Esta entrega incluye los resúmenes de algunas de las Tesis Doctorales defendidas en España en el curso 2010–2011 junto con otras no recogidas en reseñas anteriores. Se ha seguido una ordenación alfabética por Universidades y, dentro de ellas, por año y orden alfabético del autor.
The distribution pattern and abundance of species is the outcome of their ecology and of their evolutionary history, reflecting the influence of different ecological processes acting at different spatial scales. Large-scale distribution is mainly influenced by abiotic factors, fundamentally climatic ones, and this constitutes the species’ fundamental niche. On a smaller scale other factors such as resource availability, local climate or biotic interactions come into play, forming the realised niche, which is defined through thespecies’ habitat selection. This thesis is placed within this framework, applying conceptual and methodological advances of habitat selection and ecological niche theories and their effects on the study of population dynamics and distribution at different spatial scales of a steppe bird, the little bustard (Tetrax tetrax). Thus, the first chapter tackles the intermediate scales (landscape), showing that little bustard males included a larger than expected proportion of old and same-year fallows within their display sites relative to their availability. This indicates a significant preference for permanent and semi-permanent habitat types, which offer them both shelter and food. The selection pattern was constant between study years, indicating fidelity in habitat selection pattern. On the other hand, display sites were not spatially clumped. The relevance of food availability in the selection process was analysed in the next chapter, highlighting the existence of a higher abundance of large beetles within males’ territories than elsewhere in the surrounding landscape. Since large beetles constitute a relevant element of little bustard's diet during the breeding season, it can be concluded that males make a positive selection of areas holding valuable food resources to establish territories. The results of both previous chapters are discussed in terms of little bustard's mating system in the study population. The inclusion in the territories of areas with higher proportion of food resources or of particular habitat types that females could potentially use, could support the existence of real exploded or resource-based lek mating system (which is typical in other European populations). However, the fact that territories were not spatially aggregated suggests that, at least at the studied spatial scale, little bustards in this population may not form leks, for which clumped territories are an essential requirement. The fidelity in the selection of permanent and semi-permanent habitat types suggests that this preference may be related to some structural characteristics in the vegetation which are common to these substrates. This smaller scale (microhabitat) may allow measuring several parameters directly related to different ecological compromises. The results of the next chapter showed the existence of sexual segregation in microhabitat selection, which can be related to males and females’ different ecological constraints due to different life history traits. Thus, vegetation structure selected by females is determined by a compromise between the need for shelter and anti-predator surveillance. For its part, males’ selection was related mainly to the need of conspicuousness for courtship and territory defence. Accessibility to food resources seemed to be equally important for both sexes. Next chapter evaluates the influences of meteorological factors and land management on the oscillations and medium-term trends of two important little bustard populations. Both populations declined during 2001–2007, especially in Valdetorres (60%). Variation in habitat composition di