The main biological factors responsible for the variability of pollutant concentrations in cetaceans are reviewed. Diet is significant because many pollutants are concentrated through food webs. This explains most interspecific differences in pollutant levels and it may also contribute to variation among populations of the same species or even among different components of the same population when diet is subject to age-related or sex-related variations. The effect of body size is complex. Excretion rate and activity of detoxifying enzymes decrease as body weight increases, processes which would lead to higher pollutant concentrations in large animals. In contrast, a high metabolic rate, which is inversely correlated to body size, is associated with high pollutant concentrations. These opposing effects usually result in higher residue levels in smaller individuals. Body composition affects the contribution of each body compartment to the overall pollutant load. Therefore, the body load of lipophilic pollutants will strongly depend on the relative mass of blubber, a variable that shows a threefold variation among cetacean species or, in seasonal feeders, among individuals. Nutritive condition also affects the dynamics of lipophilic pollutants. Lipid mobilisation results in an increase in residue levels, but this variation is not as large as a purely concentrative model would suggest because of enhancement of detoxification processes following a rise in tissue pollutant concentrations. Disease affects pollutant levels in different ways: impoverishing nutritive condition; altering normal physiological functions; and depressing reproduction therefore reducing reproductive transfer in females. The combined result of these processes is usually an increase in pollutant levels in diseased individuals. The concentration of lipophilic pollutants normally increases with age in males because input exceeds the ability of the organism to excrete pollutants. Variable proportions of the pollutant load are transferred to offspring during gestation and lactation, for which reason tissue concentrations in females decrease or stabilise, thus producing lower residue levels than in males. However, because not all compounds are transferred at the same rate, their relative abundance varies with age and sex.Intensity of reproductive transfer is also associated with the reproductive traits of the species, particularly the length of lactation. With the exception of zinc, concentrations of heavy metals increase with age in both sexes but, by contrast with lipophilic pollutants, concentrations in females are similar or higher than in males. The significance of these factors of variation should be taken into account when designing sampling methodology, comparing sample groups, or evaluating toxicological impact.

A central paradigm in conservation biology is that population bottlenecks reduce genetic diversity and population viability. In an era of biodiversity loss and climate change, understanding the determinants and consequences of bottlenecks is therefore an important challenge. However, as most studies focus on single species, the multitude of potential drivers and the consequences of bottlenecks remain elusive. Here, we combined genetic data from over 11,000 individuals of 30 pinniped species with demographic, ecological and life history data to evaluate the consequences of commercial exploitation by 18th and 19th century sealers. We show that around one third of these species exhibit strong signatures of recent population declines. Bottleneck strength is associated with breeding habitat and mating system variation, and together with global abundance explains much of the variation in genetic diversity across species. Overall, bottleneck intensity is unrelated to IUCN status, although the three most heavily bottlenecked species are endangered. Our study reveals an unforeseen interplay between human exploitation, animal biology, demographic declines and genetic diversity.

Genetic variability is an important component in the ability of populations to adapt in the face of environmental change. Here we report the first description of nuclear genetic variability in the only remaining sizable colony of the Mediterranean monk seal (Monachus monachus), located at Cap Blanc (Western Sahara, Mauritania), whose estimated size during the study period (1994-May 1997) was about 320 individuals. We tested 42 microsatellite loci isolated from five pinniped species in a sample of 52 pups. Three loci failed to give any product, and of the remaining 39, only 15 were polymorphic, with a maximum of 3 alleles detected. Three loci appeared to be X-linked. No departures from Hardy-Weinberg equilibrium were detected and no genetic structure was found between the two nursing caves currently occupied by the seals. Several analytical methods show that, as a consequence of a severe bottleneck, the population has suffered a decrease in genetic variability over the last few centuries.

The Mediterranean monk seal Monachus monachus, is a critically-endangered species of which only two populations, separated by c. 4000 km, remain: the eastern Mediterranean (150-300 individuals) and the Atlantic/western Sahara populations (100-130 individuals). We measured current levels of nuclear genetic variation at 24 microsatellite loci in 12 seals from the eastern Mediterranean and 98 seals from the western Sahara population and assessed differences between them. In both populations, genetic variation was found to be low, with mean allelic richness for the loci polymorphic in the species of 2.09 and 1.96, respectively. For most loci, the observed allele frequency distributions in both populations were discontinuous and the size ranges similar. The eastern Mediterranean population had 14 private alleles and the western Sahara had 18, but with a much larger sample size. Highly significant differences in allele frequencies between the two populations were found for 14 out of 17 loci. F ST between the two populations was 0.578 and the estimated number of migrants per generation was 0.046, both clearly indicating substantial genetic differentiation. From a conservation perspective, these results suggest that each population may act as a source for introducing additional genetic variation into the other population.

123 Genet Resour Crop Evol (2011) 58:125-137 DOI 10.1007/s10722 -010-9601-5 currently consists of 220 accessions from 15 countries: 169 of these come from European cultivation countries, 18 from commercial areas in non EU countries, 26 from regions of minimal or relict production and/or from abandoned fields and 7 from commercial nurseries. The non-saffron Crocus collection currently comprises 352 accessions: 179 collected from the wild in 12 countries of natural distribution, 24 from donations of public and private institutions, 91 from commercial nurseries and 58 acquired from BGV-CU collection management. Here we provide a record of collections, activities concerns and current strategies for documentation, conservation, characterisation, and management of the collection as important tools for researchers with interest in these valuable genetic resources.