Tetraophasis (Galliformes; Phasianidae) includes T. obscurus and T. szechenyii, which are endemic and distributed in the west and central parts of China. The phylogenetic status of Tetraophasis in the Phasianidae and the divergence of the two species are still controversial. We performed a phylogenetic study using DNA sequences of 828bp of the mitochondrial cytochrome b (Cytb) genes of Tetraophasis and of selected species of several other genera of Phasianidae. The phylogenetic trees suggest that Tetraophasis species belong to Phasianinae, which is inconsistent with the traditional taxonomic view that these species belong to Perdicinae. Sequence difference between T. obscurus and T. szechenyii was 3.0-3.1% and the divergence time was 1.88-1.94 Myr based on molecular clock estimate. Compared with other genera, T. obscurus and T. szechenyii should be classified as two distinct species. Our data suggest that the divergence of Tetraophasis may have been induced by the uplift of the Qinghai-Tibet Plateau and by environmental changes.
Islands are ideal settings for the study of evolution, ecology and genetic diversity. The tree sparrow (Passer montanus), which is distributed both inside and outside the Sichuan Basin and is relatively easy to capture, was used as our study species to test whether any genetic differences exist between within and outside of the Sichuan Basin. We analyzed mitochondrial and nuclear gene sequence variations to illustrate the continental island effect within the Sichuan Basin. Overall, fragments from four mtDNA and one nuclear sequence (Cytb + COI + 12S rRNA + Dloop + Myo) were amplified, with the concatenated alignment comprising 3234 bp. The results of Bayesian and maximum parsimony trees indicated two major branches, one of which is composed mainly of populations within the Sichuan Basin, while the other comprised populations distributed in the surrounding mountains. The population in Sichuan Basin was more basal than that in the surrounding mountains. The genetic distance between inner and outer populations was 0.095 and genetic differentiation index (FST) between inner and outer populations was 0.342. This study shows that the overall distribution pattern of tree sparrow populations in the Sichuan Basin and its surrounding mountains is probably the result of a vicariance event due to spatial isolation.
We have used phylogeographic methods to investigate the genetic structure and population history of the endangered Himalayan snowcock (Tetraogallus himalayensis) in northwestern China. The mitochondrial cytochrome b gene was sequenced of 102 individuals sampled throughout the distribution range. In total, we found 26 different haplotypes defined by 28 polymorphic sites. Phylogenetic analyses indicated that the samples were divided into two major haplogroups corresponding to one western and one eastern clade. The divergence time between these major clades was estimated to be approximately one million years. An analysis of molecular variance showed that 40% of the total genetic variability was found within local populations, 12% among populations within regional groups and 48% among groups. An analysis of the demographic history of the populations suggested that major expansions have occurred in the Himalayan snowcock populations and these correlate mainly with the first and the second largest glaciations during the Pleistocene. In addition, the data indicate that there was a population expansion of the Tianshan population during the uplift of the Qinghai-Tibet Plateau, approximately 2 million years ago.