Suchergebnisse

6 pages, 1 figure, 1 table. ; Size-related selection of insular lizards by two sympatric predatory bird species (Southern Grey Shrike and Eurasian Kestrel) was studied in an arid insular environment. The endemic lizard genus Gallotia was a key resource in the diet of both predators, constituting more than 50% of the total biomass. Shrikes captured smaller lizards than kestrels during all seasons (mean snout-vent length (SVL): 7.4 ± 1.9 vs. 9.4 ± 2.1 cm respectively), presenting a sequential use of lizard sizes and avoiding potential competition. On the other hand, shrikes and kestrels showed the same seasonal variation pattern, capturing the largest lizards during their breeding periods (spring). Considering lizard availability, shrikes displayed less selective predation than kestrels in all seasons. Shrikes positively selected the medium lizard size (SVL: 5-10 cm) during the nestling period, but negatively selected the small lizard size (SVL: 10 cm). ; This research was supported by grants to David P. Padilla and Patricia Marrero from the Canarian Government and Proyectos Intramurales Especiales (2004 3 0E 169) of the Spanish National Scientific Research Council, respectively. It was also partially financed by the project PI042004/037 (Consejería de Educación, Cultura y Deportes, Gobierno de Canarias), which are partially supported by Feder funds from the European Union.

4 pages, 2 figures. ; Bolle's Laurel Pigeon Columba bollii and the White-tailed Pigeon C. junoniae are two endangered endemic frugivorous pigeons from the relict laurel forest of the Canary Islands (Eastern Atlantic Ocean, Spain). These two columbids probably evolved in different habitats (laurel and thermophilous forest, respectively), but the almost total destruction of these latter forests could force the White-tailed Pigeon to occupy laurel forest areas (Martín et al. 2000). In 1985, the total population sizes were estimated at 1160–1315 and 1200–1480 birds, respectively (Emmerson 1985). Once widespread on the archipelago, their current distribution and abundance are affected by habitat destruction, illegal hunting and predation by rats (Hernández et al. 1999, Martín et al. 2000), which has led to them being listed as Near Threatened (C. bollii) and Endangered with a decreasing trend (C. junoniae; IUCN 2007). The threatened status of these Columbidae species and their elusive behaviour makes it difficult to observe and handle individuals. Therefore, non-invasive samples collected from the field are required to carry out ecological studies (Piggott & Taylor 2003). ; Faecal samples provide a valuable source for analysing diet and distribution, but previous reliable identification of faeces is required in order to identify the target species. ; P.M. and D.P.P. received grant support from the Proyectos Intramurales Especiales (2004 3 0E 169) of the Spanish National Research Council (CSIC) and the Canary Island Government, respectively. This contribution was funded by the Organismo Autónomo de Parques Nacionales (80/2005), Ministerio de Medio Ambiente of Spain. ; Peer reviewed

Many fleshy-fruited plants from the Mediterranean and Macaronesian islands are dispersed through endozoochory. In mainland Mediterranean areas, reciprocal adaptations have been found between plants and animals, although evidence is scarce. On small isolated oceanic islands, such reciprocal adaptations might well be more prevalent due to intrinsic island traits. Here we evaluate the existence of selective pressures exerted by two different disperser guilds (lizards and birds) on two seed traits (seed coat thickness and seed germination pattern) of two congeneric species present on Mediterranean and Macaronesian islands. In the continental Balearic Islands, Rubia peregrina has evolved mostly with birds, although frugivorous lizards are present in some of these islands and are known to eventually consume its fruits. By contrast, R. fruticosa, endemic to the Macaronesian archipelago, has evolved mostly interacting with lizards and only recently with birds. We hypothesized that R. fruticosa would be especially adapted to saurochory, with thicker seed coats and higher germination proportion, whereas R. peregrina would be more adapted to ornithocory, with thinner seed coats and showing a lower germination percentage after being ingested by lizards. Captivity experiments of seed ingestions by natural and non-natural dispersers (i.e., frugivores that have not evolved with those plants) were conducted. Results suggest that dispersers did not exert any strong enough selective pressure to induce changes in germination patterns. We attribute this to the fact that the Rubiaceae is an ancestral family in the Mediterranean (both on continent and islands) and thus probably interacted with lizards in the past. Lastly, although we hold that the seed coat structure of R. fruticosa is probably associated with its evolutionary success after a long interaction with insular lizards, our findings support the idea that the relationship between endozoochorous plants and the guild of dispersers with whom they evolved is rather unspecific. © 2013 Nogales et al. ; A. Gonzalez-Castro (JAE-pre) and E. Bonnaud (JAE-doc) were funded by two grants from the Spanish National Research Council. P. Marrero has a postdoctoral fellowship from the Spanish Ministry of Education. This paper is framed within projects CGL2007-61165/BOS and CGL2010-18759/BOS financed by the Ministry of Education and Science of the Spanish Government and partially funded by the European Union. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ; Peer reviewed ; Peer Reviewed