Levkov, Zlatko

Preferred name

Levkov, Zlatko

Official Name

Levkov, Zlatko

Translated Name

Златко Левков

Main Affiliation

Web Site

12804778000

zlevkov@pmf.ukim.mk

zlevkov@yahoo.com

Scopus Author ID

12804778000

Researcher ID

0000-0002-1184-2356

Now showing 1 - 10 of 30

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Environmental filtering drives assembly of diatom communities over evolutionary time‐scales
(Wiley, 2022-02-25)
Jovanovska, Elena
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Hauffe, Torsten
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Stelbrink, Björn
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Cvetkoska, Aleksandra
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<jats:title>Abstract</jats:title><jats:sec><jats:title>Aim</jats:title><jats:p>Ecological communities are structured through the interplay of deterministic assembly processes such as competition and environmental filtering. Whereas the drivers of spatial community structure are frequently studied in extant communities, little is known about the relative importance of assembly processes in response to environmental factors over evolutionary time‐scales. Here, we use an integrative framework to unravel community assembly processes since the inception of a long‐lived lake ecosystem.</jats:p></jats:sec><jats:sec><jats:title>Location</jats:title><jats:p>Lake Ohrid.</jats:p></jats:sec><jats:sec><jats:title>Time period</jats:title><jats:p>From lake formation 1.36 million years ago to the present.</jats:p></jats:sec><jats:sec><jats:title>Major taxa studied</jats:title><jats:p>Planktonic diatoms.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We constructed a dated phylogeny of extant and extinct diatoms and collected trait data for 380 fossil communities to quantify phylogenetic community structure and functional richness and to determine the relative importance of deterministic assembly processes over time. We then used regression analysis to correlate the phylogenetic community structure with palaeoenvironmental and intrinsic biological predictors and to identify primary drivers of assembly processes.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Our results suggest a dense packing of niche space with higher species richness and co‐occurrence of closely related species. There are only two short episodes in the very recent past dominated by distantly related taxa. We found distinct changes in phylogenetic community structure upon speciation or extinction events and an increase in mean community relatedness over time.</jats:p></jats:sec><jats:sec><jats:title>Main conclusions</jats:title><jats:p>Our finding of closely related co‐occurring species implies environmental filtering as the primary assembly mechanism, with a minor but increasingly important role of competition towards the present, driven by evolutionary dynamics. Such an increase in the relative contribution of competition to the assembly of communities in relation to the aging of an insular ecosystem, together with a denser packing of morphospace in the early phase of system ontogeny is compatible with ecological predictions according to the theory of island biogeography.</jats:p></jats:sec>
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Cymbopleura amicula stat nov. et. nom. nov. (Bacillariophyceae)—a rare diatom species from a karst river in Croatia
(Magnolia Press, 2022-01-28)
GLIGORA UDOVIČ, MARIJA
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KULAŠ, ANTONIJA
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ŠUŠNJARA, MIRELA
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ARAPOV, JASNA
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BLANCO, SAUL
<jats:p>The Krka River is located at Balkan Peninsula in the Dinaric region of Croatia and it is a typical groundwater-fed karst river characterized by an unusual phenomenon-tufa. Tufa designates porous CaCO3 deposits forming under specific physical and chemical conditions and hosting very diverse freshwater biota. Karst springs are considered one of the most diverse habitats for diatoms and are usually inhabited by specific diatom assemblages, which include the Krka spring zone. However, such habitats are particularly impacted by human activities, so previous studies have recently been conducted to raise awareness of the importance of karstic spring zones, especially because they are inhabited by specific and rare species. During the research at Krka River, samples were collected in the spring zone in May 2017, and the observations revealed the existence of a one Cymbopleura species characterized by slightly convex to almost linear valves, which are slightly protracted, broadly rounded and weakly dorsally bent at the apices. Based on detailed morphological analyses on light and scanning electron microscopy it appears that this population resembles two previously described taxa: C. rupicola var. minor Krammer and C. rupicola var. korana Krammer. Here we provide a more detailed description of the mentioned population under the new name Cymbopleura amicula stat. nov. et nom. nov. due to the significant differences from C. rupicola, together with a comparison with similar taxa in Cymbopleura.</jats:p>
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Asymmetry in Luticola species
(Informa UK Limited, 2019-04-03)
Kulichová, Jana
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Neustupa, Jiří
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Vrbová, Kateřina
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Kopalová, Kateřina
Morphological asymmetry in raphid pennate diatoms is detectable not only by valve outline and specific frustule features, but also in their ontogeny. All raphid pennate diatoms exhibit cryptic lateral polarity, which is associated with the asymmetric formation of the valve sides along the apical axis. Differences in the relative widths of primary and secondary valve sides have proven taxonomically important for separating dorsiventral genera within the Cymbellales. However, rigorous studies examining subtle asymmetric differences in valve outline are scarce. In the present geometric morphometric study of 23 Luticola species, the total asymmetry in valve outline of natural populations was decomposed into components of directional asymmetry (DA) and fluctuating asymmetry (FA) to test whether cryptic directional asymmetry has a significant effect on valve outlines across the genus as a whole. The patterns of asymmetric variation provide a view on average asymmetry of populations (evaluated by DA) and individual asymmetric deviations (associated with FA). Subtle, but statistically significant, average irregularities between the primary and secondary sides of Luticola species (i.e., the effect of DA) were found in all but two species. Patterns of DA between valve sides were quite similar in 17 of the analysed species. This likely indicates common developmental patterns in their morphogenesis. The effect of FA, which has often been used as a proxy of developmental instability of populations, was significant in all Luticola species. Since FA scores of individual cells were not correlated with size diminution of most species, FA might reflect the effect of environmental factors but not life cycle changes. The methodological framework presented in this study could be valuable for future work focused on evolutionarily and/or environmentally related shape aberrations and valve variation in pennate diatoms.
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Diatom eDNA metabarcoding and morphological methods for bioassessment of karstic river
(Elsevier BV, 2022-07)
Kulaš, Antonija
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Gligora Udovič, Marija
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Tapolczai, Kálmán
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Žutinić, Petar
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Orlić, Sandi
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New Amphora and Halamphora (Bacillariophyta) species from springs in the northern Apennines (Emilia-Romagna, Italy)
(Botanical Garden Meise, 2019-07-09)
Cantonati, Marco
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Angeli, Nicola
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Lange-Bertalot, Horst
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Background and aims – The detailed analysis of algae and cyanoprokaryotes in a heterogeneous group of spring habitats (including all the different typologies) of the northern Apennines (Emilia-Romagna Region, Italy) revealed a new Amphora species in a small mountain flowing spring with low conductivity, and a new Halamphora species in a large, inland-saline (Triassic gypsum), fast flowing spring (Poiano spring). The present study aims to describe in detail these two new species found in contrasting spring types. Methods – This study is based on light microscopy (both fresh –for plastids – and prepared materials) and scanning electron microscopy observations, as well as a thorough morphological, physical, chemical, and biological characterization of the habitats. Key results – Amphora eileencoxiae sp. nov. is most similar to A. vetula (and allied taxa), and is characterized by the outline with acutely rounded, moderately ventrally bent ends, by the dimensions, and by the well-defined, semi-elliptic dorsal area. Halamphora poianensis sp. nov. is most similar to H. gasseae but differs by the higher stria density, the clearly ventrally bent ends, and the strongly developed dorsal raphe ledge. Conclusions – This is a contribution to the knowledge of the genera Amphora and Halamphora in mountain springs in understudied geographic areas and inland-saline springs, the species communities of which are likely insufficiently explored.
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Observations of the genus Muelleria (Bacillariophyceae) from the Republic of North Macedonia
(Botanical Garden Meise, 2019-07-09)
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Vidaković, Danijela
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Cvetkoska, Aleksandra
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Mitić-Kopanja, Danijela
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Krstić, Svetislav
Background and aims – An increased interest in the diatom flora from subaerial habitats in the Republic of North Macedonia has revealed the presence of a large number of interesting and often unknown, species. During a recent biodiversity survey, seven Muelleria species were recorded, several of which could not be identified based on the available literature. Methods – Using both Light Microscopy and Scanning Electron Microscopy techniques, the morphology of several Muelleria species has been analysed. The morphology of all taxa is described, illustrated and compared with other possible similar Muelleria taxa, known worldwide. Key results – Four already documented Muelleria species, M. gibbula, M. islandica, M. terrestris and M. undulata (= Navicula gibbula f. undulata) were identified, while two distinct species are described as new. These new species belong to the M. gibbula complex, and can be differentiated by valve size, stria density, shape of the proximal raphe ends and the shape of external areola foramina. The identity of one taxon remains uncertain due to a low number of observed specimens in the samples. As their ultrastructure is almost entirely unknown, they are briefly discussed. Conclusions – The diversity of Muelleria in Europe and the North Hemisphere is most likely underestimated and some of the previous records of M. gibbula belong to other species. Observations of diatoms from “extreme” habitats such as intermittent ponds, wet mosses and soils can reveal the existence of interesting and new species.
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Envekadea vranaensis sp. nov. a new diatom species (Bacillariophyta) from the lacustrine Holocene sediments of Lake Vrana, Croatia
(Schweizerbart, 2020-03-13)
Mihalić, Katarina Caput
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Galović, Ines
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Wetzel, Carlos E.
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Ector, Luc
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Ilijanić, Nikolina
A new species, Envekadea vranaensis Caput Mihalić, Galović & Levkov sp. nov., is described from Holocene sediments of Lake Vrana, Croatia. The new species is characterized by linear-lanceolate valves with broadly capitate apices and is 40.0–67.5 μm long and 7.5–9.0 μm wide. Based on its morphological features it is similar to E. hedinii and E. pseudocrassirostris. Also, E. vranaensis shares morphological and ultrastructural features with E. vanlandinghamii, from which it can be differentiated by the valve outline, shape of the apices, stria density and the shape of proximal raphe endings. We present stratigraphic occurrence and ecological preferences for E. vranaensis based on associated paleoecological proxies.
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Filling reference libraries with diatom environmental sequences: strengths and weaknesses
(Informa UK Limited, 2023-04-03)
Kochoska, Hristina
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Chardon, Cécile
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Chonova, Teofana
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Keck, François
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Kermarrec, Lenaïg
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Two new Amphora species from European rivers compared to morphologically similar species of the Amphora copulata complex (Catenulaceae, Bacillariophyceae)
(Informa UK Limited, 2025-12-15)
Heudre, David
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Van de Vijver, Bart
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Werum, Marcus
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Lange-Bertalot, Horst
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Moreau, Laura
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Description of Gomphonella saldanensis sp. nov. (Bacillariophyceae) from hydromagnesite stromatolites in Salda Lake, Turkey
(Informa UK Limited, 2023-04-03)
Solak, Cüneyt Nadir
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Hamilton, Paul B.
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Wishkerman, Asher
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Yilmaz, Elif

Levkov, Zlatko

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