Marina Vladimirovna Olonova

Rapid plant radiations under climatic oscillations are widely recognised, yet our understanding of how taxonomically complex, polyploid-rich lineages diversify in extreme environments remains limited. Here, we investigated non-model Eurasian bluegrasses ( Poa sect. Stenopoa ), a challenging group inhabiting cold deserts, alpine grasslands, and semi-arid steppes. We utilised DArTseq genotyping of 373 individuals to infer phylogenetic relationships, identify key adaptive traits, test evolutionary scenarios, estimate demographic histories, and integrate palaeoclimatic niche reconstructions to trace the role of glacial–interglacial cycles in shaping diversification. Our findings reveal three major genetic groups that diverged during the Middle Pleistocene, partly uncoupled from morphological differentiation. Demographic analyses indicate divergence from a small ancestral population, followed by niche partitioning, secondary contact, and episodic gene flow promoted by glacial oscillations. Morphological traits associated with cold and arid tolerance further demonstrate ecological adaptation beyond genetic divergence. This research highlights how climate fluctuations and episodic hybridisation structure the diversification of this complex polyploid lineage. Moreover, our results illustrate a general framework for resolving evolutionary histories of challenging taxonomic groups, underscoring that integrative genomic and palaeoclimatic approaches can reveal mechanisms of rapid speciation in non-model taxa under changing environments.

Brachypodium sylvaticum is a perennial woodland grass selected as a model species for perenniality, which is widely distributed across the Palearctic. This plant forms a symbiosis with the endophytic fungus Epichloë sylvatica. Despite its widespread distribution and ecological importance, the evolutionary history of the B. sylvaticum complex and the role of its fungal symbiont remain poorly understood, and no integrative phylogeographic study of the grass-endophyte holobionts has been conducted to date. We hypothesize that niche dynamics and host-fungal interactions shaped the diversification and current distribution of the complex. We integrate whole-genome phylogenomics, plastome analysis, environmental niche modeling (ENM), and coevolutionary analyses to investigate the diversification of B. sylvaticum and its fungal symbiont. Using 94 representative individuals spanning Eurasia and North Africa, we recovered two deeply divergent sister lineages (Eastern and Western Palearctic), with cytonuclear discordances suggesting historical plastid capture events in the western group. Admixture analysis revealed four genetic clusters, including signatures of secondary contact and hybridization in the Western lineage. Filtered ITS sequences of E. sylvatica recovered from holobiont genome skimming reads enabled phylogenetic reconstruction, revealing two fungal clades that broadly mirror their host's evolutionary history in the West. Parafit and Procrustes Application to Cophylogenetic (PACO) analyses supported partial co-divergence between hosts and endophytes. ENM projections identified climatically stable glacial refugia for both B. sylvaticum main lineages during the Last Glacial Maximum and asymmetric postglacial expansion, with moderate niche shifts in the West and stronger turnover in the East. Evidence of niche overlap and similarity indicated niche conservatism among clades, suggesting that geographic isolation, rather than adaptive divergence, was the primary driver of lineage splitting. IBD and IBE patterns significantly influenced divergences in the Western, but not the Eastern, group, highlighting contrasting demographic and ecological dynamics. Our results provide the first evidence of coevolutionary and ecological structuring in B. sylvaticum–E. sylvatica holobionts across their Western native range, highlighting how this ubiquitous host–endophyte association may have contributed to the ecological success, persistence, and expansion of the complex under Quaternary climatic fluctuations.

The names of five Alopecurus L. varieties and three Puccinellia Parl. varieties, described by V. V. Reverdatto from Yenisei Siberia, namely Alopecurus pratensis L. var. caesius Reverd., A. pratensis var. firmus Reverd., A. ventricosus Pers. var. hirtulus Reverd., A. ventricosus var. lobatus Reverd., A. ventricosus var. submuticus Reverd., Puccinellia hauptiana (V. I. Krecz.) Kitag. var. elata Reverd., P. hauptiana var. minor Reverd., and P. tenuiflora (Griseb.) Scribn. et Merr. var. capillifolia Reverd., are validated by translating the original Reverdatto’s descriptions into English, and/or indicating type specimens.

Pоа bashkirica, a new species from Bashkiria, South Ural (Russia) is described and illustrated. Morphologically, it is similar to P. korshinskyi, P. transbaicalica and P. argunensis but differs from the first two species with lemmas, pubescent between veins, and from P. argunensis with the distribution. From all mentioned species it differs by culms purple at the base.

Brachypodium sylvaticum is a perennial woodland grass selected as model species for perenniality, which is widely distributed across the Palearctic. This plant forms a symbiosis with the endophytic fungus Epichloë sylvatica . We integrate whole-genome phylogenomics, plastome analysis, environmental niche modeling (ENM), and coevolutionary analyses to investigate the diversification of B. sylvaticum and its fungal symbiont. Using 94 representative individuals spanning Eurasia and North Africa, we recovered two deeply divergent sister lineages (Eastern and Western Palearctic), with cytonuclear discordances suggesting historical plastid capture events in the western group. Admixture analysis revealed four genetic clusters, including signatures of secondary contact and hybridization in the Western lineage. Filtered ITS sequences of E. sylvatica recovered from holobiont genome skimming reads enabled phylogenetic reconstruction, revealing two fungal clades that broadly mirror their host’s evolutionary history in the West. PACo and ParaFit analyses supported partial co-divergence between hosts and endophytes. ENM projections identified climatically stable glacial refugia for both B. sylvaticum main lineages during the Last Glacial Maximum and asymmetric postglacial expansion, with moderate niche shifts in the West and stronger turnover in the East. Evidence of niche overlap and similarity indicated niche conservatism among clades, suggesting that geographic isolation, rather than adaptive divergence, was the primary driver of lineage splitting. IBD and IBE patterns significantly influenced divergences in the Western, but not the Eastern, group, highlighting contrasting demographic and ecological dynamics. Our results provide the first evidence of coevolutionary and ecological structuring in B. sylvaticum – E. sylvatica holobionts across their Western native range.

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Poa sorengiana,a new species from Uttarakhand, Western Himalaya is described and illustrated. Morphologically, it is somewhat similar to P. nemoralis and P. orinosa but differs from both with unique combination of main qualitative characteristics.

The Siberian kandyk (Erythronium sibiricum (Fisch. et Mey.) Kryl.) is listed in the Red Books of the Russian Federation and in the regions where it grows. The Siberian kandyk is widespread in Southern Siberia and Mongolia. This species has many useful qualities, for example, it is used for decorative purposes, for introduction, in folk medicine and for obtaining honey. The purpose of the work is to identify the ecological and climatic niche of the species and build on its basis a model of suitable habitats in the conditions of modern climate. The MaxEnt 3.4.4 and BIOCLIM methods implemented in the statistical programming environment R (CRAN) were chosen as tools for analysis and modeling. For visualization and information of previously obtained layers, the ArcGIS 10.8 program is convenient. As a result of the work done, it became obvious that the current distribution of the species as a whole corresponds to the obtained model of distribution of favorable conditions for the growth of the species, and the reduction in the number of plants is caused by other reasons.

Poa botryoides (Trin. ex Griseb.) Kom. is a predominantly Siberian mountain-steppe species, occupying an intermediate position between P stepposa (Kryl.) Roshev. and P attenuata Trin., from which it is poorly isolated morphologically. A digital map of P botryoides distribution was compiled, based on 143 localities, revealed from herbarium materials and reliable literary sources; the ecologo-climatic niche of this species was constructed on the basis of 19 climatic parameters. The histograms revealed similarities between the precipitation plots of the driest quarter and the coldest quarters, as well as the wettest and warmest quarters. This can be explained by the high correlation between the season and the amount of precipitation. Two-dimensional “climatic envelopes” constructed both for the average annual values of temperature and precipitation, and for the values of temperature and precipitation during the growing season, showed the spread of values, as well as the number of individuals in atypical climatic conditions. Maps reflecting the spatial location of these “atypical” points showed that most of them are located in the humid regions of the Far East, which makes us pay more attention to the P. botryoides samples collected in these territories.