Cricetidae Research Articles

Neotropical non‐primate canopy mammals: historical trends, omissions, and geographic gaps in the knowledge

ABSTRACT Canopy mammals constitute a diverse and widely distributed group. However, these species have not been widely studied, and there are currently many gaps in our knowledge of their ecology, behaviour, distribution, and conservation status. We identified crucial trends and omissions in terms of research effort on research themes, taxonomic groups, countries, and protected areas (PAs) and geographic information biases. A systematic review was conducted by consulting two electronic databases (Web of Science and Scopus), including research conducted within neotropical countries (from central Mexico to northern Argentina) until the end of the first half of 2021. All the references obtained were reviewed and categorised, and the geographical location of each study was extracted to evaluate geographical gaps. We found that two orders (Carnivora and Didelphimorphia) and three families (Didelphidae, Felidae, and Cricetidae) were the most studied taxa, and were featured in more than 50% of cases. Brazil had the highest number of studies. Topics concerning diseases (19% of cases), distribution (14%), and ecology (14%) were the most frequently addressed; only 4.6% of the studies focused on anthropogenic disturbances, and less than 30% of the studies were conducted within PAs. We found that one of the largest and most important geographical biases in knowledge was in the northern Amazon region, where the number of studies was low or null. This study lays the groundwork for future research on these understudied mammals, to develop better research that can allow us to design more appropriate conservation strategies.

Comparative analysis of optional hunting behavior in Cricetinae hamsters using the data compression approach

Research into the hunting behavior in members of the Cricetidae family offers an opportunity to reveal what changes in the predatory behavioral sequences occur when a rodent species shifts from an omnivorous to a predatory lifestyle. The study tests the following hypotheses: are there phylogenetic differences in the divergence of species’ predatory lifestyles in hamsters or do ecological factors lead to shaping their hunting behavior? We applied the data compression approach for performing comparative analysis of hunting patterns as biological “texts.” The study presents a comparative analysis of hunting behaviors in five Cricetinae species, focusing on the new data obtained for the desert hamster Phodopus roborovskii whose behavior has never been studied before. The hunting behavior of P. roborovskii appeared to be the most variable one. In contrast, behavioral sequences in P. campbelli and Allocricetulus curtatus display more significant order and predictability of behavior during hunting. Optional hunting behavior in the most ancient species P. roborovskii displayed similarities with obligate patterns in “young” Allocricetulus species. It thus turned out to be the most advanced hunter among members of the Phodopus genus. Differences in hunting sequences among Phodopus representatives suggest that the hunting behavior of these species, despite its optional mode, was subject to selection during species splitting within the genus. These results did not reveal the role played by phylogenetic differences in the divergence of species’ predatory lifestyles. They suggested that ecological conditions are the main factors in speciation of the hunting behavior in hamsters.

Testicular histomorphometric patterns and spermatogenesis dynamics of Oecomys bicolor tomes, 1860 (Rodentia: Cricetidae).

Although the order Rodentia does not present a high risk of extinction compared to mammals as a whole, several families demonstrate high levels of threat and/or data deficiency, therefore highlighting the need for targeted research and the application of ecological and reproductive data to the development of conservation actions. The order Rodentia, the largest among mammals, includes 9 families, and the family Cricetidae is the most diverse of the Brazilian rodents. In Brazil, 12 of the 16 genera of Oecomys are found. Oecomys bicolor is known in Brazil as the 'arboreal rat' and is, found in dry, deciduous and tropical forests. The mean body weight of Oecomys bicolor was 35.8 g and the gonadal, tubular and epithelial somatic indexes were, 0.53%, 0.47% and 0.37%, respectively. Seminiferous tubules volume density was 89.72% and the mitotic and meiotic indexes corresponded to 8.59 and 2.45 cells, respectively, and the yield of spermatogenesis was 23.83 cells. The intertubular compartment represented 10.28% of the testis parenchyma and around 5% of the interstitial space was occupied by Leydig cells, whose number per gram of testis was 11.10 × 107 cells. By evaluating the biometric and histomorphometric characteristics of the testis, there is evidence that this species has a high investment in reproduction. Due to the high contribution of the seminiferous epithelium and the intertubular compartment in this species, compared to the others of the same family, it is possible to infer that the species Oecomys bicolor has a promiscuous reproductive behaviour.

The diet of the Eurasian eagle-owl (Bubo bubo) in various natural environments across Eurasia

Abstract The Eurasian eagle-owl (Bubo bubo) has adapted to hunt local fauna that are subject to the influence of human agricultural activities. In the sparse forests, marshes and lakes of the mountainous regions of central Norway, the eagle-owl’s diet is dominated by small mammals and gallinaceous birds, but the common frog Rana temporaria features more frequently in regions near the fjords, with various species of seabirds predominating on some islands. The eagle-owls, breeding in several protected regions of the Czech Republic, hunting in agricultural areas small mammals and game animals in addition to waterbirds nesting by fishponds. In Slovakia, the majority of the eagle-owl population nests on the edges of mountain valleys. In the past, they hunted small mammals and amphibians on pastureland located deep in the mountains, but they have adapted to hunting larger prey in more intensively farmed valleys. Predominantly in the eastern part of Turkey, the diet of Eurasian eagle-owl hunting on natural mountain steppes has been studied, where mammals of the family Cricetidae dominate. In the arid conditions of the southern countries of Syria, Jordan and Israel, mammals of the Gerbillinae sub-family predominated in addition to a higher proportion of birds. In the more variable areas of Iran, eagle-owl diets feature a wide range of indigenous mammals and birds, with different species represented in several territories. Studies from the edges of the Fergana Valley in southern Kyrgyzstan found differences in the diets of eagle-owls living at lower elevations and those living higher in the mountains, while birds were the predominant prey in the Kalek site. Smaller samples of eagle-owl diets were also collected in the Altai Mountains of Mongolia, the Barguzinsky Mountains to the east of Lake Baikal and the Vaida Mountain on Sakhalin Island. The results presented in this study can also contribute to our knowledge about the fauna of the above-mentioned regions.

Molecular epidemiology and phylogeny of the emerging zoonotic virus Rocahepevirus: A global genetic analysis

Human infections with Rocahepevirus ratti genotype C1 (HEV-C1) in Hong Kong of China, Canada, Spain, and France have drawn worldwide concern towards Rocahepevirus. This study conducted a global genetic analysis of Rocahepevirus, aiming to furnish comprehensive molecular insights and promote further research. We retrieved 817 Rocahepevirus sequences from the GenBank database through October 31, 2023, categorizing them according to research, sample collection area and date, genotype, host, and sequence length. Subsequently, we conducted descriptive epidemiological, phylogenetic evolutionary, and protein polymorphism (in length and identity) analyses on these sequences. Rocahepevirus genomes were identified across twenty-eight countries, predominantly in Asia (71.73%, 586/817) and Europe (26.44%, 216/817). The HEV-C1 dominates Rocahepevirus (77.2%, 631/817), while newly discovered Rocahepevirus genotypes (C3/C4/C5 and other unclassified genotypes) were primarily identified in Europe (25/120) and China (91/120). Muridae animals (72.5%, 592/817) serve as the primary hosts for Rocahepevirus, with other hosts encompassing species from the families Soricidae, Hominidae, Mustelidae, and Cricetidae. Additionally, Rocahepevirus genomes (C1 genotype) were identified in sewage samples recently. The phylogenetic evolution of Rocahepevirus exhibits considerable variation. Specifically, HEV-C1 can be classified into at least six genetic groups (G1 to G6), with human HEV-C1 distributed across multiple evolutionary clades. The overall ORF1 and ORF2 amino acid sequence lengths were significantly different (P < 0.001) across Rocahepevirus genotypes. HEV-C1/C2/C3 and HEV-C4/C5 displayed substantial differences in amino acid sequence identity (58.4%–59.6%). The identification of Rocahepevirus genomes has expanded across numerous countries, particularly in European and Asian countries, coinciding with an expanding host range and emergence of new genotypes. The evolutionary path of Rocahepevirus is intricate, where the HEV-C1 dominates globally and internally forms multiple evolutionary groups (G1 to G6), exhibiting diverse genetic variation within human HEV-C1. Significant differences exist in the protein polymorphism (in length and identity) across Rocahepevirus genotypes. Given Rocahepevirus's shift from an animal virus to a zoonotic pathogen, worldwide cooperation in monitoring Rocahepevirus genomes is vital.

A simple and low-cost environmental enrichment program improves the welfare of Calomys callosus, a species that adapts to animal facilities.

An environmental enrichment protocol is essential for testing experimental models because it upholds animal welfare, aligns with ethical principles in animal experimentation, and reduces the number of animals needed. Calomys callosus, a South American rodent from the Cricetidae family, is bred in rodent animal facilities for its ease of handling, longevity, prolificacy, and effectively mimicking diseases like Toxoplasmosis, Leishmaniasis, Chagas, and Schistosomiasis. There are no reports on environmental enrichments for this species or their impact on reproductive parameters. This study aimed to analyze the influence of the Environmental Enrichment Program (EEP) on the reproductive and zootechnical performance of C. callosus kept in the Rodents Animal Facilities Complex of Universidade Federal de Uberlândia (UFU). Two experimental groups were established: with environmental enrichment EE+ and without environmental enrichment EE-. The materials used in the experimental design were changed weekly and alternated between dietary, occupational, physical/cognitive, and non-enrichment items. After the inclusion of the EEP, an improvement in the reproductive indices of C. callosus was identified in the EE+ group. These improvements included increased female precocity, a decreased interbirth interval, and a higher number of pairs producing more offspring. The postpartum zootechnical indices were also better, such as the number of animals born alive, improved weaning rates, and a reduced average number of deaths from birth to weaning. After the inclusion of the EEP, the general health status of C. callosus improved, reducing cases of non-infectious lumbar alopecia. Therefore, EEP allows C. callosus to express natural reproductive behaviors and improves parental care.

Видовий склад і чисельність хом’якових у степових заповідниках південного сходу України

The article presents information about the family Cricetidae in the steppe reserves located in south-eastern Ukraine within Donetsk and Luhansk oblasts, including data on the species composition and the population sizes. The study also sheds light on the limitations of individual species in their biotopes and identifies differences in rodent population density between areas subject to different economic regimes. The author suggests that periodic mowing and grazing may have a negative impact on the population sizes. It was established that cricetids make up the majority of all rodents in the diet of the short-eared owl.

Матеріали до фауни Бузького Гарду: огляд знахідок дрібних ссавців (Soricidae, Muridae, Cricetidae)

New data on micromammals of the Bug Gard National Nature Park obtained in 2022–2023 are presented. Eight species of this survey group were recorded. They include three species of shrews of the family Soricidae (Crocidura suaveolens, Sorex araneus, and Neomys fodiens); four species of rodents of the family Muridae (Sylvaemus uralensis, S. sylvaticus, Apodemus agrarius, and Mus spicilegus); and one species of rodents of the family Cricetidae (Microtus levis). Two species were found for the first time in the fauna of the Bug Gard NNP: Sylvaemus uralensis and Neomys fodiens. Information on the morphometry and habitats of the collected animals is presented.

Temporal changes in small mammal (Eulipotyphla, Rodentia) assemblages in Košice Zoo (Slovakia)

Abstract This study summarizes 17-year results of teriological research of small mammal fauna in Košice Zoo (near the village of Kavečany, 48°47’10.04”N, 21°12’3.26”E, 380 – 420 m a.s.l.). The small mammals evaluated in this study were obtained by trapping in three periods (1992 – 1994, 2000 – 2001, 2003 – 2004) and were the results of three diploma theses. In total, 688 small mammals belonging to 13 species of four families Soricidae, Gliridae, Cricetidae and Muridae were recorded by trapping during the study period. Rodents significantly dominated with 8 species, 583 ex. (84.7%) compared to insectivores represented by 5 species, 105 ex. (15.3%). A gradual diversity decline of small mammal fauna was recorded, with only four mammal species confirmed in 2003 – 2004. This marked difference over the last 17 years was probably the result of anthropic modifications of the Zoo area, mainly the cutting of trees and shrubs of the alluvium, technical modifications of the streambeds as well as the deratization of the building areas and animal enclosures. The assemblage’s structure of captured small mammals could also be influenced by other factors, such as the predominant type of traps used, or the number of exposed traps in the vegetation and non-vegetation periods of the year. The obtained results are also a suitable basis and source of information for comprehensive and long-term monitoring in this area, given the epidemiological importance of this group of animals and the possibility of contact with exotic animals.

Expression analysis suggests that DNMT3L is required for oocyte de novo DNA methylation only in Muridae and Cricetidae rodents

BackgroundDuring early mammalian development, DNA methylation undergoes two waves of reprogramming, enabling transitions between somatic cells, oocyte and embryo. The first wave of de novo DNA methylation establishment occurs in oocytes. Its molecular mechanisms have been studied in mouse, a classical mammalian model. Current model describes DNA methyltransferase 3A (DNMT3A) and its cofactor DNMT3L as two essential factors for oocyte DNA methylation—the ablation of either leads to nearly complete abrogation of DNA methylation. However, DNMT3L is not expressed in human oocytes, suggesting that the mechanism uncovered in mouse is not universal across mammals.ResultsWe analysed available RNA-seq data sets from oocytes of multiple mammals, including our novel data sets of several rodent species, and revealed that Dnmt3l is expressed only in the oocytes of mouse, rat and golden hamster, and at a low level in guinea pigs. We identified a specific promoter sequence recognised by an oocyte transcription factor complex associated with strong Dnmt3l activity and demonstrated that it emerged in the rodent clade Eumuroida, comprising the families Muridae (mice, rats, gerbils) and Cricetidae (hamsters). In addition, an evolutionarily novel promoter emerged in the guinea pig, driving weak Dnmt3l expression, likely without functional relevance. Therefore, Dnmt3l is expressed and consequently plays a role in oocyte de novo DNA methylation only in a small number of rodent species, instead of being an essential pan-mammalian factor. In contrast to somatic cells, where catalytically inactive DNMT3B interacts with DNMT3A, forming a heterotetramer, we did not find evidence for the expression of such inactive Dnmt3b isoforms in the oocytes of the tested species.ConclusionsThe analysis of RNA-seq data and genomic sequences revealed that DNMT3L is likely to play a role in oocytes de novo DNA methylation only in mice, rats, gerbils and hamsters. The mechanism governing de novo DNA methylation in the oocytes of most mammalian species, including humans, occurs through a yet unknown mechanism that differs from the current model discovered in mouse.

Using archived and biocollection samples towards deciphering the DNA virus diversity associated with rodent species in the families cricetidae and heteromyidae

Rodentia is the most speciose order of mammals, and they are known to harbor a wide range of viruses. Although there has been significant research on zoonotic viruses in rodents, research on the diversity of other viruses has been limited, especially for rodents in the families Cricetidae and Heteromyidae. In fecal and liver samples of nine species of rodents, we identify 346 distinct circular DNA viral genomes. Of these, a large portion are circular, single-stranded DNA viruses in the families Anelloviridae (n = 3), Circoviridae (n = 5), Genomoviridae (n = 7), Microviridae (n = 297), Naryaviridae (n = 4), Vilyaviridae (n = 15) and in the phylum Cressdnaviricota (n = 13) that cannot be assigned established families. We also identified two large bacteriophages of 36 and 50 kb that are part of the class Caudoviricetes. Some of these viruses are clearly those that infect rodents, however, most of these likely infect various organisms associated with rodents, their environment or their diet.

The discovery of multiple active mys-related LTR-retroelements within the Neotominae subfamily of cricetid rodents.

Retrotransposon families in the rodent family Cricetidae have been understudied in contrast to Muridae, both taxa classified within the superfamily Muroidea. Therefore, we carried out a study to advance our knowledge of the unique mys LTR-retroelement identified in Peromyscus leucopus, by incorporating intra-ORF PCR, quantitative dot blots, DNA and protein library screens, the generation of molecular phylogenies, and analyses of orthologous LTR-retroelement loci. These analyses led to the discovery of three additional related families of LTR-retroelements, which include a 2900bp full-length element of mys-related sequences (mysRS), an 8000bp element containing the mys ORF1 sequence (mORF1) with ERV-related sequences downstream in the reverse orientation, as well as an 1800bp element primarily consisting of mys ORF2 (mORF2) related sequences flanked by LTRs. Our data revealed only a few full-length mys elements among genera of the Neotominae subfamily of cricetid rodents, most existing as partial copies. The mysRS and mORF1 elements are also limited to the genomes of the Neotominae subfamily, whereas mORF2 appears to be restricted to the Peromyscus genus. Molecular phylogenies demonstrating concerted evolution along with an assessment of orthologous loci in Peromyscus for the presence or absence of elements are consistent with activity of these novel LTR-retroelement families within this genus. Together with known activity of various families of non-LTR retroelements in Peromyscus species, we propose that retrotransposons have been continually contributing to the dynamics of Peromyscus genomes promoting genomic diversity and may be correlated with the evolution of more than 50 identified Peromyscus species.

Editing the Genome of the Golden Hamster (Mesocricetus auratus).

The golden (Syrian) hamster (Mesocricetus auratus) is a small rodent belonging to the Cricetidae family. Golden hamsters have several unique characteristics that are advantageous in the study of reproductive and developmental biology: a highly stable 4-day estrous cycle, a high responsiveness to conventional superovulation methods, and a shortest gestation period (16days) known among eutherian mammals. Besides these advantages, the technical ease of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in this species has contributed much to our understanding of the basic mechanisms of mammalian fertilization. However, the exceptionally strong in vitro developmental block of hamster embryos, especially at the two-cell stage, has hampered the production of genetically modified hamsters, which has resulted in limited use of this species for biomedical research. However, the recently developed in vivo genome editing method (improved genome editing via oviductal nucleic acid delivery, i-GONAD) has overcome this shortcoming and made production of gene-edited hamsters much easier than before. This method has the potential to provide a means of reexamining genes whose functions cannot be identified using mouse models, thus leading to the better understanding of gene functions in mammals. In this chapter, we present our procedure for editing the genome of the golden hamster using i-GONAD.

A method for visualizing of reproductive organs in immature small mammals using Soricidae (Insectivora) and Cricetidae (Rodentia) as an example

The article is devoted to determination of sex of juveniles of small mammals. The definition of which is the most time-consuming part of anatomical research. The method of visualizing the sex of young animals by reproductive organs using 3% hydrogen peroxide (H2O2) and 6% apple cider vinegar (CH3COOH) is used. Earlier in 2020, this method was successfully used on immature shrews (Sorex). The results of the study served as an impetus for the continuation of the study on juveniles of the hamster family (Cricetidae Fischer, 1817) and repeated testing on young individuals of the shrew family (Soricidae Fischer, 1814). The collection of material was carried out in 2021 in the central part of the White Sea-Kuloy Plateau. A total of 475 small mammals from three families were studied (Cricetidae – 291, Soricidae – 183, birch mice Sminthidae Brandt, 1855 – 1). Anatomical examination of biological material showed that 24% (n = 114) of young animals turned out to have indeterminate sexual characteristics. These juvenile individuals belonged to the families of shrews (15.8%) and hamsters (8.2%). As a result of the method, gender differences were found in 92.1% of juvenile individuals. During the reaction of hydrogen peroxide with blood catalase, in 35.2% of males (of the identified individuals), the spermatic ducts were elevated, and in 51.4% of them, seminal ducts and testes were discolored. In 43.8% of females, the horns and the body of the uterus increased in size by 2 times, and it turned white in 48.6%. In 7.9% of specimens, the sex has not been set due to postmortem damage to internal organs. The study proves that the method of visualizing sex by reproductive organs is effective for immature animals of Cricetidae and Soricidae. The method makes it possible to reduce the number of unrecorded juveniles and to obtain reliable information about the sex and age structure of the population.

Andean rain shadow effect drives phenotypic variation in a widely distributed Austral rodent

AbstractAimMountains cover approximately 22% of the planet's terrestrial surface and have dramatic effects on climate and biodiversity. The rain shadow effect is a common feature on mountain ranges worldwide and its effects on ecology and evolution of species, particularly morphology, are incompletely known. Our aim is to identify the correlates that best describe morphological variation along a pronounced rain shadow gradient.LocationPatagonia and Tierra del Fuego (southern South America), including Valdivian and Magellanic forests and steppes.TaxaShaggy soft‐haired mouse Abrothrix hirta (Order Rodentia, Family Cricetidae).MethodsWe measured 450 skulls of A. hirta from 67 localities between 35°S and 54°S, from the Pacific to the Atlantic coasts. We analysed geographic differences in skull morphology using 17 linear skull measurements. Discriminant function analysis revealed clear evidence for sexual dimorphism; thus, analyses were conducted for the entire dataset, and separately by sex. We implemented regression tree analysis to test the environmental correlates that best describe morphological variation along this gradient.ResultsSkull size variation in shaggy soft‐haired mice does not follow Bergmann's rule; however, latitude was the second node for PC1 of all samples. Regression tree analyses showed that the variables that best explained size for the various datasets were longitude, precipitation of the coldest quarter and temperature seasonality. Longitude appeared in eight of the nine regression tree analyses. We find that organisms attain greater sizes in the western Andes where there is no rain shadow effect, below 500 m of elevation.Main ConclusionsMorphological variation and size of A. hirta is highly structured along a longitudinal gradient, which mirrors patterns of primary productivity and the Andean rain shadow effect in this region, best described by the “resource rule”. Mountains are a formidable land feature that clearly affects the morphology of species distributed at both sides of them.

Modelling relative abundance of Oligoryzomys flavescens, an Orthohantavirus reservoir, in an endemic hantavirus pulmonary syndrome zone.

Hantavirus pulmonary syndrome (HPS) is a zoonotic emerging infectious disease caused by New World orthohantaviruses (family Hantaviridae) hosted by rodents of the family Cricetidae. In Argentina, one of its main hosts is the sigmodontine rodent Oligoryzomys flavescens, a widely distributed mouse of the Pampas, Delta and Espinal ecoregions of central-east Argentina. Because the abundance of the reservoir and its proportion in the rodent community affects both virus prevalence and human exposure risk, its estimation throughout its known geographical distribution is of key importance for the design of public health strategies to prevent HPS. The aim of this study was therefore to model the relative abundance of O.flavescens in most of the Pampas ecoregion within Buenos Aires Province, Argentina, where hantavirus pulmonary syndrome is endemic. To do this we used owl-pellet samples collected between 2006 and 2008 from 51 sites distributed throughout most of Buenos Aires province. Mammalian prey in each pellet was identified to the lowest possible taxonomic level by examination of the skulls, dentaries and molars. We modelled the frequency of O.flavescens found in each sample as a function of climatic, environmental, and topographic data of each site. The two best models were applied to a Geo referential Information System to build maps of estimated frequency (as a proxy of relative abundance) within Buenos Aires province. Estimated relative abundance of O.flavescens in Buenos Aires province was significantly associated with annual mean temperature, annual precipitation and presence of freshwater bodies, and varied among sub-regions, with the Inland and Rolling Pampas being the regions with highest frequencies. Knowing in which areas O.flavescens abundance is expected to be higher can be used to concentrate limited sanitary efforts in those areas that are most needed in order to reduce transmission and increase detection.

Dietary Patterns Suggest West Virginia Bobcats Are Generalist Carnivores

Abstract The proportion and diversity of prey species consumed by bobcats Lynx rufus are often correlated with prey abundances, individual skill level, environmental conditions, and habitat quality. Bobcats generally consume prey species that rely on mast—the fruits of trees—for basic life-history requirements. In West Virginia forests, many mast-producing tree species have declined over the past 40 y, yet the last known study on bobcat diet in the state was in 1977. Thus, we need current data to understand the effects of forest compositional changes on bobcat dietary patterns. We evaluated stomach contents of 300 bobcats collected over the 2014–2015 (n = 150) and 2015–2016 (n = 150) hunting and trapping seasons in West Virginia. Simpson's index of diversity indicated an 87% probability that two randomly selected prey items belong to different species, supporting the idea of bobcats as generalist carnivores. White-tailed deer (hereafter deer) Odocoileus virginianus (32%), mice and rats (families Cricetidae, Dipodidae, and Muridae; 30.7%), rabbits (family Leporidae; 21.3%), Virginia opossum Didelphis virginiana (18.7%), and squirrels (family Sciuridae; 17.3%) occurred most frequently. We found 92% dietary overlap between sexes and 35% between stage classes. Deer, opossum, and raccoon Procyon lotor occurred more frequently in males, whereas rabbits occurred more frequently in females. Deer occurred more frequently in adults; raccoons in yearlings; and mice and rats in juveniles. Overall occurrence of deer (−17.1%), rodents (order Rodentia; −9.5%), opossum (+13.5%), and raccoon (+5.1%) differed significantly between the 1977 study and this study, which may allude to changes in the abundance of mast-dependent prey species over time. Similarly, hard mast (i.e., nuts) production had a significant interaction effect with study season on the overall occurrence of squirrels in bobcat diets. By improving our understanding of bobcat trophic interactions, we can better manage their populations and ecological communities by managing for the dietary requirements of their common prey species.

PROPOZYCJA MONITORINGU NORNICY RUDEJ (MYODES GLAREOLU, SCHREBER 1780)

There are many reasons why it might be necessary to monitor the bank voles. It causes damage to trees and eats seeds in orchards and tree plantations, and the determination of its presence as well as the effectiveness of the measures taken to minimize losses is very important in the activity of the above-mentioned. The rodent is also the main for central Europe reservoir of the Puumala virus, which is dangerous to humans, so observing the trends in the number of voles may be crucial. The small number of the species may indicate environmental poisoning, especially with copper. And finally, it is a very important species for the environment, both transformed by man and natural, so it is very important to preserve it despite the climate changes. The bank vole is a small mammal from the Cricetidae family. It occurs all over Europe. It lives mainly in deciduous forests of medium density and rich undergrowth, although it is also found in other areas, including anthropogenic ones. The proposed monitoring is based on catching with the use of wooden box traps and the analysis of pellets. The indicators used would be: the number of individuals caught per 100 trap-nights, the percentage of the species in total number of small mammals and the age structure of the population. In the first method one should remember about practices that will reduce or eliminate the mortality of captured animals – the appropriate setting of traps and selection of weather conditions. Also collecting pellets, one should bear in mind the limitations of this method and the differences between the spring-summer and autumn-winter material. The determination of the condition of the habitat may be based on the percentage of deciduous trees, density of trees and the appearance of the undergrowth.

Mitochondrial DNA Diversity of Mesocricetus auratus and Other Cricetinae Species among Cricetidae Family.

Unique anatomical and physiological features have made hamster species desirable research models. Comparative genomics and phylogenetic analysis of the hamster family members to clarify their evolution and genetic relationship, can provide a genetic basis for the comprehension of the variable research results obtained using different hamster models. The Syrian golden hamster (Mesocricetus auratus) is the most widely used species. In this study, we sequenced the complete mitochondrial genome (mitogenome) of M. auratus, compared it with the mitogenome of other Cricetinae subfamily species, and defined its phylogenetic position in the Cricetidae family. Our results show that the mitogenome organization, gene arrangement, base composition, and genetic analysis of the protein coding genes (PCGs) of M. auratus are similar to those observed in previous reports on Cricetinae species. Nonetheless, our analysis clarifies some striking differences of M. auratus relative to other subfamily members, namely distinct codon usage frequency of TAT (Tyr), AAT (Asn), and GAA (Glu) and the presence of the conserved sequence block 3 (CSB-3) in the control region of M. auratus mitogenome and other hamsters (not found in Arvicolinae). These results suggest the particularity of amino acid codon usage bias of M. auratus and special regulatory signals for the heavy strand replication in Cricetinae. Additionally, Bayesian inference/maximum likelihood (BI/ML) tree shows that Cricetinae and Arvicolinae are sister taxa sharing a common ancestor, and Neotominae split prior to the split between Cricetinae and Arvicolinae. Our results support taxonomy revisions in Cricetulus kamensis and Cricetulus migratorius, and further revision is needed within the other two subfamilies. Among the hamster research models, Cricetulus griseus is the species with highest sequence similarity and closer genetic relationship with M. auratus. Our results show mitochondrial DNA diversity of M. auratus and other Cricetinae species and provide genetic basis for judgement of different hamster models, promoting the development and usage of hamsters with regional characteristics.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10528-022-10195-7.

Variability of Calodium hepaticum eggs from sigmodontine host species through geometric morphometric analysis.

Calodium hepaticum is a zoonotic nematode with a worldwide distribution. Although the host range of C. hepaticum includes a wide spectrum of mammals (including humans), this parasite is predominantly associated with the families Muridae and Cricetidae. Several Sigmodontinae species from Argentina were found to be infected by C. hepaticum, with a high prevalence in Akodon azarae. The present study focuses on C. hepaticum eggs from natural infection of three species of sigmodontine rodents from Argentina. Eggs were genetically characterized (intergenic 18S rRNA region). The objectives of this work are: (i) to propose a new analytical methodology; and (ii) to morphologically characterize C. hepaticum eggs, from three Sigmodontinae species (A. azarae, Calomys callidus and Oligoryzomys flavescens). Analyses were made by the Computer Image Analysis System based on the new standardized measurements and geometric morphometric tools. The resulting factor maps clearly illustrate global size differences in the parasite eggs from the three Sigmodontinae species analysed. The degree of similarity between egg populations was assessed through pairwise Mahalanobis distances, showing that the largest distances were detected between parasite eggs from C. callidus and O. flavescens. Herein, the phenotypical plasticity of C. hepaticum eggs is shown. Significant positive correlations were obtained between each egg parasite principal component 1 and rodent corporal characteristics: weight; liver weight; rodent length; and rodent body condition. The usefulness of the geometric morphometric analysis in studies of the relationship between C. hepaticum and its host must be highlighted. The high prevalence observed in A. azarae, associated with the wide size range of the parasite eggs evidenced by principal component analysis, suggests A. azarae to be the Sigmodontinae host species that plays the most important role as reservoir host for C. hepaticum in the New World.