Systematics,biogeography and evolution of Asaccus gallagheri (Squamata,Phyllodactylidae) with the description of a new endemic species from Oman

The Hajar Mountains are the highest mountain range in eastern Arabia. Despite being classified as a mountain desert, it is considered one of the top biodiversity hotspots of Arabia. As a result of its relatively old geological origin, complex topography, environmental heterogeneity and geographic isolation from other mountain ranges, its fauna and flora have diversified significantly producing high levels of endemicity, particularly amongst reptiles. Several genetic studies indicate that this diversity may still be underestimated, especially within some groups containing morphologically similar species like the nocturnal geckos of the genus Asaccus. These have radiated extensively on both sides of the Gulf of Oman, in the Hajar Mountains and the Zagros Mountains of south-west Asia, and are a good example of the faunal affinities between these two mountain ranges. In the present work, we analyse A. gallagheri, the smallest species of the Arabian radiation, using an unprecedented sampling across its entire distribution range and an integrative approach combining morphological, macroecological and multilocus molecular data with the objective of clarifying its systematics and phylogeography. The results support the presence of two allopatric species within A. gallagheri that split approximately 6 Ma. The newly discovered species is endemic to the Eastern Hajars and is described herein mainly on the basis of its smaller size and high genetic divergence from A. gallagheri. The molecular analyses also uncovered remarkable levels of genetic diversity within both species. The present study highlights the diversity of the genus Asaccus in south-east Arabia and stresses its relevance from a conservation point of view.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:62EB3146-9F79-4857-8CC6-36FE235D84D4     

Impact of Robertsonian translocation on meiosis and reproduction: an impala (Aepyceros melampus) model

The captive bred animal populations showing centric fusion polymorphism can serve as a model for analysis of the impact of the rearrangement on meiosis and reproduction. The synapsis of homologous chromosomes and the frequency and distribution of meiotic recombination events were studied in pachytene spermatocytes of captive bred male impalas (Aepyceros melampus) polymorphic for der(14;20) by immunofluorescent analysis and fluorescence in situ hybridization. The chromosomes 14 and 20 involved in the centric fusion were significantly shorter due to the loss of sat I repeats indicating ancient origin of the rearrangement. The fused chromosome and the normal acrocentric chromosomes 14 and 20 formed trivalent in pachynema which showed either protruding proximal ends of the acrocentric chromosomes or single axis with synaptic adjustment in the pericentromeric region. There was no significant difference in the number of recombination events per cell between the group of translocation heterozygotes and the animals with normal karyotype. A significant reduction in the number of recombination events was observed in the trivalent chromosomes compared to the normal chromosomes 14 and 20. The level of the recombination reduction was related to the trivalent configuration. The centric fusion der(14;20) was not apparently demonstrated by any spermatogenic defects or reproductive impairment in heterozygous impalas. However, the high incidence of the chromosomal polymorphism within the captive bred population shows the importance of cytogenetic examinations in captive breeding and wildlife conservation programs, especially in the case of reintroduction of the endangered species.     

Systematics,biogeography, and evolution of Pristurus minimus (Squamata,Sphaerodactylidae) with the discovery of the smallest Arabian vertebrate

Almost 20% of Oman’s terrestrial reptiles are found on Masirah Island. Despite its ancient geological history and its long isolation, Masirah Island only harbours one endemic reptile species, Hemidactylus masirahensis. In this study, we use an integrative approach to explore the variation in Pristurus minimus, to revise its systematics and to assess its phylogeography by using molecular (mitochondrial and nuclear DNA sequences) and morphological data. Our results uncovered a deep divergence within P. minimus that dates back to ～4?Ma, during the Pliocene Epoch. The old divergence separated P. minimus into two allopatric species: one from mainland Arabia, P. minimus, and one endemic to Masirah Island, described as a new species herein. Despite the general similarity between the two sister species, there are morphological differences related mainly to body size. The new Pristurus species endemic to Masirah Island is significantly smaller than its mainland sister taxon, becoming the smallest known vertebrate species in Arabia and one of the smallest lizard species in the world. The phylogenetic analyses also uncovered a low level of genetic diversity within the newly described Pristurus species endemic to Masirah Island and a relatively deep genetic divergence within P. minimus that dates back to the Pleistocene. Once more, the present study highlights the relatively high levels of reptile diversity and endemicity in south-eastern Arabia despite its harsh, arid climate and stresses its relevance from a conservation point of view.

The LSIDs for this publication is: urn:lsid:zoobank.org:pub:DB0658D5-7F68-4E66-885F-75E27F9CD512.