Vol 102, No 10 (2023)

The fine structure and chemical composition of the shell growth margin were compared in diploid and triploid oysters, Crassostrea gigas (Thunberg 1793), reared to commercial size in a Crimean marine farm. The diploid oysters were deposited from plankton, whereas the triploid ones were obtained from an Atlantic coast nursery. An electron scanning microscope SEM Hitachi U 3500 with built-in software Oxford Ultin Max 65 for microanalysis was employed in the study. The shell growth margin is shown to consist of two layers: periostracum and prismatic. The periostracum in diploid oysters is smooth and porous, whereas the periostracum of triploid oysters is volumetric and shows longitudinal folds. The prismatic layer of both right and left shell valves consists of prisms surrounded by organic membranes. In contrast to diploid oysters, triploid ones have longer prism facets, their calcite filling is significantly lower than normal, their interprismatic organic membranes are discontinuous and contain calcium carbonate. The proportion of organic matter in diploid oyster shells is significantly higher than that in triploid ones. The factors affecting the fine structure of oyster shells differing in ploidy are discussed.

The faunal composition of Amphipoda crustaceans of mainland water bodies in northwestern Russia is analyzed. To compile a checklist of amphipod species, data from original collections made in 1998–2021, the collections of the Zoological Institute, and literary information are used. To date, 29 species of amphipods have been recorded from the continental waters of the region. An arealogical analysis of the faunal composition reveals six groups or distribution patterns: Holarctic, West Palearctic, and North Atlantic estuaries, and further three groups of emigrants (settlers) from the Baikal-Siberian, Ponto-Caspian, and Arctic regions. The greatest species richness is recorded in estuarine sections of Baltic Sea rivers in the territories of the Leningrad and Kaliningrad regions, as well as fresh water bodies of the Republic of Karelia. In terms of species richness, estuarine species amphi-Atlantic in distribution and representatives of allochthonous faunas (invasive species) from the Ponto-Caspian basin dominate the region. The most common in the region are representatives of Holarctic and Palearctic patterns, as well as species of Arctic and Baikal-Siberian origins. Among them, the following species are most often to be recorded in lakes: Gammarus lacustris, Monoporeia affinis, Palaseopsis quadrispinosa and Gmelinoides fasciatus, vs G. zaddachi, G. oceanicus, G. tigrinus and Pontogammarus robustoides in estuarine brackish waters. Human-mediated introductions, both intentional and accidental, must have facilitated the appearance of invasive species in the fauna of Russia’s northwestern region. In the future, an increase in species richness in the region can be expected to occur in two ways: through the introduction of marine species into fresh waters and due to speciation.

A brief historical review is presented of the development of approaches to the study of the territorial space of songbirds (Oscines), using both older and modern research methods. The study of bird territoriality lasts more than a century, but there are still not only little-known aspects that remain in this direction, but also no consensus on terminology and methods. The description of the territorial space plays leading roles in such works. In turn, the classic objects of such research are songbirds demonstrating their territories by singing and defending them from invasion by other individuals. There have been many definitions of the term “territory” proposed, which reflect different concepts of territoriality. The most common definition of a territory thereby is a defended (conceptually) and demonstrated (operationally) space. As a rule, this space is a certain area, a projection of the real territory to the surface on the ground. In recent decades, however, publications have appeared on the topic of exploring territories as three-dimensional (3D) structures. The most effective method of field registration of territories remains the territory mapping method based on visual observations of tagged individuals, which has also been adapted for 3D-territories. Alternative approaches to the registration of territories, including radio telemetry, have significant limitations. In terms of quantitative data-processing methods, there has been a shift over the past decades from an analysis of territories as polygons to their analysis as kernel isopleths. This approach allows for not only the territory contours to be understood, but also the frequency of the use of different points within its limits to be assessed. A significant achievement in the recent years is the adaptation of the kernel methods to three-dimensional structures. It can be said that there is a need to study the territoriality of birds in a 3D-environment. Such research seems very promising because it can provide fundamentally new information on such things as habitat selection and space use, the formation of the spatial and ethological structure of settlements, the separation of territories under high population densities and limited resources, and both intra- and interspecific competition.

Human activity generates new global processes, including range expansions caused by landscape transformations, climate change, and biological invasions. The study of the causes and processes that accompany the colonization of new areas, as well as its ecological and evolutionary consequences, has been rapidly developing in the last 20 years at the junction between such areas of biology as spatial ecology, ecology of movement, ecology of invasions, metapopulation theory, behavioural ecology, evolutionary ecology, population genetics, and personality research. In our review, we summarize theoretical ideas and empirical studies to answer two main questions: what makes colonists distinguished from the residents of source populations and what specific demographic and genetic processes drive and accompany the wave of population expansion?

This research was supported by the Russian Science Foundation (project number 22-14-00223, https://rscf.ru/project/22-14-00223/).

The Asiatic wild ass is one of the last wild, free-roaming equid species left in Northern Eurasia. Once widespread across Asia and Eastern Europe, the wild ass is presently listed as a near-threatened species on the IUCN Red List. The conservation of this species is one of important issues of wildlife ecology, while investigating its prehistoric range may provide some perspective into its current distribution and abundance. However, the data available on its past distribution are limited to the last few centuries. We review the available information using both published and unpublished sources to document the sub-fossil sites in Kazakhstan where bones of the species have been reported. Our analysis reveals 70 such sites of Holocene age ranging from Neolithic to modern years. The past range in the Neolithic-Eneolithic and Bronze Age extended from the steppe zone in the north to the desert zone in the south of Kazakhstan. In the Iron Age, remains of Equus hemionus became absent from the fossil record in the northern and central parts of Kazakhstan, thus suggesting a decreased range or abundance of the equid. This coincided with climate changes that occurred during the Bronze–Iron Age transition and the development of nomadic pastoralism. Since the Iron Age human societies in western and central Kazakhstan were predominantly nomadic herders, and livestock impacts on resources could have limited the wild ass distribution. An increased anthropogenic disturbance in 19–20 centuries could eventually have led to population decline in Asiatic wild ass and its extinction in the wild.