We studied the effects of grazing on plant community structure and total plant biomass across the landscape while taking account of nutrient gradient, from wet and nutrient‐rich sites (north‐facing steppe) to dry and nutrient‐poor sites (south‐facing steppe) in semiarid steppe of northern Mongolia. Livestock grazing increased species richness of wet and nutrient‐rich sites, while no significant change was observed in dry and nutrient‐poor sites. The species richness increase in the wet and nutrient‐poor sites was explained by local colonization of grazing‐tolerant species. Species that adapted in the wet and nutrient‐rich sites were driven to local extinction as a consequence of competitive exclusion. At a large spatial scale, livestock grazing can have a potential negative effect on a regional species pool, as it excludes species adapted in wet and nutrient‐rich sites. Although grazing did not affect species richness in the dry and nutrient‐poor south‐facing steppe, plant communities under grazing shifted to dominance by short and prostrate forb species. A spatial difference of the total plant biomass across the landscape was higher in non‐grazed landscape but this difference lessened in grazed landscape. The greatest percentage reductions of the total plant biomass due to grazing were in wet and nutrient‐rich sites. In conclusion, at a community level, plant communities responded differently to livestock grazing, but at an ecosystem level, the total plant biomass decreased under grazing across the landscape of the semiarid boreal steppe. The livestock grazing in the wet and nutrient‐rich sites resulted in the disappearance of moss cover, which is the main insulator of permafrost. The loss of moss cover could potentially accelerate a thawing of permafrost and warming of this region. Also, we found different results on dominance of Artemisia frigida Willd. from those reported in the steppe of Inner Mongolia. At a regional scale, this species might not be considered as an indicator species of livestock grazing.

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Land-use practices in Mongolia can lead to environmental degradation and consequently affect the structure and function of biological communities. The main aim of this study was to determine land-use effects on freshwater macroinvertebrate communities based on their response to grazing and mining, using a trait-based approach (TBA). The functional structure of macroinvertebrate communities was examined using 86 categories of 16 traits. A total of 13 physical and chemical variables were significantly different among the levels of land-use intensity. Significant declines in functional diversity were observed with increased land-use intensity. The community weighted mean of 19 trait categories for 11 traits varied significantly among different levels of land-use intensity. Traits were significantly explained by environmental variables across a land-use intensity gradient. Water temperature, gravel, nitrate, silt, and cobble were the main predictor variables and explained 28% of the total variance of the trait variation. The functional structure of the macroinvertebrate community was strongly related to environmental conditions. The TBA is an important method in assessing disturbance responses in freshwater communities of steppe and taiga regions, such as in Mongolia and other countries in Central Asia and will be useful in finding best management practices for conserving aquatic ecosystems. Handling editor: Checo Colón-GaudElectronic supplementary material The online version of this article (https://doi.

A macrogenomic investigation of a Holarctic clade of black flies—the Simulium cholodkovskii lineage—provided a platform to explore the implications of a unique, synapomorphic whole-arm interchange in the evolution of black flies. Nearly 60 structural rearrangements were discovered in the polytene complement of the lineage, including 15 common to all 138 analyzed individuals, relative to the central sequence for the entire subgenus Simulium. Three species were represented, of which two Palearctic entities (Simulium cholodkovskii and S. decimatum) were sympatric; an absence of hybrids confirmed their reproductive isolation. A third (Nearctic) entity had nonhomologous sex chromosomes, relative to the other species, and is considered a separate species, for which the name Simulium nigricoxum is revalidated. A cytophylogeny is inferred and indicates that the two Palearctic taxa are sister species and these, in turn, are the sister group of the Nearctic species. The rise of the S. cholodkovskii lineage encompassed complex chromosomal and genomic restructuring phenomena associated with speciation in black flies, viz. expression of one and the same rearrangement as polymorphic, fixed, or sex linked in different species; taxon-specific differentiation of sex chromosomes; and reciprocal translocation of chromosome arms. The translocation is hypothesized to have occurred early in male spermatogonia, with the translocated chromosomal complement being transmitted to the X- and Y-bearing sperm during spermatogenesis, resulting in alternate disjunction of viable F1 translocation heterozygotes and the eventual formation of more viable and selectable F2 translocation homozygous progeny. Of 11 or 12 independently derived whole-arm interchanges known in the family Simuliidae, at least six are associated with subsequent speciation events, suggesting a facilitating role of translocations in adaptive radiations. The findings are discussed in the context of potential structural and functional interactions for future genomic research.

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