In the contemporary context of zoonosis emergence and spread, invasive species are a major issue since they represent potential pathogen hosts. Even though many progresses have been done to understand and predict spatial patterns of invasive species, the challenge to identify the underlying determinants of their distribution remains a central question in invasion biology. This is particularly exacerbated in the case of commensal species that strictly depend on humankind for dispersal and perennial establishment of new populations. The distribution of these species is predicted to be influenced by dispersal opportunities and conditions acting on establishment and proliferation, such as environmental characteristics, including spatio-temporal components of the human societies. We propose to contribute to the understanding of the recent spread of a major invasive rodent species, the black rat (Rattus rattus), in the changing southeastern of Senegal. We address the factors that promote the dispersal and distribution of this invasive rodent from the perspective of human geography. We first describe characteristics of human settlements in terms of social and spatial organization of human societies (i.e. economic activities, commercial and agricultural networks, roads connectivity). We then explore the relationship between these characteristics and the distribution of this invasive rodent. Finally we propose that historical and contemporary dynamics of human societies have contributed to the risk of invasion of the black rat. We argue that the diffusion processes of invasive species cannot be considered as a result of the spatial structure only (i.e. connectivity and distance), but as a part of the human territory that includes the social and spatial organization. Results suggest that the distribution of invasive rodents partly results from the contemporary and inherited human socio-spatial systems, beyond the existence of suitable ecological conditions that are classically investigated by biologists.

We assessed the quality of fishermen’s local ecological knowledge, or LEK, as a potential source of information about coastal ecosystem functioning in the Republic of Guinea. Interviews were conducted by means of partial immersion or repeated surveys at six landing sites. In each site and for each topic, discussions were conducted with 3 to 15 individual fishermen and 1 to 10 groups of fishermen. Knowledge was obtained about habitats, substrate preferences, the location of nurseries, reproductive cycles, fish diet, and the trophic network of the Sciaenid community, the major resource for fisheries in this area. We systematically compared the reliability of the information collected with that of scientific information collected in parallel surveys or published data. The contribution of LEK should be considered on a case-by-case basis. Indeed, LEK could be used as (i) a supplementary source of scientific studies (seabed description), (ii) a basis for new scientific investigation (species reproductive cycle), (iii) the only possibility to obtain information (nursery location), (iv) a surrogate to scientific surveys providing an identical level of validity (fish diets) or a satisfactory proxy (trophic network) in a context of limited resources and data in which wide-ranging knowledge relating to the entire coast must be obtained.