Cândida G. Vale

Unravelling biodiversity, evolution and threats to conservation in the Sahara‐Sahel

Deserts and arid regions are generally perceived as bare and rather homogeneous areas of low diversity. The Sahara is the largest warm desert in the world and together with the arid Sahel displays high topographical and climatic heterogeneity, and has experienced recent and strong climatic oscillations that have greatly shifted biodiversity distribution and community composition. The large size, remoteness and long‐term political instability of the Sahara‐Sahel, have limited knowledge on its biodiversity. However, over the last decade, there have been an increasing number of published scientific studies based on modern geomatic and molecular tools, and broad sampling of taxa of these regions. This review tracks trends in knowledge about biodiversity patterns, processes and threats across the Sahara‐Sahel, and anticipates needs for biodiversity research and conservation. Recent studies are changing completely the perception of regional biodiversity patterns. Instead of relatively low species diversity with distribution covering most of the region, studies now suggest a high rate of endemism and larger number of species, with much narrower and fragmented ranges, frequently limited to micro‐hotspots of biodiversity. Molecular‐based studies are also unravelling cryptic diversity associated with mountains, which together with recent distribution atlases, allows identifying integrative biogeographic patterns in biodiversity distribution. Mapping of multivariate environmental variation (at 1 km × 1 km resolution) of the region illustrates main biogeographical features of the Sahara‐Sahel and supports recently hypothesised dispersal corridors and refugia. Micro‐scale water‐features present mostly in mountains have been associated with local biodiversity hotspots. However, the distribution of available data on vertebrates highlights current knowledge gaps that still apply to a large proportion of the Sahara‐Sahel. Current research is providing insights into key evolutionary and ecological processes, including causes and timing of radiation and divergence for multiple taxa, and associating the onset of the Sahara with diversification processes for low‐mobility vertebrates. Examples of phylogeographic patterns are showing the importance of allopatric speciation in the Sahara‐Sahel, and this review presents a synthetic overview of the most commonly hypothesised diversification mechanisms. Studies are also stressing that biodiversity is threatened by increasing human activities in the region, including overhunting and natural resources prospection, and in the future by predicted global warming. A representation of areas of conflict, landmines, and natural resources extraction illustrates how human activities and regional insecurity are hampering biodiversity research and conservation. Although there are still numerous knowledge gaps for the optimised conservation of biodiversity in the region, a set of research priorities is provided to identify the framework data needed to support regional conservation planning.

Overlooked mountain rock pools in deserts are critical local hotspots of biodiversity.

Background The world is undergoing exceptional biodiversity loss. Most conservation efforts target biodiversity hotspots at large scales. Such approach overlooks small-sized local hotspots, which may be rich in endemic and highly threatened species. We explore the importance of mountain rock pools (gueltas) as local biodiversity hotspots in the Sahara-Sahel. Specifically, we considered how many vertebrates (total and endemics) use gueltas, what factors predict species richness, and which gueltas are of most priority for conservation. We expected to provide management recommendations, improve local biodiversity conservation, and simultaneously contribute with a framework for future enhancement of local communities’ economy. The identification of local hotspots of biodiversity is important for revaluating global conservation priorities. Methodology/Principal Findings We quantified the number of vertebrate species from each taxonomic group and endemics present in 69 gueltas in Mauritania, then compared these with species present in a surrounding area and recorded in the country. We evaluated the predictors of species number’s present in each guelta through a multiple regression model. We ranked gueltas by their priority for conservation taking into account the percentage of endemics and threats to each guelta. Within a mere aggregate extent of 43 ha, gueltas hold about 32% and 78% of the total taxa analysed and endemics of Mauritania, respectively. The number of species present in each guelta increased with the primary productivity and area of gueltas and occurrence of permanent water. Droughts and human activities threaten gueltas, while 64% of them are currently unprotected. Conclusion/Significance Gueltas are crucial for local biodiversity conservation and human activities. They require urgent management plans in Mauritania’s mountains. They could provide refugia under climate change being important for long-term conservation of Sahara-Sahel biodiversity. Given their disproportional importance in relation to their size, they are local hotspots of biodiversity deserving global attention.

Distribution, suitable areas and conservation status of the Felou gundi (Felovia vae Lataste 1886)

Abstract Felovia vae is an endemic rodent from West Africa with special conservation concern. Although the global range is relatively well known, the lack of knowledge on its local distribution patterns and ecological parameters resulted in the IUCN category of Data Deficient. This study identifies environmental factors related to the occurrence of Felovia vae, quantifies suitable areas of occurrence, and evaluates its conservation status. High-resolution presence data (1×1 km) were combined with environmental factors to derive ecological niche-based models of species occurrence. Ecological models predicted that Felovia vae occurs more frequently in areas with high slope and close to gueltas, bare areas and rocky deserts. The fine-scaled ecological models suggest eight suitable habitat patches, representing fragmented subpopulations located in the Mauritanian mountains and in the Bafing, Felou, Nioro, and Yelimane regions of Mali. Fieldwork observations and predicted suitable areas were used to evaluate conservation status. Felovia vae was categorised as Least Concern, given that values for all parameters analysed were above the thresholds of Threatened classification. The species may be susceptible to human-induced habitat loss, global warming and natural disasters, such as drought, given its reliance on water availability.

Distribution, suitable areas and conservation status of the Boulenger’s agama (Agama boulengeri, Lataste 1886)

Agama boulengeri is a West African endemic lizard. It occurs in arid rocky areas in the Mauritanian mountains and Kayes region of Mali. Data on the distribution of Agama boulengeri is however very coarse, and the contribution of climatic and habitat factors for population isolation are unknown. Using Maxent, GLM, and high-resolution data, we generated environmental niche models, and quantified suitable areas for species occurrence. Field observations and predicted suitable areas were used to evaluate the conservation status of Agama boulengeri. Results revealed the species occurs preferentially close to gueltas, bare areas, and rocky deserts and in areas of increasing rainfall. Suitable cells were mostly located in Mauritania, and four potentially fragmented subpopulations were identified. The conservation status of Agama boulengeri was determined to be of Least Concern.