Vijabilnost populacija tekunice Spermophilus citellus (L., 1766) na području Srbije
Viability of European ground squirrel Spermophilus citellus (L., 1766) populations in Serbia
Doctoral thesis (Published version)
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The European ground squirrel (Spermophilus citellus, L. 1766) is endemic species to the Central and Southeastern Europe. Its recent range is divided in two main parts by the Carpathian Mountains. The northern part of the range is characterized by uniform steppe habitats at low altitudes, while the southern part is situated on the Balkan Peninsula, where different types of habitats, with different environmental conditions and at different altitudes are present. The majority of Serbian populations is located in the northern part of the country, i.e. in Vojvodina, while only a few small and isolated mountain populations are present in the east and southeastern part of the country. The European ground squirrel inhabits steppes, meadows and pastures covered with short grass. These once widely distributed habitats, which were commonly inhabited by European ground squirrels, had disappeared due to their intensive transformation into agricultural land during the past few decades. Today, species survives only in very isolated steppe-meadow fragments which are preserved within the dominant agricultural matrix. Given that a number of populations is continually declining throughout the range and that the future survival of the species is put in danger, the European ground squirrel has been protected since 2008 under the IUCN Red List of threatened species as a vulnerable species (VU). Its status in Europe is governed by the EU Habitats and Species Directive (Annexes II and IV) and the Convention on the Conservation of European Wildlife and Natural Habitats, known as the Bern Convention (Annex II). Also, 414 of its habitats are under protection regime within the Natura 2000 network. At the national level, European ground squirrel is protected by law as a strictly protected species. In order to analyze the genetic diversity and the structure of the European ground squirrel in Serbia, a total of 180 tissue samples from 11 localities (Krušedol, Neradin, Mala Remeta, Sremska Mitrovica, Banatska Palanka, Šušara, Mokrin, Lok and Tomislavci from area of Vojvodina, one locality from Vlasina and one from Stara Planina Mountain were collected during the 2007-2009. Density and abundance of the European ground squirrel populations were estimated during the period 2004-2014 on the localities Krušedol and Neradin, which are located on the periphery of Fruška Gora Mountain, as well as on the locality Banatska Palanka, which is located on the periphery of the Deliblato Sands. Finally, the minimum viable population size (MVP) was estimated using the Vortex software. The results gained in this study clearly indicated that the genetic diversity of populations from Vojvodina is significantly higher than those from the periphery of the species range, and similar to the genetic diversity of surrounding Pannonian populations which are occupying a central position within the Northern phylogenetic group. On the other hand, the results showed that the genetic diversity of mountain populations from Vlasina and Stara Planina Mountain is significantly lower compared to the populations from Vojvodina. All analyzed populations from Serbia showed high level of genetic differentiation, indicating the presence of isolation and the absence of gene flow between existing populations. According to the cluster analysis, eleven studied populations from Serbia are optimally grouped into four clusters. Populations from Vojvodina made first three clusters, while two far mountainous populations from Vlasina and Stara Planina made the fourth cluster. Arrangement of populations from Vojvodina by clusters indicates that the Danube River, but not the Tisza River, represents a significant barrier to gene flow among populations. Observed populations showed high fluctuations in density and abundance during the eleven studied years, both within and between localities. During this period, positive population growth was observed only in the locality Neradin, while large fluctuations were recorded on the localities Krušedol and Banatska Planka, followed by dramatic decline in density and abundance. According to the MVP analysis, for the survival of isolated populations of European ground squirrel, preservation of 90% of genetic diversity and avoidance of the harmful effects of inbreeding, it is necessary to ensure the presence of at least 300 individuals over 50 years. However, if we take into account different levels of demographic and environmental stochasticity, MVP would be considerably larger. This pointed out the need to establish more optimal habitat conditions and thus minimize large fluctuations in the abundance caused by extremely adverse factors and increase the likelihood of population survival. The loss of suitable habitats, as well as the formation of barriers that prevent the migration and gene flow between populations, currently represent the most important factors that directly and indirectly affect the survival of populations of the European ground squirrel. The results from this study represent a good conservation basis and provide guidance for an active approach to the protection and preservation of the European ground squirrel in Serbia, development of the Action and Management Plans, as well as a basis for the future fundamental ecological and conservation research of this endangered species. Future conservation of the European ground squirrel in Serbia has not only the national relevance. Namely, populations from Serbia and Bulgaria are of key importance for the future preservation of the whole species, as these areas served as refugia from which the species spread to the Central Europe during favorable climatic conditions in the past. Therefore, we have a great obligation to preserve viable populations of the European ground squirrel with a minimum loss of the existing genetic diversity.
Keywords:European ground squirrel; European ground squirrel; Viability; Genetic diversity; Genetic structure; Microsatellites; Density; Abundance; MVP; Probabilities of extiction; Threatening factors; viability; genetic diversity; genetic structure; microsatellites; density; abundance; MVP; probabilities of extiction; threatening factors
Source:University of Belgrade, Faculty of Biology, 2015, 1-111