Trypanosome diversity in small mammals in Uganda and the spread of Trypanosoma lewisi to native species.

Uganda's diverse small mammalian fauna thrives due to its rich habitat diversity, which hosts a wide range of blood parasites, including trypanosomes, particularly the subgenus Herpetosoma typical for rodent hosts. We screened a total of 711 small mammals from various habitats for trypanosomes, with 253 microscopically examined blood smears and 458 tissue samples tested by nested PCR of the 18S rRNA gene. Of 51 rodent and 12 shrew species tested, microscopic screening reaches 7% overall prevalence (with four rodent species positive out of 15 and none of the shrew species out of four), while nested PCR indicated a prevalence of 13% (17 rodent and five shrew species positive out of 49 and 10, respectively). We identified 27 genotypes representing 11 trypanosome species, of which the majority (24 genotypes/9 species) belong to the Herpetosoma subgenus. Among these, we detected 15 new genotypes and two putative new species, labeled AF24 (found in Lophuromys woosnami) and AF25 (in Graphiurus murinus). Our finding of three new genotypes of the previously detected species AF01 belonging to the subgenus Ornithotrypanum in two Grammomys species and Oenomys hypoxanthus clearly indicates the consistent occurrence of this avian trypanosome in African small mammals. Additionally, in Aethomys hindei, we detected the putative new species of the subgenus Aneza. Within the T. lewisi subclade, we detected eleven genotypes, including six new; however, only the genotype AF05b from Mus and Rattus represents the invasive T. lewisi. Our study has improved our understanding of trypanosome diversity in African small mammals. The detection of T. lewisi in native small mammals expands the range of host species and highlighting the need for a broader approach to the epidemiology of T. lewisi.

Parasitic Arthropods of Soricinae Shrews in North-Eastern Poland.

The study of the ectoparasite fauna of the insectivores-Sorex araneus, Sorex minutus, Neomys fodiens, and Neomys anomalus (subfamily Soricinae)-was carried out in three locations in Poland: Bialowieza National Park, Kosewo Górne in the Masurian Lake District, and in vicinity of Warsaw. Three species of Ixodidae ticks, eleven species of fleas, and four species of mites from the order Mesostigmata were noted. The most numerous ectoparasites are ticks Ixodes ricinus (larvae), Dermacentor reticulatus (nymphs), and fleas Palaeopsylla soricis, Megabothris walkeri, and Hystrichopsylla orientalis. These species show the highest prevalence and show the highest dominance index. The parasitofauna of S. araneus is much richer in species than other shrew species. The structure and dominance of parasite assemblages differ between locations.

The complete mitochondrial genome of the Hainan Island Shrew, Crocidura wuchihensis.

The Hainan Island Shrew Crocidura wuchihensis is a small-bodied insectivore species belonging to the Soricidae family. In this study, we determined its the complete mitochondrial genome. The whole mitochondrial genome was found to be 17,253 bp in length and comprises 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a control region. The base composition of the C. wuchihensis total mitogenome as follows: A, 32.8%; G, 13.0%; T, 32.1%; and C, 22.1%, with an A + T content of 64.9%. Notably, a tandem repeat sequence (5'-CAC ACG TGT ACA-3') was identified in the control region with 24 copy numbers. Additionally, phylogenetic analysis indicated that C. wuchihensis is closely related to Crocidura tanakae and Crocidura dongyangjiangensis based on the concatenated sequences of the 13 protein-coding genes. The characterization of the shrew's mitogenome will provide the foundation for its use in population genomics and systematic studies of Soricidae.

Histological and MRI brain atlas of the common shrew, Sorex araneus, with brain region-specific gene expression profiles.

The common shrew, Sorex araneus, is a small mammal of growing interest in neuroscience research, as it exhibits dramatic and reversible seasonal changes in individual brain size and organization (a process known as Dehnel's phenomenon). Despite decades of studies on this system, the mechanisms behind the structural changes during Dehnel's phenomenon are not yet understood. To resolve these questions and foster research on this unique species, we present the first combined histological, magnetic resonance imaging (MRI), and transcriptomic atlas of the common shrew brain. Our integrated morphometric brain atlas provides easily obtainable and comparable anatomic structures, while transcriptomic mapping identified distinct expression profiles across most brain regions. These results suggest that high-resolution morphological and genetic research is pivotal for elucidating the mechanisms underlying Dehnel's phenomenon while providing a communal resource for continued research on a model of natural mammalian regeneration. Morphometric and NCBI Sequencing Read Archive are available at https://doi.org/10.17617/3.HVW8ZN.

Shrews Under-Represented in Fruit Farms and Homesteads.

Shrews are a less studied group of small mammals than rodents. Between 2018 and 2022, we surveyed 23 sites in Lithuania, including natural and anthropogenic habitats, with the aim to assess the proportion of Soricidae in small mammal communities and their diet based on stable isotope analysis. The average representation of Soricidae was 3.1%, about half the long-term average in other habitats in the country. The highest proportions were in meadows and farmsteads, at 4.9% and 5.0% respectively. Shrews were not trapped on farms or in young orchards, and their relative abundance was very low in intensively managed orchards (0.006 individuals per 100 trap days). Neomys fodiens and N. anomalus were unexpectedly found in homesteads, including in outbuildings. Sorex araneus and S. minutus had similar diets. The trophic carbon/nitrogen discrimination factor between invertebrates and shrew hair was 2.74‱/3.98‱ for S. araneus, 1.90‱/3.78‱ for S. minutus in the orchards. The diet of N. fodiens and N. anomalus at the homesteads requires further investigation. We propose that the under-abundance of shrews may be due to contamination by plant protection products and a lack of invertebrates under intensive agricultural practices.

Characteristics of cytochrome P450-dependent metabolism against acetamiprid in the musk shrew (Suncus murinus).

Soricidae spp. (shrews) play an essential role in soil ecosystems and, due to their habitat and behavior, are exposed to soil pollutants, such as pesticides. Still, toxicity risk in Soricidae spp. has not been appropriately assessed. In this study, the musk shrew (Suncus murinus) was used as a model organism for toxicity assessment in Soricidae. Considering their carnivorous diet, it is reasonable to assume that the musk shrew has unique metabolic traits that are different from those of other common experimental models. This study describes the cytochrome P450 (CYP)-dependent metabolism affected by acetamiprid (ACP), a neonicotinoid insecticide. Pharmacokinetics analysis, an in vitro metabolic assay, and genetic analysis of CYP were performed and compared with data from mice and rats. Through phylogenetic and syntenic analyses, three families of CYP were identified in the musk shrew. Pharmacokinetic analysis showed that the blood concentration of ACP decreased more quickly in musk shrews than in mice. Moreover, the in vitro metabolic assay suggested more efficient metabolic responses toward ACP in musk shrews than in mice or rats. One of the CYP2A isoforms in musk shrews might be linked to a better ACP metabolism. From the results above, we describe novel metabolic traits of the musk shrew. Future research on recombinant CYP enzymes is necessary to fully understand CYP-dependent metabolism of xenobiotics in musk shrews.

Mammals in Tawny Owl (Strixaluco) pellets from Kharkiv Region, Ukraine.

Background: The Tawny owl (Strixaluco) is a common owl species in Europe, demonstrating generalist diet strategy. Its main prey are small rodents and numerous studies show that the composition of its diet broadly reflects changes in prey species abundance in its habitats. Due to strictly sedentary habits of adult birds and their year-round territoriality, it is possible to locate habitats of their prey with a precision of several hundred metres. Analysis of owl pellets is a traditional method in faunistic studies to provide data on distribution of small mammals, especially cryptic species which are hard to be found using trapping. New information: Here, we present a dataset on mammals found in Tawny owl pellets collected during up to 13-year studies in the Kharkiv Region, Ukraine in three territories. Data from two territories were collected in a systematic way and allowed us to make analysis of seasonal, year-to-year and habitat variability in the Tawny owl diet and local mammal species composition.

Dive Performance and Aquatic Thermoregulation of the World's Smallest Mammalian Diver, the American Water Shrew (Sorex palustris).

Allometry predicts that the 12-17-g American water shrew (Sorex palustris)-the world's smallest mammalian diver-will have the highest diving metabolic rate coupled with the lowest total body oxygen storage capacity, skeletal muscle buffering capacity, and glycolytic potential of any endothermic diver. Consistent with expectations, and potentially owing to their low thermal inertia, water shrews had a significantly higher diving metabolic rate in 10°C water (8.77 mL O2 g-1 h-1) compared with 30°C water (6.57 mL O2 g-1 h-1). Unlike larger-bodied divers, muscle myoglobin contributed minimally (7.7%-12.4%) to total onboard O2 stores of juvenile and adult water shrews, respectively, but was offset by high blood O2 carrying capacities (26.4%-26.9% v/v). Diving was predominantly aerobic, as only 1.2%-2.3% of dives in 10°C and 30°C water, respectively, exceeded the calculated aerobic dive limits at these temperatures (10.8-14.4 s). The mean voluntary dive time of water shrews during 20-min trials in 3°C-30°C water was 5.0±0.1 s (N=25, n=1,628), with a mean maximum dive time of 10.1±0.4 s. However, the average dive duration (6.9±0.2 s, n=257) of radio-telemetered shrews exclusively foraging in a simulated riparian environment (3°C water) for 12-28 h suggests that mean (but not maximum) dive times of water shrews in the wild may be longer. Mean dive duration, duration of the longest dive, and total time in water all decreased significantly as water temperature declined, suggesting that shrews employed behavioral thermoregulation to defend against immersion hypothermia. Additionally, free-diving shrews in the 24-h trials consistently elevated core body temperature by ∼1°C immediately before initiating aquatic foraging bouts and ended these bouts when body temperature was still at or above normal resting levels (∼37.8°C). We suggest that this observed predive hyperthermia aids to heighten the impressive somatosensory physiology, and hence foraging efficiency, of this diminutive predator while submerged.

Infestation of chigger mites on Chinese mole shrew, Anourosorex squamipes, in Southwest China and ecological analysis.

The Chinese mole shrew, Anourosorex squamipes Milne-Edwards, 1872, is a common species of insectivorous mammal in Southwest China. Based on field investigations between 2001 and 2019, the present study reports the infestation of chiggers (larvae of chigger mites) on the shrew in Southwest China and certain ecology parameters for the first time. A total of 3169 chiggers were collected from 1694 A. squamipes and they were identified into 72 species and 10 genera in the family Trombiculidae. The overall infestation prevalence (Pm), mean abundance (MA) and mean intensity (MI) of A. squamipes with chiggers reached 11.1%, 1.87 and 16.86, respectively. The species diversity, species composition and infestation of chiggers on A. squamipes fluctuated in different environments (latitudes, altitudes, habitats and landscapes) and on different sexes and ages of the shrew hosts with high heterogeneity and low species similarity. In the established linear regression equation (M* = 0.173 + 1.054 M) for dominant mite Leptotrombidium densipunctatum, both the α and ß values (α = 0.173, ß = 1.054) exceeded the boundary values (F = 4.67, p < 0.05), and therefore the spatial distribution pattern of this mite was determined as an aggregated distribution among different individuals of shrew hosts. The species abundance distribution of the chigger community on A. squamipes conformed to the lognormal distribution, and its curve showed a gradually descending tendency from the rare mite species to the dominant mite species. The curve tendency of species-sample relationship implies that more species of chiggers would be found if the host samples infinitely keep increasing.

Title: Infestation de la musaraigne Anourosorex squamipes par les acariens dans le sud-ouest de la Chine et analyse écologique. Abstract: La musaraigne Anourosorex squamipes Milne-Edwards, 1872 est une espèce commune de mammifère insectivore dans le sud-ouest de la Chine. Sur la base d'enquêtes de terrain entre 2001 et 2019, la présente étude signale pour la première fois l'infestation et certains paramètres écologiques des acariens larvaires sur cette musaraigne dans le sud-ouest de la Chine. Un total de 3169 acariens ont été collectés sur 1694 A. squamipes et ils ont été identifiés en 72 espèces et 10 genres de la famille des Trombiculidae. La prévalence globale de l'infestation (Pm), l'abondance moyenne (MA) et l'intensité moyenne (MI) des acariens sur A. squamipes ont atteint respectivement 11,1 %, 1,87 et 16,86. La diversité des espèces, la composition des espèces et l'infestation des acariens sur A. squamipes ont fluctué selon différents environnements (latitudes, altitudes, habitats et paysages) et selon le sexe et l'âge des hôtes avec une forte hétérogénéité et une faible similitude entre espèces. Dans l'équation de régression linéaire établie (M* = 0,173 + 1054 M) pour l'acarien dominant Leptotrombidium densipunctatum, les valeurs α et ß (α = 0,173, ß = 1,054) dépassaient les valeurs limites (F = 4,67, p < 0,05), et par conséquent, le modèle de distribution spatiale a été déterminé comme une distribution agrégée entre différents individus d'hôtes. La distribution de l'abondance des espèces de la communauté d'acariens sur A. squamipes se conformait à la distribution log-normale et la courbe a montré une tendance progressivement descendante des espèces d'acariens rares à l'espèce d'acarien dominante. La tendance de la courbe de la relation espèce-échantillon implique que davantage d'espèces d'acariens seraient trouvées si l'échantillonnage des hôtes continuaient à augmenter à l'infini.

Shrews of the Genus Chodsigoa (Soricidae, Lipotyphla) from the Pleistocene of Vietnam.

The first finds of the fossil remains of the members of the genus Chodsigoa outside China are described from the Pleistocene of northern Vietnam. They are assigned to C. caovansunga Lunde, Musser et Son, 2003 (a maxillary fragment with A3-M3, an isolated M1, and a dentary with I1 and P4-M2) from the Middle Pleistocene of the Tham Hai cave (Lang Son Province) and C. hoffmanni Chen et al., 2017 (a maxillary fragment with P4-M2) from the Upper Pleistocene of the Lang Trang cave (Thanh Hoa Province). The described specimens are the first fossil finds of these species. They indicate that representatives of the genus Chodsigoa in Vietnam spread to the south much further in the Pleistocene than today.

Dissimilar use of an external heat source for thermoregulation by shrews from different geographic regions.

Ambient temperature has a substantial influence on the thermoregulation costs of small mammals due to their high surface-to-volume ratio. Shrews are among the smallest of mammals and have adopted different behavioral and physiological strategies to deal with cold temperatures. In this study, we assessed the use of an external heat source in the thermoregulatory strategy of two Crocidurinae species, Crocidura russula and C. suaveolens, and one Soricinae species, Sorex araneus. Crocidura russula inhabits western Europe and is better adapted to a Mediterranean climate; C. suaveolens inhabits central Europe; and S. araneus inhabits northern Europe and is better adapted to a Palearctic climate. We predicted that C. russula (most southern species) would spend larger amounts of time using an external heat source because it is the most cold-sensitive species, while S. araneus (most northern species) would spend less time using an external heat source or not respond to it. Shrews were experimentally tested in captivity inside a terrarium where they had access to a heat rock, which could be turned off (cold) or on (heated), depending on treatment. Our results confirmed our initial prediction: C. russula was the species that spent significantly more time on the heated rock, followed by C. suaveolens. Only a quarter of S. araneus individuals spent large amounts of time on the heat rock, which suggests this thermoregulation strategy is not generally adopted by this species, but may be rather associated with some individual personalities. We also analyzed the influence of the heat rock on rewarming from heterothermy, but heterothermy was not different between rock treatments. Overall, our results show that shrew species use external heat sources for thermoregulation according to their sensitivity to cold.

Early Pleistocene White-toothed Shrew Crocidura kornfeldi (Lipotyphla, Soricidae) from Crimea.

The remains of the white-toothed shrew Crocidura kornfeldi Kormos, 1934 (one skull fragment with almost complete dentition, the fragmental rostral part of a skull with the left upper incisor, a maxillary fragment, five mandibular fragments and an isolated upper incisor) from the Lower Pleistocene deposits of the Taurida cave in the central Crimea (Belogorsk district, Zuya village) are described. This earliest European species of the genus Crocidura was quite common in the Early Pleistocene of Central Europe and the Mediterranean; for the first time, it is described from Crimea and the entire Eastern Europe.

Mitogenome and phylogenetic analyses support rapid diversification among species groups of small-eared shrews genus Cryptotis (Mammalia: Eulipotyphla: Soricidae).

The small-eared shrew genus Cryptotis is the third largest in the family Soricidae and occurs in North, Central, and northern South America. In Mexico and Central and South America, most species inhabit geographically isolated moist, montane habitats at middle and high elevations in a typical sky-island pattern. The 49 recognized species have been partitioned into as many as six species groups based on morphological and molecular phylogenetic studies. The relationships among these species groups are poorly resolved, and their evolutionary histories, including migration patterns and locomotor adaptations, remain unclear. Herein, we provide a new phylogeny incorporating complete mitochondrial genomes (mitogenomes) and supermatrix approach. We compared different evolutionary scenarios using approximately unbiased (AU), Kishino-Hasegawa (KH), and Shimodaira-Hasegawa (SH) statistical tests. The phylogenetic hypothesis based on mitogenomes revealed novel relationships supporting a basal position for the Cryptotis parvus-group in the genus, and a close relationship between C. gracilis and one clade of the C. thomasi-group. The former relationship is consistent with the least derived humerus morphology and northern distribution of the species. The latter relationship implies multiple migrations between Central and South America. The lack of fine resolution for the species group relationships may be due partly to the lack of taxon sampling. In contrast, multi-approach analyses suggest that the unresolved relationships may be a result of rapid diversification during the early stages of Cryptotis evolution.

Demodex crocidurae, a New Demodecid Mite (Acariformes: Prostigmata) Parasitizing the Lesser White-Toothed Shrew and a Redescription of Demodex talpae from European Mole with Data on Parasitism in Soricomorpha.

Only six parasitic species of Demodecidae mite have thus far been described from the Soricomorpha, these being associated with the common shrew Sorex araneus Linnaeus, 1758, and the Mediterranean water shrew Neomys anomalus Cabrera, 1907 (two species from each host), and with the lesser white-toothed shrew Crocidura suaveolens (Pallas, 1811) and the European mole Talpa europaea Linnaeus, 1758 (one from each host species). Presently, Demodex crocidurae, a new species, has been described from the territory of Poland for C. suaveolens; in order to confirm its validity, it was necessary to redescribe D. talpae Hirst, 1921, from T. europaea, a demodecid species first described by Hirst in 1921 from England and then noted only in Poland. Both species colonized the hairy skin of the body in their hosts, where no disease symptoms of infestation were observed. However, D. crocidurae showed higher infection parameters (prevalence 100%, mean intensity 11.7, intensity range 3-26 individuals) than those of D. talpae (30.0%, 4.7, 2.0-8.0), possibly due to different host biology.

Myoglobin primary structure reveals multiple convergent transitions to semi-aquatic life in the world's smallest mammalian divers.

The speciose mammalian order Eulipotyphla (moles, shrews, hedgehogs, solenodons) combines an unusual diversity of semi-aquatic, semi-fossorial, and fossorial forms that arose from terrestrial forbearers. However, our understanding of the ecomorphological pathways leading to these lifestyles has been confounded by a fragmentary fossil record, unresolved phylogenetic relationships, and potential morphological convergence, calling for novel approaches. The net surface charge of the oxygen-storing muscle protein myoglobin (ZMb), which can be readily determined from its primary structure, provides an objective target to address this question due to mechanistic linkages with myoglobin concentration. Here, we generate a comprehensive 71 species molecular phylogeny that resolves previously intractable intra-family relationships and then ancestrally reconstruct ZMb evolution to identify ancient lifestyle transitions based on protein sequence alone. Our phylogenetically informed analyses confidently resolve fossorial habits having evolved twice in talpid moles and reveal five independent secondary aquatic transitions in the order housing the world's smallest endothermic divers.

The shrews, moles and hedgehogs that surround us all belong to the same large group of insect-eating mammals. While most members in this 'Eulipotyphla order' trot on land, some, like moles, have evolved to hunt their prey underground. A few species, such as the water shrews, have even ventured to adopt a semi-aquatic lifestyle, diving into ponds and streams to retrieve insects. These underwater foragers share unique challenges, burning a lot of energy and losing heat at a high rate while not being able to store much oxygen. It is still unclear how these semi-aquatic habits have come to be: the fossil record is fragmented and several species tend to display the same adaptations even though they have evolved separately. This makes it difficult to identify when and how many times the Eulipotyphla species started to inhabit water. The protein myoglobin, which gives muscles their red color, could help in this effort. This molecule helps muscles to capture oxygen from blood, a necessary step for cells to obtain energy. Penguins, seals and whales, which dive to get their food, often have much higher concentration of myoglobin so they can spend extended amount of time without having to surface for air. In addition, previous work has shown that eight groups of mammalian divers carry genetic changes that help newly synthetized myoglobin proteins to not stick to each other. This means that these animals can store more of the molecule in their muscles, increasing their oxygen intake and delivery. He et al. therefore speculated that all semi-aquatic Eulipotyphla species would carry genetic changes that made their myoglobin less likely to clump together; underground species, which also benefit from absorbing more oxygen, would display intermediate alterations. In addition, reconstructing the myoglobin sequences from the ancestors of living species would help to spot when the transition to aquatic life took place. A variety of approaches were harnessed to obtain myoglobin and other sequences from 55 eulipotyphlan mammals, which then were used to construct a strongly supported family tree for this group. The myoglobin results revealed that from terrestrial to subterranean to semi-aquatic species, genetic changes took place that would diminish the ability for the proteins to stick to each other. This pattern also showed that semi-aquatic lifestyles have independently evolved five separate times ­ twice in moles, three times in shrews. By retracing the evolutionary history of specific myoglobin properties, He et al. shed light on how one of the largest orders of mammals has come to be fantastically diverse.

The legacy of the fieldwork of E. W. Nelson and E. A. Goldman in Mexico (1892-1906) for research on poorly known mammals.

More than a century ago, Edward W. Nelson and Edward A. Goldman spent 14 years (1892-1906) traveling across much of Mexico in one of the most critical biological expeditions ever undertaken by two naturalists. This long-term survey was a cornerstone in Mexican mammalogy development; however, their specific role in discovering taxa that were practically unknown before the expedition is not yet necessarily recognized. In a time when the historical aspect of knowledge on mammals is being ignored for the new generations of mammalogists, a detailed analysis of the legacy of the survey is essential. Here I focus on shrews (Eulipotyphla, Soricidae) to analyze how the fieldwork and the specimens they collected have contributed to the current knowledge of shrews in the country. Nelson and Goldman collected 474 specimens of shrews, representing 31 of the 40 species that have currently been recognized. This collection has been key to building taxonomic, evolutionary, and biogeographic knowledge of shrews in the country. The success of the expedition was primarily due to the epistemic role of novel methods and approaches in natural history research at the time. The collection also offers the opportunity to document the loss of species and ecological interactions as indirect consequences of human activities, especially in montane regions. I argue that the value of this expedition can still increase with the use of modern biodiversity study tools and the digitization and access of ancient material such as photographs, field notes, and correspondence.

Eimeria longirostris (Apicomplexa: Eimeriidae) from Vagrant Shrew, Sorex vagrans (Mammalia: Eulipotyphla: Soricidae), from Montana, USA.

PURPOSE: Nothing is known about the coccidian parasites of vagrant shrews, Sorex vagrans Baird, 1868. Here we report, for the first time, the occurrence of Eimeria longirostris Hertel and Duszynski, 1987 from faecal contents of S. vagrans from Montana, USA. METHODS: Faecal samples, collected in July and August 2020 from six pitfall-trapped vagrant shrews as well as faeces from two masked shrews, Sorex cinereus Kerr, 1792, and one American pygmy shrew, Sorex hoyi Baird, 1857 from Missoula County, Montana, USA, were examined for coccidian parasites. Samples were placed in individual vials containing aqueous potassium dichromate. They were examined for coccidia after flotation in Sheather's sugar solution, measured, and photographed. RESULTS: Three (50%) S. vagrans and one (50%) S. cinereus were found to be passing oocysts of Eimeria longirostris Hertel and Duszynski, 1987; the single S. hoyi was negative. Oocysts from S. vagrans were subspheroidal and measured (average L × W) 16.1 × 14.4 µm with an L/W ratio of 1.1. One (typically) to two polar granules was present but a micropyle and oocyst residuum were absent. Sporocysts were ovoidal and measured 9.6 × 6.2 µm with an L/W ratio of 1.6. A Stieda body was present but subStieda and paraStieda bodies were absent. The sporocyst residuum was composed of various sized granules typically scattered between and across the sporozoites but sometimes formed a loose aggregate or compact mass. CONCLUSION: We document a new host and new geographic record for E. longirostris from S. vagrans and report the coccidian from S. cinereus for the third time but the first report from specimens from Montana. This coccidian has now been reported from at least 12 species of shrews within the genus Sorex in 14 US states and two provinces in Canada.

The Influence of the Interaction between Climate and Competition on the Distributional Limits of European Shrews.

It is known that species' distributions are influenced by several ecological factors. Nonetheless, the geographical scale upon which the influence of these factors is perceived is largely undefined. We assessed the importance of competition in regulating the distributional limits of species at large geographical scales. We focus on species with similar diets, the European Soricidae shrews, and how interspecific competition changes along climatic gradients. We used presence data for the seven most widespread terrestrial species of Soricidae in Europe, gathered from GBIF, European museums, and climate data from WorldClim. We made use of two Joint Species Distribution Models to analyse the correlations between species' presences, aiming to understand the distinct roles of climate and competition in shaping species' distributions. Our results support three key conclusions: (i) climate alone does not explain all species' distributions at large scales; (ii) negative interactions, such as competition, seem to play a strong role in defining species' range limits, even at large scales; and (iii) the impact of competition on a species' distribution varies along a climatic gradient, becoming stronger at the climatic extremes. Our conclusions support previous research, highlighting the importance of considering biotic interactions when studying species' distributions, regardless of geographical scale.

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A total of 64 haplotypes were obtained from the complete Cytochrome b gene (Cyt b) of 77 Sorex isodon collected from three populations (Daxing'anling, Xiaoxing'anling, and Changbai Mountains) in Northeast China. The haplotype diversity was 0.9920 and the nucleotide diversity was 0.0105, indicating high genetic diversity. The genetic diversity of Changbai Mountains population was significantly higher than that of Daxing'anling and Xiaoxing'anling populations. The F-statistics, the number of migrants per generation and the genetic distance results showed that the genetic distances among the populations and among the sampling sites were generally consistent with geographical distance. Analysis of molecular variance showed that the differentiation among populations, among sampling sites, and within sampling site accounted for 33.4%, 10.2% and 56.4% of total variation, respectively. The analysis of population history showed that S. isodon in Northeast China experienced no population expansion. The reported complete sequence of Cyt b gene of S. isodon (GenBank) of Europe and other parts of Asia was downloaded to examine the genetic structure of S. isodon. The phylogenetic tree was divided into two large branches. One branch consisted mainly of Daxing'anling and Xiaoxing'anling samples. The other branch was departed into two sub-branches. Median-joining network analysis showed that there were three lineages: one lineage mainly consisted of haplotypes from Daxing'anling and Xiaoxing'anling, and also four haplotypes of Changbai Mountains, while the other lineage included a few haplotypes of three populations in Northeast China, and those from Baikal Lake, Russia and Finland. The last lineage was entirely composed of haplotypes from Changbai Mountains. The results of genetic diversity, phylogenetic tree and median-joining network all suggested that the Changbai Mountains was the refuge for S. isodon during last glacial.

Functional volumes, niche packing and species richness: biogeographic legacies in the Congo Basin.

Understanding the determinants of species coexistence in complex and species-rich communities is a fundamental goal of ecology. Patterns of species coexistence depend on how biotic interactions and environmental filtering act over ecological and evolutionary time scales. Climatic fluctuations in lowland rainforests of the Congo Basin led to the number of vertebrate species being significantly lower in central compared with northern ecoregions of the Basin. We used null models to assess whether climatic variations affected the community assembly of shrews. A consistent limit to functional similarity of species was not related to species richness. Rather, species richness is constrained by environmental factors, and these constraints are stronger in the central lowland forests of the Congo Basin. By constraining species geographic distributions, historical effects of rainforest refugia arising from climatic fluctuations may affect contemporary species composition of local shrew communities. The Congo River represents a vicariance event that led to allopatric speciation of shrews and continues to represent a barrier to dispersal. Ultimately, the historical effects of this barrier have led to differences in the functional volume of shrew communities in northern and central ecoregions. We suggest that the analyses of community assembly can be used to identify Holocene refugia in the Congo Basin.