Žurnal obŝej biologii

Endophytic bacterial communities in leaves participate in pathogen control, plant immune responses and the induction and mediation of stress resistance through the production of hormones and antioxidants. Understanding the composition, structure and factors influencing microbiome formation will enable us to consider plants as holobionts. Consequently, adaptation can be viewed not merely as a physiological and biochemical response, but rather as the ability of plants to shape the composition of their own microbiome. For the first time, data were obtained on the composition and structure of bacterial endophytes in the leaves of plants from four communities of the alpine belt of the Northwest Caucasus. These communities differed significantly in the number of bacterial taxa and the Shannon diversity index. However, no significant differences were observed between alpine snow bed communities and Geranium–Hedysarum meadows at various taxonomic levels. The factors studied had differing effects on abundant and less-represented bacterial taxa, often the factor has a significant effect only at the level of one group. The greatest influence on the composition of bacterial endophytes in plant leaves in the alpine communities was exerted by the community type and plant taxonomy. The contribution of the factors examined to the formation of leaf endophytic bacterial communities decreased in the following order: host plant taxonomy → community type → plant functional traits ≈ topographic factors.

The introduction of pike-perch (Sander lucioperca) into Alakol Lake system (south–east of the Republic of Kazakhstan) and the ongoing acclimatization measures led to the transformation of fish community and changed the pattern of food relationships between predators. The native Balkhash perch (Perca schrenki) in the native fish community, being an optional predator, was at the top of the food pyramid. After naturalization, pike-perch acquired a higher trophic status, and perch began to play the role of an intermediate predator. There occurred an extension of the trophic network and the involvement of acclimatizing species in it. The increase in the numbers of pike-perch led to the “squeezing” of the Balkhash perch on freshwater lakes Sasykkol and Koshkarkol from the pelagic zone into the tributary system. This was facilitated by the availability of non-utilized resources of the native fauna, as well as its high reproductive potential. At the same time, the biomass of the alien in freshwater lakes increased faster than the food resource was produced and utilized, whereas in Lake Alakol this was prevented by environmental factors (mineralization). In the early 90s of the last century, the numbers of pike-perch in all lakes of the system stabilized, and since the early 2000s, high fishing pressure began to restrain its growth, which allowed Balkhash perch in freshwater lakes Sasykkol and Koshkarkol to increase their numbers and repopulate the pelagic waters of these water bodies. Regulation of pike-perch numbers opens up the possibilities of preserving the Balkhash perch as a unit of biological diversity. However, the detection of a catfish predator in the lakes of the system in 2024 may again curtail the process of restoring its numbers.