Resources

The Quaternary glaciations profoundly shaped the biogeography of plants and animals, yet their impact on microbial eukaryotes remains largely unexplored. We tested the “genetic legacy of the Quaternary” (GLQ) paradigm in terrestrial protists using Arcellinida testate amoebae diversity distribution across the Iberian Peninsula, a well‐established glacial refugium. To do so, we compiled the most extensive Arcellinida metabarcoding dataset to date (ArKOI), including 615 samples from multiple continents and ecosystems. Our results showed that hotspots of intra‐OTU genetic diversity align with known Iberian refugia, supporting the concept of “refugia within refugia,” and displaying clear ecoregion‐specific climatic niches. Patterns of spatial clustering, niche breadth, and historical demographic reconstruction revealed repeated range contractions and expansions during the Pleistocene, mirroring those observed in macro‐organisms. These findings extend the GLQ paradigm to protists, highlighting shared historical and ecological processes across the eukaryotic tree of life and contributing to a unified theory of biogeographic responses to climatic change.

Climate change models point to a possible rise in air temperature, ranging from 2 °C to 4 °C. Global changes will therefore have a particularly pronounced effect on the functioning of shallow water bodies known as peat ponds, i.e., habitats formed after peat extraction in peatlands. However, the extent of this impact is still unknown. The main objective of the study was to determine the impact of water level and water physicochemical properties on the functioning of selected groups of aquatic organisms in peat ponds of different origins. The study was conducted in spring, summer and autumn of the years 2024 and 2025, in 10 peat ponds with different trophic status and typology, located in the Polesie National Park in eastern Poland. Considerable fluctuations in water levels, resulting from a scarcity of precipitation, accelerated the drying out and overgrowth of peat ponds, particularly the alkaline and acidic types. Within the zoocoenotic communities, a significant decline in the abundance of planktonic species and an increase in the abundance of littoral or periphytic species were recorded (F = 6.24, p < 0.015). Regarding trophic structure, an increase in the abundance of mixotrophic species and a decrease in the abundance of top-level predators were observed. Hydrological changes were reflected in an increase in species richness and abundance of communities of organisms with broad ecological tolerance (mainly ciliates), and a decrease in the number of species and abundance of planktonic crustaceans and macroinvertebrates. The RDA model explains over 84% of the total variability, indicating excellent model fit to the data and a strong correlation between environmental variables and species composition. Based on p values, water level, temperature, pH, and COD were selected as significant variables, with conductivity, O2, and Ptot demonstrating less statistical significance. Peat ponds ecosystems can serve as an excellent model system for studying the impact of intensifying climate change on the functioning of shallow water bodies.

Testate amoebae are known among the proxies for paleolimnological investigations but, despite their recognized importance and recent findings, they have not been sufficiently studied in alpine lakes, particularly in Europe. The present study analyzes fossil testate amoeba assemblages from the Upper Balma Lake (2216 m a.s.l., Western Alps, Italy) to reconstruct ecological changes over the past 1200 years. 21 species belonging to 5 genera were identified, with Centropyxis and Difflugia being the most abundant. Multivariate statistical analyses, combined with sedimentological and geochemical data, revealed five paleoenvironmental phases corresponding to known climatic events, including the Medieval Climate Anomaly, the Little Ice Age, and the Recent Warming period. Assemblage composition and diversity were related to grain size variations, nutrient input, and trace element concentrations (e.g., As, Mn, Mo) and periods of climatic stability were associated with higher biodiversity, while cold or disturbed intervals, marked by floods or sediment reworking, resulted in reduced abundances and diversity. In recent decades, a decline was observed for the genus Centropyxis , possibly indicating reduced oxygenation and changes in contaminant levels. Comparative analysis with the Lower Balma Lake, located downstream in the same area, highlighted the influence of morphological/hydrological differences between lakes on species distributions. The findings underscore the value of testate amoebae as sensitive bioindicators and their applicability in paleoecological reconstructions of alpine lakes. This study contributes to understanding long-term ecological responses to climate change and provides insights into flood regime variability in high-mountain environments.

Non-pollen palynomorphs (NPPs) are important ecological indicators and are increasingly used in the study of Arctic ice-wedge polygon mires in Siberia. This paper provides an overview of NPPs found in high-spatial-resolution (1 m sample distance) surface samples along transects crossing various polygon microtopographical elements, and in high-temporal-resolution (sample distance 0.5 cm) contiguous samples in peat profiles. Whereas algal palynomorphs - of e.g. Botryococcus, Pediastrum, and various Zygnemataceae - show a distinct presence in open water settings, testate amoebae tests - of Arcella, Assulina, and Amphitrema flavum - are typical for dry peatland settings such as polygon rims. Various other NPPs were encountered including types not yet described. The latter have been denominated using morphological terms to facilitate future identification. These types are often typical for distinct polygon microhabitats and thus have indicator values that allow the reconstruction of past ecological settings without knowing the taxa that produce them.

Peatlands are susceptible not only to direct disturbance, but also to indirect changes in their surroundings, including land management. Changes in agricultural practices or forest management can significantly influence peatland functioning, for example, their trophic status or surface vegetation. Here, we investigate the effects of planned forestry on two Sphagnum -dominated peatlands in northern Poland’s Tuchola Forest. We use testate amoebae and compare them to available pollen and historical data to reconstruct past environmental conditions and assess anthropogenic pressure. The Tuchola Forest has undergone significant transformations as a result of human activities, notably during Prussia’s promotion of pine monoculture in the 19th century. We hypothesized that forest management activities and other related disturbances have led to wetland acidification and water table alterations. Our results show that these changes have had profound effects on both peatlands. Radiocarbon dating revealed a correlation between forest management practices and peatland dynamics. Quantitative reconstructions based on testate amoebae showed that, as a result of the introduced pine monoculture, both peatlands experienced rapid acidification (pH levels dropping from ca. 6.2 to 3.5) and water table lowering of over 15 cm. The predominance of pine monoculture has not only reduced biodiversity but also enhanced the susceptibility of the forest to fires and pest outbreaks, further affecting peatland conditions. These findings contribute to understanding of how historical land-use changes continue to influence present-day peatland dynamics, offering insights into restoration and conservation efforts in forested peatland landscapes.

The application of molecular approaches has revealed an immense biodiversity of lobose testate amoebae (Amoebozoa, Tubulinea, Elardia, Arcellinida). However, most newly discovered species are difficult or impossible to differentiate morphologically from already described forms, even though they are genetically distinct. Consequently, while diversity assessments based on sequence data overtake classical estimations of Arcellinida diversity, only a handful of morphologically divergent species have been discovered recently. These species are of key importance for reconstructing the evolutionary history of Arcellinida, including both morphology and morphogenesis. Here, we describe a large and conspicuous new species, Cylindrifflugia luciferina , found in an urban pond located in the Royal Botanical Garden of Madrid, Spain . We characterize it morphologically and molecularly, together with the closely related species Cylindrifflugia elegans . Our phylogenetic reconstruction based on the SSU rRNA gene brings evidence for three main well supported and morphologically consistent clades within the infraorder Cylindrothecina. This example illustrates that the quest for new Arcellinida diversity is far from being over and even the less expected ecosystems can bring new discoveries.

This article examines the shelled amoebae of freshwater bodies. From 2017 to 2022, a total of 28 species, 2 classes, 2 orders, 7 families, and 28 genera of shelled amoebae have been identified within the Nakhchivan Autonomous Republic. As an ecological indicator, shelled amoebae are used to assess the environmental condition, particularly the level of pollution in soil and water.

Species delimitation in unicellular organisms remains a significant challenge, primarily due to the limited number of taxonomically informative traits and their often adaptive nature. Moreover, most original descriptions of testate amoebae, dating from the late 19th to mid-20th century, relied solely on light microscopy, were often accompanied by inadequate diagnoses, and lacked illustrative drawings. To address the limitations of the historic phenetic classification, modern approaches are needed to resolve fundamental questions concerning true biodiversity and phylogenetic relationships. In this study, I employed an integrative framework that combines ecological data, morphological data (light and scanning electron microscopy), and biometric measurements to investigate the testate amoeba Galeripora dentata (Ehrenberg, 1830) Siemensma, 2021 from Bulgaria. I provide an improved diagnosis of the species, along with a synthesis of its global geographical distribution and ecological preferences.

Abstract: Aim We aimed to understand how testaceous amoebae spread in new sites, assessing their dispersal potential by wind and animals in freshwater ecosystems. Methods We conducted a field experiment over 33 days between July and August 2018. The study included four different approaches: (i) a control group exposed exclusively to wind, (ii) the addition of propagules dispersed by Odonata (aquatic insects), (iii) the addition of propagules dispersed by amphibians, and (iv) the combined addition of propagules of both animals. Results We detected a total of 13 species of testate amoebae. Regarding species richness, we observed a steady increase throughout the experimental period. In terms of abundance, a similar trend was observed, with differences in the treatment of all vectors combinated, when comparing the treatments with only wind, and the combination of wind and vectors alone, indicating a possible progressive colonization of these organisms in the new aquatic environment. Regarding the composition of testate amoebae, we did not detect significant differences between treatments within each period or between different treatments throughout the experiment. Conclusions Our results demonstrate the importance of animal vectors in the transport of testate amoebae cysts.

Peatlands have been among the world's fastest-disappearing ecosystems, facing human pressure, especially over the last two centuries. The drainage of peatlands has long been pursued to expand agricultural and forestry areas as well as for peat extraction. One of the most degraded peatlands in western Poland is the Bagno Chlebowo, of which a small part is legally protected, having a raised bog status. The peatland has been undergoing drainage and peat mining since the 19th century, and regardless of its partial protection since 1959, it continues to be subjected to drainage, further compromising the function of the nature reserve. Our research focuses on reconstructing the impact of anthropogenic pressure on the state of the peatland over the last 600 years. We applied palaeoecological methods to reconstruct changes in water table levels, acidity (pH) and local plant cover over time. Additionally, we utilized historical maps to gather data on the area's land use and land cover changes. Our findings reveal that drainage and peat harvesting significantly increased the pH level of the peatland, consequently promoting Sphagnum expansion. These recent changes in vegetation cover and increased acidity have led to inaccuracies in correctly identifying peatland type. Therefore, the palaeoecological record makes us question its current protection status as a true raised bog, suggesting that the site was a fen for most of the time of its functioning. We demonstrate that long-term reconstructions are, therefore, substantial for nature conservation to (1) properly assess the status of wetlands, (2) identify baseline conditions, and (3) plan suitable restoration and protection methods. • Drainage and peat extraction have altered peatland, revealing human impact on ecosystem. • Paleoecology offers insights into peatland changes and aids in setting restoration goals. • Overlooking ecological history may misclassify peatlands, stressing history's role in conservation. • Using outdated data in conservation plans may mislead efforts and harm fragile peatlands.