Browsing by Author "Mendez, Marco A."

Now showing 1 - 17 of 17
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    A flagship for Austral temperate forest conservation: an action plan for Darwin's frogs brings key stakeholders together
    (2021) Azat, Claudio; Valenzuela-Sanchez, Andres; Delgado, Soledad; Cunningham, Andrew A.; Alvarado-Rybak, Mario; Bourke, Johara; Briones, Raul; Cabeza, Osvaldo; Castro-Carrasco, Camila; Charrier, Andres; Correa, Claudio; Crump, Martha L.; Cuevas, Cesar C.; de la Maza, Mariano; Diaz-Vidal, Sandra; Flores, Edgardo; Harding, Gemma; Lavilla, Esteban O.; Mendez, Marco A.; Oberwemmer, Frank; Carlos Ortiz, Juan; Pastore, Hernan; Penafiel-Ricaurte, Alexandra; Rojas-Salinas, Leonora; Manuel Serrano, Jose; Sepulveda, Maximiliano A.; Toledo, Veronica; Ubeda, Carmen; Uribe-Rivera, David E.; Valdivia, Catalina; Wren, Sally; Angulo, Ariadne
    Darwin's frogs Rhinoderma darwinii and Rhinoderma rufum are the only known species of amphibians in which males brood their offspring in their vocal sacs. We propose these frogs as flagship species for the conservation of the Austral temperate forests of Chile and Argentina. This recommendation forms part of the vision of the Binational Conservation Strategy for Darwin's Frogs, which was launched in 2018. The strategy is a conservation initiative led by the IUCN SSC Amphibian Specialist Group, which in 2017 convened 30 governmental, non-profit and private organizations from Chile, Argentina and elsewhere. Darwin's frogs are iconic examples of the global amphibian conservation crisis: R. rufum is categorized as Critically Endangered (Possibly Extinct) on the IUCN Red List, and R. darwinii as Endangered. Here we articulate the conservation planning process that led to the development of the conservation strategy for these species and present its main findings and recommendations. Using an evidence-based approach, the Binational Conservation Strategy for Darwin's Frogs contains a comprehensive status review of Rhinoderma spp., including critical threat analyses, and proposes 39 prioritized conservation actions. Its goal is that by 2028, key information gaps on Rhinoderma spp. will be filled, the main threats to these species will be reduced, and financial, legal and societal support will have been achieved. The strategy is a multi-disciplinary, transnational endeavour aimed at ensuring the long-term viability of these unique frogs and their particular habitat.
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    A hybrid zone of two toad sister species, Rhinella atacamensis and R-arunco (Anura: Bufonidae), defined by a consistent altitudinal segregation in watersheds
    (2013) Correa, Claudio; Mendez, Marco A.; Araya, Sergio; Lobos, Gabriel; Eduardo Palma, R.
    Delimiting the spatial extension of a hybrid zone is essential to understand its historical origin and to identify the geographical and/or environmental factors which delimit it. Rhinella atacamensis and R. arunco are two sister species which together inhabit Chile between 25 degrees and 38 degrees S. Their distribution limits coincide at about 32 degrees S, where recently it was reported that they hybridize in a small watershed (Pupio creek). Although the genetic evidence suggests that these two species form a hybrid swarm, they are not mixed homogeneously in the entire watershed, but rather are spatially segregated: R. arunco is found in the lower part of the creek and R. atacamensis in the higher part. An extensive exploration north and south of 32 degrees S revealed other instances of hybridization, with the same pattern of spatial segregation within other watersheds. This study describes the hybrid zone combining mitochondrial sequences and nuclear AFLP markers. In the northern part, the hybrid zone is a narrow strip which crosses several watersheds and extends more than 130 km from NW-SE, so that R. atacamensis is found at higher altitudes towards the south. However, two points south of this strip show that the hybrid zone is more extensive and complex, and probably extends along the entire border of the mountain chains which form the watershed of the Aconcagua River (32 degrees 30' - 33 degrees S). We propose an explanation for the origin of this hybrid zone considering paleoclimatic and orographic information, and briefly discuss the taxonomic implications of these results.
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    A new species of Alsodes (Anura: Alsodidae) from Altos de Cantillana, central Chile
    (MAGNOLIA PRESS, 2015) Charrier, Andres; Correa, Claudio; Castro, Camila; Mendez, Marco A.
    Based on morphological and molecular evidence (mitochondrial and nuclear sequences) we describe a new species of spiny-chest frog, Alsodes cantillanensis, from central Chile (around 34 degrees S). The type locality, Quebrada Infiernillo, is located in the Coastal Range at approximately 65 km from Santiago (Metropolitan Region), the capital of Chile. The distribution of the new species is included entirely in that of A. nodosus (32-36 degrees S approximately), which was identified as the sister taxon according to molecular phylogenetic analyses. Moreover, both species are sympatric in the type locality. The new species was found in a Nothofagus macrocarpa relict forest potentially threatened by gold mining activities. We identify other threats for its conservation and some biological data needed for understanding the evolution of this species. This discovery reveals the scarce knowledge about biogeography, evolution and ecology of spiny- chest frogs from central Chile.
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    Amphibian phylogenetic diversity in the face of future climate change: not so good news for the chilean biodiversity hotspot
    (2022) Rodriguez, Leonardo J.; Barbosa, Olga A.; Soto-Azat, Claudio; Alvarado-Rybak, Mario; Correa, Claudio; Mendez, Marco A.; Moreno-Gomez, Felipe N.; Rabanal, Felipe E.; Vidal, Marcela A.; Velasquez, Nelson A.; Bacigalupe, Leonardo D.
    Climate change is projected to be the most extensive human-induced disturbance to occur on natural ecosystems, inducing changes in different biodiversity features including the evolutionary history of a region through the decline and loss of its phylogenetic diversity. Amphibians, given their ectothermic life cycle and critical conservation status, would potentially be exposed to extinction processes under conditions of climate change, with the corresponding loss of evolutionary history in regions of high biodiversity. This research addresses the effects of climate change on the evolutionary history of amphibians in the Chilean Biodiversity Hotspot, by estimating the PD (Phylogenetic diversity) and PE (Phylogenetic endemism) of 27 species. Using different RCP (RCP 4.5 and 8.5) and time frames (years 2050 and 2070), we create species distribution models (SDM) to evaluate the species range dynamics and the phylodiversity in the Hotspot. Also, given that Protected Areas (PA) are the main global strategy to ensure the conservation of species and their features, we evaluate the capacity of PA to conserve the evolutionary history in the Hotspot. Our results show a set of modeled species that will become extinct, or will experiment changes in their distributional ranges, inducing a clear decline of amphibian evolutionary history for the next 30 to 50 years, and a worrying low capacity of the PA to contain current and future PD and PE. Given the critical amphibian scenario, our results highlight the need for further research to improve the decision-making process in the hotspot area addressing the potential amphibian extinction risk, the lack of protection by the PA system, and the loss of evolutionary history as a key aspect of biodiversity.
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    Confirmation of the presence of Alsodes pehuenche Cei, 1976 (Anura, Alsodidae) in Chile: morphological, chromosomal and molecular evidence
    (2013) Correa, Claudio; Pastenes, Luis; Iturra, Patricia; Calderon, Pilar; Vasquez, Dayana; Lam, Natalia; Salinas, Hugo; Mendez, Marco A.
    The presence of Alsodes pehuenche in Chile was reported in the year 2010, based on the observation of larvae near the Chilean-Argentinean border, about 3 km east of the northeast corner of the Laguna del Maule (Region del Maule, Chile). The taxonomic history of this species dates from 1965, with the re-discovery of Telmatobius montanus (which was later transferred to the genus Alsodes) in two localities, near the Laguna del Maule and Valle Pehuenche, located in Chile and Argentina, respectively. The literature review shows that the locality of Argentina described in 1965 became the type locality of A. pehuenche, while the Chilean locality was ignored; thus this latter locality continues to be a valid record for A. montanus. In this study we provide morphological, chromosomal and molecular evidence, which confirms the presence of A. pehuenche in Chile, in two new localities located near the site recorded in 2010 and the Laguna del Maule. We also include some field observations, which are discussed in the context of the information available for this species.
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    Coping With Dynamism: Phylogenetics and Phylogeographic Analyses Reveal Cryptic Diversity in Heleobia Snails of Atacama Saltpan, Chile
    (2022) Valladares, Moises A.; Fabres, Alejandra A.; Collado, Gonzalo A.; Saez, Paola A.; Mendez, Marco A.
    The species that inhabit systems highly affected by anthropic activities usually exhibit this external influence in their gene pool. In this study, we investigated the genetic patterns of populations of Heleobia atacamensis, a freshwater microgastropod endemic to the Atacama Saltpan, a system historically exposed to environmental changes, and currently subjected to conditions associated with metallic and non-metallic mining and other anthropic activities. Molecular analyses based on nuclear and mitochondrial sequences indicate that the saltpan populations are highly fragmented and that the genetic structure is mainly explained by historical geographic isolation, with little influence of contemporary factors. The microsatellite results suggest a moderate genetic diversity and sharp differentiation mediated by isolation by distance. Additionally, despite the high environmental heterogeneity detected and the marked historical dynamism of the region, our data reveal no signs of demographic instability. The patterns of contemporary gene flow suggest a change in the current genetic structure, based on the geographic proximity and specific environmental conditions for each population. Our results, highlight the role of fragmentation as a modulator of genetic diversity, but also suggest that the historical persistence of isolated populations in naturally dynamic environments could explain the apparent demographic stability detected.
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    Evidence of predation on the Helmeted water toad Calyptocephalella gayi (Dumeril & Bibron, 1841) by the invasive African clawed frog Xenopus laevis (Daudin 1802)
    (2020) Fibla, Pablo; Serrano, Jose M.; Cruz-Jofre, Franco; Fabres, Alejandra A.; Ramirez, Francisco; Saez, Paola A.; Otalora, Katherin E.; Mendez, Marco A.
    We report the first record of predation on a Helmeted water toad Calyptocephalella gayi tadpole by an adult specimen of the invasive African clawed frog Xenopus laevis in the locality of Pichi, Alhue (Santiago Metropolitan Region). This finding is discussed in the light of new sightings, in which both species have been detected to coexist in different localities of central Chile.
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    Genetic and Reproductive Evidence of Natural Hybridization between the Sister Species Rhinella atacamensis and Rhinella arunco (Anura, Bufonidae)
    (2012) Correa, Claudio L.; Mendez, Marco A.; Veloso, Alberto; Sallaberry, Michel
    Rhinella atacamensis and Rhinella arunco are sister species which, together, are distributed from 25 degrees S to 38 degrees S in Chile. Until recently they were considered to be allopatric, with the dividing line around 32 degrees S, but in 2007 a possible zone of secondary contact was found in the Estero Pupio (32 degrees 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 Pupio will require additional information.
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    Genetic divergence in the endangeredfrog Insuetophrynus acarpicus (Anura: Leptodactylidae)
    (2006) Mendez, Marco A.; Torres-Perez, Fernando; Correa, Claudio; Soto, Eduardo R.; Nunez, Jose J.; Veloso, Alberto; Armesto, Juan
    Insuetophrynus acarpicus is a poorly known frog restricted to the temperate forests of the coastal range of Chile (39 degrees 25' S, 73 degrees 10' W). Until recently, this species was known only from one type locality since its original description in 1970. However, in 2002 two new localities were reported, extending its distribution range to about 40 km(2). In order to evaluate genetic divergence, provide a preliminary evaluation of the genetic diversity of this species and the phylogenetic relationships among individuals from the three known populations, we analyzed the nucleotide variation of a fragment of the mitochondrial gene cytochrome b. We sampled just two or four individuals per population of this endangered frog. We found a low nucleotide divergence among populations suggesting a genetic homogeneity across the entire range. This highlights the need for further studies to define the conservation status of this endangered frog.
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    Genome sequencing and transcriptomic analysis of the Andean killifish Orestias ascotanensis reveals adaptation to high-altitude aquatic life
    (2022) Di Genova, Alex; Nardocci, Gino; Maldonado-Agurto, Rodrigo; Hodar, Christian; Valdivieso, Camilo; Morales, Pamela; Gajardo, Felipe; Marina, Raquel; Gutierrez, Rodrigo A.; Orellana, Ariel; Cambiazo, Veronica; Gonzalez, Mauricio; Glavic, Alvaro; Mendez, Marco A.; Maass, Alejandro; Allende, Miguel L.; Montecino, Martin A.
    Orestias ascotanensis (Cyprinodontidae) is a teleost pupfish endemic to springs feeding into the Ascotan saltpan in the Chilean Altiplano (3,700 m.a.s.l.) and represents an opportunity to study adaptations to high-altitude aquatic environments. We have de novo assembled the genome of O. ascotanensis at high coverage. Comparative analysis of the O. ascotanensis genome showed an overall process of contraction, including loss of genes related to Gprotein signaling, chemotaxis and signal transduction, while there was expansion of gene families associated with microtubule-based movement and protein ubiquitination. We identified 818 genes under positive selection, many of which are involved in DNA repair. Additionally, we identified novel and conserved microRNAs expressed in O. ascotanensis and its closely-related species, Orestias gloriae. Our analysis suggests that positive selection and expansion of genes that preserve genome stability are a potential adaptive mechanism to cope with the increased solar UV radiation to which high-altitude animals are exposed to.
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    Genomes of the Orestias pupfish from the Andean Altiplano shed light on their evolutionary history and phylogenetic relationships within Cyprinodontiformes
    (2024) Morales, Pamela; Gajardo, Felipe; Valdivieso, Camilo; Valladares, Moises A.; Di Genova, Alex; Orellana, Ariel; Gutierrez, Rodrigo A.; Gonzalez, Mauricio; Montecino, Martin; Maass, Alejandro; Mendez, Marco A.; Allende, Miguel L.
    Background To unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order.
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    Insect Fluctuating Asymmetry: An Example in Bolivian Peridomestic Populations of Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae)
    (2022) Vilaseca, Carolina; Pinto, Carlos F.; Ordenes-Claveria, Rodrigo; Laroze, David; Mendez, Marco A.; Benitez, Hugo A.
    Fluctuating asymmetry (FA) is a morphometric tool used to measure developmental instability in organisms which have been exposed to stress or other adverse conditions. Phenotypic variability in response to stressors are the result of interactions between genomes and the environment, acting in a noisy developmental system. Most of the organisms have bilateral symmetry with a repetition of structures in different positions or orientations; asymmetrical variation has been a morphological response associated with insecticide application inducing disturbances in endocrinal system product of the chemicals. Triatoma infestans (is the main vector of Chagas disease in South America. The availability of food sources varies for populations of T. infestans living in different habitats; insects that inhabit the intradomicile feed preferentially on human blood, whereas insects that develop in the peridomicile feed on the blood of the other mammals and birds. The following research evaluate the FA to the different ecotopes in two geographical areas of Chuquisaca Bolivia; Yamparaez/Sotomayor of the high inter-Andean valleys and Huacaya/Imbochi of the boreal Chaco and a CIPEIN laboratory strain population. A combination of advanced morphometrics tools and multivariate analysis were used to quantify the levels of asymmetry produced by pyretroid near to the peridomiciles in Bolivia. Populations from Yamparaez/Sotomayor were found to have higher levels of FA which the combination of environmental conditions such as low temperatures avoid greater permanence in the habitat and more exposition to insecticide. A better understanding of the combination of these tools will allow researchers to implement better public policies to regulate insecticide applications and to understand how certain organisms adapt to multiple stressors.
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    Invasive Pleurodema thaul from Robinson Crusoe Island: molecular identification of its geographic origin and comments on the phylogeographic structure of this species in mainland Chile
    (2008) Correa, Claudio; Lobos, Gabriel; Pastenes, Luis; Mendez, Marco A.
    Robinson Crusoe Island, located 670 kin west of the coast of central Chile, is characterized by a high number of endemic and introduced species of plants and animals. This island lacks native amphibians or reptiles, but Somewhat more than 30 years ago the toad Pleurodema thaul, native to continental Chile, was introduced. The coast of central Chile was identified as the geographic Source of the introduced population of Robinson Crusoe by means of phylogenetic analyses of mitochondrial sequences. These analyses also suggest a high degree of phylogeographic structure for this species in continental Chile.
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    Phylogeography of Rhinella spinulosa (Anura: Bufonidae) in northern Chile
    (2010) Correa, Claudio; Pastenes, Luis; Sallaberry, Michel; Veloso, Alberto; Mendez, Marco A.
    The southern part of the Altiplano of the Andes Range is characterized by a complex hydrography, due to an intense geologic activity and the effects of the Pleistocene glaciations. This has produced a high degree of diversity at the species level in some aquatic taxa (e. g., fish and amphibians), which suggests that these same processes have produced divergence at the intraspecific level in co-distributed taxa. We investigated the genetic variation in populations of the anuran Rhinella spinulosa which represent its entire distribution in the extreme north of Chile (17 degrees 44'S-23 degrees 47'S). Haplotype networks of the mitochondrial control region recognized two main lineages, one of which is distributed from the northern boundary of Chile to the Salar de Alconcha and the other from the Salar de Carcote to the locality of Tilomonte. The northern lineage showed little phylogeographic structure; a few very frequent haplotypes are widely distributed. The southern lineage had greater structure, due principally to the high divergence of the populations from the eastern springs of the Salar de Atacama. Fu's Fs test and the mismatch distributions suggested that most of the populations of both lineages are in the process of demographic expansion. The spatial distribution of the genetic variability was correlated with the hydrography and the paleoclimatological data available for the region, which suggested that geographic expansions followed by periods of contraction of population ranges, together with sporadic floods may explain the observed phylogeographic patterns.
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    PSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ions
    (2012) Soto-Liebe, Katia; Mendez, Marco A.; Fuenzalida, Loreto; Krock, Bernd; Cembella, Allan; Vasquez, Monica
    Paralytic shellfish poisoning (PSP)toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Na+ channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous fresh-water cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and SIX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Na+ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Na+/drug antiporters. Conserved domains for Na+ and drug recognition have been described in NorM. For the D9 sxt cluster, the Na+ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Na+, K+) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition mechanism by the SxtF/M transporters for GTX2/3 and SIX. We propose that these toxins in cyanobacteria could act extracellularly as a protective mechanism to ensure homeostasis against extreme salt variation in the environment. (C) 2012 Elsevier Ltd. All rights reserved.
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    Relationship between the genetic structure of the Andean toad Rhinella spinulosa (Anura: Bufonidae) and the northern Chile landscape (21°-24° S)
    (2011) Gallardo, Carolina E.; Hernandez, Hector J.; Diniz-Filho, Jose A. F.; Eduardo Palma, R.; Mendez, Marco A.
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    Systematics and evolutionary relationships of the mountain lizard Liolaemus monticola (Liolaemini): how morphological and molecular evidence contributes to reveal hidden species diversity
    (2009) Torres-Perez, Fernando; Mendez, Marco A.; Benavides, Edgar; Moreno, Rodrigo A.; Lamborot, Madeleine; Palma, R. Eduardo; Ortiz, Juan Carlos
    The delimitation of species is a major issue in systematic biology and has been a re-emerging discipline in the last decade. A number of studies have shown that the use of multiple data sets is critical for the identification of cryptic species, particularly in groups with complex evolutionary histories. Liolaemus monticola is a montane lizard species distributed in central Chile (32 degrees-42 degrees S), with four described subspecies in a latitudinal gradient from north to south: L. m. monticola, L. m. chillanensis, L. monticola ssp. and L. m. villaricensis. In order to test the systematic status and phylogenetic relationships of the taxa included in the L. monticola group, we analysed morphological (morphometric and meristic) and molecular (allozyme and mitochondrial DNA) data sets. The results of the morphological analyses showed that meristic variables correctly assigned individuals with higher accuracy than did morphometric characters. The results of the analyses of allozyme data revealed eight diagnostic loci that are evidence for significant differences among the four L. monticola subspecies. Phylogenetic analyses with mitochondrial DNA data, including additional species, showed that the L. monticola group is polyphyletic. We postulate that the four current subspecies represent independent evolutionary lineages and must be raised to the specific level as L. monticola, L. chillanensis and L. villaricensis. The taxonomic status of the unnamed L. monticola ssp. remains unresolved, although we provide a preliminary proposal. (C) 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 635-650.