Niche conservatism and species richness patterns of squamate reptiles in eastern and southern Africa

Niche conservatism has been proposed as a mechanism influencing large‐scale patterns of taxonomic richness. We document the species richness patterns of five monophyletic squamate reptile groups (gekkonids, cordylids‐scincids, lacertids, chameleons and alethinophidian snakes) in eastern and southern Africa, and explore if observed patterns reflect niche conservatism processes. We quantified richness and its relationships with current climatic conditions by gridding species' range maps at 110 × 110 km. Also, dated phylogenies and palaeoclimatic reconstructions, coupled with evidence from the fossil record, were used to approximate the areas and climate characteristics in which each group originated and/or radiated. Mean species richness and geographically corrected confidence intervals in current climate types were calculated for each group in order to establish their climatic preferences. On average, the species richness of older groups (gekkonids, cordylids‐scincids and lacertids) was lower in equatorial climates and higher in arid and temperate conditions, whereas more recent groups (chameleons and alethinophidian snakes) were richer in equatorial and temperate climates and less rich in arid conditions. Across all groups, higher richness was associated with climatic characteristics similar to those prevailing at the time in which each group originated/radiated. The congruence of the current climates where reptile groups are richer and the past climates amidst which those groups originated is consistent with an explanation for their diversity gradients based on niche conservatism.     

Phylogeography of an Italian endemic salamander (genus Salamandrina): glacial refugia,postglacial expansions,and secondary contact

The Italian endemic genus Salamandrina has been historically regarded as monotypic but, recently, studies based on both mitochondrial and nuclear markers have indicated the existence of two distinct species of spectacled salamanders: Salamandrina perspicillata, in central and northern Italy, and Salamandrina terdigitata, in southern Italy. We analyzed nucleotide variation at mitochondrial and nuclear genes [cytochrome b, 12S and 16S rRNA, recombination activating gene (RAG 1)] in 223 individuals from 56 locations, aiming to investigate their genetic structure and recent evolutionary histories. Phylogenetic and phylogeographical analyses revealed the existence of three and two genetically distinct groups of populations in northern and southern salamander, respectively. Historical demographic analyses led to the inference of range expansion for both species in the late Pleistocene. During the last glacial stage, each salamander survived in a single refugium, namely the southern in Calabria and the northern in central Italy. At the end of this period, both lineages expanded northward and established secondary contact. Spatial distribution of RAG 1 haplotype variation revealed two differentiated population groups corresponding to the major mitochondrial (mt)DNA clades. Nuclear pattern of introgressive hybridization was more extensive than the highly limited introgression of mtDNA markers. From a conservation standpoint, southern Latium and Calabria proved to be the major genetic diversity reservoirs, thus deserving particular conservation efforts. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 903–922.     

Genetic structure of a novel biofuel-producing microorganism community

Biofuels are an important alternative, renewable source of energy in the face of the ongoing depletion of fossil fuels. Cheese whey is a dairy industry waste characterized by high lactose concentration, which represents a significant environmental problem. Bio-ethanol production by cheese whey could be an effective nonvegetable source for renewable energy production. Here, we report the isolation of a mixed microbial population, able to produce ethanol as main fermentation product from fermenting whey. The microbial consortium has been used to perform a batch fermentation of crude whey in both anoxic and hypoxic conditions. Maximum ethanol concentrations achieved in this study was obtained using the mixed culture in hypoxic conditions, grown at pH 4 and 30°C, with ethanol production yield of 60 g/L. Our research has pointed out an alternative way to both dispose and valorize cheese whey, a dairy by-product that could cause water pollution and harm to the environment if not properly treated.     

The cost of living slowly: metabolism,Q10 and repeatability in a South American harvestman

Abstract Resources are usually considered to be limited in caves and underground habitats. Therefore, lower metabolic rates of ectotherms in these environments should be advantageous. The standard metabolic rate (SMR) of the common harvestman Pachylus paessleri Roewer, 1913 (Arachnida, Opiliones) is determined at two ambient temperatures. Repeatability of SMR is estimated by two methods: (i) product–moment correlation on residuals of body mass and (ii) variance components. Estimations of the thermal sensitivity of metabolic rate (individual Q₁₀). SMR of P. paessleri at 20 °C show a mean of 19.01 ± 6.04 and 14.99 ± 3.64 μL CO₂ h^?1 for males and females, respectively. Thermal sensitivity of SMR is 2.11 ± 0.23 with a substantial coefficient of variation of 26.7%. In males, residuals of CO₂ release are significantly repeatable (r_p = 0.61) between measurements realized 5 months apart, which reflects the consistency of this trait over time. As typical soil inhabitants, the harvestman P. paessleri present a lower metabolic rate in comparison with arthropods of similar body mass (e.g. arachnids). Although the coefficient of thermal sensitivity is within of the range reported for arthropods inhabiting Mediterranean zones, it is lower than expected for an organism with such a low SMR. This appears to be the first report of repeatability of metabolic rate in a harvestman species.     

Genetic variation and its evolutionary implications in a Mediterranean island endemic lizard

The peculiar bioclimatic and geographic features of Corso–Sardinian islands may provide an ideal scenario for investigating microevolutionary processes, given their large heterogeneity of environments, which could affect dispersal and gene flow among populations, as well as processes of local adaptation. The genetic variation and differentiation among populations of the endemic lizard Archaeolacerta bedriagae were studied by allozyme electrophoresis at 20 presumptive loci. The genetic structure of this species is characterized by relatively high levels of polymorphism and low differentiation among populations. The pattern of genetic differentiation cannot be explained by genetic drift as a function of geographic distance. Genetic distance data show that genetic variation is distributed into three geographically coherent population groups and suggest a recent (Late Pleistocene) origin for the observed geographic fragmentation. The analysis of environmental correlates of allozymic variation indicates a strong correlation of the Idh-1 locus with climatic variables. The frequency of the Idh-1¹⁰⁶ allele is negatively correlated with annual temperature, and positively correlated with annual precipitation. In addition, the observed heterozygosity at this locus decreases towards more arid climatic regimes. The results obtained support the assumption of differential selection acting on Idh-1 allozymes under diverse climates. An association between Idh-1 allozymes and local bioclimatic regimes was also observed for the sympatric lizard Podarcis tiliguerta , suggesting a key role for such selective agents on Idh-1 polymorphism in these two Corso–Sardinian lacertids.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 661–676.     

What is Geosaurus? Redescription of Geosaurus giganteus (Thalattosuchia: Metriorhynchidae) from the Upper Jurassic of Bayern,Germany

The holotype and referred specimens of Geosaurus giganteus, a metriorhynchid crocodile from the Tithonian (Upper Jurassic) of Germany, is redescribed, along with a historical overview of the genus and species. This taxon is unique among metriorhynchids as its serrated, strongly lateromedially compressed dentition is arranged as opposing blades, suggesting it was adapted to efficiently slice through fleshy prey. A new phylogenetic analysis of Crocodylomorpha is presented, which finds G. giganteus to be nested within what is currently considered Dakosaurus, whereas the other species currently assigned to Geosaurus form a clade with Enaliosuchus and the holotype of Cricosaurus. The phyletic relationship of G. giganteus with other metriorhynchids indicates that the current definition of the genus Geosaurus is polyphyletic, and that the inclusion of subsequent longirostrine species to this genus is in error. The re‐analysis presented herein demonstrates Geosaurus to be composed of three species sensu stricto. The appropriate taxonomic amendments to the Metriorhynchidae are also provided. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 551–585.