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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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Physiological mechanisms of adaptive developmental plasticity in Rana temporaria island populations

Physiological mechanisms of adaptive developmental plasticity in Rana temporaria island populations

Adaptive plasticity is essential for many species to cope with environmental heterogeneity. In particular, developmental plasticity allows organisms with complex life cycles to adaptively adjust the timing of ontogenetic switch points. In this study, the physiological mechanisms underlying divergent degrees of developmental plasticity across Rana temporaria island populations inhabiting different types of pools in northern Sweden is investigated. In a laboratory experiment it was estimated developmental plasticity against pond drying of amphibian larvae from six populations coming from three different island habitats: islands with only permanent pools, islands with only ephemeral pools, and islands with a mixture of both types of pools. It was found that populations from islands with only temporary pools had a higher degree of developmental plasticity than those from the other two types of habitats. Tadpoles from islands with temporary pools showed lower constitutive activities of catalase and glutathione reductase, and also showed overall shorter telomeres. The observed differences are indicative of physiological costs of increased developmental plasticity, suggesting that the potential for plasticity is constrained by its costs. Thus, high levels of responsiveness in the developmental rate of tadpoles have evolved in islands with pools at high but variable risk of desiccation. Moreover, the physiological alterations observed may have important consequences for both short-term odds of survival and long term effects on lifespan. informacion[at]ebd.csic.es: Burraco et al (2017) Physiological mechanisms of adaptive developmental plasticity in Rana temporaria island populations. BMC Evol Biol doi: 10.1186/s12862-017-1004-1 


https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-017-1004-1