Structure of macrozoobenthos of the East Dongting nature reserve, with emphasis on relationships with environmental variables

Ecological survey of macrozoobenthos assemblages was carried out at 32 sites in the East Dongting Nature Reserve, located in the northern region of the East Dongting Lake in the middle basin of the Yangtze River, China. All total 51 taxa including 18 oligochaetes, 15 mollusks, 14 insects and four other animals were recorded. Mollusks composed the dominant group and accounted for more than 70% of the total abundance. Assemblages were composed mainly of scrapers (66.7%) and collector-gatherers (nearly 20%), and to a lesser extent collector-filterers (roughly 12%), predators (ca. 7%), and shredders (ca. 6%). Two-way indicator species analysis, detrended correspondence, and canonical correspondence analysis (CCA) were employed to identify the relationships between macrozoobenthos assemblages and environmental variables. Thirty-two sites were separated into four site groups based on composition and relative abundance of benthic macroinvertebrates. CCA detected that water depth, pH, conductivity, SiO2, total nitrogen, total phosphorus, alkalinity, hardness, and Ca2+, were significant environmental factors influencing the pattern of macozoobenthos. In this minimal subset, water depth, pH, alkalinity and hardness were the most influential variables.

Mitochondrial cytochrome b sequence variations and phylogeny of the East Asian bagrid catfishes

The mitochondrial DNA cytochrome b gene was sequenced from 8 bagrid catfishes in China. Aligned with cytochrome b sequences from 9 bagrid catfishes in Japan, Korea and Russia retrieved from GenBank, and selected Silurus meridionalis, Liobagrus anguillicauda, Liobagrus reini and Phenacogrammus interruptus as outgroups, we constructed a matrix of 21 DNA sequences. The Kimura's two-parameter distances were calculated and molecule phylogenetic trees were constructed by using the maximum parsimony (MP) and neighbor-joining (NJ) methods. The results show that (i) there exist 3-bp deletions of mitochondrial cytochrome b gene compared with cypriniforms and characiforms; (ii) the molecular phylogenetic tree suggests that bagrid catfishes form a monophyletic group, and the genus Mystus is the earliest divergent in the East Asian bagrid catfishes, as well as the genus Pseudobagrus is a monophyletic group but the genus Pelteobagrus and Leiocassis are complicated; and 60 the evolution rate of the East Asian bagrids mitochondrial cytochrome b gene is about 0.18%-0.30% sequence divergence per million years.

Sequences of cytochrome b gene for primitive cyprinid fishes in East Asia and their phylogenetic concerning

1140 bp of cytochrome b gene were amplified and sequenced from 14 species of primitive cyprinid fishes in East Asia. Aligned with other ten cytochrome b gene sequences of cyprinid fish from Europe and North America retrieved from Gene bank, we obtained a matrix of 24 DNA sequences. A cladogram was generated by the method of Maximum likelihood for the primitive cyprinid fishes. The result indicated that subfamily Leuciscinae and Danioninae do not form a monophyletic group. In the subfamily Danioninae, Opsariichthys biden and Zacco platypus are very primitive and form a natural group and located at the root. But the genera in subfamily Danioninae are included in different groups and have not direct relationship. Among them, Aphyocypris chinensis and Yaoshanicus arcus form a monophyletic group. Tanichthys albonubes and Gobiocypris rarus have a close relation to Gobioninae. The genus Danio is far from other genera in Danioninae, In our cladogram, the genera in Leuciscinae were divided into two groups that have no direct relationship. The genera in Leuciscinae distributed in Europe, Sibera and North America, including Leuciscus, Rutilus, Phoxinus, N. crysole, Opsopoeodus emilae, form a monophyletic group. And the Leuciscinae in southern China including Ctenopharyngodon idellus, Mylopharyngodon piceus, Squalibarbus and Ochetobius elongatus have a common origination.

Molecular systematics of Xenocyprinae (Teleostei : Cyprinidae): Taxonomy, biogeography, and coevolution of a special group restricted in east Asia

We surveyed mitochondrial DNA (mtDNA) sequence variation in the subfamily Xenocyprinae from China and used these data to estimate intraspecific, interspecific, and intergeneric phylogeny and assess biogeographic scenarios underlying the geographic structure of lineages. We sequenced 1140 bp of cytochrome b from 30 individuals of Xenocyprinae and one putative outgroup (Myxocypris asiaticus) and also sequenced 297 bp of ND4L, 1380 bp of ND4, 68 bp of tRNA(His), and 69 bp of tRNA(Ser) from 17 individuals of Xenocyprinae and the outgroup (M. asiaticus). We detected high levels of nucleotide variation among populations, species, and genera. The phylogenetic analysis suggested that Distoechodon hupeinensis might be transferred to the genus Xenocypris, the taxonomic status of the genus Plagiognathops might be preserved, and species of Xenocypris and Plagiognathops form a monophyletic group that is sister to the genus Distoechodon and Pseudobrama. The introgressive hybridization might occur among the populations of X. argentea and X. davidi, causing the two species to not be separated by mtDNA patterns according to their species identification, and the process and direction of hybridization are discussed. The spatial distributions of mtDNA lineages among populations of Xenocypris were compatible with the major geographic region, which indicated that the relationship between Hubei + Hunan and Fujian is closer than that between Hubei + Hunan and Sichuan, From a perspective of parasite investigation, our data suggested that the fauna of Hexamita in Xenocyprinae could be used to infer the phylogeny of their hosts. (C) 2001 Academic Press.