Dubravka Milić

Heavy metal content in halophytic plants from inland and maritime saline areas

We investigated the concentration of Aluminium (Al), Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni) and Zinc (Zn) in the root and aboveground organs of four halophyte species (Salicornia europaea, Suaeda maritima, Salsola soda and Halimione portulacoides), as well as in the soil from maritime and inland saline areas. The aim of our research was to evaluate the capability of some halophyte species to absorb different heavy metals and to detect differentiation of heavy metal accumulation within populations from inland and maritime saline areas. Generally, the plant roots had significantly higher concentrations of metals when compared to stems and leaves. Zinc was the only metal with concentrations significantly higher in the leaves than in the root and stem. Populations from maritime saline areas had higher trace root and stem metal concentrations than populations from inland saline areas. Excepting zinc, populations from inland saline areas had higher heavy metal concentrations in the leaves. The factors that affected metal accumulation by halophytes included the percentage of salt in the soil. We also discuss the potential use of these halophytes in phytoremediation.

Molecular and Morphological Inference of Three Cryptic Species within the Merodon aureus Species Group (Diptera: Syrphidae).

The Merodon aureus species group (Diptera: Syrphidae: Eristalinae) comprises a number of different sub-groups and species complexes. In this study we focus on resolving the taxonomic status of the entity previously identified as M. cinereus B, here identified as M. atratus species complex. We used an integrative approach based on morphological descriptions, combined with supporting characters that were obtained from molecular analyses of the mitochondrial cytochrome c oxidase I gene as well as from geometric morphometry of wing and surstylus shapes and environmental niche comparisons. All applied data and methods distinguished and supported three morphologically cryptic species: M. atratus stat. nov., M. virgatus sp. nov. and M. balkanicus sp. nov., which constitute the M. atratus species complex. We present an identification key for the sub-groups and species complexes of the M. aureus species group occurring in Europe, describe the taxa and discuss the utility of the applied methods for species delimitation. The estimated divergence times for the species splits of these taxa coincide with the Pleistocene Günz-Mindel interglaciation and the Great interglaciation (between the Ris and Mindel glacial periods).

Alien invasive neophytes of the Southeastern part of the Pannonian Plain

Floristic diversity in the Pannonian Plain is the result of mosaic habitat composition, characterized by steppes, saline meadows, and lowland forests along major rivers. In the last few centuries, the flora has become enriched by species introduced by human activities, such as colonization and industrialization. Presently it consists of nearly 1800 species. As a result of 30 years of field research as well as herbarium and literature searches, a list of invasive alien neophytes has been compiled and is presented here. The list includes 152 species, classified as either naturalized, casual, or unknown. One of the species is listed in Red Book of Serbian Flora. Eighty species are naturalized, and 61 are casual species. The majority of the introduced flora originates from North America (66) and the Old World (43). Most alien invasive species of the Southeastern part of the Pannonian Plain, were introduced accidentally by seed material or deliberately by nursery saplings. The annual and perennial herbaceous plants, which flower in the summer and summer-autumn periods, are represented in the greatest numbers. The alien flora was further analyzed with respect to taxonomy, life forms, pollination, and seed dispersal mode. The greatest number of alien species appears in anthropogenic and semi-natural habitats (59). In natural habitats, 45 invasive taxa were recorded, representing a conservation threat to biodiversity.

Environmental niche divergence of species from Merodon ruficornis group (Diptera: Syrphidae)

In this paper we analyzed environmental differentiation of closely related species from the Merodon ruficornis group. By applying principal component analysis (PCA) and environmental niche modelling (ENM)-based techniques, we estimated the level of niche divergence of closely related species. Our results indicate that ecology has an important role in the diversification process in related species from the M. ruficornis group. Distribution patterns of all analyzed species are mainly affected by the limiting effects of the temperature of the coldest quarter and month, as well as by the precipitation of the wettest and driest quarters. Our results demonstrated that among all related species, with the exception of M. ovaloides , overall or partial divergence in environmental space is present. Importantly, the results indicate that the environmental niches of all endemic species are restricted to smaller parts of the environmental space. In the case of niche overlap, the niches of endemic species are placed along the border of the realized niche of the widespread related species. For species in which distribution is not limited by geographical barriers, environmental preferences could be considered as limiting factors for further expansion, as in the case of M. alexandri , a lowland species with very strict climatic adaptations. Knowledge about the environmental factors that might influence the diversification process can provide an explanation for the high diversity in other Merodon species groups. https://doi.org/10.2298/ABS160303095A Received: March 3, 2016; Revised: April 8, 2016; Accepted: May 10, 2016; Published online: October 17, 2016 How to cite this article: Acanski J, Milicic M, Likov L, Milic D, Radenkovic S, Vujic A. Environmental niche divergence of species from Merodon ruficornis group (Diptera: Syrphidae). Arch Biol Sci. 2017;69(2):247-59.

The Analysis of Petiole Histological Traits Through an Evaluation of Water Deficit Tolerance of Sugar Beet Genotypes

Water stress is considered as one of the most widespread limitations to sugar beet productivity and yield stability. Since leaf is the most significantly affected organ by drought, we focused on the petiole histological features of ten sugar beet genotypes that previously showed divergent responses to lack of water in the field. The aim was to calculate volume densities of petiole different tissues and determine the histological sources of the genotypic differences in the breeding material with respect to water use efficiency. Comparative histological analysis of the petiole was performed using classic anatomical (proximal and distal segments) and stereological methods. The plants were grown in semi-controlled glasshouse conditions. The general structure of the sample variability was established by Principal component analysis, based on the correlation matrix data. This study suggests that determination of the variation in the histological characteristics of the petioles can play an important role in water management in plants. The results reveal a higher level of variability in morphometric parameters due to the fact that petiole cross-section shapes change with its maturity. Characteristics, such as (i) petiole shape, (ii) arrangement and number of vascular bundles, (iii) number and size of vessels, (iv) volume density and distribution of collenchyma, and (v) volume density of parenchyma are promising criteria that can help in the selection of more drought tolerant genotypes.

Prediction of current species distribution of Cheilosia proxima group (Diptera: Syrphidae) on the Balkan peninsula

Predicting species distribution in different climates is most often made by climate models (“climate envelope models” - CEM) which are using the current geographical distribution of species and climate characteristics of the area. Hoverflies (Insecta: Diptera: Syrphidae) can act as bioindicators and monitors of climate change and habitat quality. Cheilosia Meigen, 1822 is one of the largest hoverflies genera, with about 450 described species. The aim of this study was to model the current potential distribution of six species from Cheilosia proxima group on the Balkan Peninsula (Cheilosia aerea Dufour, 1848, C. balkana Vujic, 1994, C. gigantea Zetterstedt, 1838, C. pascuorum Becker, 1894, C. proxima Zetterstedt, 1843 and C. rufimana Becker, 1894) using maximum entropy modeling (Maxent). It is observed that parameters with highest influence on the analyzed species are Altitude and BIO 15 (Precipitation Seasonality) for all species, except C. rufimana. Parameter that also substantially influenced for all species, except C. pascuorum, is BIO 18 (Precipitation of Warmest Quarter). The models of current distribution have shown that the most important area of the Balkan Peninsula, for species from Cheilosia proxima group, is Dinaric mountains. Information obtained in this paper can help in future monitoring of species, as well as for the conservation measures, especially for endemics and rare species. [Projekat Ministarstva nauke Republike Srbije, br. 173002 i br. 43002]