Alterations in thermal niches have been widely associated with the Anthropocene erosion of reptiles’ diversity. They entail potential physiological constraints for organisms’ performance, which can lead to activity restrictions and impact fitness and demography. Reptiles are ectotherms which rely on seasonal periodicity to maximize the performance of biological functions. Despite it, the ecological implications of shifts in local temperatures are barely explored at the seasonal scale. This study aims to assess how changes in air temperature and substrate temperature affect the activity, body temperature (Tb) and thermoregulation patterns of the sand lizard, Liolaemus arambarensis (an endangered, microendemic species from southern Brazil), throughout a four-year period. Field surveys were conducted monthly on a restricted population in a sand-dune habitat. The annual fluctuations of the seasonal temperatures led to significant changes in the activity and Tb of L. arambarensis and shaped thermoregulation trends, suggesting biological plasticity as a key factor in the face of such variability. Lizards tended to maintain seasonal Tb in mild and harsh seasons through increased warming/cooling efforts. Anomalous winter conditions seemed especially critical for individual performance due to their apparent high impact favouring/constraining activity. Activity and thermoregulation were inhibited in frigid winters, probably due to a vulnerable physiology to intense cold spells determined by higher preferred body temperatures than Tb. Our results warn of a complex sensitivity in lizards to anomalous seasonal temperatures, which are potentially enhanced by climate change. The current work highlights the importance of multiannual biomonitoring to disentangle long-term responses in the thermal biology of reptiles and, thereby, to integrate conservation needs in the scope of global change.

Aim The biogeographic history of the Sahara‐Sahel desert is tightly linked to its extreme and fluctuating palaeoclimate and diverse topography. For the mesic species inhabiting the region, coastal areas and the Nile Valley are perceived as the main pathways to disperse through desert habitats, but past connections may have also occurred throughout currently isolated mountain regions. Herein, we test the trans‐Sahara mountain corridor hypothesis (i.e., mesic connectivity across Central Sahara highlands) and its role in the diversification of a small terrestrial vertebrate. Location North Africa and Arabia. Taxon Acanthodactylus boskianus (Squamata: Lacertidae). Methods We integrated multi‐locus mitochondrial and nuclear phylogenies with species’ climate‐niche modelling, including palaeo‐projections. Genetic analyses aimed to assess the species’ genetic structure, identify its main mitochondrial lineages and nuclear diversity, and reconstruct its ancestral biogeography. Species’ climate‐niche stability was modelled independently for the Late Pleistocene‐Holocene and the Plio‐Pleistocene, to infer historical climatic refugia and dispersal corridors. Results Four spatially structured mitochondrial lineages, integrating several parapatric sub‐lineages, originated during the Plio‐Pleistocene. Nuclear data revealed nine potential candidate species. Climatic refugia were located in mountains and desert fringes, remaining consistent for the Late Pleistocene‐Holocene and the Plio‐Pleistocene. Recurrent North‐South climatic corridors were located along the desert periphery, while others less frequent were found across Central Sahara. Ancestral biogeography analyses recovered a recent Pleistocene colonization of the Sahel throughout eastern Sahara and either Sahara or Sahel origin for Central Sahara populations. Main conclusions Species’ diversification was triggered by a combination of Plio‐Pleistocene climatic cycles across a complex topographic region, where mountains acted as the main diversification hotspots. The historical role of Central Sahara highlands as main non‐peripheral mesic refugia was corroborated. In addition, intermittent climatic connections linked Mediterranean and Sahel ecoregions with Central Sahara refugia, suggesting the existence of alternative trans‐Sahara dispersal routes to the putative coastal and Nile corridors.

Article impact statement: If not carefully assessed, landscape changes could negatively affect dryland-adapted imperiled biodiversity in the Sahel.

Aim Hyper‐arid sandy and rocky fields rank among the least biologically diverse habitats of the desert biome, yet knowledge of local biodiversity patterns is also extremely poor. In the Sahara Desert, palaeoclimate oscillations affected the extent of hyper‐arid habitats, but it is unclear how these dynamics determined the evolution and distribution of local specialists. Herein, we assessed cryptic diversity, diversification patterns and spatial connectivity within a Sahara‐widespread group of dryland‐adapted lizards. Location Sahara‐Sahel ecoregions. Taxon Acanthodactylus scutellatus species group. Methods Inter‐ and intraspecific phylogenetic structure, divergence times, spatial genetic patterns and cryptic diversity were assessed using nuclear and mitochondrial loci. The effects of topography and land cover on phylogeographic structure and diversity were tested with generalized linear models. Interspecific hybridization was evaluated using 11 microsatellites across the group's major sympatry zone, predicted based on ecological niche models. Results Species of Acanthodactylus scutellatus group exhibit Late Miocene origins, followed by extensive intraspecific divergence throughout the Pliocene. The northern Sahara worked as a major diversification hotspot, harbouring a patchwork of small‐ranged, divergent lineages. These lineages are parapatric or sympatric and present concordant nuclear and mitochondrial differentiation, suggesting species status. Genetic connectivity increases in southern latitudes, with wide‐ranging lineages spanning from the Red Sea to the Atlantic coast. Within these potential corridors, mountain outskirts and sand fields in the Sahara interior seemingly acted as origins for recent population expansions. Genetic diversity and connectivity are favoured by terrain roughness and soft‐sand cover respectively. Three species inhabit the Atlantic Sahara sympatry zone without evidence of gene flow. Main conclusions Overlooked species‐level diversity within a major specialist group of Sahara drylands exposes the recurrent knowledge shortfalls present in hyper‐arid desert environments. Humidity and sandy habitat shifts triggered potential successions of population isolation and re‐connectivity, which favoured cladogenesis in northern desert regions and population expansions across southern east–west corridors.