Guillermo Velo-Antón

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.

Deep evolutionary lineages in a Western Mediterranean snake (Vipera latastei/monticola group) and high genetic structuring in Southern Iberian populations.

Phylogeographic studies during the last decade confirmed an internal complexity of the Iberian Peninsula and northern Maghreb as refugial areas during the Miocene to Pleistocene period. Species with low vagility that experienced the complex climatic and palaeogeographic processes occurred in the Western Mediterranean Basin are excellent candidates to study the extent of lineage diversification in this region. We applied phylogenetic analyses based on mitochondrial data to infer the evolutionary history of Vipera latastei/monticola and identify the major biogeographic events structuring the genetic diversity within this group. We obtained a well-resolved phylogeny, with four highly divergent lineages (one African and three Iberian) that originated in the Tertiary. Coalescence-based estimations suggest that the differentiation of the four major lineages in V. latastei/monticola corresponds to the Messinian salinity crisis and the reopening of the Strait of Gibraltar during the Miocene. Subsequent Pliocene and Pleistocene climatic oscillations continued to isolate both Iberian and Maghrebian populations and led to a high genetic structuring in this group, particularly in Southern Iberia, a complex palaeogeographic and topographic region with high endemism levels. This study does not support the current taxonomy of the group, thus suggesting that an integrative evaluation of Iberian and African populations is needed to resolve its systematics.

Where are you from, stranger? The enigmatic biogeography of North African pond turtles (Emys orbicularis)

The European pond turtle (Emys orbicularis) is a Nearctic element in the African fauna and thought to have invaded North Africa from the Iberian Peninsula. All North African populations are currently identified with the subspecies E. o. occidentalis. However, a nearly range-wide sampling in North Africa used for analyses of mitochondrial and microsatellite DNA provides evidence that only Moroccan populations belong to this taxon, while eastern Algerian and Tunisian pond turtles represent an undescribed distinct subspecies. These two taxa are most closely related to E. o. galloitalica with a native distribution along the Mediterranean coast of northern Spain through southern France to western and southern Italy. This group is sister to a clade comprising several mitochondrial lineages and subspecies of E. orbicularis from Central and Eastern Europe plus Asia, and the successive sisters are E. o. hellenica and E. trinacris. Our results suggest that E. orbicularis has been present in North Africa longer than on the Iberian Peninsula and that after an initial invasion of North Africa by pond turtles from an unknown European source region, there was a phase of diversification in North Africa, followed by a later re-invasion of Europe by one of the African lineages. The differentiation of pond turtles in North Africa parallels a general phylogeographic paradigm in amphibians and reptiles, with deeply divergent lineages in the western and eastern Maghreb. Acknowledging their genetic similarity, we propose to synonymize the previously recognized Iberian subspecies E. o. fritzjuergenobsti with E. o. occidentalis sensu stricto. The seriously imperiled Moroccan populations of E. o. occidentalis represent two Management Units different in mitochondrial haplotypes and microsatellite markers. The conservation status of eastern Algerian pond turtles is unclear, while Tunisian populations are endangered. Considering that Algerian and Tunisian pond turtles represent an endemic taxon, their situation throughout the historical range should be surveyed to establish a basis for conservation measures.

Assignment tests applied to relocate individuals of unknown origin in a threatened species, the European pond turtle (Emys orbicularis)

The pet trade is an important business around the world and one of the factors that might menace some wild populations. If wild animals are collected to maintain them as pets, this activity can produce several problems: i) an increase of population vulnerability, especially in the case of rare species; ii) the release of exotic pets in natural habitats, with the risk of competition with native species and the spreading of parasites and diseases, and iii) the maintenance of animals of unknown origin in Recovery Centres or zoos, which if too numerous are sacrificed or re-located to their supposed original regions. In this paper, we used seven microsatellite loci to analyze genetic diversity and genetic structure of the European pond turtle (Emys obicularis) covering the species range in the Iberian Peninsula. A Bayesian test revealed a genotypic differentiation between the regions sampled where most individuals (90%) were assigned to their sampling location with a probability higher than 95%. The likelihood values for individuals from Recovery Centres to came from one of our populations was higher than 90% in 22 out of 36 individuals. This work is a first step to relocate animals of unknown origin taking into account genetic similarities and contribute to reinforcement programs of endangered species.

β -fibrinogen intron 7 variation in Discoglossus (Anura: Discoglossidae): implications for the taxonomic assessment of morphologically cryptic species

The generalized use of nuclear introns in combination with mitochondrial DNA data in molecular systematic and intraspecific phylogeographical studies is providing new insights into the complex evolutionary histories of taxa surviving the Quaternary glaciations. Previous studies have highlighted the suitability of the beta-fibrinogen intron 7 (β-fibint7 )f or phylogenetic and phylogeographic studies in a wide variety of taxa, including amphibians. Here we use sequences of this marker to assess inter- and intraspecific variation in Discoglossus (Discoglossidae), with special emphasis on geographic patterns of genetic structure in the Iberian Peninsula, where recent studies have questioned the taxonomic status of D. jeanneae. We obtained 81 sequences of β-fibint7 from samples including all currently recognized species except D. montalentii and 37 populations in the Iberian Peninsula and compared levels of genetic variation with those observed in a fragment of similar length of the mtDNA gene cytochrome b. The sequence of β-fibint7 in Discoglossus is the shortest described for amphibians so far, 378 base pairs. In general, we found low levels of variability (only 26 parsimony-informative sites in the dataset), with no alternatively fixed haplotypes in samples attributed to D. galganoi or D. jeanneae based on their mtDNA. Values of pairwise sequence divergence between non-Iberian species ranged from 1.1% to 4.5% (13.3% to 20.9% in mtDNA). The patterns observed in samples from the Iberian Peninsula are consistent with either incomplete lineage sorting or ongoing gene flow between D. galganoi and D. jeanneae. We conclude by reviewing the genetic evidence available to address the taxonomic status of Iberian species of Discoglossus.

Genetic variation across Tunisian populations of the anuran species Discoglossus pictus and Pelophylax saharicus

The intraspecific variation of mitochondrial cytochrome b sequence was analysed for two widely distributed Tunisian anuran species, Discoglossus pictus and Pelophylax saharicus. We observed low genetic variation within both species (D. p. auritus 0.6% uncorrected genetic distances, P. saharicus 0.2%) and the absence of genetic structure within both species in the studied region. There is no correspondence between previously described morphotypes of P. saharicus in Tunisia and our genetic data. Our results show a lack of phylogeographic structure in both species despite their fragmented distribution across Tunisia.

phylin: an r package for phylogeographic interpolation.

phylin is a package for the r programming environment which offers different methods to spatially interpolate genetic information from phylogeographic data. These interpolations can be used to predict the spatial occurrence of different lineages within a phylogeny using a modified method of kriging, which allows the usage of a genetic distance matrix to derive a model of spatial dependence. phylin improves the available methods to generate interpolated surfaces from a phylogenetic trees by assessing the autocorrelation structure of the genetic information, interpolating the genetic data based on a statistical model, estimating the uncertainty of the predictions and identifying lineage occurrence and contact zones probability without projection of pairwise genetic distances into mid‐points between sample locations. The package also includes methods to plot interpolation surfaces and provide summary tables from the generated data and models. We provide an example of the usefulness of this tool by inferring the spatial occurrence of distinct historical evolutionary lineages of the Latastes viper (Vipera latastei Boscá, 1878) in the Iberian Peninsula and identifying potential contact areas. The maps of phylogenetic patterns obtained with these methods provide a spatial context to test hypotheses related to processes underlying the geographic distribution of genetic diversity and to inform conservation planning.

Differentiation of North African foxes and population genetic dynamics in the desert—insights into the evolutionary history of two sister taxa, Vulpes rueppellii and Vulpes vulpes

The effects of Pleistocene glaciations on moulding biodiversity have been extensively investigated within temperate biomes, yet arid ecosystems are largely neglected. A clear example comes from North Africa and the successive range of expansion/contraction cycles of the Sahara desert. This study focuses on North African foxes (genus Vulpes), in particular two sister taxa, Vulpes rueppellii and Vulpes vulpes, but also Vulpes zerda and Vulpes pallida. A set of two mitochondrial markers (Cyt-b and D-loop) and 31–33 autosomal microsatellites were used to conduct phylogenetic and population analyses, as well as to investigate the possible occurrence of hybridisation events. Phylogenetic analysis revealed V. rueppellii to be more closely related to North African V. vulpes than the latter with Eurasian V. vulpes, along with the occurrence of two sub-clades of V. vulpes within the Maghreb. In contrast, microsatellite analysis identified V. rueppellii and V. vulpes as clearly separate entities, and no sign of population structure was observed for both species within North Africa. Both mitochondrial and nuclear markers separated North African and Eurasian V. vulpes in two distinct groups. We propose two explanatory scenarios, both influenced by past climatic shifts: (1) past introgression of V. vulpes mitochondrial genome into V. rueppellii and (2) V. rueppellii represents an arid ecotype of V. vulpes trapped in the Sahara during a humid/arid transition. The successive expansions/contractions of the Sahara were also likely responsible for the mitochondrial structure of North African V. vulpes. We unveil intriguing insights on the genetic structure of carnivore species in North Africa, suggesting that further integrative research is needed.

Development and characterization of polymorphic microsatellite loci for spiny-footed lizards, Acanthodactylus scutellatus group (Reptilia, Lacertidae) from arid regions.

BackgroundSpiny-footed lizards constitute a diverse but scarcely studied genus. Microsatellite markers would help increasing the knowledge about species boundaries, patterns of genetic diversity and structure, and gene flow dynamics. We developed a set of 22 polymorphic microsatellite loci for cross-species amplification in three taxa belonging to the Acanthodactylus scutellatus species group, A. aureus, A. dumerili/A. senegalensis and A. longipes, and tested the same markers in two other members of the group, A. scutellatus and A. taghitensis.ResultsAmplifications in A. aureus, A. longipes and A. dumerili/A.senegalensis were successful, with markers exhibiting a number of alleles varying between 1 and 19. Expected and observed heterozygosity ranged, respectively, between 0.046–0.893 and 0.048–1.000. Moreover, 17 and 16 loci were successfully amplified in A. scutellatus and A. taghitensis, respectively.ConclusionThese markers are provided as reliable genetic tools to use in future evolutionary, behavioural and conservation studies involving species from the A. scutellatus group.

Challenges for assessing vertebrate diversity in turbid Saharan water-bodies using environmental DNA

The Sahara desert is the largest warm desert in the world and a poorly explored area. Small water-bodies occur across the desert and are crucial habitats for vertebrate biodiversity. Environmental DNA (eDNA) is a powerful tool for species detection and is being increasingly used to conduct biodiversity assessments. However, there are a number of difficulties with sampling eDNA from such turbid water-bodies and it is often not feasible to rely on electrical tools in remote desert environments. We trialled a manually powered filtering method in Mauritania, using pre-filtration to circumvent problems posed by turbid water in remote arid areas. From nine vertebrate species expected in the water-bodies, four were detected visually, two via metabarcoding, and one via both methods. Difficulties filtering turbid water led to severe constraints, limiting the sampling protocol to only one sampling point per study site, which alone may largely explain why many of the expected vertebrate species were not detected. The amplification of human DNA using general vertebrate primers is also likely to have contributed to the low number of taxa identified. Here we highlight a number of challenges that need to be overcome to successfully conduct metabarcoding eDNA studies for vertebrates in desert environments in Africa.