Hibridación natural en Tupinambis (Teiidae): un abordaje multidisciplinario

Fil: Cabaña, Imanol. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Cabaña, Imanol. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Cabaña, Imanol. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.Fil: Gardenal, Cristina N. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Gardenal, Cristina N. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.Fil: Chiaraviglio, Margarita. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Rivera, Paula C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Rivera, Paula C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Rivera, Paula C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.La similitud o divergencia del nicho ecológico de dos linajes puede generar barreras a la dispersión o favorecer la ocurrencia de zonas de simpatría donde se produzca hibridación. Tupinambis merianae y T. rufescens son dos especies de lagarto, filogenéticamente muy cercanas, que hibridan de manera recíproca; presentan amplias distribuciones en regiones biogeográficas diferentes, aunque se encuentran en simpatría en la región de contacto de sus distribuciones. Utilizando este modelo se integró, en un marco filogenético y filogeográfico, el análisis de nicho ambiental y de aspectos demográficos para identificar barreras y/o áreas de contacto entre las poblaciones de ambas especies.Se utilizaron como marcadores moleculares un gen mitocondrial y un gen nuclear para estimar las relaciones filogenética, las redes de haplotipos y alelos y la magnitud y direccionalidad de la hibridación. Los análisis de nicho ambiental se desarrollaron utilizando las variables bioclimáticas de Worldclim. La proporción de especies en cada localidad del área de simpatría fue estimada a partir de un muestreo de 3 años. Los análisis filogenético muestran que los ejemplares de cada especie se agrupan en un clado diferente. Las incongruencias entre los árboles y redes revelan los eventos de hibridación entre estas especies. Todos ellos presentaron los haplotipos más frecuentes para uno u otro gen y fueron encontrados en el área de simpatría. El patrón de distribución de los haplotipos sugiere flujo génico actual restringido en cada especie. El análisis del espacio de nicho ambiental reveló que estas especies habitan zonas con características ambientales diferentes y solapan en una pequeña porción de su distribución. Las dos especies presentaron marcada diferenciación genética entre simpátrica y alopátrica, pero no se correlacionó con la distancia geográfica ni con la ambiental.Encontramos que la hibridación no es homogénea en todo el área de superposición. En general, el haplotipo mitocondrial de los híbridos pertenece a la especie más escasa, sugiriendo que las hembras tienden a aparearse con los machos de la especie mas abundante. Es decir, que la direccionalidad de la hibridación dependería de la proporción de especies en cada localidad.Considerando que el contexto ambiental no influye significativamente en la estructura genética de estas especies y que ambas especies son fenotípicamente y ecológicamente similares, la competencia interespecífica podría actuar como barrera a la dispersión entre las poblaciones simpátricas y alopátricas.Fil: Cabaña, Imanol. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Cabaña, Imanol. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Cabaña, Imanol. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.Fil: Gardenal, Cristina N. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Gardenal, Cristina N. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.Fil: Chiaraviglio, Margarita. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Rivera, Paula C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Biología del Comportamiento; Argentina.Fil: Rivera, Paula C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Laboratorio de Genética de Poblaciones y Evolución; Argentina.Fil: Rivera, Paula C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Diversidad y Ecología Animal; Argentina.Ecologí

Genetic Evidence of Expansion by Passive Transport of Aedes (Stegomyia) aegypti in Eastern Argentina

Aedes (Stegomyia) aegypti (Linnaeus) (Diptera: Culicidae) is the principal vector of the yellow fever virus, the five dengue virus serotypes (DENV-1 to DENV-5), chikungunya virus, Zika virus, and several types of encephalitis [1–3]. The behavior of this species is synanthropic and anthropophilic, being the culicid most closely associated with human populations [4]. The incidence of dengue has increased 30-fold over the last 50 years; according to the World Health Organization, up to 50–100 million infections occur each year in over 100 endemic countries, and at least one half of the world’s population has risk of being infected with dengue virus [5]. Chikungunya virus has been responsible for over 2 million human infections during the past decade and is currently moving to subtropical latitudes as well as to the western hemisphere. Up until April 2015, there have been 1,379,788 suspected cases of this disease in the Caribbean islands, Latin America, and the United States. This expansion into novel habitats brings unique risks associated with further spread of the virus and the disease it causes [6]. On the other hand, there are about 200,000 cases of yellow fever each year worldwide responsible for about 30,000 deaths, most of them from Africa. Zika virus is an emerging mosquito-borne virus, with outbreaks in Africa, Asia, and the Pacific between 2007 and 2014. Since 2015, there has been an increase in reports of ZIKV infection in the Americas, with Brazil being the most affected country, with 534 confirmed cases and 72,062 suspected cases between 2015 and 2016 [7]. All these viruses and the mosquito vector A. aegypti present in the Americas represent a serious risk. So far, in 2016, 39,926 dengue cases produced by DENV-1 and DENV-4 serotypes and 319 autochthonous cases of chikungunya fever have been reported in Argentina. According to the last census, Argentina has approximately 40 million people (National Institute of Statistics and Censuses of Argentina [INDEC], Census 2010), and over 38 million live in areas suitable for the transmission of dengue and chikungunya viruses [8]. Moreover, although there were 22 imported cases of Zika and 24 autochthonous cases confirmed in Argentina, there is a high incidence of cases in Brazil, and besides that, there is an internal circulation of the virus in the neighboring countries Brazil, Paraguay, and Bolivia [7,8], in addition to the constant expansion of the mosquito vector.Facultad de Ciencias Naturales y Muse

Genetic Evidence of Expansion by Passive Transport of Aedes (Stegomyia) aegypti in Eastern Argentina

Aedes (Stegomyia) aegypti (Linnaeus) (Diptera: Culicidae) is the principal vector of the yellow fever virus, the five dengue virus serotypes (DENV-1 to DENV-5), chikungunya virus, Zika virus, and several types of encephalitis [1–3]. The behavior of this species is synanthropic and anthropophilic, being the culicid most closely associated with human populations [4]. The incidence of dengue has increased 30-fold over the last 50 years; according to the World Health Organization, up to 50–100 million infections occur each year in over 100 endemic countries, and at least one half of the world’s population has risk of being infected with dengue virus [5]. Chikungunya virus has been responsible for over 2 million human infections during the past decade and is currently moving to subtropical latitudes as well as to the western hemisphere. Up until April 2015, there have been 1,379,788 suspected cases of this disease in the Caribbean islands, Latin America, and the United States. This expansion into novel habitats brings unique risks associated with further spread of the virus and the disease it causes [6]. On the other hand, there are about 200,000 cases of yellow fever each year worldwide responsible for about 30,000 deaths, most of them from Africa. Zika virus is an emerging mosquito-borne virus, with outbreaks in Africa, Asia, and the Pacific between 2007 and 2014. Since 2015, there has been an increase in reports of ZIKV infection in the Americas, with Brazil being the most affected country, with 534 confirmed cases and 72,062 suspected cases between 2015 and 2016 [7]. All these viruses and the mosquito vector A. aegypti present in the Americas represent a serious risk. So far, in 2016, 39,926 dengue cases produced by DENV-1 and DENV-4 serotypes and 319 autochthonous cases of chikungunya fever have been reported in Argentina. According to the last census, Argentina has approximately 40 million people (National Institute of Statistics and Censuses of Argentina [INDEC], Census 2010), and over 38 million live in areas suitable for the transmission of dengue and chikungunya viruses [8]. Moreover, although there were 22 imported cases of Zika and 24 autochthonous cases confirmed in Argentina, there is a high incidence of cases in Brazil, and besides that, there is an internal circulation of the virus in the neighboring countries Brazil, Paraguay, and Bolivia [7,8], in addition to the constant expansion of the mosquito vector.Facultad de Ciencias Naturales y Muse

Oligoryzomys flavescens (Rodentia, Muridae): gene flow among populations from central-eastern Argentina

Fil: Chiappero, Marina B. Universidad Nacional de Córdoba. Facultad de Ciencias Médicas. Cátedra de Química Biológica; Argentina.Fil: Calderón, Gladys E. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Gardenal, Cristina N. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales, Córdoba; Argentina.In species acting as hosts of infectious agents, the extent of gene flow between populations is of particular interest because the expansion of different infectious diseases is usually related to the dispersal of the host. We have estimated levels of gene flow among populations of the sigmodontine rodent Oligoryzomys flavescens, in which high titers of antibodies have been detected for a Hantavirus in Argentina that produces a severe pulmonary syndrome. Enzyme polymorphism was studied by means of starch gel electrophoresis in 10 populations from the area where human cases of Hantavirus have occurred. Genetic differentiation between populations was calculated from FST values with the equation Nm = [(1/FST) - 1]/4. To assess the relative importance of current gene flow and historical associations between populations, the relationship of population pairwise log Nm and log geographic distance was examined. Low FST (mean = 0.038) and high Nm (15.27) values suggest high levels of gene flow among populations. The lack of an isolation by distance pattern would indicate that this species has recently colonized the area. The northernmost population, located on the margin of a great river, shows very high levels of gene flow with the downstream populations despite the large geographic distances. Passive transport of animals down the river by floating plants would promote unidirectional gene flow. This fact and the highest mean heterozygosity of that northernmost population suggest it is a center of dispersal within the species' range

Distribution and hybridization between Culex pipiens and Culex quinquefasciatus (Diptera: Culicidae) in Argentina

To better undesrtand the distribution of Culex pipiens and Cx. quinquefasciatus in Argentina, samples were collected from six localities situated in a North-South line from Castelli (Chaco Province) to Puerto Madryn (Chubut Province). Identification was based on the morphology of male genitalia. Only Cx. quinquefasciatus was found in Castelli and Esperanza, while in Rosario, 95.3% belonged to this species and 4.7% represented hybrid forms. Southern samples included only Cx. pipiens. With the purpose of verfying if Cx. pipiens and Cx. quinquefasciatus hybridize, different crosses between the two species were perfomed. All crosses produced viable egg rafts. Hatching ranged from 70 to 100%, except in one cross, female Cx. pipiens x male Cx. quinquefasciatus, where a high incompatibility was observed (11.1%hatch). The F1 hybrids obtained all crosses were fertile. The finding of hybrid forms in nature can be interpreted as evidence for subspecific status of Cx. pipiens and Cx. quinquefasciatus in Argentina

COMUNIDADES DE ROEDORES DE CULTIVOS DE SORGO EN LA PROVINCIA DE CÓRDOBA Y SU POSIBLE VINCULACIÓN CON LA FIEBRE HEMORRÁGICA ARGENTINA

The composition of rodent communities in fields dedicated to sorghum culture was studied in seven sites situated along two transects about 500 km long, in the SE of Córdoba Province (Argentina). Four of the sites are in the endemic area of ArgentineHemorrhagic Fever and the other three in the marginal area, free of Junin virus. The animáis were trapped during a short period in May and June, 1977. Eight Crieetidae (Calomys musculinus, Akodon azarae, Calomys laucha, Oligoryzomys flavescens, Cabreramys benefactus, Akodon dolores, Graomys griseoflavus y Calomys callosus) and one Muridae species (Mus musculus) were obtained. Comparative analysis of the species composition of the communities has been performed by using the Mountford Índex.Total number of specimens from Calomys plus Akodon represented, in all the samples, more than 80%. The most abundant species in six out of seven samples was C. musculinus, the most important reservoir of Junin virus. The structure of this species populationswas very similar for most of the endemic and marginal areas.The composition of rodent communities in fields dedicated to sorghum culture was studied in seven sites situated along two transects about 500 km long, in the SE of Córdoba Province (Argentina). Four of the sites are in the endemic area of ArgentineHemorrhagic Fever and the other three in the marginal area, free of Junin virus. The animáis were trapped during a short period in May and June, 1977. Eight Crieetidae (Calomys musculinus, Akodon azarae, Calomys laucha, Oligoryzomys flavescens, Cabreramys benefactus, Akodon dolores, Graomys griseoflavus y Calomys callosus) and one Muridae species (Mus musculus) were obtained. Comparative analysis of the species composition of the communities has been performed by using the Mountford Índex.Total number of specimens from Calomys plus Akodon represented, in all the samples, more than 80%. The most abundant species in six out of seven samples was C. musculinus, the most important reservoir of Junin virus. The structure of this species populationswas very similar for most of the endemic and marginal areas

Molecular identification of two Culex (Culex) species of the neotropical region (Diptera: Culicidae).

Culex bidens and C. interfor, implicated in arbovirus transmission in Argentina, are sister species, only distinguishable by feature of the male genitalia; however, intermediate specimens of the species in sympatry have been found. Fourth-instar larvae and females of both species share apomorphic features, and this lack of clear distinction creates problems for specific identification. Geometric morphometric traits of these life stages also do not distinguish the species. The aim of the present study was to assess the taxonomic status of C. bidens and C. interfor using two mitochondrial genes and to determine the degree of their reproductive isolation using microsatellite loci. Sequences of the ND4 and COI genes were concatenated in a matrix of 993 nucleotides and used for phylogenetic and distance analyses. Bayesian and maximum parsimony inferences showed a well resolved and supported topology, enclosing sequences of individuals of C. bidens (0.83 BPP, 73 BSV) and C. interfor (0.98 BPP, 97 BSV) in a strong sister relationship. The mean K2P distance within C. bidens and C. interfor was 0.3% and 0.2%, respectively, and the interspecific variation was 2.3%. Bayesian clustering also showed two distinct mitochondrial lineages. All sequenced mosquitoes were successfully identified in accordance with the best close match algorithm. The low genetic distance values obtained indicate that the species diverged quite recently. Most morphologically intermediate specimens of C. bidens from Córdoba were heterozygous for the microsatellite locus GT51; the significant heterozygote excess observed suggests incomplete reproductive isolation. However, C. bidens and C. interfor should be considered good species: the ventral arm of the phallosome of the male genitalia and the ND4 and COI sequences are diagnostic characters

Temporal Fluctuation of Effective Size in Populations of Calomys musculinus (Muridae: Sigmodontinae)

Fil: Chiappero, Marina B. Cátedra de Genétìca de Poblaciones y Evolución, FCEFyN, Universidad Nacional de Córdoba, Córdoba; Argentina.Fil: Garcia, B. A. Cátedra de Bioquímica y Biología Molecular, FCM, Universidad Nacional de Córdoba, Córdoba; Argentina.Fil: Calderón, G. E. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Gardenal, Cristina N. Cátedra de Genétìca de Poblaciones y Evolución, FCEFyN, Universidad Nacional de Córdoba, Córdoba; Argentina.Calomys musculinus is the natural reservoir of Junin virus, the etiological agent of Argentine hemorrhagic fever. In this paper we measure the effective size of 2 populations of the rodent over a 2-year period. Twenty enzyme-coding loci were analyzed using vertical starch gel electrophoresis. Effective population sizes (Nes) were estimated by the pseudolikelihood method in 2 populations 280 km apart in central Argentina. Both populations experienced marked seasonal changes in relative density and in Ne (between 19.8 and infinity). Changes in percentage of polymorphic loci and mean number of alleles per locus were statistically significant and were roughly correlated with density and Ne. Observed changes in heterozygosity, in contrast, were not significant. After low-density periods, mixing of surviving individuals coming from different demes may play an important role in the maintenance of variability and recovery of Ne in populations of C. musculinus