than direct climate effects (38 %) on shrew distribution. Shrews were more abundant in the warmer lowland sites, but were able to colonize highland cold areas by selecting habitats with well-developed understory vegetation (low shrubs or bracken). Vegetation effects were additive to climatic restrictions, seemingly providing more favorable microclimatic, and presumably food, conditions under shrub cover. Results indicate that predictions of range changes for shrews under climate change scenarios may underestimate expected range expansions under the current conditions of general land abandonment and shrub encroachment.     

Artificial light affects the foraging behavior in greater white-toothed shrews (CROCIDURA RUSSULA)

Light pollution is one of the forms by which human-induced alterations are changing natural environments. Artificial light at night (ALAN) has been increasing over the past decades and it is already known that ALAN can have a major influence on the ecology, behavior, and physiology of different taxa. Nocturnal small mammals are particularly vulnerable, as ALAN can increase their predation risk while foraging. The aim of this study was to investigate foraging strategies under different light conditions in a nocturnal small insectivore, the greater white-toothed shrew (Crocidura russula). Compared with rodents, shrews have a higher metabolic rate and thus present a good model for a foraging study. In three laboratory experiments with wild-caught shrews we tested (i) food preference under dark conditions as well as the effect of different light conditions on (ii) foraging strategies and (iii) food choice. The results showed that shrews had a clear food preference under dark conditions. They also preferred to forage under dark over light conditions when presented with the same food in both conditions. However, when presented with the choice of foraging their preferred food under illuminated conditions or a lower food quality in the dark, the food preference of shrews overruled their preference for feeding in the dark. It seems that food preference, rather than risk perception, is the main driver determining the foraging strategy of the greater white-toothed shrews. This study suggests that ALAN does not necessarily prevent high-metabolic nocturnal insectivores from achieving their energetic needs, which might help explain their persistence in urban environments.     

First record of greater white‐toothed shrew Crocidura russula in Ireland

• 1 Skeletal remains of greater white‐toothed shrew Crocidura russula were recovered from barn owl Tyto alba and kestrel Falco tinnunculus pellets collected at 15 locations in Counties Tipperary and Limerick in Ireland in September 2007 and March 2008. Seven greater white‐toothed shrews were trapped at four locations in Tipperary in March 2008. This is the first Irish record of C. russula and compelling evidence that the species is established in Ireland.
• 2 The absence of C. russula from earlier surveys of owl pellets and small mammals in Ireland suggests a recent introduction by uncertain means, possibly since 2001. It seems likely that C. russula will expand its range in Ireland. Its impact on the ecology of habitats in which it is found is uncertain but may be considerable.

     

Seasonal changes in social behaviour and spatial structure of<Emphasis Type="Italic">Crocidura leucodon</Emphasis> in north-western Bulgaria

The patterns of social behaviour and spatial structure ofCrocidura leucodon (Hermann, 1780) were studied against the background of the seasonal changes in its density and demographic features. Field and lab research were conducted. Field investigations (with CMR method) were conducted from 1997 to 1999 in north-western Bulgaria, in a grassland with patches of tree-shrub vegetation. In the lab, the social interactions were studied in male-male, female-female and male-female dyadic encounters during summer and autumn. A total of 26 shrews were tested. The number ofC. leucodon was lowest in spring and greatest in autumn. In early summer the sex ratio was balanced, the home range of one male overlapped that of one female, and aggressiveness and marking activity was increased. So, it can be assumed that in this period males and females form pairs, which possess defended territories. Higher aggressiveness and marking activity displayed by males suggest their greater role in defending the territories. In autumn the home ranges overlapped greatly and amicable interactions prevailed over agonistic ones probably due to shifting to a gregarious way of life. So, the patterns of spatial structure and social behaviour undergo the seasonal changes inC. leucodon life-cycle and its density dynamics.     

Does bite force provide a competitive advantage in shrews? The case of the greater white‐toothed shrew

Competition for resources has long been considered a major driver of evolution by natural selection. Thus, the ability to gain access to resources not available to other individuals and species should be under strong selection. In the present study, we focus on the potential role of biting in a shrew (Crocidura russula) because this trait may confer two advantages: (1) a broadening of the dietary niche and (2) the provision of direct superiority in interspecific interactions. The model chosen is the greater white‐toothed shrew, which is considered as invasive in northern Europe and which is also known to displace native species of shrew in this area. Moreover, its distribution appears to constrain the distributional ranges of other species of shrew in the Maghreb. We use geometric morphometrics and a simple biomechanical model to describe shape variation and to evaluate the mechanical potential of the mandible of ten species of white‐toothed shrews, with a special emphasis on C. russula and Crocidura suaveolens. We find that C. russula possesses an intermediate mechanical potential linked with an intermediate level of shape variability. Our results suggest that the higher mechanical potential may explain the observed pattern of colonization of the Atlantic islands by C. russula at the expense of C. suaveolens. Finally, our results also suggest that the ability to bite hard may be under strong selection in shrews. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 795–807.     

Species distribution models contribute to determine the effect of climate and interspecific interactions in moving hybrid zones

Climate is a major factor delimiting species’ distributions. However, biotic interactions may also be prominent in shaping geographical ranges, especially for parapatric species forming hybrid zones. Determining the relative effect of each factor and their interaction of the contact zone location has been difficult due to the lack of broad scale environmental data. Recent developments in species distribution modelling (SDM) now allow disentangling the relative contributions of climate and species’ interactions in hybrid zones and their responses to future climate change. We investigated the moving hybrid zone between the breeding ranges of two parapatric passerines in Europe. We conducted SDMs representing the climatic conditions during the breeding season. Our results show a large mismatch between the realized and potential distributions of the two species, suggesting that interspecific interactions, not climate, account for the present location of the contact zone. The SDM scenarios show that the southerly distributed species, Hippolais polyglotta, might lose large parts of its southern distribution under climate change, but a similar gain of novel habitat along the hybrid zone seems unlikely, because interactions with the other species (H. icterina) constrain its range expansion. Thus, whenever biotic interactions limit range expansion, species may become ‘trapped’ if range loss due to climate change is faster than the movement of the contact zone. An increasing number of moving hybrid zones are being reported, but the proximate causes of movement often remain unclear. In a global context of climate change, we call for more interest in their interactions with climate change.     

北小麝鼩的代谢产热和体温调节特征

为探讨食虫目小型哺乳动物的代谢产热和体温调节特征,本文采用封闭式流体压力呼吸仪测定了北小麝鼩在环境温度5 ～ 30℃下的静止代谢率(RMR),结果显示:在环境温度(Ta)为17 5 ～25℃ 的范围内,北小麝鼩的体温基本维持恒定,平均体温为36.55 ± 0.38℃ ;热中性区(TNZ) 为20 ～ 25℃ ;基础代谢率BMR 为5.46 ±0.23 (mLO₂ /g· h),其中环境温度在25℃ 时静止代谢率最低,为4.84 ± 0.39 (mLO₂ /g· h)。在5 ～ 25℃环境温度范围内,热传导值保持稳定;在此温度范围内,北小麝鼩的热传导率(C) 最低,平均为0.42 ± 0.01mLO₂ / (g·h·℃ )。总之,北小麝鼩的产热和体温调节特征为较高的BMR,中等的热传导率,较低的体温和较宽的热中性区。这些特征可能与该物种体型小、夜行性、主要以无脊椎动物为食等生活习性密切相关。     

Geographic variation of the Greater white-toothed shrew (Crocidura russula Hermann, 1780 Mammalia, Soricidae)

A multivariate morphometric study of the Greater white-toothed shrew ( C. russula ) throughout its Palearctic range was carried out to search for patterns of geographic variation within the species boundary. Burnaby's and multiple group principal component analysis allowed the adjustment of raw data with respect to within-sample allometric variation. Multivariate 'size-free'results show a stepped cline with the phenotypical trait reduction and shape change from the eastern to the western Maghreb. Pleistocene fossil mandibles proved to have low phenetic distances with eastern populations (Tunisia, east Algeria) and it is argued that their character set is the primitive condition. The ancestral Mid-Pleistocene shrews lived in a relatively more humid climate. Geo-climatic changes in the north African range during the Quaternary provoked phenetic variation of C. russula and, it can be argued, evolution of the modern western C.r. yebalensis. A historical process can thus be assumed as the main cause of this categorical variation, by segmentation of the species range due to geo-climatic events. Morphometric discontinuity within the C. russula Maghreb range is shown to be congruent with karyological and biochemical studies. Moroccan and Tunisian shrews differ, for example, in NFa chromosomes and electrophoretical traits. A stasipatric process should be invoked to explain categorical variation in the Maghreb range. Colonization and divergence of insular populations results in more or less differentiated geographic races. The populations of Ibiza and Pantelleria are close to the species threshold (Nei's D ≥ 0.1). The process of speciation undergone by the Greater white-toothed shrew results in a complex pattern of geographic variation, including both allopatric and non-allopatric modes.     

Habitat use and potential interactions between the house mouse and lesser white-toothed shrew on an island undergoing habitat restoration

To forecast the potential impact of plant community and dry-stone wall restoration on an insular population of the lesser white-toothed shrewCrocidura suaveolens Pallas, 1811, shrew and house mouseMus musculus Linnaeus, 1758 abundances were assessed in 3 anthropogenic habitats on Béniguet Island, Brittany, France, by a standardised annual trapping system checked yearly for 9 years and in 6 “natural” habitats by trap-lines. The standardised trapping system showed that abundances of both species fluctuated synchronously for nine years, suggesting that interactions between the species had little impact if any on abundances. Mice were trapped in all habitats, but shrews only in “stone” habitats except for rare occurrences in one damp depression. Ruderal habitat was rarely used by either species. Data suggest that on Béniguet Island: (1)M. musculus is associated with anthropogenic habitats but is not as strictly tied to them as at nearby continental sites; (2)C. suaveolens is synanthropic, as has been reported in continental northern France; (3) shingle beaches and seashore food resources are particularly important forC. suaveolens; (4) the relationship betweenC. suaveolens andM. musculus could not be determined by the experiments and, if it exists at all, appears to be more competitive than predatory. Grassland restoration is unlikely to affect shrew populations. Dry-stone wall restoration may temporarily affect shrews but should ultimately benefit them.     

Modelling the effects of climate change on the potential feeding activity of Thaumetopoea pityocampa (Den. & Schiff.) (Lep., Notodontidae) in France

Aim We investigated whether climate change has affected the potential feeding activity of a winter active larva, the pine processionary moth (PPM), Thaumetopoea pityocampa L., and whether it may explain its range expansion. Location The study area is France and, at a smaller scale, the Paris Basin. Methods We used a statistical model derived from Huchon and Démolin [1970 Revue Forestière Française (special issue: La lutte biologique en forêt), 220–234] to test whether their model, updated with climate change, could explain the observed range expansion. Since Battisti and colleagues have recently shown that climate could affect survival of the PPM through its effect on feeding activity, we also developed a mechanistic model based on larval feeding requirements (night air temperature above 0 °C and temperature inside the nest above 9 °C on the preceding day). We reconstructed the geographical distribution of feeding activity and we compared the resulting change with the PPM range expansion. Results The statistical model did not successfully predict the observed expansion but the mechanistic model showed considerable change in the feeding activity of the PPM. In the Paris Basin, the PPM border coincided with a zone unfavourable for feeding activity in the period 1992–96. Feeding conditions became more favourable in the period 2001–04, and the PPM succeeded in crossing this zone. Over larger temporal and spatial scales improved feeding conditions in the north‐western part of France were forecast by the mechanistic model. Main conclusions (1) The range distribution of the PPM in the Paris Basin is no longer limited by unfavourable feeding conditions. (2) The pattern of range expansion of the PPM is now governed mainly by its dispersal capabilities and host tree distribution. (3) At the country scale, this approach gives an approximate prediction of the potential distribution of the PPM, though the model may not be reliable in mountainous regions.     

First results on the feeding ecology of sympatric shrews (Insectivora: Soricidae) in the Tai National Park,Ivory Coast

The feeding ecology of a multi-species community of shrews inhabiting secondary forest and cacao-coffee plantations in the Tai National Park (Ivory Coast) was investigated. A total of 553 shrews were captured and 194 alimentary tracts were examined. Ten species were found, includingSylvisorex megalura and nine species ofCrocidura, forming a series with respect to body size. New ecological data on these little known African species are presented. All species of shrews ate a wide diversity of arthropods, with Coleoptera, Araneae, Formicidae and Diplopoda making the largest dietary contributions. Lumbricidae were eaten by two species.C. obscurior had an exceptionally long intestine for its size but there was no evidence of dietary specialisation in this or other shrew species. All species investigated ate predominantly small prey and there was no correlation between size of prey items consumed and body mass of shrew species. There was little evidence of resource partitioning amongst the shrews, despite differences in body size.     

Y chromosome microsatellite isolation from BAC clones in the greater white‐toothed shrew (Crocidura russula)

We constructed a microsatellite library from four Crocidura russula Y chromosome‐specific bacterial artificial chromosome (BAC) clones. Only one of eight microsatellites was male‐specific, despite genome walking to obtain more flanking sequence and testing of 93 primer combinations. Potential reasons for this low success are discussed. The male‐specific locus, CRY3, was genotyped in 90 males, including C. russula from across the species range and two related species. The large difference in CRY3 allele size between eastern and western lineages supports earlier reports of high divergence between them. Despite polymorphism of CRY3 in Morocco, only one allele was found throughout the whole of Europe, consistent with previous studies that suggest recent colonization of Europe from a small number of Moroccan founders.     

Signatures of local adaptation along environmental gradients in a range‐expanding damselfly (Ischnura elegans)

Insect distributions are shifting rapidly in response to climate change and are undergoing rapid evolutionary change. We investigate the molecular signatures underlying local adaptation in the range‐expanding damselfly, Ischnura elegans. Using a landscape genomic approach combined with generalized dissimilarity modelling (GDM), we detect selection signatures on loci via allelic frequency change along environmental gradients. We analyse 13,612 single nucleotide polymorphisms (SNPs), derived from restriction site‐associated DNA sequencing (RADseq), in 426 individuals from 25 sites spanning the I. elegans distribution in Sweden, including its expanding northern range edge. Environmental association analysis (EAA) and the magnitude of allele frequency change along the range expansion gradient revealed significant signatures of selection in relation to high maximum summer temperature, high mean annual precipitation and low wind speeds at the range edge. SNP annotations with significant signatures of selection revealed gene functions associated with ongoing range expansion, including heat shock proteins (HSP40 and HSP70), ion transport (V‐ATPase) and visual processes (long‐wavelength‐sensitive opsin), which have implications for thermal stress response, salinity tolerance and mate discrimination, respectively. We also identified environmental thresholds where climate‐mediated selection is likely to be strong, and indicate that I. elegans is rapidly adapting to the climatic environment during its ongoing range expansion. Our findings empirically validate an integrative approach for detecting spatially explicit signatures of local adaptation along environmental gradients.     

Molecular and morphological insights into the origin of the invasive greater white-toothed shrew (<Emphasis Type="Italic">Crocidura russula</Emphasis>) in Ireland

Identifying routes of invasion is a critical management strategy in controlling the spread of invasive species. This is challenging however in the absence of direct evidence. Therefore, indirect methodologies are used to infer possible invasion sources and routes, such as comparisons of genetic and morphological data from populations from invasive ranges and putative source areas. The greater white-toothed shrew (Crocidura russula) was first discovered in Ireland from skeletal remains in the pellets of birds of prey collected in 2007 and is it is now sufficiently established that the species has a detrimental impact on Ireland’s small mammal community. In this study, we address the uncertain origin(s) of the Irish population of C. russula. The cytochrome b gene of mitochondrial DNA was analysed from 143 individuals from throughout its range within a phylogenetic and approximate Bayesian computation framework. These analyses revealed that the Irish population stemmed from Europe as opposed to North Africa. Additionally, mandibles from 523 individuals from Ireland and 28 other European populations were subjected to multivariate and distance-based analyses, which demonstrated an association between the Irish population and those in France, Switzerland and Belgium. When the genetic and morphological analyses were considered together, an origin stemming from France was deemed the most likely scenario for the source of the invasive Irish population. This study has demonstrated the importance of utilising a multidisciplinary approach when attempting to identify the origins and invasion routes of invasive species.     

Development of temperature regulation in the common white-toothed shrew, Crocidura russula

1. Body temperature and oxygen consumption were measured during the first month of postnatal life in two litters of Crocidura russula at four different ambient temperatures. 2. Body temperature in the nest varies from 30.5-35.0 degrees C during the first 10 days; afterwards it becomes more constant (35.5-37.0 degrees C). 3. First homoiothermic reactions occur on the 2nd day of life and become effective on the 4th day. 4. In the case of undernourished shrews, torpor is already developed on the 2nd day. 5. After the 7th day torpor is the obligatory reaction in cooling experiments. 6. This discontinuous development of temperature regulation is interpreted as typical for shrews capable of torpor.     

Evidence for evolutionary change associated with the recent range expansion of the British butterfly, Aricia agestis, in response to climate change

Poleward range expansions are widespread responses to recent climate change and are crucial for the future persistence of many species. However, evolutionary change in traits such as colonization history and habitat preference may also be necessary to track environmental change across a fragmented landscape. Understanding the likelihood and speed of such adaptive change is important in determining the rate of species extinction with ongoing climate change. We conducted an amplified fragment length polymorphism (AFLP)‐based genome scan across the recently expanded UK range of the Brown Argus butterfly, Aricia agestis, and used outlier‐based (DFDIST and BayeScan) and association‐based (Isolation‐By‐Adaptation) statistical approaches to identify signatures of evolutionary change associated with range expansion and habitat use. We present evidence for (i) limited effects of range expansion on population genetic structure and (ii) strong signatures of selection at approximately 5% AFLP loci associated with both the poleward range expansion of A. agestis and differences in habitat use across long‐established and recently colonized sites. Patterns of allele frequency variation at these candidate loci suggest that adaptation to new habitats at the range margin has involved selection on genetic variation in habitat use found across the long‐established part of the range. Our results suggest that evolutionary change is likely to affect species’ responses to climate change and that genetic variation in ecological traits across species’ distributions should be maximized to facilitate range shifts across a fragmented landscape, particularly in species that show strong associations with particular habitats.