[Geographic patterns and ecological factors correlates of snake species richness in China].

Understanding large-scale geographic patterns of species richness as well its underlying mechanisms are among the most significant objectives of macroecology and biogeography. The ecological hypothesis is one of the most accepted explanations of this mechanism. Here, we studied the geographic patterns of snakes and investigated the relationships between species richness and ecological factors in China at a spatial resolution of 100 km×100 km. We obtained the eigenvector-based spatial filters by Principal Coordinates Neighbor Matrices, and then analyzed ecological factors by multiple regression analysis. The results indicated several things: (1) species richness of snakes showed multi-peak patterns along both the latitudinal and longitudinal gradient. The areas of highest richness of snake are tropics and subtropical areas of Oriental realm in China while the areas of lowest richness are Qinghai-Tibet Plateau, the grasslands and deserts in northern China, Yangtze-Huai Plain, Two-lake Plain, and the Poyang-lake Plain; (2) results of multiple regression analysis explained a total of 56.5% variance in snake richness. Among ecological factors used to explore the species richness patterns, we found the best factors were the normalized difference vegetation index, precipitation in the coldest quarter and temperature annual range ; (3) our results indicated that the model based on the significant variables that (P<0.05) uses a combination of precipitation of coldest quarter, normalized difference vegetation index and temperature annual range is the most parsimonious model for explaining the mechanism of snake richness in China. This finding demonstrates that different ecological factors work together to affect the geographic distribution of snakes in China. Studying the mechanisms that underlie these geographic patterns are complex, so we must carefully consider the choice of impact-factors and the influence of human activities.

[Microstructure comparison of jaw sheaths between the Megophryid tadpoles (Amphibia, Anura) by the technology of electron microscope].

The jaw sheaths morphology of eight megophryid larvae were examined using scanning electron microscope. The morphology of jaw sheaths of Leptobrachiinae and Leptolalaginae larvae was similar. Their jaw sheaths were U-shaped and strong keratinized, the serrations were pyramidal, with broad-based and short pointed. While the jaw sheaths of Megophryinae larvae were less curved and weak keratinized, the serrations were ivory-shaped, with narrow-based and long pointed. It has been found that the relationship between serration's diameter and density was negatively correlated, the changing trend reflected the functional significance of serrations. These distinctions among the jaw sheaths of tadpoles most could be related to their specific ecological habits and to their dietary specializations.

[Population genetic differentiation of Phrynocephalus axillaris in east of Xinjiang Uygur Autonomous Region based on sequence variation of mitochondrial ND4-tRNALeu gene].

A 838 bp fragment of mtDNA ND4-tRNALeu gene was sequenced for 66 individuals from five populations (DB: Dabancheng, TU: Turpan, SS: Shanshan, HL: Liushuquan, HD: East district of Hami) of Phrynocephalus axillaris distributed in east of Xinjiang Uygur Autonomous Region. Seventeen haplotypes were identified from 29 nucleotide polymorphic sites in the aligned 838 bp sequence. Excluding DB, there were relatively high haplotype diversity [(0.600+/-0.113)

[The research on the karyotypes of six species in the genus Eremias from China].

Based on the Giemsa-dyeing karyotypes and silver-staining bands of 15 populations from different localities in China belonging to 6 species of the genus Eremias , We found all species studied have 19 pairs of chromosomes, the size of chromosomes reduces gradually and there are no marked differences between the arranged pairs of macrochromosomes except the last pair of microchromosome. There are the same karyotype formula as 2n=38=36I+2m with NF=38 in E. argus, E. multiocellata, E. velox, E. arguta and E. grammica; but the karyotype formula of E. vermiculata is different as 2n=38=12V+2sI+22I+2m with NF=50. The NOR are all located on one small pair in female of E. velox, and E. arguta , in male of E. grammica and E. vermiculata ,and in both male and female of E. multiocellata. We have not found two or more than two pairs of NOR. Having one pair of NOR may be common in Genus Eremias and also the trait of Eremias. We speculate that the derivation of the karyotype of E. vermiculata had two possible way: one experienced the stage of triploid, and later the Robertsonian transposal of chromosomes; the other way was through the inversions between the arms on the chromosome and the phenomenon of inversions might occur during or subsequently after the upheaval of the Tibet and Qinghai plateau and the founding of the Tianshan . With regard to the trend of the evolution of chromosomes in the lizards ([1]), the karyotype of E. vermiculata is more advanced. Making specialties of E. vermiculata will help in building the phylogenic tree of Eremias. In both male and female of the species studied, the heteromorphic sex-chromosomes were not found.