Dissertação de mestrado em Ecologia ; Habitat destruction and bushmeat hunting are promoting world-wide fragmentation and demographic contractions of primate populations, of which insular populations are thought to be particularly susceptible to extinction because of a presumably reduced genetic diversity and evolutionary potential. The Bijagós archipelago (BA), located off the coast of Guinea-Bissau (GB) in West Africa, sustain high levels of biodiversity of worldwide-recognised importance. The primate species occurring at BA – the Western lesser spot-nosed guenon (Cercopithecus petaurista buettikoferi), mona monkey (Cercopithecus campbelli) and, the green monkey (Chlorocebus sabaeus) – are at the fringe of distribution and may have a high conservation value. Insular populations of C. p. buettikoferi are presumably the last populations in GB but have never been genetically surveyed across different islands. In this work, I aimed at updating the occurrence of the three primates species in BA, investigate their most likely mainland origin and evaluate their extinction vulnerability by estimating genetic diversity, population substructure and demographic history. Non-invasive DNA sampling was conducted in seven islands of BA and five different protected areas in the mainland. Fragments of mitochondrial DNA (cytochrome b gene and, mitochondrial control region) and ten autosomal microsatellite loci were used as genetic markers. C. p. buettikoferi’s and C. campbelli‘s occurrence in sampled islands seems to remain unaltered from the most recent but twenty-years-old surveys carried out in BA. However, Chl. sabaeus seems to be currently absent from Galinha, Canhabaque, Uno, Uracane and Caravela. For the primates occurring at both BA and mainland, insular populations were genetically less diverse, particularly C. campbelli. The surrounding areas of the Geba Channel (Quinara administrative region) were suggested as the probable source of insular populations. The genetic diversity of insular C. p. buettikoferi was not ...