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Andueza M.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Barba E.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Arroyo J.L.,CSIC - Doñana Biological Station | Feliu J.,Institute Investigacion en Recursos Cinegeticos IREC | And 10 more authors.
Ornis Fennica | Year: 2014

On their route to tropical Africa, European trans-Saharan migrants must cross two major geographical barriers, the Mediterranean Sea and the Sahara Desert, which necessitates the accumulation of large fuel loads.While northernAfrica is the chief region wheremost migrants gain fuel for the Sahara crossing, Iberia is a target area to gain fuel before the sea crossing existing between Europe andAfrica. Despite the large body of studies approaching the question of fuel accumulation before geographic barriers, it is still poorly known which factors apart from distance to a certain barrier shape the geographical pattern of fuel reserves. To investigate this question in detail we used data of first-year Reed Warblers from 12 localitieswithin Iberia during the autumnmigration period of 2009.We run linearmodels to analyze the effects of location in Iberia, date, and body size on bodymass variation at each migratory flyway (eastern, central and western Iberia). Flight ranges from each site were also calculated. Our results showed that ReedWarblers in Iberia had the necessary fuel needed to arrive in northernAfrica but not to tropical Africa. However, bodymass patterns varied depending on the geographical region (eastern, central or western Iberia).Date did not affect bodymass in central andwestern Iberia, but in eastern Iberia heavier birds tended to pass later. Thus, the factors shaping body mass of Reed Warblers in Iberia before the sea crossing to Africa seemed to be more complex than just the distance to this geographical barrier, with underlying stopover quality-associated factors possibly playing a relevant role.

Andueza M.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Arizaga J.,Aranzadi science Society | Barba E.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Tamayo-Uria I.,CIBER ISCIII
Behaviour | Year: 2014

Spatial behaviour and habitat selection at stopover sites have a strong influence on the foraging and fuelling performance of migrating birds and hence are important aspects of stopover ecology. The aim of this study was to analyse the spatial behaviour and habitat use of reed warblers Acrocephalus scirpaceus during the autumn migration. We used radio tracking data from reed warblers surveyed at a stopover site in northern Iberia and assigned to three different groups: (1) local adult birds which were still at their breeding site, (2) migrating first-year birds (originating from beyond Iberian peninsula) and (3) migrating adult birds. Overall, migrating first-year birds tended to have larger home ranges than both local and migrating adults and to move more widely in the study area. They also showed lower fat deposition rates than adults. The proportion of habitats in home ranges (reed-beds and tidal flats being the most abundant habitats) was similar amongst groups. The spatial distribution and habitat use of organisms have been theorised to follow an ideal-free or idealdespotic distribution. However, according to our results, other complex underlying mechanisms may play an important role in shaping the spatial behaviour of birds at stopover sites. © 2014 Koninklijke Brill NV, Leiden.

Luque V.J.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Luque V.J.,University of Valencia
Biology and Philosophy | Year: 2016

This paper provides a philosophical analysis of the Price equation and its role in evolutionary theory. Traditional models in population genetics postulate simplifying assumptions in order to make the models mathematically tractable. On the contrary, the Price equation implies a very specific way of theorizing, starting with assumptions that we think are true and then deriving from them the mathematical rules of the system. I argue that the Price equation is a generalization-sketch, whose main purpose is to provide a unifying framework for researchers, helping them to develop specific models. The Price equation plays this role because, like other scientific principles, shows features as abstractness, unification and invariance. By underwriting this special role for the Price equation some recent disputes about it could be diverted. © 2016 Springer Science+Business Media Dordrecht

News Article | April 8, 2016
Site: phys.org

Research at the Cavanilles Institute of Biodiversity and Evolutionary Biology of the University of Valencia, led by professor Rafael Sanjuán, reveals that viruses work in groups to attack host cells more effectively.  The results of this study were published in the journal Cell Host & Microbe.

Andueza M.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Barba E.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Arizaga J.,Aranzadi science Society
Ardeola | Year: 2014

Bird migration is usually performed in several consecutive flights, interrupted by stopovers when birds rest or replenish their fuel loads. As a result, migrants must decide when and where to land. Here, we studied the effects of meteorological conditions (wind and rain) and age (used here as a indicator of bird experience) on the probabilities of sedge warblers Acrocephalus schoenobaenus landing at a stopover site in northern Iberia. Data were collected over three consecutive years at a ringing station during the autumn migration period. We used reverse-time capture-mark-recapture models to estimate seniority, λ (i.e., the probability that an individual at time t was already present in the population at time t - 1), as an indicator of landing decisions, since 1-λ represents the probability of recording new individuals (i.e. recent landings). We ran 14 models with the above mentioned variables, four of which were best supported by the data. In these, only rain showed a significant positive effect on λ, indicating that birds of any age class avoid flying during rainfall and prefer to interrupt their migration. These results are similar to those obtained from an analysis of day-to-day variation in first captures that was used to validate the usefulness of capture-markrecapture models. They suggest that CMR models can serve to study bird landing decisions during migration in some specific cases.

Arizaga J.,Aranzadi science Society | Andueza M.,Aranzadi science Society | Andueza M.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Tamayo I.,Epidemiological Surveillance Unit
Acta Ornithologica | Year: 2013

Coastal marshes play a relevant role as stopover and fuelling sites for birds during migration period. The importance of tide in such ecosystems is well studied for aquatic species such as waders, but its impact on the stopover behavior of land birds that also depend on these sites is still unknown. Bluethroats Luscinia svecica are small-sized passerines that feed on the ground and low vegetation and, therefore, experience continuous changes of habitat availability due to the tide regimens. The aim of this study was to analyse the habitat use and to test the impact of tide on home range size of Bluethroats stopping over at coastal marshes. For that, we used data on radio-tagged birds at a tidal marsh in Northern Iberia. Bluethroats were radiotracked from the 20th of August to the 20th of September. Individuals were surveyed from 3 to 17 days, and birds with lower body mass at the day of capture stayed for longer period. Mean home range size was 2.0 ha (SE = 0.2), and the main habitats occupied were reedbeds (ca. 30% of a home range area) together with tidal flats with both free-and low-halophytic vegetation (30%). Reedbeds were situated at a higher altitude over the sea level than open waters, mudflats and low halophytic vegetation. Home ranges tended to be larger in birds found to occupy zones close to the sea level, thus with a longer tide-mediated flooding period, suggesting a negative effect of tide on home range size, and/or that Bluethroats staying at lower altitude did not find as much food as at higher altitude, so they were forced to move over larger surfaces.

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