The reproductive periods of brown trout (Salmo trutta) populations in 12 rivers in the Baetic Mountains in southern Spain were studied from 2008 to 2013. This area is an ecological and geographical limit for the distribution of this species in Europe. We found that the spawning period has been markedly extended in these fish. The mean spawning dates in the studied populations are consistent with the European trend at this latitude, but our data suggest that females from most of the populations that we studied are able to produce eggs from early October through late April or early May, yielding a reproductive period of between 150 and 170 days, the longest and most delayed brown trout reproduction periods that have been reported in the literature. We believe that such expanded spawning periods result primarily from the unpredictability of the Mediterranean climate, although it is possible that other factors may have contributed to the development of this reproductive behaviour. This hypothesis is discussed in the context of a comparison of our results with those found for other European S. trutta populations.
Andalusian brown trout populations represent the southwestern limit of this species in Europe, show a high genetic diversity, are subjected to extreme habitat conditions and environmental alterations, and are very sensitive to extinction. However, there is a lack of scientific studies on them. A necessary first step to preserve them is to describe their spatial distribution. We detected the species in eastern Andalusia along almost 710 km of rivers, finding 38 populations inhabiting streams and reservoirs in the upper reaches of three basins (Guadalquivir, Segura and South) in an altitude range between 200 and 2200 m above sea level. Populations are constrained by natural causes in their upper limits, and by anthropogenic causes in their lower limits (mainly related to water management). Currently, the populations are very isolated in protected areas (62% of their distribution) or downstream of those areas (32%), and a range displacement towards higher altitudes compared with their distribution in the nineteenth century is observed.
ResumenEl meloncillo es una especie en expansión en el centro y norte de la Península Ibérica. Ningún trabajo, hasta la fecha, había confirmado este proceso dispersivo en su borde de distribución suroriental, situado en trabajos previos entre las provincias de Málaga y Granada. Por medio de un muestreo sistemático e intensivo focalizado en la especie (con trampas de pelo, rastreo de indicios, recolección de citas y encuestas), se muestrearon 49 cuadrículas UTM (10x10 km) en aproximadamente la mitad occidental de la provincia de Granada, entre noviembre de 2014 y enero de 2015. Se detectó la presencia segura de la especie en 16 cuadrículas (bibliografía científica, trampas de pelo, atropello, entrada en centro de recuperación, capturas en coto de caza, fototrampeo y taxidermia) y seis con presencia probable (avistamientos sin foto, huellas y encuestas). Nuestros resultados muestran que el meloncillo está experimentando una expansión hacia el extremo suroriental de la Península. Este estudio pone de relieve que las trampas de pelo constituyen un método no invasivo de gran eficacia para el seguimiento de la distribución de la especie. Los resultados obtenidos tienen gran utilidad como herramienta de gestión en proyectos de conservación e investigación sobre dicha especie. Palabras clave: Granada, meloncillo, presencia, rastreo de indicios, trampa de pelo. AbstractThe Egyptian mongoose is expanding in the center and north of the Iberian Peninsula. So far no studies confirm the dispersal process in the most southeastern distribution, which was previously located between the provinces of Malaga and Granada. Through a systematic and intensive methodology focused on detecting mongoose (hair-traps, sign surveys and questionnaires), 49 UTM-grids (10x10 km) were sampled in approximately the western region of the province of Granada, between November 2014 and January 2015. The presence of the species has been confirmed in 16 grids (scientific literature, hair-traps, roadkills, records from wildlife recovery centers, kills in hunting grounds, reliable quotes from camera traps and/or taxidermy) and in other 6 grids the presence was considered probable (sightings without photo, fingerprints and surveys). Our results show that the mongoose is undergoing an expansion to the southeastern part of the Peninsula. This study also shows that hair-traps are a non-invasive method highly effective for monitoring the distribution of this species. These results could be a useful management tool in conservation projects and research on this species.
The classical debate about the roles of endogenous factors and external drivers in regulating populations continues to be a very active area of scientific research, and these roles are even more complex in populations located in geographically marginal areas. We tested three hypotheses on two separate brown trout populations inhabiting the southernmost basins of the Iberian Peninsula, with the aims of determining the relationships among (a) rainfall and air temperature for each season preceding fish sampling and the observed age group densities; (b) environmental synchrony and density synchrony for all possible pairs of sites; and (c) physical habitat similarity and the similarity of the density response to climatic drivers among pairs of sites. For this purpose, demographic series (98 surveys at 14 sampling sites), climatic conditions (rainfall and air temperature) and site habitat characteristics (physiogeographic and quality index values) were analysed between 2006 and 2014. The results show how the synchrony in the study populations is the result of a Moran effect directed mainly by winter precipitation and conditioned by the habitat similarity (highlighting the altitude, the distance to the upper limit and IHF index, along with the Euclidian distance among pairs of sites of the whole set of habitat variables). Preserving the heterogeneity of these habitat characteristics will increase the resilience of trout populations that inhabit this rear edge of distribution. The current context of global climate warming predicts extremely drastic changes in the dynamics of external drivers that regulate the trout populations in the study region.
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