Machos azules y hembras verdes: dicromatismo sexual en el Saí Azul (Dacnis cayana) y la Tersina (Tersina viridis)

Las diferencias entre sexos en la coloración del plumaje, conocidas como dicromatismo sexual, son un fenómeno común entre los fruteros Neotropicales (familia: Thraupidae). En muchas especies de este grupo, el dicromatismo sexual es percibido, por observadores humanos bajo condiciones de luz natural, como machos azules y hembras verdes. Por ejemplo, este patrón es recurrente en especies de varios géneros, tales como Chlorochrysa, Tangara, Dacnis, Chlorophanes, Cyanerpes y Tersina. Con el objetivo de entender la naturaleza física de este fenómeno, y de determinar el grado de similitud y/o diferencia en el dicromatismo sexual exhibido por diferentes especies, describimos la coloración del plumaje del Saí Azul (Dacnis cayana) y la Tersina (Tersina viridis) mediante espectrofotometría de reflectancia. No se encontraron diferencias sexuales en el tono de ambas especies. En cambio, los machos mostraron un pico de reflectancia secundario en la región de longitudes de onda corta (UV a violeta), el cual estuvo ausente en las hembras. Este patrón de reflectancia bimodal de los machos difiere de los patrones unimodales más comúnmente descriptos en plumajes azules. Dada la similitud en los espectros a través de los cuales ambas especies estudiadas adquieren el mismo dicromatismo sexual azul-verde, sumado a que la evidencia molecular indica una relación cercana entre los géneros Tersina y Dacnis, interpretamos el marcado dicromatismo sexual encontrado en el Saí Azul y la Tersina como una condición homóloga.Sexual differences in plumage coloration, referred to as sexual dichromatism, are a common phenomenon among tanagers (family Thraupidae). In many species of this group, sexual dichromatism is perceived, by human observers under natural light conditions, as blue males and green females. For instance, this pattern is recurrent among species of several genera, such as Chlorochrysa, Tangara, Dacnis, Chlorophanes, Cyanerpes and Tersina. To understand the physical nature of this phenomenon, and to assess the degree of similarity/difference in sexual dichromatism exhibited by different species, we described the plumage color of the Swallow Tanager (Tersina viridis) and the Blue Dacnis (Dacnis cayana) using reflectance spectrophotometry. In both species there were no sexual differences in hue. Instead, males showed a secondary peak of reflectance in the short-wavelength (UV-violet) part of the spectrum, which was absent in females. This bimodal reflectance shape of males is different from the most commonly found unimodal pattern of blue plumages. Given the spectral similarity by which both studied species achieve the same blue-green sexual dichromatism, and the fact that molecular evidence indicates a close relationship between the genera Tersina and Dacnis, we interpret the particular sexual dichromatism found in both the Swallow Tanager and the Blue Dacnis as a homologous condition.Fil: Barreira, Ana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: García, Gabriela Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lougheed, Stephen. Queens University; CanadáFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Continental phylogeography of an ecologically and morphologically diverse Neotropical songbird, Zonotrichia capensis

[Background]: The Neotropics are exceptionally diverse, containing roughly one third of all extant bird species on Earth. This remarkable species richness is thought to be a consequence of processes associated with both Andean orogenesis throughout the Tertiary, and climatic fluctuations during the Quaternary. Phylogeographic studies allow insights into how such events might have influenced evolutionary trajectories of species and ultimately contribute to a better understanding of speciation. Studies on continentally distributed species are of particular interest because different populations of such taxa may show genetic signatures of events that impacted the continent-wide biota. Here we evaluate the genealogical history of one of the world's most broadly-distributed and polytypic passerines, the rufous-collared sparrow (Zonotrichia capensis). [Results]: We obtained control region DNA sequences from 92 Zonotrichia capensis individuals sampled across the species' range (Central and South America). Six additional molecular markers, both nuclear and mitochondrial, were sequenced for a subset of individuals with divergent control region haplotypes. Median-joining network analysis, and Bayesian and maximum parsimony phylogenetic analyses all recovered three lineages: one spanning Middle America, the Dominican Republic, and north-western South America; one encompassing the Dominican Republic, Roraima (Venezuela) and La Paz (Bolivia) south to Tierra del Fuego, Argentina; and a third, including eastern Argentina and Brazil. Phylogenetic analyses suggest that the Middle American/north-western South American clade is sister to the remaining two. Bayesian and maximum likelihood coalescent simulations used to study lineage demographic history, diversification times, migration rates and population expansion together suggested that diversification of the three lineages occurred rapidly during the Pleistocene, with negligible gene flow, leaving genetic signatures of population expansions. [Conclusions]: The Pleistocene history of the rufous-collared sparrow involved extensive range expansion from a probable Central American origin. Its remarkable morphological and behavioral diversity probably represents recent responses to local conditions overlying deeper patterns of lineage diversity, which are themselves produced by isolation and the history of colonization of South America.Funding was provided by NSERC Discovery grants to Lougheed and Handford, by CONICET, ANPCyT and IDRC, and by a National Geographic Society Research Grant to Chris Moyes.Peer Reviewe

Continental phylogeography of an ecologically and morphologically diverse neotropical songbird, Zonotrichia capensis

The Neotropics are exceptionally diverse, containing roughly one third of all extant bird species on Earth. This remarkable species richness is thought to be a consequence of processes associated with both Andean orogenesis throughout the Tertiary, and climatic fluctuations during the Quaternary. Phylogeographic studies allow insights into how such events might have influenced evolutionary trajectories of species and ultimately contribute to a better understanding of speciation. Studies on continentally distributed species are of particular interest because different populations of such taxa may show genetic signatures of events that impacted the continentwide biota. Here we evaluate the genealogical history of one of the world’s most broadly-distributed and polytypic passerines, the rufous-collared sparrow (Zonotrichia capensis).Fil: Lougheed, Stephen C.. Queen’s University. Department of Biology; Canadá;Fil: Campagna, Leonardo. Cornell University; Estados Unidos de América; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Dávila, José A.. Instituto de Investigación en Recursos Cinegéticos; España;Fil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales. División de Ornitología; Argentina;Fil: Handford, Paul. University of Western Ontario. Department of Biology; Canadá

Diferencias de Coloracio´n entre Especies Cercanamente Emparentadas de Pechos Colorados (Sturnella)

Interspecific differences in sexually selected traits may be important for maintaining reproductive isolation among closely related species living in sympatry. We present the first study of plumage color differences among males of partially sympatric species of South American red-breasted meadowlarks (the Long-tailed Meadowlark, the Pampas Meadowlark and the White-browed Blackbird, Sturnella loyca, S. defilippii and S. superciliaris, respectively) using reflectance spectrophotometry and the avian visual model of Vorobyev and Osorio (1998). Reflectance values of sexually dichromatic red plumage patches were measured on study skins. Total reflectance, reflectance in the short wavelength part of the spectrum and several measures of spectral shape were extracted directly from the spectra data. These variables were subjected to two-way ANCOVAs, with species and season (breeding/non-breeding) as main factors and year of capture as a covariate. These analysis revealed that S. loyca and S. defilippii were brighter and had a higher reflectance in the short wavelength part of the spectrum than S. superciliaris. The wavelength of minimum reflectance showed higher values in breeding plumage versus non-breeding. Interspecific distances in avian visual space were considerably higher than the threshold value for color discrimination, denoting that the differences found are also detectable by birds. Taken together, these results showed that the red plumage patches of these three species present significant color differences throughout the year not only in the visible but also in the UV part of the spectrum.Las diferencias interespecíficas en caracteres sexualmente seleccionados pueden ser importantes para mantener el aislamiento reproductivo entre especies simpátricas cercanamente emparentadas. Este es el primer estudio de las diferencias de coloración de plumaje entre machos de especies parcialmente simpátricas de pechos colorados sudamericanos (Sturnella superciliaris, S. defilippii,yS. loyca) usando espectrofotometría de reflectancia y el modelo de percepción visual de Vorobyev y Osorio (1998). Los valores de reflectancia de los parches rojos sexualmente dimórficos fueron medidos en pieles de estudio. La reflectancia total, la reflectancia en la porción de onda corta del espectro y varias medidas de forma espectral fueron obtenidas directamente de los espectros. Nuestros análisis revelaron que S. loyca y S. defilippii fueron más brillantes y tuvieron mayor reflectancia en la regio´n de onda corta del espectro que S. superciliaris. La posición de reflectancia mínima se localizó a longitudes de onda mayores en el plumaje reproductivo comparado con el no reproductivo. Las distancias interespecíficas en el espacio visual aviano obtenidas del modelo de Vorobyev y Osorio (1998) fueron considerablemente mayores que el valor umbral de discriminación de color, indicando que estas diferencias son también detectables por las aves. Tomados en su conjunto, estos resultados muestran que los parches de plumaje rojo de estas tres especies presentan diferencias significativas en la coloración durante todo el año tanto en la porción visible del espectro como en la UVFil: Benites, Maria del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. University of Kansas; Estados UnidosFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lougheed, Stephen C.. Queens University. Department Of Biology; CanadáFil: Eaton, Muir D.. University of Kansas; Estados Unido

First genetic assessment of the level of endemism in the avifauna of the Central Sierras in southern South America

The Andes constitute one of the main factors that have promoted diversification in the Neotropics. However, the role of other highland regions in the southern cone of South America has been barely studied. We analyzed the level of endemism in the avifauna of the Central Sierras in Córdoba, a high region in central Argentina, to evaluate the effect of its geographic isolation from the Andes. There are 11 species with endemic subspecies in this region, all of them described based only on differences in morphology (mainly plumage color) with no genetic evidence. We performed the first genetic analyses of seven of these species using mitochondrial DNA obtained from fresh tissue and toe pad samples. Our results show that for three of these species, Catamenia inornata, Phrygilus unicolor and Cinclodes atacamensis, the population in the Central Sierras is clearly differentiated from those of other regions, and the first two of them also show divergence among Andean subspecies. In the remaining species we found a varying degree of differentiation, ranging from a small divergence in Muscisaxicola rufivertex to the presence of different haplotypes but with an apparent lack of phylogeographic structure in Phrygilus plebejus and Sturnella loyca (being the latter the only species with a continuous distribution between the Central Sierras and the Andes) to haplotype sharing in Asthenes modesta. While further analyses including additional markers, morphological characters and vocalizations are needed, our results show that some of the species that have disjunct distributions, with a population in the Central Sierras isolated geographically from the Andes, possess distinct genetic lineages in the Central Sierras that suggest an evolutionary isolation from other populations. These findings highlight the importance of montane regions in general, and the Central Sierras in particular, as drivers of diversification in the Neotropics.Fil: Bukowski Loináz, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lavinia Oblanca, Pablo Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Trujillo Arias, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Kopuchian, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Probing Evolutionary Patterns in Neotropical Birds through DNA Barcodes

Background: The Neotropical avifauna is more diverse than that of any other biogeographic region, but our understanding of patterns of regional divergence is limited. Critical examination of this issue is currently constrained by the limited genetic information available. This study begins to address this gap by assembling a library of mitochondrial COI sequences, or DNA barcodes, for Argentinian birds and comparing their patterns of genetic diversity to those of North American birds. Methodology and Principal Findings: Five hundred Argentinian species were examined, making this the first major examination of DNA barcodes for South American birds. Our results indicate that most southern Neotropical bird species show deep sequence divergence from their nearest-neighbour, corroborating that the high diversity of this fauna is not based on an elevated incidence of young species radiations. Although species ages appear similar in temperate North and South American avifaunas, patterns of regional divergence are more complex in the Neotropics, suggesting that the high diversity of the Neotropical avifauna has been fueled by greater opportunities for regional divergence. Deep genetic splits were observed in at least 21 species, though distribution patterns of these lineages were variable. The lack of shared polymorphisms in species, even in species with less than 0.5M years of reproductive isolation, further suggests that selective sweeps could regularly excise ancestral mitochondrial polymorphisms. Conclusions: These findings confirm the efficacy of species delimitation in birds via DNA barcodes, even when tested on a global scale. Further, they demonstrate how large libraries of a standardized gene region provide insight into evolutionary processes.Fil: Kerr, Kevin C. R.. University of Guelph; CanadáFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Barreira, Ana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Hebert, Paul David Neil. University of Guelph; CanadáFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

José Julián Bakedano. Sin pausa

Reseña del libro José Julián Bakedano. Sin paus

Metabarcoding, direct stomach observation and stable isotope analysis reveal a highly diverse diet for the invasive green crab in Atlantic Patagonia

The European green crab Carcinus maenas and its sister species C. aestuarii are highly invasive species causing damage to coastal ecosystems and contributing to severe economic losses worldwide. C. maenas was first detected at the Atlantic Patagonian coast in 2001. In this work, we studied the diet of the green crab in a recently invaded location in Golfo Nuevo, using three complementary techniques: direct stomach observation, metabarcoding of gut content and stable isotope analysis. Direct stomach observation and metabarcoding showed that green crabs have a broad omnivorous diet, ingesting most of the phyla present in the study area. Gut content metabarcoding allowed a detailed description of algal diversity and revealed other taxa that went unnoticed in the visual stomach analysis. Stable isotope analysis showed that the major contribution to the crabs' diet was from the phytoplankton chain (by bivalve consumption) and not directly from algae. This study approach combining three complementary techniques also allowed us to detect some differences in the diet between sexes, which suggests that male and female crabs are not as ecologically equivalent as previously thought. Besides, we detected sequences corresponding to C. aestuarii suggesting that the green crab Patagonian population is a hybrid of both sister species. These findings are key to understanding the impacts green crabs can have on the local ecosystem.Fil: Cordone, Georgina Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Lozada, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Vilacoba, Elisabet. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Thalinger, Bettina. University of Guelph; CanadáFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Steinke, Dirk. University of Guelph; CanadáFil: Galvan, David Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin

Genetic variation in neotropical butterflies is associated with sampling scale, species distributions, and historical forest dynamics

Previous studies of butterfly diversification in the Neotropics have focused on Amazonia and the tropical Andes, while southern regions of the continent have received little attention. To address the gap in knowledge about the Lepidoptera of temperate South America, we analysed over 3000 specimens representing nearly 500 species from Argentina for a segment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Representing 42% of the country's butterfly fauna, collections targeted species from the Atlantic and Andean forests, and biodiversity hotspots that were previously connected but are now isolated. We assessed COI effectiveness for species discrimination and identification and how its performance was affected by geographic distances and taxon coverage. COI data also allowed to study patterns of genetic variation across Argentina, particularly between populations in the Atlantic and Andean forests. Our results show that COI discriminates species well, but that identification success is reduced on average by ~20% as spatial and taxonomic coverage rises. We also found that levels of genetic variation are associated with species' spatial distribution type, a pattern which might reflect differences in their dispersal and colonization abilities. In particular, intraspecific distance between populations in the Atlantic and Andean forests was significantly higher in species with disjunct distributions than in those with a continuous range. All splits between lineages in these forests dated to the Pleistocene, but divergence dates varied considerably, suggesting that historical connections between the Atlantic and Andean forests have differentially affected their shared butterfly fauna. Our study supports the fact that large-scale assessments of mitochondrial DNA variation are a powerful tool for evolutionary studies.Fil: Attiná, Natalí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Núñez Bustos, Ezequiel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lijtmaer, Dario Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Hebert, Paul David Neil. University of Guelph; CanadáFil: Tubaro, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Lavinia Oblanca, Pablo Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad Nacional de Río Negro; Argentin