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.

Summary 1.Many studies have been performed in an attempt to explain physiological, ecological and evolutionary factors behind inter-and intraspecific variation in basal metabolic rate (BMR) and maximum aerobic metabolic rate (VO 2max ). However, very little is known about the association between the traits and fitness components in populations of free-living animals. 2. We studied the association between body size and the metabolic rates of bank voles Myodes ( = Clethrionomys ) glareolus and their survival, measured by repeated trappings across 2 years in an isolated, island population. All measured traits (body mass, BM; head width, HW; VO 2max and BMR) were significantly repeatable over short (mean 5·4 days) and long (mean 56·4 days) intervals. 3. Logistic regression analyses showed no consistent relationship between the measured traits and survival until the next trapping session. The correlations, if present, differed in direction between sessions and sexes. Survival over winters was negatively correlated with BM in males ( P = 0·001) but not in females ( P = 0·43). The logistic regression with quadratic effects revealed stabilizing selection on VO 2max in males (across all sessions: P = 0·010; in breeding seasons only: P = 0·001). 4. Both the presence of stabilizing selection and the opposite direction of the selection between sexes and/or seasons could contribute to the relatively high additive genetic variance of metabolic rates, reported earlier in the bank voles. 5.The results indicate that the maximum rather than the basal rate of metabolism is important to individual fitness of the voles. However, lack of consistency in the association between survival and the metabolic traits casts doubt on previous assumptions regarding the importance of the level of metabolism to an individual's fitness.

Summary1. Because energy is a crucial resource, adaptive significance of variation in the rate of energy metabolism, and especially in basal (BMR) and maximum aerobic (VO 2max ) metabolic rates, is a popular theme in evolutionary and ecological physiology. However, little is known about the association of these traits with fitness components in populations of free-living animals. 2. We studied the association between body size, the metabolic rates, and reproductive success in bank voles (Myodes glareolus) in an isolated, small island population. Correlation analyses were performed for two measures of reproductive performance: mating success (the number of partners with which an individual had any offspring), and overall reproductive success (the number of offspring trapped in the field, calculated for all individuals, including those with no offspring). 3. Direction of the selection on metabolic traits varied between sexes and over time, which could contribute to maintaining a high additive genetic variance of the traits. 4. Mating success and overall reproductive success of males were positively correlated with body size (head width), but not with mass-independent VO 2max . The latter result undermines the hypothesis that evolution of high aerobic capacity could be driven by a selection for traits important in male competition. 5. Overall reproductive success was positively correlated with basal metabolic rate. The result corroborates the hypothesis that high BMR and endothermy in mammals could evolve as consequences of intensive parental care evolution. However, the generality of such a correlation remains uncertain and warrants further research.