Data on the long-distance dispersal of Laxmann's shrew (Sorex caecutiens Laxmann, 1788) and the pygmy shrew (Sorex minutus Linnaeus, 1766)

We studied the long-distance dispersal of two species of shrews – Laxmann's shrew (Sorex caecutiens) and the pygmy shrew (Sorex minutus). Group marking with bait containing rhodamine B was used. These were the first data obtained on the long-distance movements of the pygmy shrew (n = 5), which extended from 475 m to 2570 m in a straight line. In the course of dispersion, Laxmann's shrews (n = 12) moved distances of up to 4500 m, which is the maximum movement distance known for this species.

Commensals of underground mammals: European mole (Talpa europaea, Eulipotyphla, Talpidae) and the greater mole-rat (Spalax microphthalmus, Rodentia, Spalacidae)

Stepanova I, Andreychev A, Kulakhmetov R, Lobachev E. 2021. Commensals of underground mammals: European mole (Talpa europaea, Eulipotyphla, Talpidae) and the greater mole-rat (Spalax microphthalmus, Rodentia, Spalacidae). Biodiversitas 22: 4665-4670. The study of lodgers of burrows of underground mammals was carried out using the method of hunting cylinders (cans). In the study, 29 different representatives from the following classes were identified in the courses of the greater mole-rat and European mole: Diplopoda, Chilopoda, Gastropoda, Insecta, Amphibia, and Mammalia. Among the vertebrates captured are Eurasian common shrew (Sorex araneus), Eurasian pygmy shrew (Sorex minutus), bank vole (Clethrionomys glareolus), common spadefoot toad (Pelobates fuscus), moor frog (Rana arvalis), and common toad (Bufo bufo). Twenty-six different species have been identified among invertebrates. Many animals seek shelter in the burrows of underground mammals from enemies and adverse climatic factors for food or conditions for reproduction. In the central part of Russia, more species of commensals were found in European mole burrows (29) than in greater mole-rat burrows (21).

First Data on the Helminth Community of the Smallest Living Mammal on Earth, the Etruscan Pygmy Shrew, Suncus etruscus (Savi, 1822) (Eulipotyphla: Soricidae)

Suncus etruscus is the smallest living mammal on Earth by mass. Most adults weigh 1.8–3 g with a body length of 35–48 mm. Catching it in small mammal traps in nature is extremely difficult due to its minute size, and therefore special trapping methods must be used. We had the unique opportunity of studying, for the first time, the helminth parasites of 166 individuals of S. etruscus, part of the largest collection in the world, which belonged to the French scientist Dr Roger Fons (1942–2016). A total of 150 individuals were captured in the Banyuls-Cerbère area (France) and 16 in the island of Corsica (France). We found seven helminth species, specifically, the cestodes Joyeuxiella pasqualei larvae, Mesocestoides sp. larvae, Staphylocystis claudevaucheri, S. banyulsensis, S. cerberensis, and Pseudhymenolepis sp., and the nematodes Aonchotheca sp. and Nematoda gen. sp. larvae. Neither trematodes nor acanthocephalans were detected. We provide prevalences, infracommunity compositions, and helminth associations. The adult helminth community of S. etruscus seems to be highly specific, i.e., oioxenous, and linked to its insectivore diet. Due to its small size, S. etruscus has undergone numerous physiological adaptations that have probably influenced its helminth spectrum as well as its helminth specificity.

Primer biases in the molecular assessment of diet in multiple insectivorous mammals

Our understanding of trophic interactions of small insectivorous mammals has been drastically improved with the advent of DNA metabarcoding. The technique has continued to be optimised over the years, with primer choice repeatedly being a vital factor for dietary inferences. However, the majority of dietary studies examining the effect of primer choice often rely on in silico analyses or comparing between species that occupy an identical niche type. Here, we apply DNA metabarcoding to empirically compare the prey detection capabilities of two widely used primer sets when assessing the diets of a flying (lesser horseshoe bat; Rhinolophus hipposideros) and two ground-dwelling insectivores (greater white-toothed shrew; Crocidura russula and pygmy shrew; Sorex minutus). Although R. hipposideros primarily rely on two prey orders (Lepidoptera and Diptera), the unique taxa detected by each primer shows that a combination of primers may be the best approach to fully describe bat trophic ecology. However, random forest classifier analysis suggests that one highly degenerate primer set detected the majority of both shrews’ diet despite higher levels of host amplification. The wide range of prey consumed by ground-dwelling insectivores can therefore be accurately documented from using a single broad-range primer set, which can decrease cost and labour. The results presented here show that dietary inferences will differ depending on the primer or primer combination used for insectivores occupying different niches (i.e., hunting in the air or ground) and demonstrate the importance of performing empirical pilot studies for novel study systems.

Primer biases in the molecular assessment of diet in multiple insectivorous mammals

Our understanding of trophic interactions of small insectivorous mammals has been drastically improved with the advent of DNA metabarcoding. The technique has continued to be optimised over the years, with primer choice repeatedly being a vital factor for dietary inferences. However, the majority of dietary studies examining the effect of primer choice often rely on in silico analyses or comparing single-niche species. Here we apply DNA metabarcoding to empirically compare the prey detection capabilities of two widely used primer sets when assessing the diets of a flying (lesser horseshoe bat; Rhinolophus hipposideros) and two ground dwelling insectivores (greater white-toothed shrew; Crocidura russula and pygmy shrew; Sorex minutus). Although R. hipposideros primarily rely on two prey orders (Lepidoptera and Diptera), the unique taxa detected by each primer shows that a combination of primers may be the best approach to fully describe bat trophic ecology. However, random forest classifier analysis suggest that one highly degenerate primer set detected the majority of both shrews’ diet despite higher levels of host amplification. The wide range of prey consumed by ground-dwelling insectivores can therefore be accurately documented from using a single broad-range primer set, which can decrease cost and labour. The results presented here show that dietary inferences will differ depending on the primer or primer combination used for insectivores occupying different niches (i.e. hunting in the air or ground) and demonstrate the importance of performing empirical pilot studies for novel study systems.

Extreme hyperallometry of mammalian antibacterial defenses

Terrestrial mammals span 7 orders of magnitude in body size, ranging from the < 2 g pygmy shrew (Suncus etruscus) to the > 3900 kg African elephant (Loxodonta africana). Although body size has profound effects on the behavior, physiology, ecology, and evolution of animals, how body mass affects immune functions is unknown. Here, using data from >160 terrestrial species of mammals, we show that the size-scaling of antibacterial activity in serum exhibits extreme hyperallometry. Compared to small mammals, the serum of large mammals is remarkably inhospitable to bacteria. Such hypermetric scaling of immune defenses provides novel perspectives on the ecology of host-pathogen interactions, and on their co-evolutionary dynamics. These results also have implications for effectively modeling human immunity and for identifying reservoirs of zoonotic pathogens.

Phylogeographical structure of the pygmy shrew: revisiting the roles of southern and northern refugia in Europe

Southern and northern glacial refugia are considered paradigms that explain the complex phylogeographical patterns and processes of European biota. Here, we provide a revisited statistical phylogeographical analysis of the pygmy shrew Sorex minutus Linnaeus, 1766 (Eulipotyphla, Soricidae), examining its genetic diversity, genetic differentiation and demographic history in the Mediterranean peninsulas and in Western and Central Europe. The results showed support for genetically distinct and diverse phylogeographical groups consistent with southern and northern glacial refugia, as expected from previous studies. We also identified geographical barriers concordant with glaciated mountain ranges during the Last Glacial Maximum (LGM), early diversification events dated between the Late Pleistocene and Early Holocene for the main phylogeographical groups, and recent (post-LGM) patterns of demographic expansions. This study is the most comprehensive investigation of this species to date, and the results have implications for the conservation of intraspecific diversity and the preservation of the evolutionary potential of S. minutus.

Speciation of North American pygmy shrews (Eulipotyphla: Soricidae) supports spatial but not temporal congruence of diversification among boreal species

Speciation among many animals was rapid through the Pleistocene, impacted by climate and periodic isolation and reconnection. As such, species limits among often morphologically cryptic lineages may remain unresolved despite clear mitogenomic partitioning. Accumulating evidence from phylogeographical studies is revealing congruent regional differentiation of lineages across taxonomic groups that share ecological and evolutionary traits. Here, we analyse multiple DNA loci and morphology to resolve the geography and timeframe associated with evolutionary history of North American pygmy shrews (genus Sorex). We then assess lineage diversification among three co-distributed shrew complexes using phylogenetic and approximate Bayesian computation approaches to test a hypothesis of spatial congruence but temporal incongruence of species formation on a continental scale. Our results indicate consistency in regional lineage distributions, partial congruence of the sequence of divergence, and strong but not definitive support for temporal incongruence, suggesting that successive glacial cycles initiated the process of diversification repeatedly through the Pleistocene. Our results emphasize a continuing need for greater genomic coverage in comparative phylogeography, with persistent challenges. We recognize distinct eastern (Sorex hoyi Baird, 1857) and western (Sorex eximius Osgood, 1901) species of pygmy shrew based on available evidence, but discuss issues with taxonomic designations considering the continuum of speciation throughout the boreal biome.

Phylogeographic structure of the pygmy shrew: revisiting the roles of southern and northern refugia in Europe

ABSTRACTSouthern and northern glacial refugia are considered paradigms that explain the complex phylogeographic patterns and processes of European biota. Although the Eurasian pygmy shrew Sorex minutus Linnaeus, 1766 (Eulipotyphla, Soricidae) has been used a model species to study geographic isolation and genetic diversification in Mediterranean peninsulas in the Last Glacial Maximum (LGM), and post-glacial population expansion from cryptic northern glacial refugia in Western and Central Europe, there has been incomplete knowledge about the phylogeographic structure, genetic differentiation and demographic history within these regions. Here, we provide a revisited statistical phylogeographic study of S. minutus with greater sampling coverage in terms of numbers of individuals and geographic range, making it the most comprehensive investigation of this species to date. The results showed support for genetically distinct and diverse phylogeographic groups consistent with southern and northern glacial refugia, as expected from previous studies, but also identified geographical barriers concordant with glaciated mountain ranges during the LGM, early diversification events dated between the Upper Pleistocene and Lower Holocene for the main phylogeographic groups, and recent (post-LGM) patterns of demographic expansions. The results have implications for the conservation of intraspecific diversity and the preservation of the evolutionary potential of S. minutus.