Phylogeographical and speciation patterns in subterranean worm lizards of the genus Blanus (Amphisbaenia: Blanidae)

Abstract

The peculiar lifestyle of subterranean reptiles must determine their modes of speciation and diversification. To further understand the evolutionary biology of subterranean reptiles, we studied the phylogeny of worm lizards of the genus Blanus and the phylogeography of its Iberian representatives. We used mitochondrial (ND4 and 16S rRNA) and nuclear (anonymous) partial gene sequences to resolve phylogenetic relationships within Blanus. The Eastern Mediterranean Blanus strauchi was recovered as sister group of Western Mediterranean species. Iberian and North African Blanus were recovered as reciprocally monophyletic groups. The same genes were used to determine phylogeography of 47 populations of Blanus cinereus. Mitochondrial and nuclear sequence data recovered two highly supported Iberian clades. Parapatry and high sequence divergences between them suggest that these clades may represent independent taxonomic units. A molecular clock was calibrated considering that the split between Iberian and North African Blanus was due to the re-opening of the Betic Strait in the Upper Tortonian (8-9 million years ago). Differentiation between the two Iberian clades was estimated to date back to 5.2 million years ago. The Central Iberian clade included five mitochondrial haplotype lineages (A-E). Geographical ranges of two of them broadly overlap in the central Iberian plateau. After testing alternative hypotheses, the most likely explanation for this striking phylogeographical pattern involves recent dispersal of one of the lineages (C) over the geographical range of the other (B). The inferred recent dispersal of this fossorial reptile is explained in terms of demographic advantages associated to underground lifestyle.

Rudimentary Eyes of Squamate Fossorial Reptiles (Amphisbaenia and Serpentes)

“…Considering that degeneration and reduction of the eyes are considered as typical examples of fossorial adaption, because these characteristics are also observed in fossorial amphibious and mammals, (Duke-Elder, 1958;Sanyal et al, 1990;Cooper et al, 1993b;CernudaCernuda et al, 2002;Nikitina et al, 2004;Schepper et al, 2005;Albert et al, 2007), Burda et al (1990) raise a question on what could explain a tendency to eye reduction in most underground animals; the authors state that the absence of selective forces that would promote functional development of the eyes propitiate a stagnation in the development of these organs. Nonetheless, the little eye can be considered as a positive feature, because the fossorial animals are constantly protected from receiving dirt on such sensitive organ; this protective role is also played by the spectacles.…”

Biogeographical patterns derived from remote sensing variables: the amphibians and reptiles of the Iberian Peninsula

“…Effectively, most biogeographical studies on these taxonomic species group have been carried out at regional scale (Busack, 1977;Bas López, 1984;Flores et al, 2004); at national scale (Araújo, 1999); or in protected areas (e.g., Soares and Brito, 2007). However, the Iberian Peninsula is a very appealing region to study the chorotypes of amphibians and reptiles because it is a species-rich area and, considered as a biodiversity hotspot in the Mediterranean Basin, it is a well known glacial refugia for amphibians and reptiles with high levels of genetic diversity (Gómez and Lunt, 2007), where many cryptic forms has been identified in the last years (e.g., Blanus worm lizards, Albert, Zardoya and Garcia-Paris, 2007; Podarcis wall lizards, Pinho, Harris and Ferrand, 2007). As these taxonomic groups are particularly susceptible to habitat-and climatic changes due to their ectothermic physiology and low dispersal capacity, the study on the distribution of amphibians and reptiles in the Iberian Peninsula can as well be considered as a priority for the development of studies related with their biogeographical traits (Gibbons et al, 2000;Houlahan et al, 2000).…”

Salt lakes of La Mancha (Central Spain): A hot spot for tiger beetle (Carabidae, Cicindelinae) species diversity

“…As a result of this complex history, the diversification of the Iberian biota has attained such a level as to be considered part of one of the 25 world hotspots of biodiversity (Myers et al 2000). The complexity of the Iberian faunal assemblages is enhanced by the persistence of representatives of ancient lineages (Machordom and Doadrio 2001, Martínez-Solano et al 2006, Albert et al 2007, Gonçalves et al 2007), together with the settlement of Holocene recent immigrants from the African Continent (Carranza et al 2004, Recuero et al 2007). …”