No description available.

The Galapagos Islands arc considered a hotspot in terms of biodiversity, but an increase in tourism over the past 30 years and its consequential human immigration is posing new threats to the wildlife. Blue-footed boobies Sula nebouxii breed in Galapagos and its population is considered to be one of the largest for the species in the world, but there is some indication that it has declined. I studied blue-footed boobies at two breeding colonies (San Cristobal and North Seymour) to look at potential causes of decline; specifically low food availability at sea and poor health status. Additionally, I examined how impacts differ between the sexes in relation to sexual size dimorphism. Low provisioning parameters and low chick growth and survival, particularly at North Seymour, suggest that blue-footed boobies in Galapagos are facing low food availability compared to colonies elsewhere in the eastern Pacific Ocean. Blood parasite prevalence was high in adults and chicks at both sites, and higher on adults at North Seymour than at San Cristobal. Provisioning was not affected by blood parasites, but infected female chicks at North Seymour had lower asymptotic size. Physiological condition (evaluated using haematological variables) was lower for adults and chicks at North Seymour. Differences between the sexes were found on levels of parental care and isotopic segregation during non-breeding at San Cristobal, but not at North Seymour. Male and female adults also differed in their immune response to parasites. Male and female chicks differed in the nitrogen and carbon isotopic values of feathers and blood, suggesting differences in physiological processes between the sexes during growth. Physiological parameters did not show repeatability within individuals, between members of a pair or between parents and chicks, suggesting that it is more influenced by environmental factors than by genetic effects.

Dispersal is a fundamental ecological and evolutionary process that can create demographic and genetic linkage between neighbouring and distant locations, influencing the dynamics, structure and ultimately the persistence of populations. To understand observed population dynamics and structure and to predict future change, accurate and comprehensive data are required describing the pattern and magnitude of dispersal and gene flow across all relevant spatial scales. However, this is a major empirical challenge. In this thesis, I aimed to obtain comprehensive empirical data quantifying natal dispersal patterns and population genetic structure across multiple spatial scales using the European shag (Phalacrocorax aristotelis) as a model species. I used a combination of field observations of shags individually ringed on the Isle of May, Scotland and molecular genetic techniques to accomplish these aims. By locating adult shags that had been ringed as chicks on the Isle of May at their breeding locations across eastern Scotland, I demonstrated divergent dispersal distributions at small versus large spatial scales. Using both mitochondrial DNA markers and a newly developed set of microsatellite markers, I quantified population genetic structure across a pan-European scale. This was weak across both molecular markers suggesting a role for occasional effective long-distance dispersal. However, a suite of evolutionary forces besides gene flow can create observed population genetic structure. Therefore, I quantified population genetic structure across populations in eastern Scotland, and quantitatively linked this indirect estimate of gene flow with my direct field observations of dispersal. Dispersal parameters derived explicitly from field observations and the spatial organisation of populations were shown to strongly influence observed population genetic structure. Overall, these data demonstrate the need to utilise both field observations and genetic methods to comprehensively estimate the extent and effectiveness of dispersal and highlight the importance of accurately quantifying long-distance dispersal in particular for predicting future change.