Variation in fine-scale genetic structure and local dispersal patterns between peripheral populations of a South American passerine bird

Indexación: Scopus.The distribution of suitable habitat influences natal and breeding dispersal at small spatial scales, resulting in strong microgeographic genetic structure. Although environmental variation can promote interpopulation differences in dispersal behavior and local spatial patterns, the effects of distinct ecological conditions on within-species variation in dispersal strategies and in fine-scale genetic structure remain poorly understood. We studied local dispersal and fine-scale genetic structure in the thorn-tailed rayadito (Aphrastura spinicauda), a South American bird that breeds along a wide latitudinal gradient. We combine capture-mark-recapture data from eight breeding seasons and molecular genetics to compare two peripheral populations with contrasting environments in Chile: Navarino Island, a continuous and low density habitat, and Fray Jorge National Park, a fragmented, densely populated and more stressful environment. Natal dispersal showed no sex bias in Navarino but was female-biased in the more dense population in Fray Jorge. In the latter, male movements were restricted, and some birds seemed to skip breeding in their first year, suggesting habitat saturation. Breeding dispersal was limited in both populations, with males being more philopatric than females. Spatial genetic autocorrelation analyzes using 13 polymorphic microsatellite loci confirmed the observed dispersal patterns: a fine-scale genetic structure was only detectable for males in Fray Jorge for distances up to 450 m. Furthermore, two-dimensional autocorrelation analyzes and estimates of genetic relatedness indicated that related males tended to be spatially clustered in this population. Our study shows evidence for context-dependent variation in natal dispersal and corresponding local genetic structure in peripheral populations of this bird. It seems likely that the costs of dispersal are higher in the fragmented and higher density environment in Fray Jorge, particularly for males. The observed differences in microgeographic genetic structure for rayaditos might reflect the genetic consequences of population-specific responses to contrasting environmental pressures near the range limits of its distribution.http://onlinelibrary.wiley.com/doi/10.1002/ece3.3342/epd

Exploratory behavior, but not aggressiveness, is correlated with breeding dispersal propensity in the highly philopatric thorn-tailed rayadito

Studies on the relationship between behavioral traits and dispersal are necessary to understand the evolution of dispersal syndromes. Empirical studies have mainly focused on natal dispersal, even though behavioral differences between dispersers and philopatric individuals are suspected to hold through the whole life cycle, potentially affecting breeding dispersal propensity. Using capture–mark–recapture data and behavioral trials in a forest passerine, the thorn-tailed rayadito Aphrastura spinicauda, we describe inter-individual differences in exploratory behavior and aggressiveness, and investigate the relationship between those traits and breeding dispersal. Our study took place in Fray Jorge National Park, north-central Chile, where a relatively isolated population of rayaditos inhabits a naturally fragmented environment. We found that scores for behavioral traits were consistent between years. Exploratory behavior was similar between sexes, while males showed higher levels of aggression towards a conspecific male intruder. Only exploratory behavior was related to breeding dispersal propensity, with fast-exploring rayaditos being more likely to have dispersed between seasons. This finding provides indirect evidence for the existence of a dispersal strategy that could reduce dispersal costs in the fragmented landscape of Fray Jorge. To our knowledge, this is the first study documenting an association between breeding dispersal and exploratory behavior in a wild bird population. A longitudinal individual-based study will help determining whether this association constitutes a behavioral syndrome.Indexación: Scopu

Extrapair paternity in two populations of the socially monogamous Thorn-tailed Rayadito Aphrastura spinicauda (Passeriformes: Furnariidae)

Studies on extrapair paternity (EPP) are key to understanding the ecological and evolutionary drivers of variation in avian mating strategies, but information is currently lacking for most tropical and subtropical taxa. We describe the occurrence of EPP in two populations of a South American socially monogamous bird, the Thorn-tailed Rayadito, based on data from 266 broods and 895 offspring that were sampled during six breeding seasons in north-central and southern Chile. In the northern population, 21% of the broods contained at least one extrapair young and 14% of all offspring were sired by an extrapair male, while in the southern population, we detected extrapair offspring (EPO) in 14% of the broods, and 6% of all offspring were EPO. Variation in the frequency of EPP could stem from population differences in the duration of the breeding season or the density of breeding individuals. Other factors such as differences in breeding synchrony and variation in food availability need to be evaluated. More reports on EPP rates are necessary to determine the patterns of taxonomic and geographic variation in mating strategies in Neotropical birds, and to better understand the differences in ecological dynamics between northern and southern hemisphere populations.Fil: Botero Delgadillo, Esteban. Max Plank Institute For Ornithology; Alemania. SELVA: Investigación para la Conservación en el Neotrópico; Colombia. Universidad de Chile; ChileFil: Quirici, Verónica. Universidad Andrés Bello; ChileFil: Poblete, Yanina. Universidad de Las Américas; ChileFil: Ippi, Silvina Graciela. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Departamento de Ecología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Kempenaers, Bart. Max Plank Institute For Ornithology; AlemaniaFil: Vásquez, Rodrigo A.. Universidad de Chile; Chil

Range-wide genetic structure in the thorn-tailed rayadito suggests limited gene flow towards peripheral populations

Indexación ScopusUnderstanding the population genetic consequences of habitat heterogeneity requires assessing whether patterns of gene flow correspond to landscape configuration. Studies of the genetic structure of populations are still scarce for Neotropical forest birds. We assessed range-wide genetic structure and contemporary gene flow in the thorn-tailed rayadito (Aphrastura spinicauda), a passerine bird inhabiting the temperate forests of South America. We used 12 microsatellite loci to genotype 582 individuals from eight localities across a large latitudinal range (30°S–56°S). Using population structure metrics, multivariate analyses, clustering algorithms, and Bayesian methods, we found evidence for moderately low regional genetic structure and reduced gene flow towards the range margins. Genetic differentiation increased with geographic distance, particularly in the southern part of the species’ distribution where forests are continuously distributed. Populations in the north seem to experience limited gene flow likely due to forest discontinuity, and may comprise a demographically independent unit. The southernmost population, on the other hand, is genetically depauperate and different from all other populations. Different analytical approaches support the presence of three to five genetic clusters. We hypothesize that the genetic structure of the species follows a hierarchical clustered pattern. © 2020, The Author(s).https://www-nature-com.recursosbiblioteca.unab.cl/articles/s41598-020-66450-

The Subantarctic Rayadito (Aphrastura subantarctica), a new bird species on the southernmost islands of the Americas

We describe a new taxon of terrestrial bird of the genus Aphrastura (rayaditos) inhabiting the Diego Ramírez Archipelago, the southernmost point of the American continent. This archipelago is geographically isolated and lacks terrestrial mammalian predators as well as woody plants, providing a contrasted habitat to the forests inhabited by the other two Aphrastura spp. Individuals of Diego Ramírez differ morphologically from Aphrastura spinicauda, the taxonomic group they were originally attributed to, by their larger beaks, longer tarsi, shorter tails, and larger body mass. These birds move at shorter distances from ground level, and instead of nesting in cavities in trees, they breed in cavities in the ground, reflecting different life-histories. Both taxa are genetically differentiated based on mitochondrial and autosomal markers, with no evidence of current gene flow. Although further research is required to define how far divergence has proceeded along the speciation continuum, we propose A. subantarctica as a new taxonomic unit, given its unique morphological, genetic, and behavioral attributes in a non-forested habitat. The discovery of this endemic passerine highlights the need to monitor and conserve this still-pristine archipelago devoid of exotic species, which is now protected by the recently created Diego Ramírez Islands-Drake Passage Marine Park.Fil: Rozzi, Ricardo. Universidad de Magallanes; Chile. University of North Texas; Estados UnidosFil: Quilodrán, Claudio S.. Universidad de Magallanes; Chile. Universite de Fribourg;Fil: Botero Delgadillo, Esteban. Max Plank Institute for Ornithology; Alemania. Universidad de Chile; ChileFil: Napolitano, Constanza. Universidad de Magallanes; Chile. Universidad de Los Lagos; Chile. Instituto de Ecología y Biodiversidad; ChileFil: Torres Mura, Juan C.. Universidad de Magallanes; Chile. Union de Ornitologos de Chile; ChileFil: Barroso, Omar. Universidad de Magallanes; ChileFil: Crego, Ramiro D.. Conservation Ecology Center; Estados UnidosFil: Bravo, Camila. Universidad de Chile; ChileFil: Ippi, Silvina Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Quirici, Verónica. Universidad Andrés Bello; ChileFil: Mackenzie, Roy. Universidad de Magallanes; ChileFil: Suazo, Cristián G.. Universidad de Magallanes; Chile. Justus Liebig Universitat Giessen; AlemaniaFil: Rivero de Aguilar, Juan. Universidad de Magallanes; ChileFil: Goffinet, Bernard. Universidad de Magallanes; Chile. University of Connecticut; Estados UnidosFil: Kempenaers, Bart. Max Plank Institute for Ornithology; SuizaFil: Poulin, Elie. Universidad de Magallanes; Chile. Universidad de Chile; ChileFil: Vásquez, Rodrigo A.. Universidad de Magallanes; Chile. Universidad de Chile; Chil

Effects of temperature and time constraints on the seasonal variation in nest morphology of the Thorn-tailed Rayadito (Aphrastura spinicauda)

Environmental adjustment is the most invoked explanation for intra-seasonal variation in bird nest morphology. However, time constraints may also be important, coming as a trade-off between the costs of nest building and the requirement to coincide a breeding attempt with maximal food supply. We describe the seasonal variation in nest morphology of the Thorn-tailed Rayadito (Aphrastura spinicauda) in a sub-Antarctic population in southern Chile, and investigate its relation with the seasonal fluctuation of ambient temperature (an ‘environmental adjustment’ hypothesis) and time constraints (an ‘optimal time frame’ hypothesis). As the breeding season progressed, rayaditos spent fewer days building their nests, built smaller nests, and used less animal-derived insulating material. After statistically removing the effects of daily temperatures on nest building periods and nest morphological measurements, we observed no seasonal trend in the amount of insulating material used, supporting an ‘environmental adjustment’ explanation. However, the nest building periods, nest depth, and nest dry weight still showed a seasonal trend, favouring an ‘optimal time frame’ hypothesis. Our study shows that both temperature fluctuations and time constraints can affect different components of the nesting ecology of birds, and that nest morphology is the consequence of distinct non-mutually exclusive forces

Morphometric and qualitative criteria for age and sex determination in <i>Mionectes olivaceus</i> (Tyrannidae).

El conocimiento de los patrones de muda y de los caracteres del plumaje de las aves del Neotrópico es incipiente. Teniendo en cuenta su utilidad para determinar la edad y el sexo de manera confiable en aves, en este trabajo se documentan algunas variables morfométricas y caracteres externos de <i>Mionectes olivaceus</i> (Tyrannidae), se evalúa su capacidad para diferenciar entre individuos de distinta edad y sexo y se propone un método rápido y confiable para tal fin. Se estudiaron 106 especímenes de museo de cuatro subespecies, entre las cuales no se encontraron diferencias morfométricas. Se identificaron importantes diferencias entre sexos y edades. Aunque la longitud de las rectrices y la cuerda alar variaron entre sexos, como se reporta para otros congéneres, no aportaron para la formación de los grupos en tres análisis discriminantes. La altura del pico y dos medidas de las emarginaciones presentes en la novena primaria resultaron ser definitivas para la determinación de edad y sexo. Estas variables permitieron que en los tres análisis más del 75% de los casos fueran clasificados correctamente. La presencia de emarginaciones largas y profundas, picos altos y rectrices externas truncadas en su ápice son caracteres clave para determinar la edad. La altura del pico es la característica clave para diferenciar entre sexos, ayudado de la longitud y profundidad de las emarginaciones de la novena primaria. Los resultados de este tipo de estudios constituyen una herramienta valiosa para una identificación certera y rápida, requisitos indispensables en estudios demográficos y ecológicos o en programas de anillamiento y monitoreo.Knowledge of molt and plumage patterns for Neotropical birds is incipient. Taking into account its usefulness to determine age and sex reliably in birds, I present data for some morphometric variables and external characters of <i>Mionectes olivaceus</i> (Tyrannidae), evaluate its ability to differentiate among age and sex and suggest a fast and reliable method for sex and age identification. I measured 106 museum specimens of four subspecies, among which I found no morphometric differences. I found important differences between sexes and ages. Though rectrix length and wing chord did vary between sexes, as has been reported for other members of the genus <i>Mionectes</i>, they did not contribute to group formation in three discriminant function analyses. Beak depth and two measures of the ninth primary emargination were the most relevant variables for ageing and sexing. These variables allowed the analysis to correctly classify more than 75 % of all the cases evaluated. Long and deep emarginations, deep beaks and truncated external rectrices are key characters to age determination. Beak depth is the key character to differentiate among sexes, along with length and depth of the ninth primary emargination. Results from this kind of studies provide invaluable tools for an accurate and fast identification, which are essential requirements in demographic and ecological studies or in banding and monitoring programs