Wenge Dong

Ectoparasitic gamasid mites on small mammals play crucial roles in transmitting zoonotic pathogens like hantaviruses associated with hemorrhagic fever with renal syndrome (HFRS). To elucidate their community, network structure, and seasonal drivers in xeric habitats, a consecutive 12-month localized survey was conducted in Waxi Village, Binchuan County, a dry–hot valley in Yunnan Province, southwest China, from November 2020 to October 2021. From 1329 captured small mammals (18 species, 89.62% rodents), 12,075 gamasid mites belonging to 33 species were identified. The community exhibited overwhelming dominance by the family Laelapidae (C_r = 99.35%) and genus Laelaps (C_r = 97.37%). Laelaps algericus, L. guizhouensis, and L. nuttalli constituted the dominant mite species (cumulative C_r = 88.96%) and formed a tightly correlated core species cluster. Overall infestation prevalence (P_M), mean intensity (MI), and mean abundance (MA) were 46.05%, 19.73 mites/host, and 9.09 mites/host, respectively. The bipartite host–gamasid network revealed a significantly nested architecture (NOD_Fobs = 31.16, Z = 14.03, p < 0.001) with high specialization (H₂′ = 0.599), anchored by dominant hosts (Rattus andamanensis, Apodemus chevrieri, and Mus caroli). α-diversity analysis showed that Margalef richness, Shannon–Wiener index, and Gini–Simpson index peaked in autumn (November), while troughs occurred in mid-spring (April) and mid-autumn (October). Non-metric multidimensional scaling (NMDS, stress = 0.0048) and PERMANOVA (R² = 0.074, p = 0.001) confirmed significant seasonal shifts in community composition. Standard redundancy analysis (RDA) suggested temperature as the primary climatic driver (F = 7.205, p = 0.001; total model explanation = 8.2%). However, partial RDA (pRDA) conditioning on host species identity demonstrated that climatic variables directly accounted for only 0.1% of net variance (F = 0.662, p = 0.521). Our findings indicate that gamasid mite community assembly in this dry–hot valley is characterized by strong species dominance and network nestedness and that seasonal fluctuations are consistent with a host-mediated pattern rather than being directly governed by climate.

Mitogenomes offer valuable insights into evolutionary adaptation. Squirrels have evolved two distinct locomotor modes, gliding and scansorial climbing. To explore whether such locomotor disparities are reflected at the mitogenome level, we newly sequenced the Priapomys leonardi mitogenome and compared it with published mitogenomes of gliding (flying squirrels) and scansorial (tree squirrels). Our result revealed highly conserved mitogenomic organization across both tribes, with consistent gene arrangement, nucleotide composition, codon site base composition, and codon usage patterns. Evolutionary rates showed higher Ka/Ks ratios of ATP8, COX1 , CYTB , and ND5 genes in the Pteromyini than in the Sciurini. Codon usage bias was more than in flying squirrels than in tree squirrels. These results suggested that divergent natural selection acted on these both lineages. We reconstructed the phylogenetic tree of the family Sciuridae. Phylogenetic analysis robustly revealed four monophyletic subfamilies: Ratufinae, Sciurinae, Xerinae, and Callosciurinae. The phylogenetic relationship among these subfamilies was ((Callosciurinae + Xerinae) + Sciurinae) + Ratufinae, with high nodal support. Phylogenetic reconstruction placed Priapomys leonardi within Sciuridae, and supported a sister relationship between Pteromyini (flying squirrels) and Sciurini (tree squirrels). This study provides insights into locomotor mode-linked adaptive evolution and offers a genetic foundation for future research on sciurid phylogeny and species evolution.

Sorex cansulus is a Near Threatened shrew species endemic to China. To elucidate the adaptive evolution and evolutionary relationships of five tribes of the subfamily Soricinae, this study presented the morphology and complete mitogenome of S. cansulus . Codon usage bias analyses indicated that natural selection was the predominant force shaping its mitochondrial protein‐coding genes, with the exception of the atp8 gene. We performed a comparative mitogenome analysis of 43 species across 13 genera and 5 tribes. The evolutionary rates ( K _a / K _s ) of 13 protein‐coding genes across all tribes were significantly less than 1, implying strong purifying selection and evolutionary conservation. Notably, tribes with more similar K _a / K _s ratios exhibited closer evolutionary relationships. Phylogenetic trees yielded identical topologies and strongly supported the monophyly of Soricinae (PP = 1.00; BS = 100%). Both divergence time estimation and phylogenetic trees supported key taxonomic revisions: the reclassification of Episoriculus fumidus to the genus Pseudosoriculus ; the elevation of Blarinella griselda to the genus Parablarinella , and the recognition of S. cansulus and Sorex sinalis as distinct sister species. However, some internal nodes within tribes showed relatively low nodal support, possibly due to incomplete taxon sampling or rapid radiative evolution. All five tribes retained the typical mammalian mitogenome organization, with the notable exception of Sorex daphaenodon , Sorex tundrensis , and Sorex araneus , which possessed an extra trnW gene (23 tRNA genes in total). These three species shared this unique feature and formed a distinct well‐supported clade, the implications of which for their mitochondrial function and adaptation warrant further research.

The genus Echinolaelaps is a group of large gamasid mites. Although only three species are currently known, its taxonomic status is controversial because the species within this genus have strikingly morphological similar characters except for the distance between genito-ventral plate and anal plate. The mitogenomes of the three known Echinolaelaps species range from 14,402 to 15,736 bp in size and share the common feature that the D-arm of trnS₁ and trnC is lacking. Notably, the lack of the D-arm in trnS₁ is common across metazoans, whereas its absence in trnC appears to be a unique, shared derived feature that unites the three Echinolaelaps species into a distinct clade, suggesting it may be a generic characteristic. Such mitogenomic data are valuable for phylogenetic estimation and molecular evolution. In particular, mitochondrial gene rearrangement pattern has been the hot topic in understanding evolutionary processes. Interestingly, the mitogenomes of all three Echinolaelaps species exhibit extensive gene rearrangements and two novel gene arrangement pattern. We found that three Echinolaelaps species share a comparable number of breakpoints with species in Laelapidae and Varroidae. Selection pressure analysis showed differences in rapidly evolving protein-coding genes of three Echinolaelaps species. Although no palindromic repeats directly associated with these rearrangements were detected, other repeat sequences were present. The phylogenetic analysis strongly supports the monophyly of the genus Echinolaelaps. However, the current data remain insufficient to conclusively resolve its precise taxonomic position within the family Laelapidae.

The Thaumapsylla breviceps orientalis is endemic to China and exhibits extreme host specificity (monoxenous). This study reports the first mitogenome sequenced for the family Ischnopsyllidae and provides comprehensive analysis of both the morphological characteristics and mitogenome of T. b. orientalis. The assembled mitogenome is 15,631 bp in length with a high AT content (78.5%), and its codon usage bias is predominantly shaped by natural selection. Evolutionary analysis based on evolutionary rates and nucleotide diversity across different families within Siphonaptera revealed that Pulicidae has the fastest evolutionary rate and the highest nucleotide diversity, a pattern likely driven by differences in their hosts and habitats. We observed that early-diverging flea lineages are predominantly polyxenous, whereas later-diverging lineages are primarily pleioxenous or monoxenous. Phylogenetic results indicate that the taxonomic status of the families Ctenophthalmidae, Vermipsyllidae, and Hystrichopsyllidae requires further study and revision. This research addresses a key knowledge gap in Ischnopsyllidae mitogenomics and clarifies the phylogenetic relationships within the order Siphonaptera.

The Millard’s rat (Dacnomys millardi), a threatened murid endemic to Southeast Asian montane rainforests and the sole member of its monotypic genus, faces escalating endangered risks as a Near Threatened species in China’s Biodiversity Red List. This ecologically specialized rodent exhibits diagnostic morphological adaptations—hypertrophied upper molars and cryptic pelage—that underpin niche differentiation in undisturbed tropical/subtropical forests. Despite its evolutionary distinctiveness, the conservation prioritization given to Dacnomys is hindered due to a deficiency of data and unresolved phylogenetic relationships. Here, we integrated morphological analyses with the first complete mitogenome (16,289 bp in size; no structural rearrangements) of D. millardi to validate its phylogenetic placement within the subfamily Murinae and provide novel insights into genetic diversity erosion. Bayesian and maximum likelihood phylogenies robustly supported Dacnomys as sister to Leopoldamys (PP = 1.0; BS = 100%), with an early Pliocene divergence (~4.8 Mya, 95% HPD: 3.65–5.47 Mya). Additionally, based on its basal phylogenetic position within Murinae, we propose reclassifying Micromys from Rattini to the tribe Micromyini. Codon usage bias analyses revealed pervasive purifying selection (Ka/Ks < 1), constraining mitogenome evolution. Genetic diversity analyses showed low genetic variation (CYTB: π = 0.0135 ± 0.0023; COX1: π = 0.0101 ± 0.0025) in fragmented populations. We propose three new insights into this genetic diversity erosion. (1) Evolutionary constraints: genome-wide evolutionary conservation and shallow evolutionary history (~4.8 Mya) limited mutation accumulation. (2) Anthropogenic pressures: deforestation-driven fragmentation of habitats (>20,000 km²/year loss since 2000) has reduced effective population size, exacerbating genetic drift. (3) Ecological specialization: long-term adaptation to stable niches favored genomic optimization over adaptive flexibility. These findings necessitate suitable conservation action by enforcing protection of core habitats to prevent deforestation-driven population collapses and advocating IUCN reclassification of D. millardi from Data Deficient to Near Threatened.

Trogopterus xanthipes (Sciuridae, Rodentia) is a medium-sized flying squirrel species in the monotypic genus Trogopterus, and is endemic to China. It is distinguishable from other squirrels by the long black hairs on the inner and outer sides at the base of the ears and numerous ridges on the crowns of the upper and lower cheek teeth. Mitogenomes have been widely used in phylogenetic studies. We described T. xanthipes morphological features and successfully sequenced its mitogenome for the first time. The T. xanthipes mitogenome was conserved in number and order of genes. We analyzed codon usage patterns, evolutionary mutation rates, K2P distance, and genetic diversity of protein-coding genes. We reconstructed the phylogeny of Sciuridae (94 species and 21 genera in 4 subfamilies). All phylogenetic trees shared the same topologies and consistently supported the monophyly of Sciuridae, and the supported subfamilies relationship as follows: ((Xerinae + Callosciurinae) + Sciurinae) + Ratufinae. The relationship within the Sciurinae clade was ((Glaucomys + Hylopetes) + ((Trogopterus+Pteromys) + Petaurista) + Sciurus). The relationship within the Callosciurinae clade was Exilisciurus + ((Tamiops + Dremomys) + ((Lariscus+Sundasciurus) + Callosciurus)). The relationship within the Xerinae clade was Sciurotamias + (Tamias + (Callospermophilus + (Marmota + (Spermophilus + (Urocitellus + (Ictidomys + Cynomys)))))). The phylogenetic position among different subfamilies of Sciuridae was consistently recovered with high support across different datasets (PCGRNA and PCG12RNA) and supported the monophyletic lineage of each genus of Sciuridae. Trogopterus xanthipes was sister species to Pteromys volans. Species within the genus formed different minor clades, suggesting relatively high interspecific divergences. The tribe Pteromyini was sister taxon of the tribe Sciurini, which was not supported by the traditional division of Sciuridae into subfamilies Pteromyinae and Sciurinae. Hence, our data supported a division of the Sciuridae into five subfamilies.

Gamasid mites (Acari: Mesostigmata) are ecologically diverse arthropods, many of which act as vectors for zoonotic diseases such as rickettsial pox and hemorrhagic fever with renal syndrome. This study investigates the faunal and ecological patterns of gamasid mites across five zoogeographic microregions in Yunnan Province, China, a biodiversity hotspot with complex topography. From 1990 to 2022, 18,063 small mammal hosts (primarily rodents) were surveyed, yielding 167 mite species (141,501 specimens). The key findings include the following: (1) Low host specificity: most mite species parasitized >10 host species, with Laelaps nuttalli, L. echidninus, Dipolaelaps anourosorecis, L. guizhouensis, L. turkestanicus, and L. chini dominating (>76.59% abundance). (2) Environmental heterogeneity: mountainous and outdoor habitats exhibited higher mite diversity than flatland/indoor environments. (3) Zoonotic risks: thirteen vector species with low host specificity were identified, potentially amplifying disease transmission. (4) Ecological niche dynamics: high niche overlaps (e.g., Laelaps guizhouensis vs. L. xingyiensis: O_ik = 0.997) and positive interspecific correlations (e.g., L. echidninus vs. L. nuttalli: R = 0.97, p < 0.01) suggest co-occurrence trends on shared hosts. (5) Biogeographic patterns: mite communities were clustered distinctly by microregion, with the highest similarity being obtained between western/southern plateaus (IV and V) and unique diversity in the Hengduan Mountains (I). (6) Chao 1 estimation predicted 203 total mite species in Yunnan, 36 of which were undetected in the current sampling. These results highlight the interplay of biogeography, host ecology, and environmental factors in shaping mite distributions, with implications for zoonotic disease surveillance in biodiverse regions.