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.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Adapt biodiversity targets to climate change Liz, André Vicente; Gonçalves, Duarte Vasconcelos; Velo-Antón, Guillermo ...
Science (American Association for the Advancement of Science),
05/2022, Volume:
376, Issue:
6593
Journal Article
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.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
DNA barcode reference libraries are now continuously produced for the tree of life, which are essential pillars for the study of biological diversity. Yet, our knowledge about global ...diversity is largely limited in undersampled regions such as the largest warm desert, the Sahara-Sahel. This dataset provides a DNA barcode reference library for the reptiles of the Western Sahara-Sahel (WSS) and neighbouring countries across this region. It includes 760 barcodes from 133 reptile taxa, distributed in 23 families, and covering the intraspecific diversity of some species. A total of 84 species were collected in the WSS (83% of the total reptile species richness) over 18 overland field expeditions conducted since 2003. DNA barcodes resulted in a high success rate (95%) of species identification and barcoding gap analysis highlighted the effectiveness of the COI fragment as a barcode marker for the WSS reptiles. This dataset represents a comprehensive and reliable DNA reference library for the WSS, filling an important biodiversity gap across a remote and hard-to-sample region.
Hyperarid habitats comprise the most dominant and harsh portion of the Sahara Desert, yet how local biotas have responded to paleoclimatic shifts and landscape heterogeneity remains unclear. Here, we ...assess the historical biogeography of Cerastes cerastes, a conspicuous but poorly known vertebrate inhabiting the hyperarid Sahara, to understand the links between intermittent and stable climatic suitability and patterns of genetic diversity and differentiation in these extreme environments. We combine phylogeographic and ecological modelling tools using a comprehensive species dataset, which includes DNA samples (n = 62) and occurrence records (n = 557) covering most of its range. We show that paleoclimatic oscillations were major evolutionary and biogeographic drivers in C. cerastes, which exhibits different levels of intra-specific diversity and allopatric lineage structuration across the desert. High lineage richness in the north-western Sahara contrasts with an overall lack of genetic diversity throughout the central and eastern Sahara. Climatic refugia along the desert's periphery and around mountain patches harbour single endemic lineages, stressing the links between stable climatic conditions and population isolation and divergence. Increasing climatic suitability during historical arid phases prompted widespread connectivity across the desert. This study lays the groundwork for better understanding the historical dynamics of the hyperarid Sahara.
•First historical biogeography study on a Saharan xeric taxon combining phylogeography and ENM.•Intra-specific diversity is concentrated in the northwestern Sahara linked to climatic refugia.•Beyond stable climate, topographic variability is associated to high intra-specific diversity.•Intermittent arid corridors prompted widespread gene flow across distant desert areas.•Dispersals across Bab-el-Mandeb during a past glacial maximum likely led to Arabian populations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Discovery rates of new species are uneven across taxonomic groups and regions, with distinctive and widely distributed species being more readily described than species with secretive habits. The ...genus
Rhynchocalamus
includes five species of secretive snakes distributed from Egypt eastwards to Iran, including the Arabian Peninsula. A wide biogeographic gap exists within the genus, which separates
R. dayanae
found in south Israel from
R. arabicus
, which occurs in the coastal areas of south Yemen and Oman. We describe
Rhynchocalamus hejazicus
sp. nov.
, a small, secretive snake, with a distinctive colouration and a melanistic morph. The new species occurs in the northwestern Hejaz region of the Kingdom of Saudi Arabia (KSA) and fills a large part of the existing distribution gap of the genus in the Arabian Peninsula. Molecular analyses of mitochondrial (
12S
,
16S
,
cytb
) and nuclear genes (
cmos
,
MC1R
,
NT3
,
RAG1
) indicate that
R. hejazicus
sp. nov.
is closely related to
R. dayanae
and
R. arabicus
, but uncertainty on the deep relationship within the genus remains. The new species has a large distribution range which potentially includes other regions in Jordan and KSA, and is associated with mountainous areas with cold wet seasons. Furthermore, it inhabits sandy and stony soils with varying vegetation cover and can be found in anthropogenically disturbed habitats, suggesting that the species should not be categorised as threatened according to IUCN criteria. The discovery of such a distinctive species highlights the existing gap in the description of rare and secretive species, and the need to enhance sampling efforts and monitoring strategies to fully capture species diversity in unexplored areas.
Encapsulation of biological components in hydrogels is a well described method for controlled drug delivery of proteins, tissue engineering and intestinal colonization with beneficial bacteria. Given ...the potential of tissue engineering in clinical practice, this study aimed to evaluate the feasibility of encapsulation of adipose tissue-derived mesenchymal stem cells (MSCs) of mules in sodium alginate. We evaluated capsule morphology and cell viability, immunophenotype and release after encapsulation. Circular and irregular pores were observed on the hydrogel surface, in which MSCs were present and alive. Capsules demonstrated good capacity of absorption of liquid and cell viability was consistently high through the time points, indicating proper nutrient diffusion. Flow cytometry showed stability of stem cell surface markers, whereas immunohistochemistry revealed the expression of CD44 and absence of MHC-II through 7 days of culture. Stem cell encapsulation in sodium alginate hydrogel is a feasible technique that does not compromise cell viability and preserves their undifferentiated status, becoming a relevant option to further studies of tridimensional culture systems and
in vivo
bioactive agents delivery.
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