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The mechanisms that make that the costs of producing high-quality signals are unaffordable to low-quality signalers are a current issue in animal communication. The size of the melanin-based bib of male house sparrows Passer domesticus honestly signals quality. The development of new bibs were induced while treating males with buthionine-sulfoximine (BSO). Final bib size was negatively related to pheomelanin levels in the bib feathers. Improved phenotypes (bibs larger than controls) were only expressed by high-quality birds. These findings suggest that a mechanism uncoupling pheomelanin and cysteine levels may have evolved in low-quality birds to avoid producing bibs of size not corresponding to their quality and greater relative costs. Indeed, greater oxidative stress in cells was not observed in low-quality birds. This may represent the first mechanism maintaining signal honesty without producing greater relative costs on low-quality signalers. informacion[at] Galvan et al (2014) Low-quality birds do not display high-quality signals: the cysteine-pheomelanin mechanism of honesty. Evolution. Doi 10.1111/evo.12549
The dominant criterion to determine when an introduced species is established relies on the viability of the population from a demographic perspective. By means of an intensive five year capture-recapture monitoring program the demography of five introduced passerine bird species established in southern Spain have been studied. Estimates of demographic parameters for one colonial species (Ploceus melanocephalus) were obtained, confirming the long-term viability of its local population. However, extremely low recapture rates prevented the estimation of these parameters for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer. The analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species. informacion[at] Sanz-Aguilar et al (2014) Can establishment success be determined through demographic parameters? A case study on five introduced bird species. PLoS ONE 9(10) e110019. Doi 10.1371/journal.pone.0110019
Determining spatio-temporal dynamics in distribution and structure of different populations is crucial to our understanding of their ecology and interactions. The winter distribution of Marsh Harrier (Circus aeruginosus) in the Iberian Peninsula is used to analyse the potential of spatial distribution models and stable isotope analyses of feathers to evaluate differences in spatial distribution of migrant and resident raptor populations in southern Europe. Most migrant harriers had a central and northern latitudinal European origin. Results revealed segregation in the winter distribution of migrant and resident populations, suggesting that ecological conditions and potential stressors could greatly differ among resident and migrant populations in winter. A useful methodological procedure is provided to evaluate spatial segregation and presenting a new challenge to the study of their ecological consequences. informacion[at] Cardador et al (2014) Breeding origin and spatial distribution of migrant and resident harriers in a Mediterranean wintering area: insights from isotopic analyses, ring recoveries and species distribution modelling. J Ornithol. Doi: 10.1007/s10336-014-1122-0


    Estación Biólogica de Doñana - Consejo Superior de Investigaciones Científicas - Apdo 1056 E - 41013 Sevilla
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