Showing papers on "Sigmodontinae published in 2018"

Distributional ecology of Andes hantavirus: a macroecological approach.

Abstract: Hantavirus pulmonary syndrome (HPS) is an infection endemic in Chile and Argentina, caused by Andes hantavirus (ANDV). The rodent Oligoryzomys longicaudatus is suggested as the main reservoir, although several other species of Sigmodontinae are known hosts of ANDV. Here, we explore potential ANDV transmission risk to humans in southern South America, based on eco-epidemiological associations among: six rodent host species, seropositive rodents, and human HPS cases. We used ecological niche modeling and macroecological approaches to determine potential geographic distributions and assess environmental similarity among rodents and human HPS cases. Highest numbers of rodent species (five) were in Chile between 35° and 41°S latitude. Background similarity tests showed niche similarity in 14 of the 56 possible comparisons: similarity between human HPS cases and the background of all species and seropositive rodents was supported (except for Abrothrix sanborni). Of interest among the results is the likely role of O. longicaudatus, Loxodontomys micropus, Abrothrix olivaceus, and Abrothrix longipilis in HPS transmission to humans. Our results support a role of rodent species’ distributions as a risk factor for human HPS at coarse scales, and suggest that the role of the main reservoir (O. longicaudatus) may be supported by the broader rodent host community in some areas.

Rodents of the eastern and western slopes of the Tropical Andes: phylogenetic and taxonomic insights using DNA barcodes

Abstract: The Andes Mountains particularly the forests along the mid-elevations of their eastern and western slopes, are a hotspot of biodiversity (high numbers of species and endemics). Among mammals, rodents are a priority group for study in the Tropical Andes given their high diversity and often relatively small geographic ranges. Here, we use DNA barcoding as a tool to help in the identification, and preliminary analysis of the phylogenetic relationships, of rodents from two natural reserves: Otonga, a private forest reserve, located on the western slopes, and Sangay National Park, located on the eastern slopes of the Ecuadorian Andes. We sequenced 657 bp of the mitochondrial Cytochrome Oxidase I (COI) gene for 201 tissue samples of sigmodontine and echimyid rodents collected primarily in Otonga and Sangay. We conducted phylogenetic analyses using maximum-likelihood and Poisson tree processes (PTP) species delimitation analyses. Three sets of data were analyzed: 1) our newly generated sequences, 2) our Mesomys sequence plus DNA sequences of Echimyidae available in GenBank, and 3) all of our sequences (all Sigmodontinae and one Echimyidae) together with relevant DNA sequences of Sigmodontinae available in GenBank. Our samples consisted of 24 species; the molecular data indicated that only one species—Microryzomys minutus—was shared between both eastern and western localities. Contrary to the currently recognized distributions of Akodon mollis and Chilomys instans, our species delimitation analysis suggests that these species are not shared between Otonga and Sangay, and may actually represent two species each. The sample of Mesomys from the eastern slopes of the Andes differs minimally from that from the lowlands of the Ecuadorian Amazon, suggesting that both populations would correspond to the same species, Mesomys hispidus. Both Mindomys hammondi and an undescribed Mindomys from Otonga do not form a reciprocally monophyletic group with relation to Nephelomys. The Nephelomys of Sangay might correspond to two different species. The eastern and western slopes of the Tropical Andes harbor different species of rodents, with only one of our study species shared between both localities, implying that other cases of shared species between the eastern and the western slopes of the Andes need further assessment. Several lineages represented in our sample may require formal taxonomic description, highlighting the need for further systematic research. The new genetic data generated in our study could speed taxonomic discovery in the Andes and help to illuminate interesting evolutionary patterns, such as the radiation of Thomasomys.

Silent Orthohantavirus Circulation Among Humans and Small Mammals from Central Minas Gerais, Brazil

Abstract: New World orthohantaviruses are emerging RNA viruses that cause hantavirus cardiopulmonary syndrome (HCPS). These viruses are a burden to public health around the world with a lethality rate of around 60%. In South America, rodents of Sigmodontinae subfamily are the main reservoirs of orthohantaviruses. We described a serosurvey for orthohantaviruses circulation in an apparently healthy human population and small mammals from rural areas in Central Minas Gerais State, Brazil. A total of 240 individuals and 50 small mammals (26 rodents belonging to 10 different species and 24 marsupials from 4 different species) were sampled during 2012-2013. The seroprevalence rates of IgG/IgM antibodies in humans were 7.1 and 1.6%, respectively. Only one rodent, an Oligoryzomys nigripes captured in peridomestic area, tested positive for IgG antibodies and viral RNA. Our findings suggest a silent circulation of orthohantaviruses in a region of intensive agriculture production. The detection of seropositive humans in an area with a lack of previous HCPS reports highlights potential oligosymptomatic cases and the need for surveillance strategies that could reduce the risk of future outbreaks.

Calodium hepaticum (Nematoda: Capillariidae) in wild rodent populations from Argentina.

Abstract: Calodium hepaticum (Nematoda; Capillariidae) is a parasitic nematode of mammals with a cosmopolitan distribution. Adults of this nematode can infect the liver of many mammalian species, including humans, but the main hosts are members of the superfamily Muroidea. Among these, Rattus spp. have the highest apparent prevalences reported worldwide. There are only two reports of C. hepaticum infecting Sigmodontinae species (Muroidea: Cricetidae). In this survey, we examined the occurrence of C. hepaticum in two assemblages of Sigmodontinae rodents from Argentina (Santa Fe and Entre Rios provinces). The diagnosis was made by morphological features, histopathological exam, and molecular characterization of 18S ribosomal RNA gene region. Here, we show that C. hepaticum is a common parasite of Sigmodontinae. We report the infection in six species (all new hosts): Akodon azarae, Calomys callidus, Calomys venustus, Oligoryzomys flavescens, Oligoryzomys nigripes, and Oxymycterus rufus. This is the first report of C. hepaticum in Sigmodontinae rodents from Argentina and the second record in this subfamily for South America. It is also the first confirmation of C. hepaticum infection in Sigmodontinae by molecular diagnosis. The genetic findings and the prevalences observed, together with the existing information on C. hepaticum, lead us to propose that Rattus spp. brought C. hepaticum to the New World exposing Sigmodontinae rodents, which are frequently infected by this parasite. The high prevalence of infection in A. azarae (41.2%) suggests that this host may be playing an important role in C. hepaticum dynamics in the New World.

Diversification of the climatic niche drove the recent processes of speciation in Sigmodontinae (Rodentia, Cricetidae)

Abstract: Evolutionary radiations are among the most intriguing natural phenomena. Sigmodontine rodents form a megadiverse group for which doubts exist about the adaptive or non‐adaptive nature of its radiation. We analysed whether or not the rates of diversification of species of Sigmodontinae are related to the rates of diversification of the climatic niches occupied by the species. Our results show a clear association between niche diversification and speciation processes. However, this association is linked to recent and independent processes of diversification in sigmodontines, as opposed to an early link that would indicate a niche‐filling consistent with an adaptive radiation of the subfamily.

A new species of Stilestrongylus (Nematoda, Heligmonellidae) from the Atlantic Forest of Misiones, Argentina, parasitic in Euryoryzomys russatus (Cricetidae, Sigmodontinae)

Abstract: A new species of Heligmonellidae (Trichostrongylina, Heligmosomoidea), Stilestrongylus kaaguyporai n. sp. is described from the small intestine of Euryoryzomys russatus (Rodentia, Cricetidae, Sigmodontinae) from the Argentine Atlantic Forest, in the Misiones province. The new species was found at Campo Anexo Manuel Belgrano, Reserva de Vida Silvestre Urugua-i and Parque Provincial Urugua-i, with a prevalence of 73% in 15 hosts examined. Stilestrongylus includes 24 Neotropical species, all parasitic in rodents, mostly Sigmodontinae. Stilestrongylus kaaguyporai n. sp. can be differentiated from its congeners by the following characters: caudal bursa dissymmetrical with right lobe larger and pattern of type1-4 in both lobes, rays 6 not forming a lateral trident with rays 4 and 5, rays 8 with dissymmetrical pathway, genital cone hypertrophied with a conspicuous hood-like projection and females with a marked dorso-ventral torsion of the posterior end. This report is the second record of a Stilestrongylus species in E. russatus, increasing to nine the number of parasitic species known from this host.

Localidades típicas de cricétidos en tierras incógnitas: Jesematathla y Waikthlatingmayalwa en el Chaco paraguayo

Abstract: Type localities of cricetids in unknown lands: Jesematathla and Waikthlatingmayalwa in the Paraguayan Chaco. Jesematathla and Waikthlatingmayalwa are two type localities of cricetid rodents from the Paraguayan Chaco. The holotypes of Akodon toba and Oryzomys wavrini were collected in the former; whereas, Akodon lenguarum and Phyllotis chacoënsis were obtained in the latter. The exact geographic location of both localities is controversial, and the goal of this note is to clarify the issue. We show that both localities are located in the Humid Chaco. Jesematathla corresponds today to the Estancia Yesamathasa. Waikthlatingmayalwa disappeared as a toponym, replaced by Misión Central and should be retained solely for historical purposes. The taxonomic implications of these findings are briefly discussed. Palabras clave: Enxet, Grubb, Paraguay, Sigmodontinae, Wavrin.

Predicting species richness of ectoparasites of wild rodents from the Río de la Plata coastal wetlands, Argentina.

Abstract: The richness of ectoparasite species associated with Sigmodontinae rodents (Cricetidae) from different sites located in the coastal wetlands of the Rio de la Plata in Argentina was predicted by a model with three components: (1) habitat type, considered analogous to rodent species; (2) average ectoparasite species richness on each rodent species, and (3) average number of rodent species parasitized by each ectoparasite species. The model, based on rodent information (number of species and total number of captured rodents) and the environmental gradient, has a reasonably good fit for the observed data as well as independent data from different localities. The model is predictive and robust, and it could be a useful tool for epidemiological and biodiversity management strategies. Furthermore, the model could be adapted to other habitats if a suitable estimate of an environmental gradient is found, and it could be also possible to adapt it to other host taxa.

The Pleistocene record attributed to the cricetid genus Nectomys (Rodentia, Sigmodontinae): unexpected connections

Abstract: Abstract Nectomys is a cricetid genus of medium-large sized oryzomyines broadly distributed in creeks and rivers of lowland South America. It has been mentioned in two localities, one in Bolivia and another in Argentina in Pleistocene assemblages. After revising the fossils that supported both records we conclude that they are not Nectomys. The record from Bolivia is Reigomys primigenus. The record from Argentina is attributable to Scapteromys. In conclusion, past occurrences of Nectomys are restricted to those of undifferentiated Quaternary age from Brazilian caves. The unexpected connections between fossils described here are discussed to explore the rationality behind detected misidentifications.

Diversification and species limits in two genera of the tribe Oryzomyini (Rodentia: Cricetidae: Sigmodontinae) revealed by combined molecular and cytogenetic approaches

Abstract: In this work, the integrative taxonomy approach was performed to understand species limits and patterns of diversification in two genera of orizomyine rodents (Cerradomys and Oligoryzomys). Therefore, molecular markers with distinct evolutionary rates were used with different approaches (phylogeny, coalescent-based species delimitation, DNA barcoding, phylogeography, molecular dating). Classic and molecular cytogenetic analyzes were performed, contributing to cytotaxonomy and revealing chromosomal evolution. This work is divided into four chapters, including a brief introduction (Chapter 1). In Chapter 2, the integrative taxonomy approach was used to study the genus Cerradomys, based on cytogenetic and molecular data. The results revealed that cytogenetics is important in the recognition of all described species (cytotaxonomy). Phylogenetic reconstruction showed that internal relationships are well supported, with the exception of C. subflavus and C. goytaca, which are not reciprocally monophyletic. Following the integrative taxonomy, in which species limits are based on the congruence of methods, this work recognizes and reiterates the eight Cerradomys species described so far. We suggest a taxonomic revision in C. langguthi and C. subflavus, since both may represent species-complex or in process of speciation. Times of divergence show that Cerradomys is a recent genus, with speciation events occurred mainly in the Pleistocene. In Chapter 3, classic and molecular cytogenetics (Fluorescence in situ hybridization FISH with telomeric and Oligoryzomys moojeni probes) were used to study chromosomal evolution in Cerradomys, based on the molecular phylogeny obtained in Chapter 2. Chromosome painting revealed extensive chromosome reshuffling in Cerradomys. Species with the highest diploid numbers showed exclusively telomeric signals whereas interstitial telomeric signals (ITS) were observed in the species with the lowest diploid numbers. Comparisons of chromosome painting with molecular phylogeny data corroborate the hypothesis that ITS, in this case, are remnants of telomeres. Nevertheless, other chromosomal rearrangements were detected with absence of ITS, indicating that these sequences may have been lost in the process of chromosomal breakages, evidencing that there was both retention and loss of ITS along the karyotypic evolution of the genus. In addition, complex rearrangements were detected between the karyotypes of C. goytaca and C. subflavus, reiterating that these two species are distinct, since hybrids probably would not be viable due to meiotic problems. In Chapter 4, aiming to recover the evolutionary history and species limits of Oligoryzomys, molecular phylogeny studies were integrated into cytogenetic data. The genus was monophyletic, but the internal relations had low support. The compilation of phylogenetic, chromosomal data and geographic distribution (interdisciplinarity) was important to understand species boundaries. Four lineages could not be related to any name and may be new species (Oligoryzomys A-D). Oligoryzomys flavescens was recovered paraphyletic in respect to O. fornesi. Oligoryzomys stramineus, O. microtis and O. nigripes were recovered in two well-structured clades each. In the case of the last two species, the subclades are probably related to exclusive karyotypes. In O. microtis, one subclade is composed of samples from the western Amazon region and the other with samples distributed in southern Amazon region, transition with Cerrado (2n=64, FN=64). In O. nigripes, one of the clades is composed of specimens from northeastern Brazil (2n=62, FN=78) and the other from central-south-southeast Brazil, Argentina, Paraguay and Uruguay (2n=62, FN=80-82). Phylogeographic results corroborate phylogenetic and cytogenetic data, revealing two distinctive phylogroups, consistent with incipient species. Chromosome data corroborate previous work and could be associated to the following names: O. mattogrossae, O. moojeni, O. chacoensis, O. stramineus, O. nigripes and O. flavescens, although the last two species should be reassessed. In addition, an undescribed karyotype is being reported for Oligoryzomys aff. utiaritensis (2n=70, FN=72), as well as new records in Brazil for four species. We suggest a taxonomic revision in O. microtis, O. flavescens and O. nigripes, as these species probably represent incipient or species-complex. In addition, samples related to Oligoryzomys aff. delicatus, Oligoryzomys aff. chacoensis, Oligoryzomys aff. rupestris and Oligoryzomys aff. utiaritensis should be evaluated morphologically to confirm their identities. The results of this work corroborate the importance of interdisciplinary studies, since the rates of evolution differ according to each character. References Agrellos, R.; Bonvicino, C.R.; Rosa, E.S.T.; Marques, A.A.R.; D’Andrea, P.S.; Weksler, M. (2012) The taxonomic status of the Castelo dos Sonhos Hantavirus Reservoir, Oligoryzomys utiaritensis Allen 1916 (Rodentia: Cricetidae: Sigmodontinae). Zootaxa 3220:1-28. Almeida, E.J.C.; Yonenaga-Yassuda, Y. (1985) Robertsonian fusion, pericentric inversion and sex chromosome heteromorphisms in Oryzomys subflavus (Cricetidae, Rodentia). Caryologia 38: 129-137. http://dx.doi.org/10.1080/00087114.1985.10797737 Avise, J.C.; Arnold, J.; Ball, R.M.; Bermingham, E.; Lamb, T.; Neigel, J.E.; Reeb, C.A.; Saunders, N.C. (1987) Intraspecific phylogeography: the mitochondrial DNA bridge between population genetics and systematics. Annual review of ecology and systematics, 18(1), 489-522. 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Historical record of Holochilus vulpinus (Rodentia, Sigmodontinae) from northern Patagonia, Argentina

Abstract: Fil: Agnolin, Federico. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina

Cafeteria experiment with Akodon montensis Thomas, 1913 (Rodentia, Cricetidae, Sigmodontinae) from a remnant of semideciduous seasonal forest in Southern Brazil

Abstract: Rodents represent the largest group of mammals in number of species,1 but the rodent fauna in Brazil is still insufficiently known. Information on the ecology of most species is still scarce,2 especially with regard to their eating habits.3 Most rodents are herbivorous, but some species are generalists, feeding on seeds, fruits and small invertebrates.1 The sigmodontine rodents, although predominantly insectivorous-omnivores, can be more herbivorous or frugivorous.4,5 Akodon montensis Thomas, 1913 is considered a generalist species,1,6,7 which adapts easily to degraded areas, occupying different types of forest formations, opening areas and fields along the Atlantic Forest.6