Fifteen shades of green: The evolution of Bufotes toads revisited.

The radiation of Palearctic green toads (Bufotes) holds great potential to evaluate the role of hybridization in phylogeography at multiple stages along the speciation continuum. With fifteen species representing three ploidy levels, this model system is particularly attractive to examine the causes and consequences of allopolyploidization, a prevalent yet enigmatic pathway towards hybrid speciation. Despite substantial efforts, the evolutionary history of this species complex remains largely blurred by the lack of consistency among the corresponding literature. To get a fresh, comprehensive view on Bufotes phylogeography, here we combined genome-wide multilocus analyses (RAD-seq) with an extensive compilation of mitochondrial, genome size, niche modelling, distribution and phenotypic (bioacoustics, morphometrics, toxin composition) datasets, representing hundreds of populations throughout Eurasia. We provide a fully resolved nuclear phylogeny for Bufotes and highlight exceptional cyto-nuclear discordances characteristic of complete mtDNA replacement (in 20% of species), mitochondrial surfing during post-glacial expansions, and the formation of homoploid hybrid populations. Moreover, we traced the origin of several allopolyploids down to species level, showing that all were exclusively fathered by the West Himalayan B. latastii but mothered by several diploid forms inhabiting Central Asian lowlands, an asymmetry consistent with hypotheses on mate choice and Dobzhansky-Muller incompatibilities. Their intermediate call phenotypes potentially allowed for rapid reproductive isolation, while toxin compositions converged towards the ecologically-closest parent. Across the radiation, we pinpoint a stepwise progression of reproductive isolation through time, with a threshold below which hybridizability is irrespective of divergence (<6My), above which species barely admix and eventually evolve different mating calls (6-10My), or can successfully cross-breed through allopolyploidization (>15My). Finally, we clarified the taxonomy of Bufotes (including genetic analyses of type series) and formally described two new species, B. cypriensis sp. nov. (endemic to Cyprus) and B. perrini sp. nov. (endemic to Central Asia). Embracing the genomic age, our framework marks the advent of a new exciting era for evolutionary research in these iconic amphibians.

Amphibians distribution and habitats in the southwestern region of Saudi Arabia.

This study surveyed 205 wetland sites in the Southwestern Saudi Arabia. We found seven species of amphibians (Anura), which belong to four families: Bufonidae; which includes four species, Sclerophrys tihamica; S. Arabica, Duttaphrynus dhufarensis, and Bufotes viridis; Hylidae, represented by only one species, the tree frog Hyla savignyi; Ranidae, which represented by one species, Pelophylax ridibundus and finally the Dicroglossidae, represented by one species, Euphlyctis ehrenbergii. The reasonable amount of rain received in southwest Arabia, and habitat diversity contribute to the relative abundance of amphibians in the region. Five types of wetland habitats were found in the study area. Valley streams, irrigated farms, seasonal ponds, dam reservoir and lagoons of treated sewage water. The current study revealed the wide spread of amphibians in southwestern Saudi Arabia than what had been reported earlier and confirmed the presence of the Bufotes viridis at three new sites in Asir Heights. It also showed the wide spread of S. arabica in all types of habitats in the southwestern region of Saudi Arabia. Habitat degradation was evident in the region, which might lead to species loss.

Histological, molecular and biochemical detection of renal injury after Echis pyramidum snake envenomation in rats.

Nephrotoxicity is a common sign of snake envenomation. The present work aimed to clarify the effect of intraperitoneal injection of 1/8 LD50 and 1/4 LD50 doses of Echis pyramidum snake venom on the renal tissue of rats after 2, 4 and 6 h from envenomation. Histopathological examination showed intense dose and time dependent abnormalities, including swelling glomerulus and tubular necrosis and damage as well as signs of intertubular medullary hemorrhage at early stages of envenomation. However, at late stages of envenomation by any of the doses under investigation, no intact renal corpuscles were recorded and complete lysis in renal corpuscles with ruptured Bowman's capsules was observed. Immunohistochemistry by immunohistochemical staining was used to test the protein expression of Bax in renal tissue of rats. The result showed that the expression of Bax in renal tissue sections of envenomated rats was increased according to dose and time-dependant manner. The isolation of DNA from the renal cells of envenomed rats pointed out to the occurrence of DNA fragmentation, which is another indicator for renal tissue injury especially after 6 h of 1/4 LD50 of E. pyramidum envenomation. Oxidative stress biomarkers malondialdehyde and nitrite/nitrate levels, antioxidant parameters; glutathione, total antioxidant capacity and catalase were assayed in renal tissue homogenates. The venom induced significant increase in the levels of malondialdehyde and nitrite/nitrate while the levels of glutathione, total antioxidant capacity and catalase were significantly decreased, especially after 6 h of envenomation. The results revealed that the E. pyramidum induced dose and time-dependant significant disturbances in the physiological parameters in the kidney. We conclude that the use of the immunohistochemical techniques, the detection of DNA integrity and oxidative stress marker estimations are more specific tools that can clarify cellular injury and could point out to the defense activity of the renal tissue at envenomation.