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Oversea migration of white storks through the water barriers of the straits of Gibraltar

Soaring landbirds typically exploit atmospheric uplift as they fly overland, displaying a highly effective energy-saving locomotion. However, large water bodies lack thermal updrafts, potentially becoming ecological barriers that hamper migration. The effects of a sea surface on the migratory performance of GPS-tagged white storks (Ciconia ciconia) were assessed before, during and after they crossed the straits of Gibraltar. Oversea movements involved only flapping and gliding and were faster, traversed in straighter, descending trajectories and resulted in higher movement-related energy expenditure levels than overland, supporting the water barrier hypothesis. Overland movements at both sides of the sea straits resulted in tortuous routes and ascending trajectories with pre-crossing flights showing higher elevations and more tortuous routes than post-crossing, thus supporting the barrier negotiation hypothesis. Individual positions at both ends of the sea narrow were predicted by zonal winds and storks´ location at entry in the European hinterland, and birds did not show compensational movements overland in anticipation to subsequent wind displacements oversea. The length of the water narrow at departure shore, the elevation therein and the winds on route affected major components of sea crossing performance (such as distances and times overwater, minimum elevations, climb angles, speeds and energy expenditure), supporting the departure position and oversea winds hypotheses. In summary, this study provides a prime example at high temporal resolution of how birds adjust their behavior and physiology as they interact with the changing conditions of the travelling medium, reallocating resources and modifying their movement to overcome an ecological barrier. informacion[at]ebd.csic.es: Blas et al (2020) Overland and oversea migration of white storks through the water barriers of the straits of Gibraltar. Scientific Reports 10: 20760. DOI 10.1038/s41598-020-77273-x. See Spanish press release


www.nature.com/articles/s41598-020-77273-x
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Evolutionary and demographic history of the Californian scrub white oak species complex: an integrative approach

Evolutionary and demographic history of the Californian scrub white oak species complex: an integrative approach

Understanding the factors promoting species formation is a major task in evolutionary biology research. In this project, the evolutionary history of the six putative species included within the Californian scrub white oak species complex has been studied. To infer the relative importance of geographical isolation and ecological divergence in driving the speciation process, authors have first analysed inter- and intra-specific patterns of genetic differentiation and employed an approximate Bayesian computation framework to evaluate different plausible scenarios of species divergence. In a second step, the inferred divergence pathways has been linked with current and past species distribution models, and tested for niche differentiation and phylogenetic niche conservatism across taxa. Analyses showed that the most plausible scenario is the one considering the divergence of two main lineages followed by a more recent pulse of speciation. Genotypic data in conjunction with species distribution models and niche differentiation analyses support that different factors (geography vs. environment) and modes of speciation (parapatry, allopatry and maybe sympatry) have played a role in the divergence process within this complex. This study shows that different mechanisms can drive divergence even among closely related taxa representing early stages of species formation and exemplifies the importance of adopting integrative approaches to get a better understanding of the speciation process and the evolutionary phenomena contributing to generate biodiversity. informacion[at]ebd.csic.es: Ortego et al (2015) Evolutionary and demographic history of the Californian scrub white oak species complex: an integrative approach. Mol Ecol 24, 6188-6208 doi: 10.1111/mec.13457


http://onlinelibrary.wiley.com/doi/10.1111/mec.13457/full