The role of climatic cycles and trans-Saharan migration corridors in species diversification: Biogeography of Psammophis schokari group in North Africa.

Highlands, hydrographic systems and coastal areas have been hypothesised to form corridors across the hyperarid Sahara desert in North Africa, allowing dispersal and gene flow for non-xeric species. Here we aim to provide a genetic test for the trans-Saharan corridor model, and predict the location and stability of ecological-corridors, by combining phylogeography and palaeoclimatic modelling. The model was the Psammophis schokari (Schokari sand racer) group, fast-moving and widely distributed generalist colubrids occurring mostly in arid and semiarid scrublands. We combined dated phylogenies of mitochondrial and nuclear markers with palaeoclimatic modelling. For the phylogeographic analysis, we used 75 samples of P. schokari and P. aegyptius, and Bayesian and Maximum-Likelihood methods. For the ecological models, we used Maxent over the distribution of P. schokari and West African lineages. Models were projected to past conditions (mid Holocene, Last Glacial Maximum and Last Inter-Glacial) to infer climatic stable areas. Climatic stability was predicted to be mostly restricted to coastal areas and not spatially continuous. A putative temporary trans-Saharan corridor was identified in Eastern Sahara, with a more stable one along the Atlantic coast. Six parapatric lineages were identified within P. schokari, four occurring in North Africa. These likely diverged during the Pliocene. The Tamanraset River might have been a vicariant agent. African lineages may have experienced further subsequent diversification during the late Pleistocene. The main P. schokari refugia were probably located along the northern margins of the Sahara, allowing its North-to-South colonization. Trans-Saharan corridors seem to have played a role in P. schokari biogeography, allowing colonization of central Saharan mountains and Sahel. Some might have worked as refugia, and even the most stable corridors may have sections working as filters, depending on each climatic phase. We expect the use of trans-Saharan corridors to decrease for more mesic species or with less dispersal capabilities.

Streams in the Mediterranean Region are not for mussels: Predicting extinctions and range contractions under future climate change.

Climate change is becoming the leading driver of biodiversity loss. The Mediterranean region, particularly southwestern Europe, is already confronting the consequences of ongoing global warming. Unprecedented biodiversity declines have been recorded, particularly within freshwater ecosystems. Freshwater mussels contribute to essential ecosystem services but are among the most threatened faunal groups on Earth. Their poor conservation status is related to the dependence on fish hosts to complete the life cycle, which also makes them particularly vulnerable to climate change. Species Distribution Models (SDMs) are commonly used to predict species distributions, but often disregard the potential effect of biotic interactions. This study investigated the potential impact of future climate on the distribution of freshwater mussel species while considering their obligatory interaction with fish hosts. Specifically, ensemble models were used to forecast the current and future distribution of six mussel species in the Iberian Peninsula, including environmental conditions and the distribution of fish hosts as predictors. We found that climate change is expected to severely impact the future distribution of Iberian mussels. Species with narrow ranges, namely Margaritifera margaritifera and Unio tumidiformis, were predicted to have their suitable habitats nearly lost and could potentially be facing regional and global extinctions, respectively. Anodonta anatina, Potomida littoralis, and particularly Unio delphinus and Unio mancus, are expected to suffer distributional losses but may gain new suitable habitats. A shift in their distribution to new suitable areas is only possible if fish hosts are able to disperse while carrying larvae. We also found that including the distribution of fish hosts in the mussels' models avoided the underprediction of habitat loss under climate change. This study warns of the imminent loss of mussel species and populations and the urgent need of management actions to reverse current trends and mitigate irreversible damage to species and ecosystems in Mediterranean regions.

Diversity, distribution and conservation of land mammals in Mauritania, North-West Africa.

Detailed knowledge about biodiversity distribution is critical for monitoring the biological effects of global change processes. Biodiversity knowledge gaps hamper the monitoring of conservation trends and they are especially evident in the desert biome. Mauritania constitutes a remarkable example on how remoteness and regional insecurity affect current knowledge gaps. Mammals remain one of the least studied groups in this country, without a concerted species checklist, the mapping of regions concentrating mammal diversity, or a national assessment of their conservation status. This work assessed the diversity, distribution, and conservation of land mammals in Mauritania. A total of 6,718 published and original observations were assembled in a spatial database and used to update the occurrence status, distribution area, and conservation status. The updated taxonomic list comprises 107 species, including 93 extant, 12 Regionally Extinct, and 2 Extinct in the Wild. Mapping of species distributions allowed locating concentrations of extant mammal species richness in coastal areas, along the Senegal River valley, and in mountain plateaus. Recent regional extinction of large-sized Artiodactyla and Carnivora has been very high (11% extinct species). From the extant mammals, 11% are threatened, including flagship species (e.g., Addax nasomaculatus and Panthera pardus). Species richness is poorly represented by the current protected areas. Despite the strong advances made, 23% of species categorise as Data Deficient. Persisting systematics and distribution uncertainties require further research. Field surveys in currently unexplored areas (northern and south-eastern regions) are urgently needed to increase knowledge about threatened mammals. The long-term conservation of land mammals in Mauritania is embedded in a complex web of socioeconomic and environmental factors that call for collaborative action and investment in sustainable human development. The current work sets the baseline for the future development of detailed research studies and to address the general challenges faced by mammals and biodiversity in the country.