David Alvarez

University of Oviedo | UNIOVI · Department of Organisms and Systems Biology

Urbanization is a severe form of habitat fragmentation that can cause many species to be locally extirpated and many others to become trapped and isolated within an urban matrix. The role of drift in reducing genetic diversity and increasing genetic differentiation is well recognized in urban populations. However, explicit incorporation and analysi...

Worldwide, many seabirds are affected by fisheries in opposing ways: as a source of mortality from bycatch, but also by providing discards as a predictable and abundant food resource. This applies to the Balearic shearwater Puffinus mauretanicus, the most endangered European seabird, whose time to extinction was estimated at only ~40 years a decade...

Climate influences the dynamics of natural populations by direct effects over habitat quality but also modulating the phenotypic responses of organisms' life-history traits. These responses may be different in males and females, particularly in dimorphic species, due to sex-specific requirements or constraints. Here, in a coastal seabird, the Europ...

Compensatory growth is an organism's reaction to buffer deviations from targeted trajectories. We explored the compensatory patterns of juvenile brown trout under field and laboratory conditions. Divergence of size and condition trajectories was induced by manipulating food levels in the laboratory and then releasing the trout into a river. In the...

The study of colour, including physical properties and patterns, is an essential step in comprehensively understanding the role, evolution and diversification of this trait involved in functions like survival, performance, reproductive success and communication. While quantitative studies on colour have primarily focused on colour attributes, such...

The study of compensatory growth in fishes has received much recent attention, especially in relation to aquaculture, but many behavioral consequences of this accelerated growth remain unexplored. The main behavioral consequence of growth compensation is that fishes have to take more risks to obtain the extra ration of food necessary to increase gr...

The environmental transformations associated with cities are expected to affect organisms at the demographic, phenotypic, and evolutionary level, often negatively. The prompt detection of stressed populations before their viability is compromised is essential to understand species’ responses to novel conditions and to integrate urbanization with bi...

The rich genetic and phenotypic diversity of species complexes is best recognized through formal taxonomic naming, but one must first assess the evolutionary history of phylogeographic lineages to identify and delimit candidate taxa. Using genomic markers, mitochondrial DNA barcoding and morphometric analyses, we examined lineage diversity and dist...

Passive rewilding means the spontaneous regeneration of ecosystems after the abandonment of human land use. It may represent an opportunity to recover biodiversity and ecosystem services under global environmental crisis, but may also entail declines of certain species, changes in disturbance regimes and losses of cultural values. In this review, w...

Timing of breeding, an important driver of fitness in many populations, is widely studied in the context of global change, yet despite considerable efforts to identify environmental drivers of seabird nesting phenology, for most populations we lack evidence of strong drivers. Here we adopt an alternative approach, examining the degree to which diff...

La utilización de un documental sobre las poblaciones urbanas de salamandra común como herramienta didáctica ha permitido revertir parcialmente la desconexión con la naturaleza urbana en los futuros docentes de Educación Infantil y Primaria, detectar las ideas previas del alumnado sobre los anfibios y analizar, mediante sus planificaciones didáctic...

El proyecto "La televisión on-line en la Formación del Profesorado: Un recurso educativo multilingüe y multidisciplinar" ha integrado el uso de la televisión a través de dispositivos móviles creando el canal televisivo DIDACTICTAC TV en la Facultad de Formación del Profesorado y Educación de la Universidad de Oviedo. Los objetivos del proyecto son:...

Amphibians are subjected to an assortment of environmental stressors responsible for their population declines and malformations. Deciphering the underlying causes of amphibian deformities is challenging due to the complex nature and interplay among factors. We evaluated morphological deformities in 9 urban and 9 woodland populations of terrestrial...

RESUMEN Las redes sociales representan una herramienta de aprendizaje de suma importancia, dentro de la educación formal e informal. YouTube se ha convertido en una de las más usadas, también para el aprendizaje de la ciencia. En este contexto, maestros en formación inicial han generado recursos didácticos audiovisuales para la enseñanza-aprendizaj...

El área de distribución del cormorán moñudo en España comprende el litoral peninsular desde las Rías Baixas gallegas hasta las costas guipuzcoanas para la subes-pecie nominal, donde se localiza de manera prácti-camente continua por toda la costa. En el caso de la subespecie mediterránea, la mayoría de las colonias se encuentran en el archipiélago b...

Nowadays the introduction of alien species represents a major problem worldwide, being seaports and marinas recognized as important hotspots of marine and non-marine alien species. In order to assess university students' previous knowledge about alien species related problems, a survey was carried out addressed to Education and Biology students in...

COVER PHOTO: In this issue, Oro et al. (doi: 10.1002/eap.1679) test several biological hypotheses about how survival changes by age and sex in two distinct regions by means of multi-event capture–recapture modeling. The cover features a pair of European shags with two medium-sized chicks in one of the studied colonies in the Cantabrian Sea. Photo c...

Environmental drivers, including anthropogenic impacts, affect vital rates of organisms. Nevertheless, the influence of these drivers may depend on the physical features of the habitat and how they affect life history strategies depending on individual covariates such as age and sex. Here, the long-term monitoring (1994-2014) of marked European sha...

Individual animals introduced to supply existing populations may show a variety of physiological and phenotypic traits that may affect their performance in the wild, but a lack of monitoring after release usually precludes us from knowing the fate of different types of individuals and their impact on the recipient populations. Mark-recapture monito...

In this study, we analysed the viability of seabird populations, specifically the European shag, after the invasion of the American mink. In the last decade the shags at Cíes islands, the southernmost archipelago of the Park, experienced a population collapse in parallel with a similar reduction in its level of heterozygosity. Data from marked indi...

Amphibians are the most threatened vertebrates on Earth, and one of the main factors involved in their decline is the loss and fragmentation of their natural habitats. Contemporary urban development is a major cause of habitat fragmentation, and populations trapped within urban environments offer a unique opportunity to study effects of fragmentati...

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Los ecosistemas acuáticos continentales se encuentran entre los más amenazados del planeta. Constantemente se ven expuestos a escorrentías que llevan restos de fertilizantes y plaguicidas a sus aguas, al derrame cotidiano de residuos domésticos e industriales sin un tratamiento previo, a la introducción intencional o accidental de especies que se h...

In organisms such as fish, where body size is considered an important state variable for the study of their population dynamics, size-specific growth and survival rates can be influenced by local variation in both biotic and abiotic factors, but few studies have evaluated the complex relationships between environmental variability and size-dependen...

Large oil spills are dramatic perturbations on marine ecosystems, and seabirds are one of the worst affected organisms in such events. It has been argued that oil spills may have important long-term consequences on marine organisms, but supporting evidence remains scarce. The European shag (Phalacrocorax aristotelis) was strongly impacted at popula...

In species with simultaneous polyandry, male-biased operational sex ratio is expected to increase the risk of sperm competition and thus sperm traits affecting siring success can differ among populations. Here, we test the hypothesis that high male–female ratios will enhance sperm competitiveness of Rana temporaria males. In this species, local pop...

Situación y problemática del salmón en el mundo y en España El declive del salmón es un fenómeno global aunque irregular-mente distribuido, si bien en la actualidad sólo 4 países-Escocia, Irlanda, Noruega e Islandia-pue-den considerar que sus poblacio-nes de salmón se mantienen de manera saludable. En el resto de su rango histórico, el 85% de sus p...

Biodiversity is a reflection of genetic diversity, which is ultimately affected by a greater number of factors associated with human activity than any other level of biodiversity. The conservation of this biodiversity is therefore a main objective in the management of the natural environment. Global change is one of the major threats for biodiversi...

Quantifying population genetic structure is fundamental to testing hypotheses regarding gene flow, population divergence and dynamics across large spatial scales. In species with highly mobile life-history stages, where it is unclear whether such movements translate into effective dispersal among discrete philopatric breeding populations, this appr...

In the winter of 2002–03 the Prestige tanker spilled 60,000 tons of oil over the northern half of the Iberian Coastal Large Marine Ecosystem (northern Portugal to France). Most (c. 85%) of the 22,981 oiled seabirds reported were alcids (i.e., auks): Common Murres (Uria aalge), Razorbills (Alca torda) and Atlantic Puffins (Fratercula arctica). Here...

At the southern European edge of Atlantic salmon (Salmo salar) distribution, all the hybrids found in nature are the product of crosses between female salmon and male brown trout (Salmo trutta). By artificially producing reciprocal crosses between salmon and trout, we demonstrate that unidirectional hybridization observed in nature is the result of...

The timing of egg laying is a critical event for the fitness of birds because to a large extent it determines their reproductive success. The effects of weather conditions and climate on the onset of reproduction have been widely studied over recent decades and an advance in the timing of breeding phenology has been confirmed in many species. We ex...

The study of compensatory growth in fishes has received much recent attention, especially in relation to aquaculture, but many behavioral consequences of this accelerated growth remain unexplored. The main behavioral consequence of growth compensation is that fish have to take more risks to obtain the extra ration of food necessary to increase thei...

Actas del 6º Congreso del GIAM y el Taller internacional sobre la Ecología de Paiños y Pardelas en el sur de Europa Boletín del GIAM 34 ¿Se justifican los controles de cormorán grande en Asturias por su impacto sobre las poblaciones salvajes de salmones? RESUMEN En 2005 el gobierno autonómico de Asturias comenzó una campaña de eliminación de cormor...

In organisms with complex life cycles, environmentally induced plasticity across sequential stages can have important consequences on morphology and life history traits such as developmental and growth rates. However, previous research in amphibians and other ectothermic vertebrates suggests that some morphological traits are generally insensitive...

Species Inhabiting habitats with different predators are expected to show divergent phenotypes for antipreciator traits. Here, we used a predator-prey system of dragonfly larvae and tadpoles to determine If vulnerability to a common predator differs in species with contrasting antipredator strategies. We examined the vulnerability of tadpoles of Ra...

Compensatory growth (CG) is a key issue in work aiming at a full understanding of the adaptive sig-nificance of growth plasticity and its carryover effects on life-history. The number of studies addressing evolutionary explanations for CG has increased rapidly during the last few years, but there has not been a parallel gain in our understanding of...

Risk-taking behaviour has important consequences for fitness. Here, we show that risk-taking behaviour in sticklebacks consistently varies according to the habitat of origin. We compared the risk-taking behaviour of individual sticklebacks from three pond and three stream populations. Specifically, we measured willingness to forage under predation...

Compensatory growth is the faster-than-normal growth that some species exhibit after a period of resource deprivation. Using three-spined sticklebacks as model species we tested the impact of compensatory growth on subsequent escape performance in populations from diverse habitats. We found clear population differences in the rate of compensatory g...

We investigated the role of constitutive morphology and previous experience in predator avoidance in two anuran species associated with different larval habitats. In Rana temporaria, deeper tails and larger body size conferred selective advantage against dragonfly predation. Previous experience with predators had a positive influence on the surviva...

Figure A1. Experimental arena used to evaluate the predator avoidance behavior of Discoglossus galganoi tadpoles in relation to food quality. The experimental trays contained "poor and safe" (P+S), and "rich and risky" (R+R) zones. In the R+R zone, larvae had full access to the food contained inside a Petri dish adjacent to a tube of plastic mesh c...

Metamorphosis can disrupt the correlation structure between juvenile and adult traits, thus allowing relatively independent evolution in contrasting environments. We used a multiple experimental approach to investigate how diet quality and larval predation risk affected the rates of growth and development in painted frogs (Discoglossus galganoi), a...

We examined the influence of habitat size, growth opportunity, and the thermal conditions experienced during early development on the standard metabolic rate (SMR) of juvenile brown trout (Salmo trutta) from six natural populations to contrast the hypothesis of countergradient selection in metabolic rate. The study populations differed significantl...

In 2003, immediately following the Prestige oil spill in Galicia, Spain, we studied the population trends and reproductive performance of European shags (Phalacrocorax aristotelis) at oiled and unoiled colonies. This bird is an important member of the nearshore marine community, breeding in the area affected by the Prestige oil spill. The European...

In salmonids, there seems to be a positive correlation between standard metabolic rate and growth rate under artificial rearing conditions. Several recent studies have suggested that phenotypic correlations between physiological or behavioural traits and developmental or life history responses might be common when assayed in low-complexity habitats...

Compensatory growth is a phase of unusually rapid growth following a period of growth depression. This response allows animals to achieve the same size-for-age as continuously fed contemporaries. We tested the hypothesis that a period of poor growth followed by compensation reduces the swimming abilities of threespine sticklebacks (Gasterosteus acu...

Juvenile brown trout Salmo trutta from natural populations reacted to the presence of piscivorous brown trout by increasing the use of refuges. In contrast, second-generation hatchery fish and the offspring of wild fish raised under hatchery conditions were insensitive to predation risk. The diel pattern of activity also differed between wild and h...

Se exponen los datos del censo de Cormorán Moñudo (Phalacrocorax aristotelis) realizado en Asturies en 1997. El número de nidos localizados fue de 194 seguros y 53 posibles, la mayoría de ellos en el sector occidental de la costa asturiana. Se constató el incremento de la población de esta especie en los últimos diez años. La mayoría de los nidos s...

1. Anurans exhibit high levels of growth-mediated phenotypic plasticity in age and size at metamorphosis. Although temperature and food quality exert a strong influence on larval growth, little is known about the interacting effects of these factors on age and size at metamorphosis. 2. Plasticity in growth rates, maximum larval mass, mass loss, lar...

Anuran larvae exhibit high levels of phenotypic plasticity in growth and developmental rates in response to variation in temperature and food availability. We tested the hypothesis that alteration of developmental pathways during the aquatic larval stage should affect the postmetamorphic performance of the Iberian painted frog (Discoglossus galgano...

1.- Se ha constatado la hipótesis de compensación metabólica en las poblaciones estudiadas de trucha común. Cuanto más cálido es el río de origen menor es la tasa metabólica estándar. 2.- La temperatura durante la reabsorción de vitelo resultó ser la fase crítica para el establecimiento de la Tasa metabólica estándar (TME) y el nivel de reservas....

A regional analysis of the status of the European Shag Phalacrocorax [Stictocarbo] aristotelis population on the Atlantic coasts of the Iberian Peninsula is presented. This is the first census to be made of this population. The total population was estimated to be approximately 2239 pairs in 1990-94. The first counts from Euskadi and Cantabria are...

The diet of Shags (Phalacrocorax aristotelis) was studied in a breeding colony in the Cantabrian Sea (Northern Spain) by examining items in regurgitated pellets. All diet remains were from fish, mostly wrasses (Labridae) and salt-smelts (Atherinidae). Invertebrates found in pellets had probably been eaten by fish. The mean number of preys per pelle...