Search Results (30)

We used stable carbon and nitrogen isotope values in plants, fur, and bone to establish baseline isotopic variability and investigate food web dynamics for small mammals at Betampona Réserve Naturelle Intégrale (BRNI), which protects an isolated parcel of tropical lowland moist evergreen forest in central eastern Madagascar. We included foliage from four understory plant genera, 13 endemic mammal species (5 bats, 5 tenrecs, and 3 nesomyine rodents), and introduced Rattus rattus and Suncus murinus that were collected along a gradient of degraded to intact forest from the southern boundary to the interior of BRNI as well as nearby villages. Isotopic data indicate niche partitioning among mammal groups, as well as among species within each of the groups. Most species appear to have foraged in the forest understory, although some, bats in particular, may have foraged outside of the protected area. We did not find evidence for competition between introduced and endemic animals but caution that some sample sizes are small. These results provide previously unknown insight into dietary preferences for some of Madagascar’s least studied mammals and establish a foundation for future work at BRNI. Full article

Excavations undertaken at Mata Menge, the securely dated Middle Pleistocene open site on the Indonesian island of Flores, have resulted in the recovery of over 670 well-preserved fossil murine molars from two distinct stratigraphic intervals. This research is the first systematic metric and morphological analysis of this material, with the results indicating the predominance of a single murine species, though the finds from the lower interval (0.7 million years ago) are for the most part significantly smaller than those recovered from the ~70,000-year-younger upper interval. Comparison of our findings with the analyses of the Flores endemic recent and fossil giant rats undertaken by Hooijer in 1957 and Musser in 1981 indicates the Mata Menge large murine maxillary molars, and, in particular, those from the lower interval are very similar to the limited Middle Pleistocene material Musser designated to be Hooijeromys nusatenggara. However, the associated Mata Menge mandibular molars are most similar to, though smaller than, the mid-Holocene Papagomys theodorverhoeveni. In addition to providing a detailed reference for future studies of large fossil murines excavated from Wallacea, our findings indicate Musser’s reassignment of Hooijer’s maxillary holotype of P. verhoeveni to P. armandvillei would benefit from re-examination. Full article

Small rodents are known hosts of various pathogens, including Hepatozoon, but until now, in Brazil, only Hepatozoon milleri has been described in these animals. In this study, liver samples and blood smears were obtained from 289 rodents belonging to 14 Cricetidae and two Muridae species that had been captured in municipalities of the states of Paraná and Rio de Janeiro. Smears were stained with Giemsa, and gametocytes were detected via microscopy in 10.72% (n = 31/289) of samples, with these individuals representing three rodent species. Significant morphometric differences were observed in gametocyte measurements in Akodon rodents. Using conventional PCR, Hepatozoon spp. 18S rDNA fragments were amplified in 24.91% (n = 72/289) of samples, with those individuals representing seven rodent species. Phylogenetic analyses clustered 41 sequences from this study into a subclade with other sequences from small mammals in Brazil, identifying four distinct haplotypes, and, for the first time, a relationship between Hepatozoon haplotype and gametocyte length was observed. Based on phylogenetic analysis, this study reinforces the trophic relationship between rodents and reptiles as a possible link in the Hepatozoon transmission cycle in South America. Furthermore, our findings expand knowledge on Hepatozoon spp. hosts, describing Oxymycterus nasutus and Oxymycterus quaestor as new host species and identifying two novel circulating haplotypes in rodents from Paraná State, southern Brazil. Full article

Probasin protein was originally identified as a basic protein present in rat prostate epithelium. So far, its physiological role, its origin, and its presence in other species including humans remain largely elusive. With the ever-growing number of genome assemblies, thus far, probasin genes (Pbsn/PBSN) have only been predicted in a subset of rodent genomes. In this study, we addressed the phylogeny of probasin genes and found them to be exclusively present in members of the superfamily Muroidea. It first emerged in the so-called pseudoautosomal region, a subtelomeric gene cluster of both mammalian sex chromosomes. During evolution of the Muroidea lineages, probasin recombined to the X-specific region of the X-chromosome in mice and hamster species. This event likely saved the gene from events that other pseudoautosomal genes suffered, namely displaying an increase in G and C nucleotide composition or accumulation of repetitive elements. We observed changes to its coding region, e.g., sequence insertions in exon 6, which challenge the current understanding of rodent phylogeny, in particular regarding the evolutionary history of tribe formation within the subfamily Murinae. Analyzing the evolution of probasin genes in Muroidea allows fostering understanding of phylogenetic relationships in one of the largest groups of mammalian species. Full article

The role of keystone species in maintaining ecosystem stability is a crucial aspect of ecology. Identifying key mammalian species within an ecosystem requires a systematic approach, utilizing criteria and indicators derived from species characteristic variables. This study presents a framework to identify key mammalian species based on various ecological, structural, and functional factors. By developing a mechanistic model of energy flow in food webs and trophic levels, the model aims to pinpoint each species’ role in the stability and sustainability of biomass flow within the ecosystem. Known as KVT version 1.0, the model explains the role of each characteristic variable of mammalian species, predicts population growth, elucidates species interactions at trophic levels, and assesses species-specific dietary compositions, including food requirements, reproduction, and activity. Factor analysis of model outputs has produced equations to determine the value of keystone species (K_v), indicating the role of mammalian species in the stability and sustainability of biomass flow in the ecosystem. Keystone species, as identified by this model, are primarily small mammals of the families Muridae, Sciuridae, Tupaiidae, Ptilocercidae, Hystricidae, Viverridae, and Herpestidae, demonstrating omnivorous and herbivorous trophic levels. This model can serve as a valuable framework for conservation management of biodiversity in an ecosystem, with potential for expansion to include characteristics of non-mammalian species in future research. Full article

Background: Small rodents and insectivores are potential reservoirs of many pathogens transmissible to humans, such as bacteria, parasites and viruses responsible for epidemics in sub-Saharan Africa, particularly in West Africa. Few studies on small mammal species in West Africa are available. Our previous findings from a study investigating emerging pathogens in two localities in Mali has determined the prevalence of pathogens in small mammals (rodents and insectivores). We used the data collected from this small mammal population with different eco-climatic characteristics to test hypothesis that small mammal distribution in different eco-climatic settings could explain the diversity and frequency of pathogens they carry. Methods: Sessions of trapping were carried out in December 2016 in Faladjè and Bougouni with “Besançon tous services” (BTS) wire mesh traps baited with peanut butter and/or onion. All animals captured were identified morphologically. Results: Out of 123 small rodents and insectivores captured over 674 trap-nights, 75 (60.97%) were from Faladjè and 48 (39.02%) from Bougouni. Of these, six species of small rodents belonged to the family Muridae (Mastomys erythroleucus, Mastomys natalensis, Rattus rattus, Praomys daltoni, Gerbilliscus gambianus, Taterillus gracilis) and two species of insectivores associated with the genus Crocidura spp. belonged to the family Soricidae and Erinaceidae (Crocidura cf olivieri and Atelerix cf albiventris), respectively. There is low species diversity within these two areas, but the variation in relative abundance is significant (binomial test, p ˂ 0.05) between Faladjè and Bougouni. Mastomys erythroleucus was the most dominant species (57.33%, 43/75) in Faladjè, while R. rattus dominated (37.5%,18/48) in Bougouni. Conclusions: These two species of small mammals potentially involved in the transmission of bacteria, parasites and pathogenic viruses to humans are differently present in two distinct eco-climatic areas in Mali. Full article

The study of sperm characteristics has proven useful for elucidating interrelationships in several groups of Platyhelminthes, such as digeneans. Thus, in the present work, the ultrastructural organization of the mature spermatozoon of the digenean Artyfechinostomum malayanum (Echinostomatidae), a parasite of Rattus norvegicus (Rodentia: Muridae) from Dong Thap Province, Vietnam, was investigated for the first time using transmission electron microscopy. The male gamete of A. malayanum exhibits two axonemes of different lengths, showing the 9 + ‘1’ pattern of the Trepaxonemata, a nucleus, two mitochondria, two lateral expansions, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies, and granules of glycogen. Thus, the mature spermatozoon follows a Type V sperm model proposed for digeneans. We also highlight some noteworthy characteristics in Echinostomatidae with possible phylogenetic implications, such as two lateral expansions in the anterior region of the spermatozoon and two mitochondria. Full article

Mites from the Demodecidae and Psorergatidae can optimally use mammalian hosts by inhabiting a number of different microhabitats in their skin. Hence, in individual hosts, several species of parasites from these groups have been described in different microhabitats. There are few data on their co-occurrence either at the host species level or at the host individual level. Most research has addressed the co-occurrence of Demodecidae in carnivorans, ungulates, soricomorphs, and rodents, while the co-occurrence of both families was found in bats. The present study examines the possibility of their co-occurrence in a Eurasian rodent—Apodemus flavicollis. It is a suitable model for such analyses, because representatives of both families have been demonstrated here so far, and our findings extend the list of specific Demodecidae in A. flavicollis with two new species: Demodex tenuis sp. nov. from the lip region and D. mediocris sp. nov. from the chin region. The study also includes the first record of Psorergates muricola in this host, which occurred in the genital–anal region. Therefore, the findings confirm the possibility that different Demodecidae and Psorergatidae species can co-occur in the same host in different body regions. This paper also includes a checklist of Demodecidae and Psorergatidae in rodents around the world. Full article

Hemorrhagic fever with renal syndrome (HFRS) and tick-borne encephalitis (TBE) are the most common viral diseases in Russia. HFRS is caused by six different types of hantaviruses: Hantaan, Amur, Seoul, Puumala, Kurkino, and Sochi, which are transmitted to humans through small mammals of the Muridae and Cricetidae families. TBE is caused by viruses belonging to five different phylogenetic subtypes. The similarities in the ecology of HFRS and TBE pathogens is presented here. Hantavirus-infected small mammals can transmit the virus to uninfected animals, and ticks can also transmit hantavirus to other ticks and mammals. Hantavirus transmission from ticks to humans is possible only hypothetically based on indirect data. Over the past 23 years, 164,582 cases of HFRS (4.9 per 10⁵ people) and 71,579 cases of TBE (2.5 per 10⁵ people) were registered in Russia. The mortality rate was 0.4% (668 cases) in HFRS and 1.6% deaths (1136 cases) in TBE. There were 4030 HFRS (2.5%) and 9414 TBE (13%) cases in children under 14 years old. HFRS and TBE cases were registered in 42 out of 85 Russian regions; in 18—only HFRS, in 13—only TBE, and 12 had no reported cases. The prospects of applying a combined vaccine for HFRS and TBE prevention are shown in this paper. Full article

Coronaviruses (CoVs), the largest positive-sense RNA viruses, have caused infections in both humans and animals. The cross-species transmission of CoVs poses a serious threat to public health. Rodents and bats, the two largest orders of mammals, serve as significant natural reservoirs for CoVs. It is important to monitor the CoVs carried by bats and rodents. In this study, we collected 410 fecal samples from bats and 74 intestinal samples from rats in Yunnan Province, China. Using RT-PCR, we identified one positive sample for alphacoronavirus (TC-14) from Rhinolophus sinicus (Chinese rufous horseshoe bat) and two positive samples for betacoronavirus (GS-53, GS-56) from Apodemus ilex (Rodentia: Muridae). We successfully characterized the complete genomes of TC-14 and GS-56. Phylogenetic analysis revealed that TC-14 clustered with bat CoV HKU2 and SADS-CoV, while GS-56 was closely related to rat CoV HKU24. The identification of positive selection sites and estimation of divergence dates further helped characterize the genetic evolution of TC-14 and GS-56. In summary, this research reveals the genetic evolution characteristics of TC-14 and GS-56, providing valuable references for the study of CoVs carried by bats and rodents in Yunnan Province. Full article

The rodents of Saudi Arabia consist of twenty species and twelve genera within four families (Gliridae, Dipodidae, Muridae, and Hystricidae). Details on the past and present distribution of the rodents were included, along with available data on their habitat preference and biology. The eastern central part of Saudi Arabia, covering the Tuwiq mountains plateau, including the vicinity of Riyadh, hosts the highest number of rodent species. An analysis of the rodent fauna of Saudi Arabia revealed that they have four major zoogeographical affinities: Palaearctic–Oriental (one species), Afrotropical–Palaearctic (six species), Palaearctic (four species), endemic to Saudi Arabia and Yemen (three species), Afrotropical–Palaearctic–Oriental (three species), and three cosmopolitan species. According to the National Red List, the Euphrates Jerboa, Scarturus euphraticus, is listed as endangered, the Indian Crested Porcupine, Hystrix indica, as near threatened, three further species as data-deficient, while the rest are considered least concern. Full article

In recent years, the transmission of viruses from wildlife to humans has raised significant public health concerns, exemplified by the COVID-19 pandemic caused by the betacoronavirus SARS-CoV-2. Human activities play a substantial role in increasing the risk of zoonotic virus transmission from wildlife to humans. Rats and mice are prevalent in urban environments and may act as reservoirs for various pathogens. This study aimed to evaluate the presence of zoonotic viruses in wild rats and mice in both urban and rural areas, focusing on well-known zoonotic viruses such as betacoronavirus, hantavirus, arenavirus, kobuvirus, and monkeypox virus, along with other viruses occasionally detected in rats and mice, including rotavirus, norovirus, and astrovirus, which are known to infect humans at a high rate. A total of 128 animals were captured, including 70 brown rats (Rattus norvegicus), 45 black rats (Rattus rattus), and 13 house mice (Mus musculus), and feces, lung, and liver were collected. Among brown rats, one fecal sample tested positive for astrovirus RNA. Nucleotide sequencing revealed high sequence similarity to both human and rat astrovirus, suggesting co-presence of these viruses in the feces. Murine kobuvirus (MuKV) was detected in fecal samples from both black (n = 7) and brown (n = 6) rats, primarily from urban areas, as confirmed by sequence analysis. These findings highlight the importance of surveillance and research to understand and mitigate the risks associated with the potential transmission of pathogens by rodents. Full article

Ultrastructural characters of spermiogenesis and the mature spermatozoon of the cestode Meggittina gerbilli (Cyclophyllidea: Catenotaeniidae), a parasite of the Lesser Egyptian gerbil (Gerbillus gerbillus) and the North African gerbil (Gerbillus campestris) (Rodentia: Muridae) in the Djebel Dahar (South of Tunisia), were studied using transmission electron microscopy. The spermiogenesis of M. gerbilli is of Bâ and Marchand’s type III, which is mainly characterized by a proximodistal fusion of a single flagellum with a cytoplasmic extension. In this catenotaeniid, the proximal fusion is preceded by a 90° rotation of the flagellum. The spermatozoon is a Levron et al. type VI, which presents a single axoneme with the 9 + ‘1’ trepaxonematan pattern, a periaxonemal sheath, two crest-like bodies, twisted cortical microtubules, and a spiraled nucleus. The obtained results show similarities with the remaining studied catenotaeniids, namely Catenotaenia pusilla and Skrjabinotaenia lobata. The results are compared and discussed according to several characteristics found in the catenotaeniids and other studied cyclophyllideans. Full article

A new spirurid nematode, Protospirura canariensis n. sp., a parasite of the black rat Rattus rattus Linnaeus, 1758 (Rodentia: Muridae), in El Hierro Island (Canary Archipelago, Spain), was described by means of light (LM) and scanning electron microscopy (SEM). The most discriminating characteristics between the new species and the remaining species of the genus Protospirura were observed to be the following: (a) the number of tooth-like outgrowths in the sub-median and lateral lobes of the pseudolabia, both in males and females (2 and 4, respectively); (b) the size of the right and left spicules in males (643–715 µm and 309–412 µm, respectively); and (c) the numbers and arrangements of the cloacal papillae in males. The new species has a total of 17 cloacal papillae (4 large and pedunculated pairs of precloacal papillae, an unpaired precloacal papilla and 4 pairs of postcloacal papillae). The arrangement of the postcloacal papillae are as follows: the first pair are large, pedunculated and placed near the posterior edge of cloaca; the three remaining postcloacal pairs are grouped and located near the posterior tip. In the latter group, the papillae in the first pair are large and pedunculated. The parasitized hosts and their geographical distributions were also useful criteria in distinguishing P. canariensis n. sp. from the remaining species of the genus Protospirura. In addition, the cytochrome c oxidase subunit I (cox1) sequence of the new species was obtained and compared with the available data of related species. Full article

Chigger mites (Acari) are common ectoparasites on rodents, and they are the exclusive vector of scrub typhus. South China field mouse (Apodemus draco) and Lantsang field mouse (A. ilex) are two sibling rodent species. Based on field investigations in southwest China (2001–2015), this paper compared the infestation of these two mouse species with chiggers. Of 42 chigger species identified from two mouse species, 36 were found on A. draco, 11 on A. ilex and 5 common species on both mice. Jaccard similarity index (J = 0.12, J < 0.25) showed a very different species composition of chiggers on two mouse species, and some parameters of the chigger community were also different. The overall mean intensity of chiggers on A. draco (MI = 4.26) was higher than that on A. ilex (MI = 3.91, p < 0.05). The dominant chigger species on A. draco were Trombiculindus yunnanus, Leptotrombidium scutellare (a major vector species in China) and L. sinicum with a total constituent ratio C_r = 42.9% (106/247). Leptorombidium sinicum and L. scutellare independently occurred on A. draco with an association coefficient V = 0.09 (V ≈ 0). The dominant chigger species on A. ilex were L. rusticum, L. densipunctatum and L. gongshanense, with a total C_r = 58.14% (25/43). Leptorombidium rusticum and L. densipunctatum on A. ilex had a slight positive association (V = 0.49, 0.5 < V < 1). All dominant chigger species were unevenly distributed among different individuals of two mouse species. Chigger infestation showed sex bias on different sexes of two mouse species. The species abundance of the chigger community on A. draco was revealed as a log-normal distribution pattern. Full article