Browsing by Author "Salazar-Bravo, Jorge (TTU)"
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Item Anomalías reproductivas en hembras de roedores sigmodontinos colectados en el norte del departamento de La Paz (Bolivia)(2021) Revollo-Cadima, Susana G.; Rico-Cernohorska, Adriana; Salazar-Bravo, Jorge (TTU)Anormalidades reproductivas en organismos silvestres se describen con poca frecuencia. En esta nota reportamos la presencia de fetos extrauterinos, un caso de cuerno uterino supernumerario y litopediones, en tres especies comunes de roedores sigmodontinos del norte del departamento boliviano de La Paz: Akodon dayi, Euryoryzomys nitidus y Oligoryzomys microtis. Lo encontrado se puede deber a un debilitamiento en las paredes de los cuernos uterinos. Es destacable que tres de los cuatro casos detectados provengan de zonas de cultivo, situación que podría sugerir una vinculación causal con agroquímicos.Item Does the widely distributed rodent calomys tener (Cricetidae: Sigmodontinae) constitute a single evolutionary unit?(2019) González-Ittig, Raul E.; Kandel, Narayan P. (TTU); Bonvicino, Cibele R.; Salazar-Bravo, Jorge (TTU)The nominal species Calomys tener (Winge, 1887) ranges broadly in open lands of the Caatinga, Cerrado, Pantanal and Mata Atlântica of Brazil, and was recently reported from the Pampas of southern Brazil, and in the Selva Paranaense of eastern Paraguay and northeastern Argentina. This rodent can be infected with the pathogenic Araraquara hantavirus in Brazil. Given that most epidemiological studies have not taken into account updated taxonomic findings of their rodent hosts, in this study, we obtained sequence data of the Cyt-b and COI genes of specimens of C. tener from 22 different geographical localities from throughout the currently known distribution of the species (including individuals from Argentina, Paraguay, Bolivia, and Brazil) to test if it constitutes a single genetic unit or if it presents genetic discontinuities that may represent different evolutionary lineages. Phylogenetic analyses including several species of Calomys recovered several clades with strong support. Regarding C. tener, it is recovered as sister to the node that cluster C. laucha (Fischer, 1814) sensu lato, C. expulsus (Lund, 1841) and species in the C. callosus (Rengger, 1830) species complex. At the intraspecific level there are no genetic gaps among haplotypes of C. tener that could suggest more than one species. The recent captures in the Pampas of southern Brazil and in the Selva Paranaense suggest that the species may be colonizing new geographic areas.Item Fine-scale spatial variation shape fecal microbiome diversity and composition in black-tailed prairie dogs (Cynomys ludovicianus)(2023) Neha, Sufia Akter (TTU); Salazar-Bravo, Jorge (TTU)Background: Host associated gut microbiota are important in understanding the coevolution of host-microbe, and how they may help wildlife populations to adapt to rapid environmental changes. Mammalian gut microbiota composition and diversity may be affected by a variety of factors including geographic variation, seasonal variation in diet, habitat disturbance, environmental conditions, age, and sex. However, there have been few studies that examined how ecological and environmental factors influence gut microbiota composition in animals' natural environments. In this study, we explore how host habitat, geographical location and environmental factors affect the fecal microbiota of Cynomys ludovicianus at a small spatial scale. We collected fecal samples from five geographically distinct locations in the Texas Panhandle classified as urban and rural areas and analyzed them using high throughput 16S rRNA gene amplicon sequencing. Results: The results showed that microbiota of these fecal samples was largely dominated by the phylum Bacteroidetes. Fecal microbiome diversity and composition differed significantly across sampling sites and habitats. Prairie dogs inhabiting urban areas showed reduced fecal diversity due to more homogenous environment and, likely, anthropogenic disturbance. Urban prairie dog colonies displayed greater phylogenetic variation among replicates than those in rural habitats. Differentially abundant analysis revealed that bacterial species pathogenic to humans and animals were highly abundant in urban areas which indicates that host health and fitness might be negatively affected. Random forest models identified Alistipes shahii as the important species driving the changes in fecal microbiome composition. Despite the effects of habitat and geographic location of host, we found a strong correlation with environmental factors and that- average maximum temperature was the best predictor of prairie dog fecal microbial diversity. Conclusions: Our findings suggest that reduction in alpha diversity in conjunction with greater dispersion in beta diversity could be indicative of declining host health in urban areas; this information may, in turn, help determine future conservation efforts. Moreover, several bacterial species pathogenic to humans and other animals were enriched in prairie dog colonies near urban areas, which may in turn adversely affect host phenotype and fitness.Item The first record of Calomys hummelincki (Rodentia: Sigmodontinae) from the Lavrados of northern Brazil(2017) Vinicius Brandão, Marcus; Oliveira Salgueiro, Yolanda; Salazar-Bravo, Jorge (TTU)The South American genus Calomys exhibits a disjunct distribution with most species inhabiting grasslands, savannas, and forest edges from ca. latitude 8° S in the highlands of Peru and the Caatinga of Brazil to ca. latitude 16° S in central Bolivia, and from there south into Argentine Patagonia. Only a single species (Calomys hummelincki) occurs in open habitats in northern South America. We report the first known specimen of Calomys hummelincki for Brazil. The specimen is deposited in the mammal collection of Museu de Zoologia da Universidade de São Paulo, São Paulo. It is a young adult female with two embryos collected on 13 March 1989 by C. M. Carvalho at Fazenda Salvamento, Roraima state, during a herpetofaunal survey. The specimen shares qualitative and quantitative characters with specimens from Venezuela and Curaçao, but also differs substantially in others. The record presented herein extends the known range of the species about 630 km southeastward from the nearest previous record (in Venezuela, Estado Bolívar, Sipao). This new record was obtained in a locality representative of the savannas of the Rio Branco – Rupununi region that supports a poorly known, but distinctive mammalian fauna. This entire eco-region represents a piece of the biogeographic puzzle resulting from the climate-dependent vegetation shifts that dominated the Quaternary of South America. This new record highlights the need to investigate and protect the biodiversity of the Rio Branco-Rupununi savannas.Item First record of proechimys pattoni da silva, 1998 (Rodentia, echimyidae) in northwestern Bolivia(2018) Sánchez-Vendizú, Pamela; Cook, Joseph A.; Wood, James; Salazar-Bravo, Jorge (TTU)Proechimys pattoni da Silva, 1998 is one of the 3 small-bodied species of Proechimys and its geographic range is only known in western Brazil and eastern and southern Peru. However, based on morphological and molecular analyses, we report P. pattoni from the lowland forest of Bolivia (Pando: Rio Madre de Dios, near San Rosa). This is the first report of P. pattoni in Bolivia and extends its distributional range 315 km to the southeast in the Amazon biogeographic region of Bolivia, representing the southeastern most record. Furthermore, we document the karyotype (2n = 40 / FN = 56) and morphological variation in diagnostic characters.Item Host-Species transferrin receptor 1 orthologs are cellular receptors for nonpathogenic new world clade B arenaviruses(2009) Abraham, Jonathan; Kwong, Jo Ann; Albarino, César G.; Lu, Jiajie G.; Radoshitzky, Sheli R.; Salazar-Bravo, Jorge (TTU); Farzan, Michael; Spiropoulou, Christina F.; Choe, HyeryunThe ability of a New World (NW) clade B arenavirus to enter cells using human transferrin receptor 1 (TfR1) strictly correlates with its ability to cause hemorrhagic fever. Amapari (AMAV) and Tacaribe (TCRV), two nonpathogenic NW clade B arenaviruses that do not use human TfR1, are closely related to the NW arenaviruses that cause hemorrhagic fevers. Here we show that pseudotyped viruses bearing the surface glycoprotein (GP) of AMAV or TCRV can infect cells using the TfR1 orthologs of several mammalian species, including those of their respective natural hosts, the small rodent Neacomys spinosus and the fruit bat Artibeus jamaicensis. Mutation of one residue in human TfR1 makes it a functional receptor for TCRV, and mutation of four residues makes it a functional receptor for AMAV. Our data support an in vivo role for TfR1 in the replication of most, if not all, NW clade B arenaviruses, and suggest that with modest changes in their GPs the nonpathogenic arenaviruses could use human TfR1 and emerge as human pathogens.Item Models for an arenavirus infection in a rodent population: Consequences of horizontal, vertical and sexual transmission(2008) Banerjee, Chandrani (TTU); Allen, Linda J.S. (TTU); Salazar-Bravo, Jorge (TTU)Arenaviruses are associated with rodent-transmitted diseases in humans. Five arenaviruses are known to cause human illness: Lassa virus, Junin virus, Machupo virus, Guanarito virus and Sabia virus. In this investigation, we model the spread of Machupo virus in its rodent host Calomys callosus. Machupo virus infection in humans is known as Bolivian hemorrhagic fever (BHF) which has a mortality rate of approximately 5-30% [31]. Machupo virus is transmitted among rodents through horizontal (direct contact), vertical (infected mother to offspring) and sexual transmission. The immune response differs among rodents infected with Machupo virus. Either rodents develop immunity and recover (immunocompetent) or they do not develop immunity and remain infected (immunotolerant). We formulate a general deterministic model for male and female rodents consisting of eight differential equations, four for females and four for males. The four states represent susceptible, immunocompetent, immunotolerant and recovered rodents, denoted as S, It, Ic and R, respectively. A unique disease-free equilibrium (DFE) is shown to exist and a basic reproduction number Tco is computed using the next generation matrix approach. The DFE is shown to be locally asymptotically stable if Ro < 1 and unstable if Ro < 1. Special cases of the general model are studied, where there is only one immune stage, either It or Ic. In the first model, SICRC, it is assumed that all infected rodents are immunocompetent and recover. In the second model, SIt, it is assumed that all infected rodents are immunotolerant. For each of these models, the basic reproduction numbers are computed and their relationship to the basic reproduction number of the general model determined. For the SI t model, it is shown that bistability may occur, the DFE and an enzootic equilibrium, with all rodents infectious, are locally asymptotically stable for the same set of parameter values. A simplification of the SI 1 model yields a third model, where the sexes are not differentiated, and therefore, there is no sexual transmission. For this third simplified model, the dynamics are completely analyzed. It is shown that there exists a DFE and possibly two additional equilibria, one of which is globally asymptotically stable for any given set of parameter values; bistability does not occur. Numerical examples illustrate the dynamics of the models. The biological implications of the results and future research goals are discussed in the conclusion.Item Molecular Mechanisms of Persistence in Protozoan Parasites(2023) Tarannum, Asfiha (TTU); Rodríguez-Almonacid, Cristian Camilo (TTU); Salazar-Bravo, Jorge (TTU); Karamysheva, Zemfira N. (TTU)Protozoan parasites are known for their remarkable capacity to persist within the bodies of vertebrate hosts, which frequently results in prolonged infections and the recurrence of diseases. Understanding the molecular mechanisms that underlie the event of persistence is of paramount significance to develop innovative therapeutic approaches, given that these pathways still need to be thoroughly elucidated. The present article provides a comprehensive overview of the latest developments in the investigation of protozoan persistence in vertebrate hosts. The focus is primarily on the function of persisters, their formation within the host, and the specific molecular interactions between host and parasite while they persist. Additionally, we examine the metabolomic, transcriptional, and translational changes that protozoan parasites undergo during persistence within vertebrate hosts, focusing on major parasites such as Plasmodium spp., Trypanosoma spp., Leishmania spp., and Toxoplasma spp. Key findings of our study suggest that protozoan parasites deploy several molecular and physiological strategies to evade the host immune surveillance and sustain their persistence. Furthermore, some parasites undergo stage differentiation, enabling them to acclimate to varying host environments and immune challenges. More often, stressors such as drug exposure were demonstrated to impact the formation of protozoan persisters significantly. Understanding the molecular mechanisms regulating the persistence of protozoan parasites in vertebrate hosts can reinvigorate our current insights into host–parasite interactions and facilitate the development of more efficacious disease therapeutics.Item Natural infection of Neotropical bats with hantavirus in Brazil(2018) Sabino-Santos, Gilberto; Maia, Felipe Gonçalves Motta; Martins, Ronaldo Bragança; Gagliardi, Talita Bianca; De Souza, William Marciel; Muylaert, Renata Lara; Luna, Luciano Kleber De Souza; Melo, Danilo Machado; De Souza Cardoso, Ricardo; Da Silva Barbosa, Natalia; Pontelli, Marjorie Cornejo; Mamani-Zapana, Priscila Rosse; Vieira, Thallyta Maria; Melo, Norma Maria; Jonsson, Colleen B.; Goodin, Douglas; Salazar-Bravo, Jorge (TTU); Dasilva, Luis Lamberti Pinto; Arruda, Eurico; Figueiredo, Luiz Tadeu MoraesBats (Order: Chiroptera) harbor a high diversity of emerging pathogens presumably because their ability to fly and social behavior favor the maintenance, evolution, and dissemination of these pathogens. Until 2012, there was only one report of the presence of Hantavirus in bats. Historically, it was thought that these viruses were harbored primarily by rodent and insectivore small mammals. Recently, new species of hantaviruses have been identified in bats from Africa and Asia continents expanding the potential reservoirs and range of these viruses. To assess the potential of Neotropical bats as hosts for hantaviruses and its transmission dynamics in nature, we tested 53 bats for active hantaviral infection from specimens collected in Southeastern Brazil. Part of the hantaviral S segment was amplified from the frugivorous Carollia perspicillata and the common vampire bat Desmodus rotundus. DNA sequencing showed high similarity with the genome of Araraquara orthohantavirus (ARQV), which belongs to one of the more lethal hantavirus clades (Andes orthohantavirus). ARQV-like infection was detected in the blood, urine, and organs of D. rotundus. Therefore, we describe a systemic infection in Neotropical bats by a human pathogenic Hantavirus. We also propose here a schematic transmission dynamics of hantavirus in the study region. Our results give insights to new, under-appreciated questions that need to be addressed in future studies to clarify hantavirus transmission in nature and avoid hantavirus outbreaks.Item Serosurvey of wild rodents for hantaviruses in Panama, 2000-2002(2004) Salazar-Bravo, Jorge (TTU); Armién, Blas; Suzaán, Gerardo; Armién, Anibal; Ruedas, Luis A.; Avila, Mario; Zaldívar, Yamizel; Pascale, Juan M.; Gracia, Fernando; Yates, Terry L.Five hundred fifty-six samples representing 24 species of small mammals (two species of marsupials and 22 rodents) were collected in Panama between February 2000 and July 2002. The samples were examined for antibodies to hantaviruses by means of enzymelinked immunosorbent assay or immunoblot assays. The serologic results indicated that several rodent species might act as hantaviral reservoirs in Panama: Costa Rican pygmy rice rat (Oligoryzomys fulvescens costaricensis), four positive of 72 tested (5.6%); Cherrie's cane rat (Zygodontomys brevicauda cherriei), five of 108 (4.6%); Mexican deer mouse (Peromyscus mexicanus), one of 22 (5%); Mexican harvest mouse (Reithrodontomys mexicanus), one of seven (14%); Chiriquí harvest mouse (Reithrodontomys creper), one of two (50%); and Sumichrast's harvest mouse (Reithrodontomys sumichrasti), three of four (75%). Hantavirus infection in Peromyscus mexicanus and the three species of Reithrodontomys was caused by Rio Segundo hantavirus, a species of virus not previously reported from Panama. At least three hantaviruses, therefore, are known to infeet populations of wild rodents in the country. However, given the total number of animals tested, the role of these rodent species in the epidemiology and epizootiology of hantavirus infections remains unclear. © Wildlife Disease Association 2004.Item Socio-ecology of the marsh rice rat (Oryzomys palustris) and the spatio-temporal distribution of Bayou virus in coastal Texas(2013) Holsomback, Tyla S. (TTU); Van Nice, Christopher J. (TTU); Clark, Rachel N. (TTU); McIntyre, Nancy E. (TTU); Abuzeineh, Alisa A.; Salazar-Bravo, Jorge (TTU)Along the southeastern coast of the United States of America (USA), the marsh rice rat (Oryzomys palustris) is the primary host for the hantavirus genotype Bayou. According to the socio-ecological model for a territorial, polygamous species, females should be distributed across space and time by habitat resources and predation risks, whereas males should space themselves according to the degree of female aggregation and reproductive synchrony. To investigate how females affect the male-male transmission paradigm of Bayou virus, rodents were captured, marked, released, and re-captured in two macrohabitat types across a 30-month period. Microhabitat cover variables were quantified around the individual trap stations. A geodatabase was created from habitat and rodent capture data and analysed in a geographical information system. The ratio of breeding to non-breeding females was ~1:1, with breeding females overly dispersed and non-breeding females randomly dispersed. Spatial analyses revealed both macro- and microhabitat preferences in females. Compared to sero-negatives, higher proportions of seropositive adult males were found consistently within closer proximities to breeding females but not to non-breeding females, indicating that male locations were not driven simply by habitat selection. Activities to acquire dispersed receptive females could be an important driver of Bayou virus transmission among male hosts. To date, socio-ecological theory has received little attention as an investigative framework for studying pathogen dynamics in small, solitary mammals. Herein, we describe an interdisciplinary effort providing a novel approach to elucidate the complexity of hantavirus trafficking and maintenance in rodent populations of a coastal marsh ecosystem.Item Systematics and diversification of the Ichthyomyini (Cricetidae, Sigmodontinae) revisited: evidence from molecular, morphological, and combined approaches(2023) Salazar-Bravo, Jorge (TTU); Tinoco, Nicolás; Zeballos, Horacio; Brito, Jorge; Arenas-Viveros, Daniela (TTU); Marín-C, David; Ramírez-Fernández, José Daniel; Percequillo, Alexandre R.; Lee, Thomas E.; Solari, Sergio; Colmenares-Pinzon, Javier (TTU); Nivelo, Carlos; Herrera, Bernal Rodríguez; Merino, William; Medina, Cesar E.; Murillo-García, Oscar; Pardiñas, Ulyses F.J.Ichthyomyini, a morphologically distinctive group of Neotropical cricetid rodents, lacks an integrative study of its systematics and biogeography. Since this tribe is a crucial element of the Sigmodontinae, the most speciose subfamily of the Cricetidae, we conducted a study that includes most of its recognized diversity (five genera and 19 species distributed from southern Mexico to northern Bolivia). For this report we analyzed a combined matrix composed of four molecular markers (RBP3, GHR, RAG1, Cytb) and 56 morphological traits, the latter including 15 external, 14 cranial, 19 dental, five soft-anatomical and three postcranial features. A variety of results were obtained, some of which are inconsistent with the currently accepted classification and understanding of the tribe. Ichthyomyini is retrieved as monophyletic, and it is divided into two main clades that are here recognized as subtribes: one to contain the genus Anotomys and the other composed by the remaining genera. Neusticomys (as currently recognized) was found to consist of two well supported clades, one of which corresponds to the original concept of Daptomys. Accordingly, we propose the resurrection of the latter as a valid genus to include several species from low to middle elevations and restrict Neusticomys to several highland forms. Numerous other revisions are necessary to reconcile the alpha taxonomy of ichthyomyines with our phylogenetic results, including placement of the Cajas Plateau water rat (formerly Chibchanomys orcesi) in the genus Neusticomys (sensu stricto), and the recognition of at least two new species (one in Neusticomys, one in Daptomys). Additional work is necessary to confirm other unanticipated results, such as the non-monophyletic nature of Rheomys and the presence of a possible new genus and species from Peru. Our results also suggest that ichthyomyines are one of the main Andean radiations of sigmodontine cricetids, with an evolutionary history dating to the Late Miocene and subsequent cladogenesis during the Pleistocene.Item Taxonomic revision and additional comments of some bats (Mammalia, Chiroptera) reported from Bolivia, with an updated checklist based on voucher material with verified identities(2023) Poma-Urey, José L.; Acosta S., Luis H.; Rivero, Kathia; Hidalgo-Cossio, Marisol; Hingst-Zaher, Erika; Gualda-Barros, Juliana; da Natividade, Beatriz D.; Barboza-Marquez, Kathrin; Ramírez-Chaves, Héctor E.; Salazar-Bravo, Jorge (TTU); Ochoa G., JoséWe review the taxonomic identities of museum specimens of three bat species previously reported from Bolivia. We comment on some erroneously reported taxa, or taxa either not represented by voucher materials or based on insufficient data (including acoustic detections) to verify their taxonomic affinities. As result of this review, the list of bat species known to occur in Bolivia is updated to eight families and 133 species, unlike the nine families and 146 species of previous lists. Some recommendations for future research and a brief historical revision of bat inventories in the country are included.Item Taxonomy based on science is necessary for global conservation(2018) Thomson, Scott A.; Pyle, Richard L.; Ahyong, Shane T.; Alonso-Zarazaga, Miguel; Ammirati, Joe; Araya, Juan Francisco; Ascher, John S.; Audisio, Tracy Lynn; Azevedo-Santos, Valter M.; Bailly, Nicolas; Baker, William J.; Balke, Michael; Barclay, Maxwell V.L.; Barrett, Russell L.; Benine, Ricardo C.; Bickerstaff, James R.M.; Bouchard, Patrice; Bour, Roger; Bourgoin, Thierry; Boyko, Christopher B.; Breure, Abraham S.H.; Brothers, Denis J.; Byng, James W.; Campbell, David; Ceríaco, Luis M.P.; Cernák, István; Cerretti, Pierfilippo; Chang, Chih Han; Cho, Soowon; Copus, Joshua M.; Costello, Mark J.; Cseh, Andras; Csuzdi, Csaba; Culham, Alastair; D’Elía, Guillermo; d’Udekem d’Acoz, Cédric; Daneliya, Mikhail E.; Dekker, René; Dickinson, Edward C.; Dickinson, Timothy A.; van Dijk, Peter Paul; Dijkstra, Klaas Douwe B.; Dima, Bálint; Dmitriev, Dmitry A.; Duistermaat, Leni; Dumbacher, John P.; Eiserhardt, Wolf L.; Ekrem, Torbjørn; Evenhuis, Neal L.; Faille, Arnaud; Fernández-Triana, José L.; Fiesler, Emile; Fishbein, Mark; Fordham, Barry G.; Freitas, André V.L.; Friol, Natália R.; Fritz, Uwe; Frøslev, Tobias; Funk, Vicki A.; Gaimari, Stephen D.; Garbino, Guilherme S.T.; Garraffoni, André R.S.; Geml, József; Gill, Anthony C.; Gray, Alan; Grazziotin, Felipe G.; Greenslade, Penelope; Gutiérrez, Eliécer E.; Harvey, Mark S.; Hazevoet, Cornelis J.; He, Kai; He, Xiaolan; Helfer, Stephan; Helgen, Kristofer M.; van Heteren, Anneke H.; Hita Garcia, Francisco; Holstein, Norbert; Horváth, Margit K.; Hovenkamp, Peter H.; Hwang, Wei Song; Hyvönen, Jaakko; Islam, Melissa B.; Iverson, John B.; Ivie, Michael A.; Jaafar, Zeehan; Jackson, Morgan D.; Jayat, J. Pablo; Johnson, Norman F.; Kaiser, Hinrich; Klitgård, Bente B.; Knapp, Dániel G.; Kojima, Jun Ichi; Kõljalg, Urmas; Kontschán, Jenő; Krell, Frank Thorsten; Krisai-Greilhuber, Irmgard; Kullander, Sven; Latella, Leonardo; Lattke, John E.; Lencioni, Valeria; Lewis, Gwilym P.; Lhano, Marcos G.; Lujan, Nathan K.; Luksenburg, Jolanda A.; Mariaux, Jean; Marinho-Filho, Jader; Marshall, Christopher J.; Mate, Jason F.; McDonough, Molly M.; Michel, Ellinor; Miranda, Vitor F.O.; Mitroiu, Mircea Dan; Molinari, Jesús; Monks, Scott; Moore, Abigail J.; Moratelli, Ricardo; Murányi, Dávid; Nakano, Takafumi; Nikolaeva, Svetlana; Noyes, John; Ohl, Michael; Oleas, Nora H.; Orrell, Thomas; Páll-Gergely, Barna; Pape, Thomas; Papp, Viktor; Parenti, Lynne R.; Patterson, David; Pavlinov, Igor Ya; Pine, Ronald H.; Poczai, Péter; Prado, Jefferson; Prathapan, Divakaran; Rabeler, Richard K.; Randall, John E.; Rheindt, Frank E.; Rhodin, Anders G.J.; Rodríguez, Sara M.; Rogers, D. Christopher; Roque, Fabio de O.; Rowe, Kevin C.; Ruedas, Luis A.; Salazar-Bravo, Jorge (TTU); Salvador, Rodrigo B.; Sangster, George; Sarmiento, Carlos E.; Schigel, Dmitry S.; Schmidt, Stefan; Schueler, Frederick W.; Segers, Hendrik; Snow, Neil; Souza-Dias, Pedro G.B.; Stals, Riaan; Stenroos, Soili; Stone, R. Douglas; Sturm, Charles F.; Štys, Pavel; Teta, Pablo; Thomas, Daniel C.; Timm, Robert M.; Tindall, Brian J.; Todd, Jonathan A.; Triebel, Dagmar; Valdecasas, Antonio G.; Vizzini, Alfredo; Vorontsova, Maria S.; de Vos, Jurriaan M.; Wagner, Philipp; Watling, Les; Weakley, Alan; Welter-Schultes, Francisco; Whitmore, Daniel; Wilding, Nicholas; Will, Kipling; Williams, Jason; Wilson, Karen; Winston, Judith E.; Wüster, Wolfgang; Yanega, Douglas; Yeates, David K.; Zaher, Hussam; Zhang, Guanyang; Zhang, Zhi Qiang; Zhou, Hong ZhangItem The Role of Historical Barriers in the Diversification Processes in Open Vegetation Formations during the Miocene/Pliocene Using an Ancient Rodent Lineage as a Model(2013) Nascimento, Fabrícia F.; Lazar, Ana; Menezes, Albert N.; Durans, Andressa da Matta; Moreira, Jânio C.; Salazar-Bravo, Jorge (TTU); DAndrea, Paulo S.; Bonvicino, Cibele R.The Neotropics harbors a high diversity of species and several hypotheses have been proposed to account for this pattern. However, while species of forested domains are frequently studied, less is known of species from open vegetation formations occupying, altogether, a larger area than the Amazon Forest. Here we evaluate the role of historical barriers and the riverine hypothesis in the speciation patterns of small mammals by analyzing an ancient rodent lineage (Thrichomys, Hystricomorpha). Phylogenetic and biogeographic analyses were carried out with mitochondrial and nuclear DNA markers to analyze the evolutionary relationships between Thrichomys lineages occurring in dry domains along both banks of the Rio São Francisco. This river is one of the longest of South America whose course and water flow have been modified by inland tectonic activities and climate changes. Molecular data showed a higher number of lineages than previously described. The T. inermis species complex with 2n = 26, FN = 48 was observed in both banks of the river showing a paraphyletic arrangement, suggesting that river crossing had occurred, from east to west. A similar pattern was also observed for the T. apereoides complex. Thrichomys speciation occurred in Late Miocene when the river followed a different course. The current geographic distribution of Thrichomys species and their phylogenetic relationships suggested the existence of frequent past connections between both banks in the middle section of the Rio São Francisco. The extensive palaeodune region found in this area has been identified as a centre of endemism of several vertebrate species and is likely to be a center of Thrichomys diversification. © 2013 Nascimento et al.