Salvador Carranza

Relationships and evolution of the North African geckos, Geckonia and Tarentola (Reptilia: Gekkonidae), based on mitochondrial and nuclear DNA sequences.

Mitochondrial (cytochrome b and 12S rRNA) and nuclear (c-mos) genes, analyzed by a variety of methods, indicate that the distinctive northwest African gecko Geckonia chazaliae is a member of the Tarentola clade, being most closely related to the species of the western Canary and Cape Verde islands. Relationships in Tarentola as a whole are as follows: (T. americana ((T. mauritanica, T. angustimentalis) ((T. deserti, T. boehmei) ((T. b. boettgeri-South (T. b. boettgeri-North (T. b. bischoffi, T. b. hierrensis))) ((T. annularis, T. ephippiata) (Geckonia, T. delalandii, T. gomerensis, Cape Verde species)))))); nearly all nodes have high bootstrap support. Results confirm that T. americana of Cuba and the Bahamas separated at the most basal dichotomy of the phylogeny and give no positive support for the monophyly of the subgenera Tarentola s. str. and Makariogecko. The latter includes Geckonia and the subgenus Sahelogecko. Continental Tarentola appear to have invaded the Sahara desert from its northern edge. They have also colonized groups of Atlantic islands five times: a single invasion of the West Indies and three of the Canary islands, one of which then went on to invade the Cape Verde archipelago. The phylogeny corroborates anatomical evidence that the ground-dwelling Geckonia had a climbing ancestry, something that is paralleled in some southern African terrestrial gekkonids related to Pachydactylus. Distinctive derived features of Geckonia occur in other gekkonids that are ground dwelling in arid habitats and may be functionally related to this environment. The evolution of such features indicates that, although Tarentola is generally very uniform and may have been so for over 10 million years, this is not due to any overwhelming phylogenetic constraint. G. chazaliae should be included in Tarentola, as Tarentola chazaliae.

DNA phylogeny of Lacerta (Iberolacerta) and other lacertine lizards (Reptilia: Lacertidae): Did competition cause long‐term mountain restriction?

Abstract West European Rock lizards, Lacerta (Iberolacerta) have small widely separated ranges in highland areas. Mitochondrial and nuclear DNA sequences corroborate the monophyly of the group and show it is not closely related to any of the other Rock lizards with which it was formerly placed in Archaeolacerta, an assemblage for which there is no evidence of clade status. L. (Iberolacerta) consists of four main units: L. (I.) horvathi of NW Croatia and neighbouring regions; the Pyrenees species, L. (I.) bonnali, L. (I.) aranica and L. (I.) aurelioi; L. (I.) cyreni of the Iberian Sistema Central, with distinctive populations in the Sierras de Bejar, Gredos and Guadarrama; and L. (I.) monticola of the Serra da Estrela of Central Portugal and NW Spain, this unit also contains L. (I.) cyrenimartinezricai of La Peña de Francia, W. Spain and a distinctive population in the Montañas de Sanabria. L. (Iberolacerta) has persisted in some mountain ranges for at least 4.2 ± 1.4 Ma and may have been restricted to mountains by competition from Wall lizards (Podarcis). Its clade status shows it has lost range extensively and has produced few external branches since its initial fragmentation. In contrast, Podarcis diversified about the time L. (Iberolacerta) fragmented, producing a series of widespread lineages that have persisted until the present time. The mainly European subfamily Lacertinae, to which both L. (Iberolacerta) and Podarcis belong, diversified rapidly 13–9 Ma ago, probably largely replacing other lacertid lizards of earlier origin. As another round of replacement started at approximately 9 Ma ago with the spread of Podarcis, this may be a recurrent phenomenon in the evolution of some lizard communities.

Divergence times and colonization of the Canary Islands by Gallotia lizards

The Canary Islands have become a model region for evolutionary studies. We obtained 1.8 Kbp of mtDNA sequence from all known island forms of the endemic lizard genus Gallotia and from its sister taxon Psammodromus in order to reanalyze phylogenetic relationships within the archipelago, estimate lineage divergence times, and reconstruct the colonization history of this group. Well-supported phylogenies were obtained using maximum parsimony and Bayesian inference. Previous studies have been unable to establish the branching pattern at the base of the tree. We found evidence that G. stehlini (Gran Canaria) originated from the most basal Gallotia node and G. atlantica from the subsequent node. Divergence times were estimated under a global clock using Bayesian Markov Chain Monte Carlo methods implemented by three different programs: BEAST, MCMCTREE, MULTIDIVTIME. Node constraints were derived from subaerial island appearance data and were incorporated into the analyses as soft or hard maximal bounds. Posterior node ages differed slightly between programs, possibly due to different priors on divergence times. The most eastern Canary Islands first emerged just over 20 mya and their colonization appears to have taken place relatively quickly, around 17-20 mya. The subsequent node is consistent with cladogenesis due to colonization of Gran Canaria from the eastern islands about 11-13 mya. The western islands appear to have been colonized by a dispersal event from Lanzarote/Fuerteventura in the east to either La Gomera or one of the ancient edifices that subsequently formed Tenerife in the west, about 9-10 mya. Within the western islands, the most recent node that is ancestral to both the G. intermedia/G. gomerana/G. simonyi and the G.galloti/G. caesaris clades is dated at about 5-6 mya. Subsequent dispersal events between ancient Tenerife islands and La Gomera are dated at around 3 mya in both clades, although the direction of dispersal cannot be determined. Finally, we show that G. galloti is likely to have colonized La Palma more than 0.5 Ma after emergence of the island 1.77 mya, while G. caesaris from the same clade may have colonized El Hierro very soon after it emerged 1.12 mya. There are tentative indications that the large-bodied endangered G. simonyi colonized El Hierro around the same time or even later than the smaller-bodied G. caesaris. This study demonstrates the effectiveness of Bayesian dating of a phylogeny in helping reconstruct the historical pattern of dispersal across an oceanic archipelago.

History of West Mediterranean newts, Pleurodeles (Amphibia: Salamandridae), inferred from old and recent DNA sequences

Abstract MtDNA sequences (396 bp cytochrome b and 369 bp 12S rRNA) from recent material and old museum specimens indicate Pleurodeles poireti and P. waltl form independent clades with 7.76% genetic divergence. Within P. poireti, populations from Djebel Edough, NE Algeria are very distinct with 6.12% genetic divergence from the remainder and may deserve separate species status. Away from Djebel Edough, P. poireti consists of three distinct clades (coastal NW Tunisia; central N Algeria; Constantine plus inland NW Tunisia) with a maximum genetic divergence of only 1%. P. waltl contains two clades with 2.96% genetic divergence, one in SE and E Spain plus north Morocco, the other in Portugal and SW and central Spain. Pleurodeles probably invaded NW Africa from SW Europe during the Messinian Salinity Crisis, when land contact was first established at 5.6 Ma, and then interrupted at 5.3 Ma. Molecular clocks, calibrated in the assumption that the latter event separated P. waltl and P. poireti, suggest that Pleurodeles diverged from its sister taxon, Tylototriton, at about 8.6–10 Ma. Djebel Edough P. poireti separated at about 4.2 Ma, perhaps through isolation on a temporary, now ‘fossil’, island initiated by the Messinian crisis. Differentiation in remaining P. poireti may have been caused by Pleistocene climatic fluctuations, while bifurcation in P. waltl appears to have taken place in the Pliocene approximately between 3.2 and 2 Ma. This species reached Morocco very recently, perhaps as a result of human introduction. Use in Pleurodeles of the slower divergence rates estimated in some other salamandrids results in a less parsimonious historical hypothesis that does not fit known geophysical events.

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.

Investigating the origin of transoceanic distributions: mtDNA shows Mabuya lizards (Reptilia, Scincidae) crossed the Atlantic twice

Abstract Phylogenies with even a rough time scale can be used to investigate the history of non‐volant taxa with disjunct distributions in widely separated land areas that were once connected. Basic methods for doing this are discussed. A partial phylogeny of Mabuya based on mtDNA (305 bp cytochrome b, 379 bp 12S rRNA and 388 bp 16S rRNA) is used to show that this genus invaded tropical America from Africa twice in the last 9 Myr, once reaching the American mainland and once the oceanic island of Fernando de Noronha, two journeys each of at least 3000 km. In general, phylogenetic evidence for multiple invasions is less equivocal than that suggesting a single invasion, which is more prone to sampling artefacts. Two alternative hypotheses explaining the presence of Mabuya in both Africa and tropical America are refuted on the basis of molecular clock considerations, namely that the occurrence of Mabuya in these continents pre‐dated their separation over 100 My ago and that it was introduced from one continent to the other by human activities. Like several other lizard groups that have made successful long‐distance transmarine colonizations, Mabuya has done this on many occasions. Phylogenetic results are also compatible with a SE Asian or Australasian origin of Mabuya followed by westward expansion.

Conquering the Sahara and Arabian deserts: systematics and biogeography of Stenodactylus geckos (Reptilia: Gekkonidae)

BackgroundThe evolutionary history of the biota of North Africa and Arabia is inextricably tied to the complex geological and climatic evolution that gave rise to the prevalent deserts of these areas. Reptiles constitute an exemplary group in the study of the arid environments with numerous well-adapted members, while recent studies using reptiles as models have unveiled interesting biogeographical and diversification patterns. In this study, we include 207 specimens belonging to all 12 recognized species of the genus Stenodactylus. Molecular phylogenies inferred using two mitochondrial (12S rRNA and 16S rRNA) and two nuclear (c-mos and RAG-2) markers are employed to obtain a robust time-calibrated phylogeny, as the base to investigate the inter- and intraspecific relationships and to elucidate the biogeographical history of Stenodactylus, a genus with a large distribution range including the arid and hyper-arid areas of North Africa and Arabia.ResultsThe phylogenetic analyses of molecular data reveal the existence of three major clades within the genus Stenodactylus, which is supported by previous studies based on morphology. Estimated divergence times between clades and sub-clades are shown to correlate with major geological events of the region, the most important of which is the opening of the Red Sea, while climatic instability in the Miocene is hypothesized to have triggered diversification. High genetic variability is observed in some species, suggesting the existence of some undescribed species. The S. petrii - S. stenurus species complex is in need of a thorough taxonomic revision. New data is presented on the distribution of the sister species S. sthenodactylus and S. mauritanicus.ConclusionsThe phylogenetic hypothesis for the genus Stenodactylus presented in this work permits the reconstruction of the biogeographical history of these common desert dwellers and confirms the importance of the opening of the Red Sea and the climatic oscillations of the Miocene as major factors in the diversification of the biota of North Africa and Arabia. Moreover, this study traces the evolution of this widely distributed and highly specialized group, investigates the patterns of its high intraspecific diversity and elucidates its systematics.

Availability of new Bayesian-delimited gecko names and the importance of character-based species descriptions

Leache & Fujita [[1][1]] present an empirical example of Bayesian species delimitation (BSD; [[2][2]]) to recognize three new species of African geckos from within the range of the widespread taxon Hemidactylus fasciatus , Gray 1842. As with any new method, BSD will undoubtedly generate questions

Molecular phylogenetics and historical biogeography of the west-palearctic common toads (Bufo bufo species complex).

In most pan-Eurasiatic species complexes, two phenomena have been traditionally considered key processes of their cladogenesis and biogeography. First, it is hypothesized that the origin and development of the Central Asian Deserts generated a biogeographic barrier that fragmented past continuous distributions in Eastern and Western domains. Second, Pleistocene glaciations have been proposed as the main process driving the regional diversification within each of these domains. The European common toad and its closest relatives provide an interesting opportunity to examine the relative contributions of these paleogeographic and paleoclimatic events to the phylogeny and biogeography of a widespread Eurasiatic group. We investigate this issue by applying a multiproxy approach combining information from molecular phylogenies, a multiple correspondence analysis of allozyme data and species distribution models. Our study includes 304 specimens from 164 populations, covering most of the distributional range of the Bufo bufo species complex in the Western Palearctic. The phylogenies (ML and Bayesian analyses) were based on a total of 1988 bp of mitochondrial DNA encompassing three genes (tRNAval, 16S and ND1). A dataset with 173 species of the family Bufonidae was assembled to estimate the separation of the two pan-Eurasiatic species complexes of Bufo and to date the main biogeographic events within the Bufo bufo species complex. The allozyme study included sixteen protein systems, corresponding to 21 presumptive loci. Finally, the distribution models were based on maximum entropy. Our distribution models show that Eastern and Western species complexes are greatly isolated by the Central Asian Deserts, and our dating estimates place this divergence during the Middle Miocene, a moment in which different sources of evidence document a major upturn of the aridification rate of Central Asia. This climate-driven process likely separated the Eastern and Western species. At the level of the Western Palearctic, our dating estimates place most of the deepest phylogenetic structure before the Pleistocene, indicating that Pleistocene glaciations did not have a major role in splitting the major lineages. At a shallow level, the glacial dynamics contributed unevenly to the genetic structuring of populations, with a strong influence in the European-Caucasian populations, and a more relaxed effect in the Iberian populations.

Origin and Evolution of Paralogous rRNA Gene Clusters Within the Flatworm Family Dugesiidae (Platyhelminthes, Tricladida)

Abstract. Analysis of the 18S rDNA sequences of five species of the family Dugesiidae (phylum Platyhelminthes, suborder Tricladida, infraorder Paludicola) and eight species belonging to families Dendrocoelidae and Planaridae and to the infraorder Maricola showed that members of the family Dugesiidae have two types of 18S rDNA genes, while the rest of the species have only one. The duplication event also affected the ITS-1, 5.8S, ITS-2 region and probably the 28S gene. The mean divergence value between the type I and the type II sequences is 9% and type II 18S rDNA genes are evolving 2.3 times more rapidly than type I. The evolutionary rates of type I and type II genes were calibrated from biogeographical data, and an approximate date for the duplication event of 80–120 million years ago was calculated. The type II gene was shown, by RT-PCR, to be transcribed in adult individuals of Schmidtea polychroa, though at very low levels. This result, together with the fact that most of the functionally important positions for small-subunit rRNA in prokaryotes have been conserved, indicates that the type II gene is probably functional.