Yanchao Liu

Gut microbiota influence nutrient acquisition, immune function, and pathogen resistance, yet are rarely considered in ex situ planning. We compared gut bacterial (16S ribosomal RNA; 16S rRNA) and fungal (internal transcribed spacer 1; ITS1) communities of the Tibetan eared pheasant (Crossoptilon harmani), a protected Galliform endemic to the Qinghai–Tibet Plateau, across a management gradient: fully captive (n = 3), wild (n = 7), and free-ranging monastery birds receiving supplementary barley (n = 6); samples were not linked to identified donors, so the kingdoms are compared at group level only. Monastery birds had the numerically highest bacterial Shannon diversity (5.79), above wild (5.54) and captive birds (2.93), although the among-group test was not significant (p = 0.13). Permutational multivariate analysis of variance (PERMANOVA) showed significant bacterial differentiation (Bray–Curtis R² = 0.309, p = 0.001), driven by the captive group, which showed Lactobacillus dominance (51.4%). Fungal communities also differed significantly (R² = 0.194, p = 0.008), with no compositional turnover (Jaccard p = 0.447). Birds in natural habitat with supplementary feeding were no more dissimilar from wild birds than wild birds were among themselves, whereas fully captive birds were clearly separated; this pattern warrants testing in replicated, multi-site studies.

Glaridoglanis verruciloba sp. nov. is described from the Zayul River in southeastern Tibet, China. It has long been misidentified as G. andersonii . This new species is diagnosed by the following combination of characters: an enlarged lower lip bearing 4–7 verruciform lobes on the central-posterior margin; an anus situated close to the origin of the anal fin; the ventral surface at the base of maxillary barbels densely covered with striae; 11 branched pectoral-fin rays; 5–6 branched anal-fin rays; and relatively short mandibular barbels. Molecular phylogenetic analyses of mitochondrial cytochrome b sequences further supported the validity of this new species, which is within a well-supported clade with substantial genetic divergence from G. andersonii .

This paper applies the von Bertalanffy growth equation to study the age structure and growth characteristics of 210 Ptychobarbus dipogon collected in September 2019 in the middle and upper reaches of the Yarlung Zangbo River and employs FISAT II software to estimate the population characteristics’ parameters. Its aim is to provide a basis for the conservation of the population resources of the Ptychobarbus dipogon. In this study, the length of the catch ranged from 137 mm to 475 mm, the weight ranged from 44.04 g to 1142.80 g, the minimum age was 5 years, and the maximum age was 47 years. The body length–weight relationship was W_(♀) = 4.1738 × 10⁻⁵L^2.7687 (n = 86, R² = 0.901); W_(♂) = 2.7784 × 10⁻⁵L^2.8434 (n = 100, R² = 0.918). The growth equation was Lt_(♀) = 505.000[1 − e^{−0.048(t−1.992)}]; Lt_(♂) = 452.254[1 − e^{−0.069(t−4.233)}]; Wt_(♀) = 1296.576[1 − e^{−0.048(t−1.992)}]^2.7687; Wt_(♂) = 1001.872[1 − e^{−0.069(t−4.233)}]^2.8434. The inflection point ages of the female and male Ptychobarbus dipogon were 7.95 and 6.05, respectively. The exploitation rate of Ptychobarbus dipogon was 0.61, which exceeds the optimum exploitation rate of resources (0.57). The population resources are overfished. It is suggested to strengthen the conservation of Ptychobarbus dipogon population resources and the protection of native fish on the Qinghai–Tibet Plateau.

The genus Exostoma is a group of stenotopic and rheophilic glyptosternine catfishes distributed in South and Southeast Asia. So far, comprehensive studies on mitogenomics referring to this genus are very scarce. In this study, we first sequenced and annotated the complete mitochondrial genomes of Exostoma tibetanum and Exostoma tenuicaudatum—two sympatric congeners from the lower Yarlung Tsangpo River, Tibet, China. The mitogenomes of both species contained 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, one light-strand origin of replication, and one control region, with lengths of 16,528 bp and 16,533 bp, respectively. The mitogenome architecture, nucleotide composition, and codon usage of protein-coding genes were almost identical between the two Exostoma species, although some estimated parameters varied. Phylogenetic analysis strongly supported the monophyly of Exostoma in the subfamily Glyptosternae, and Exostoma tibetanum had the closest relationship to Exostoma tenuicaudatum. The divergence time estimation demonstrated that these two species diverged approximately 1.51 Ma during the early Pleistocene, which was speculated to be triggered by the river system changes caused by the uplift of the southeastern Tibetan Plateau. Selection pressure analyses indicated that all protein-coding genes of Exostoma species underwent a strong purifying selection, while minority positive sites from NADH dehydrogenase complex genes were detected. These findings are expected to promote our understanding of the molecular phylogeny of the genus Exostoma and provide valuable mitogenomic resources for the subfamily Glyptosternae.