Marine turtles undergo dramatic ontogenic changes in body size and behavior, with the loggerhead sea turtle, Caretta caretta, typically switching from an initial oceanic juvenile stage to one in the neritic, where maturation is reached and breeding migrations are subsequently undertaken every 2-3 years [1-3]. Using satellite tracking, we investigated the migratory movements of adult females from one of the world's largest nesting aggregations at Cape Verde, West Africa. In direct contrast with the accepted life-history model for this species [4], results reveal two distinct adult foraging strategies that appear to be linked to body size. The larger turtles (n = 3) foraged in coastal waters, whereas smaller individuals (n = 7) foraged oceanically. The conservation implications of these findings are profound, with the population compartmentalized into habitats that may be differentially impacted by fishery threats in what is a global fishing hotspot [5]. Although the protection of discrete areas containing coastal individuals may be attainable, the more numerous pelagic individuals are widely dispersed with individuals roaming over more than half a million square kilometers. Therefore, mitigation of fisheries by-catch for sea turtles in the east Atlantic will likely require complex and regionally tailored actions to account for this dichotomous behavior.

Without genetic variation, species cannot cope with changing environments, and evolution does not proceed. In endangered species, adaptive potential may be eroded by decreased population sizes and processes that further reduce gene flow such as philopatry and local adaptations. Here, we focused on the philopatric and endangered loggerhead sea turtle (Caretta caretta) nesting in Cape Verde as a model system to investigate the link between adaptive potential and philopatry. We produced a dataset of three complementary genomic regions to investigate female philopatric behaviour (mitochondrial DNA), male-mediated gene flow (microsatellites) and adaptive potential (major histocompatibility complex, MHC). Results revealed genetically distinct nesting colonies, indicating remarkably small-scale philopatric behaviour of females. Furthermore, these colonies also harboured local pools of MHC alleles, especially at the margins of the population's distribution, which are therefore important reserves of additional diversity for the population. Meanwhile, directional male-mediated gene flow from the margins of distribution sustains the adaptive potential for the entire rookery. We therefore present the first evidence for a positive association between philopatry and locally adapted genomic regions. Contrary to expectation, we propose that philopatry conserves a high adaptive potential at the margins of a distribution, while asymmetric gene flow maintains genetic connectivity with the rest of the population.

BackgroundIn evolutionary and conservation biology, parasitism is often highlighted as a major selective pressure. To fight against parasites and pathogens, genetic diversity of the immune genes of the major histocompatibility complex (MHC) are particularly important. However, the extensive degree of polymorphism observed in these genes makes it difficult to conduct thorough population screenings.MethodsWe utilized a genotyping protocol that uses 454 amplicon sequencing to characterize the MHC class I in the endangered loggerhead sea turtle (Caretta caretta) and to investigate their evolution at multiple relevant levels of organization.ResultsMHC class I genes revealed signatures of trans-species polymorphism across several reptile species. In the studied loggerhead turtle individuals, it results in the maintenance of two ancient allelic lineages. We also found that individuals carrying an intermediate number of MHC class I alleles are larger than those with either a low or high number of alleles.ConclusionsMultiple modes of evolution seem to maintain MHC diversity in the loggerhead turtles, with relatively high polymorphism for an endangered species.

The integration of satellite telemetry, remotely sensed environmental data, and habitat/environmental modelling has provided for a growing understanding of spatial and temporal ecology of species of conservation concern. The Republic of Cape Verde comprises the only substantial rookery for the loggerhead turtle Caretta caretta in the eastern Atlantic. A size related dichotomy in adult foraging patterns has previously been revealed for adult sea turtles from this population with a proportion of adults foraging neritically, whilst the majority forage oceanically. Here we describe observed habitat use and employ ecological niche modelling to identify suitable foraging habitats for animals utilising these two distinct behavioural strategies. We also investigate how these predicted habitat niches may alter under the influence of climate change induced oceanic temperature rises. We further contextualise our niche models with fisheries catch data and knowledge of fisheries 'hotspots' to infer threat from fisheries interaction to this population, for animals employing both strategies. Our analysis revealed repeated use of coincident oceanic habitat, over multiple seasons, by all smaller loggerhead turtles, whilst larger neritic foraging turtles occupied continental shelf waters. Modelled habitat niches were spatially distinct, and under the influence of predicted sea surface temperature rises, there was further spatial divergence of suitable habitats. Analysis of fisheries catch data highlighted that the observed and modelled habitats for oceanic and neritic loggerhead turtles could extensively interact with intensive fisheries activity within oceanic and continental shelf waters of northwest Africa. We suggest that the development and enforcement of sustainable management strategies, specifically multi-national fisheries policy, may begin to address some of these issues; however, these must be flexible and adaptive to accommodate potential range shift for this species.

Abstract:Conservation rules aimed at restricting resource use are commonly used to manage and protect natural resources, but their implementation is strongly affected by resource users' compliance. The design of effective rules should be informed by an understanding of the factors that affect compliance, considering the contextual socio-economic information. Potential changes in the national legislation protecting sea turtles have been recently discussed in the Cape Verde archipelago, where historical and recent records indicate heavy human predation pressure on nesting and foraging sea turtles. The most recent assessment of levels of illegal harvesting and consumption of sea turtle products on two of the islands, Boavista and Santiago, are presented, followed by an analysis of their potential drivers.http://www.oryxthejournal.org Oryx -The International Journal of Conservation F o r P e e r R e v i e wThe perceived impact of main interventions currently employed in Cape Verde to reduce illegal sea turtle harvesting, trade and consumption were investigated by interviewing key stakeholders. Despite an apparent decrease of sea turtle harvest and consumption over recent years, our results suggest a shift from subsistence harvesting to trade in Boavista. The existence of sea turtle protection laws was perceived as a main deterrent to harvesting, while awareness campaigns and a lack of resource availability were perceived as main reasons for decrease in consumption in Boavista and Santiago, respectively. Aiming to inform ongoing discussions, we recommend a multi-targeted approach focusing both on suppliers and consumers in order to magnify conservation effectiveness. Regular impact evaluation focusing both on harvest and consumption is needed to better design regulations and robustly inform policy decisions. Tables Table S1. Drivers and assumptions underlying wildlife trade interventions (TRAFFIC, 2008) and indicators used in this study to assess their success. Table S2. Characterisation of the groups targeted for this study at Boavista (n = 147) individuals from four villages and one city) and Santiago (n = 291 individuals from six villages and one city). Boavista (n=17) 10,000 ± 4,000 5,000 -20,000 10 000Santiago (n=96) 12,000 ± 4,000 4,000 -20,000 10 000Juvenile Turtle (Whole) 1 Santiago (n=3) 5,000 ± 4,500 1,500 -10,000 N/A Boavista (n=10) 250 -600 300 Boavista. The existence of sea turtle protection laws was perceived as a main 42 deterrent to harvesting, while awareness campaigns and a lack of resource availability 43 were perceived as main reasons for decrease in consumption in Boavista and 44 Santiago, respectively. Aiming to inform ongoing discussions, we recommend a 45 multi-targeted approach focusing both on suppliers and consumers in order to 46 magnify conservation effectiveness. Regular impact evaluation focusing both on 47 harvest and consumption is needed to better design regulations and robustly inform 48 policy decisions. 49