Claudio Correa

Low phylogeographic structure of Rhinella arunco (Anura: Bufonidae), an endemic amphibian from the Chilean Mediterranean hotspot

BackgroundThe Mediterranean zone of central Chile (30° to 38°S) is one of the 25 diversity hotspots in the world. However, there are few phylogeographic studies which identify the factors that have influenced population diversification in the fauna of this area. In this study, we investigated the phylogeographic structure of Rhinella arunco, an anuran endemic to Mediterranean Chile, using 160 individuals from 23 localities representative of its entire distribution (32° to 38°S).ResultsThe haplotype network revealed four haplogroups, three of which overlap geographically and only one of which has an exclusive geographic distribution. An analysis of molecular variance indicated that neither watershed limits nor the main rivers in the current distribution of this species have been important geographic barriers against the dispersion of individuals. Finally, the Geneland analysis showed three population units, one of which concurs with one of the haplogroups found in the haplotype network. Together, these analyses indicated a low level of phylogeographic structure for this species. On the other hand, the highest levels of intrapopulational genetic variation were concentrated in the central part of the distribution (33° to 34°S), which may indicate an effect of Pleistocene glaciations on the genetic diversity of the populations in the extreme south of its range.ConclusionsThe low phylogeographic structure observed in R. arunco is a rarely documented pattern for amphibians and contrasts with the phylogeographic studies of other vertebrates which inhabit the same zone. This result may be attributed to a series of attributes of bufonids, related mainly to water retention and their reproductive biology, which have allowed them to disperse and colonize an enormous variety of environments.

Species delimitation in frogs from South American temperate forests: The case of Eupsophus, a taxonomically complex genus with high phenotypic variation

One of the most characteristic and abundant amphibian taxa of South American temperate forests is Eupsophus. The ten currently recognized species of the genus have been divided in two species groups, roseus and vertebralis, but most of them, eight, belong to the roseus group. Recent phylogeographic and phylogenetic studies have suggested that species diversity of the roseus group could be underestimated. An examination of the literature shows that species of the roseus group exhibit high levels of variation in their external characteristics, particularly those used as diagnostic characters, which compromises their taxonomy and hinders their field recognition. High levels of variation were also observed in several new populations of the roseus group discovered in southern Chile (36°-40°S), which could not be identified to the species level by their external characteristics. On the other hand, the literature reveals a scarse karyotype differentiation and a high bioacoustic uniformity among the species of the roseus group. We performed a Bayesian phylogenetic analysis using mitochondrial and nuclear genes to reevaluate the species diversity of the roseus group, including all the nominal species of Eupsophus and new populations. This analysis was complemented with three species delimitation approaches, General Mixed Yule Coalescent, multi-rate Poisson Tree Process and Automatic Barcode Gap Discovery. We favored a conservative delimitation of only four species for the roseus group, a result more consistent with the distribution of pairwise genetic distances, and the available chromosome and bioacoustic evidence. The four recognized lineages, which have nearly completely allopatric distributions, are named after the earliest nominal species that they include, but because high levels of phenotypic variation, they are not diagnosable by consistent differences in external morphology. We discuss the implications of this new proposal for the taxonomy and conservation of the genus, and the possible causes of the difficulty to estimate its species diversity.

Características reproductivas de Chaltenobatrachus grandisonae (Anura: Batrachylidae) en un área protegida en Patagonia, Chile

Basso et al. (2011) assigned the monotypic genus Chaltenobatrachus for the species described originally as Telmatobius grandisonae Lynch, 1975 (later transferred to the genus Atelognathus by Lynch 1978). The type locality of Chaltenobatrachus grandisonae (L ynch, 1975) is Puer to Eden (Wellington Island) in the Magallanes Region, Chile, where the species has not been found again. Basso et al. (2011) added two new localities from Argentina and provided a detailed description that includes morphological and osteological characteristics of adult specimens, external morphology of tadpoles, kar yotype and phylogenetic relationships. They also provide a few fi eld observations, highlighting the lack of knowledge of the natural history and population biology of this anuran. In this work we repor t a new locality for C. grandisonae in Chile, extend its altitudinal distributional range and report on its reproductive mode. The study site is within the protected area Laguna Caiquenes (LCPA), located in the Aysen Region, which holds 9.000 ha of evergreen forests of Nothofagus betuloides and regrowth of Drimys winteri with bogs of Poaceae and Cyperaceae . In this locality, C. grandisonae cohabits with other fi ve anuran species: Alsodes coppingeri (Gunther, 1881); Batrachyla antar tandica Barrio, 1967; Batrachyla taeniata (Girard, 1855); Eupsophus calcaratus (Gunther, 1881) and Nannophryne variegata Gunther, 1870. Data on the reproductive activity of these species are also reported here. REVISTA CHILENA DE HISTORIA NATURAL

Confirmation of the presence of Alsodes pehuenche Cei, 1976 (Anura, Alsodidae) in Chile: morphological, chromosomal and molecular evidence

La presencia de Alsodes pehuenche en Chile fue reportada en el ano 2010, a partir de la observacion de larvas en las cercanias del limite entre Chile y Argentina, aproximadamente a 3 km al este del extremo noreste de la Laguna del Maule (Region del Maule, Chile). La historia taxonomica de esta especie se remonta a 1965, cuando se redescubrio a Telmatobius montanus (especie que luego fue transferida al genero Alsodes) en dos localidades, cerca de la Laguna del Maule y Valle Pehuenche, ubicadas en Chile y Argentina, respectivamente. La revision bibliografica muestra que la localidad de Argentina descrita en 1965 paso a ser la localidad tipo de A. pehuenche, mientras que la de Chile fue ignorada posteriormente, por lo que esta ultima continua siendo un registro valido de A. montanus. En este trabajo se provee evidencia morfologica, cromosomica y molecular que confirma la presencia de a A.pehuenche en Chile, en dos localidades ubicadas cerca del sitio reportado en 2010 y de la Laguna del Maule. Ademas, se incluyen algunas observaciones de terreno que son discutidas en el contexto de la informacion disponible de la especie.

Importancia clínica de la prueba calórica mínima

Introduccion: En la evaluacion de la patologia vestibular habitualmente se utiliza la prueba calorica clasica de Fitzgerald y Hallpike (PCC). Sin embargo, esta solo evalua la funcion del nervio vestibular superior a traves de la estimulacion del canal semicircular lateral. La prueba calorica minima (PCM) permite evaluar tanto la funcion del nervio vestibular superior como del nervio vestibular inferior a traves de la estimulacion del canal semicircular lateral y posterior respectivamente. Se desconoce el real impacto de la PCM en la evaluacion clinica de pacientes con sintomatologia vestibular. Objetivo: Cuantificar la utilidad diagnostica de la PCM en pacientes con sintomatologia vestibular. Material y metodo: Estudio diagnostico transversal. Se obtuvo la sensibilidad y especificidad de la PCM al comparar la respuesta del canal semicircular lateral en la PCM con la prueba calorica convencional. Se evaluo en cuantos casos la informacion sobre la funcion del nervio vestibular inferior aportada por la PCM fue relevante en el diagnostico vestibular. Resultados: Se estudio a 44 pacientes. Tanto la sensibilidad como la especificidad de la PCM para detectar patologia al estimular el canal semicircular lateral fue de 93% (IC95%: 84%-100% y 80%-100% respectivamente). En 16% (N =7) de los casos la PCM detecto patologia del nervio vestibular inferior con PCC normal. Conclusiones: La PCM es un examen complementario util en la evaluacion de pacientes con sintomatologia vestibular, puesto que tiene una alta sensibilidad y especificidad para detectar patologia del nervio vestibular superior a traves de la estimulacion del canal semicircular lateral y ademas, aporta informacion sobre el estado del nervio vestibular inferior a traves de la estimulacion del canal semicircular posterior, que no aporta la PCC

Genetic and Reproductive Evidence of Natural Hybridization between the Sister Species Rhinella atacamensis and Rhinella arunco (Anura, Bufonidae)

Abstract Rhinella atacamensis and Rhinella arunco are sister species which, together, are distributed from 25°S to 38°S in Chile. Until recently they were considered to be allopatric, with the dividing line around 32°S, but in 2007 a possible zone of secondary contact was found in the Estero Pupío (32°S). We investigated the species status of adult individuals of three localities along this creek using AFLP markers. Data were analyzed with a Bayesian method that allowed the identification of different types of hybrids in a population. In two of the localities in the lower part of the watershed, the majority of the individuals were identified as backcrosses of hybrids with R. arunco or first generation hybrids, although a few individuals were classified as pure R. arunco. This information, supplemented by mitochondrial sequences and reproductive observations in both the laboratory and in the field, shows that hybridization has been a recurrent phenomenon at these two localities. By contrast, in the third locality, higher in the watershed, we detected a certain amount of nuclear introgression of R. arunco in a population where only individuals with phenotypes and mitochondrial genotypes of R. atacamensis were found. Taken together, the genetic data of the three localities suggest that the hybrid zone is a hybrid swarm which is relatively extensive in the watershed of the creek. Identifying the causes of the apparent spatial segregation of the two species in the Estero Pupío will require additional information.