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Concept of species in bears (Ursidae): practical, historical, and theoretical viewpoint
Wagner, Jan ; Fejfar, Oldřich (advisor) ; Sabol, Martin (referee) ; Musil, Rudolf (referee)
The present thesis surveys topic of taxonomic diversity and phylogeny of bears (Mammalia, Ursidae) and aspects of its contextual setting under effects of changing conceptual and methodological viewpoints. This problem is studied from several perspectives. The historical perspective is represented by a critical overview of the history of specific and infraspecific classification of bears with special respect to mutual influences of this classification and theoretical concepts of species accepted in particular periods. The perspective of material approach is exemplified by a material-based study of taxonomical and phyletic status of selected Pliocene to Middle Pleistocene ursine taxa. Along with deconstruction of some traditional hypotheses this produced a model explaining species diversification in ursine bears and its discussion in terms of factual relevance of included background concepts. In the pre-evolutionary period the bear species were usually understood broadly, as incipient immanent entities, yet exhibiting obvious certain infraspecific variability. This was established using definitions of varieties (mostly not identifiable with present subspecies or infraspecific taxa) considered as unstable modes of particular species. Although, in the post-Darwinian period, the concept and taxonomic...
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Cirque overdeepening in the High Tatras
Nadžadyová, Alexandra ; Křížek, Marek (advisor) ; Margold, Martin (referee)
Cirque overdeepening in the High Tatras Abstract: The High Tatras are currently an unglaciated mountain range with distinct glacial and periglacial shapes, as they were among the most glaciated mountain ranges during the Pleistocene. This allowed the formation of glacial cirques in the valley heads, which nowadays serve as ideal paleoenvironmental indicators. The aim of this work is therefore to determine the extent of cirque overdeepening in the Slovak part of the High Tatras and to establish the relationship of cirque overdeepening to standard morphometric, positional, and environmental characteristics of cirques. Based on the current digital elevation model (DEM), cirque edges, steps, and foot of cirque walls were defined and the values of morphometric parameters important for the construction of longitudinal profiles (k-curves, c-curves) were determined, thanks to which the overdeepening of the cirques was determined. The average value of the overdeepening of all the cirques according to the k coefficient was 0,85 (ranging from 0,51 to 1,46) and according to the c coefficient it was -0,97 (ranging from -0,11 to -2,96). The resulting inventory of 110 cirques was therefore used to analyse the relationships of the overdeepening coefficients to the above characteristics among themselves. The values of the...
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The dynamics of the north-western Laurentide Ice Sheet margin
Stoker, Benjamin James ; Margold, Martin (advisor) ; Darvill, Christopher (referee) ; Nývlt, Daniel (referee)
The Laurentide Ice Sheet (LIS) was the largest ephemeral ice sheet in the Northern Hemisphere, reaching its all-time maximum during the last glacial cycle (~115 ka to ~11.7 ka) as it coalesced with the Cordilleran and Innuitian ice sheets over northern North America and the Canadian Arctic Archipelago. At its maximum extent it was comparable in size to the modern-day Antarctic Ice Sheet and may provide a useful analogue for understanding the long-term dynamics of ice sheets. There are considerable regional variations in our understanding of the deglaciation of the LIS. In particular, the northwestern LIS remains one of the most poorly understood sectors, as the latest reconstruction of this sector dates to the early 1990s and empirical constraints on the timing of deglaciation are sparse. In this thesis, I reconstruct the deglaciation of the northwestern LIS from its local Last Glacial Maximum (LGM) position using numerical dating methods and glacial geomorphological mapping. I use a combination of high-resolution digital elevation models (DEMs) and satellite imagery to map the glacial geomorphology of much of the Northwest Territories, Canada, and reconstruct the ice margin retreat patterns, ice flow dynamics, and interaction of the northwestern LIS with other ice masses. This new information is...
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Paleozoic glaciation as an analog for Quaternary glacial cycles?
Kubíček, Martin ; Laurin, Jiří (advisor) ; Laibl, Lukáš (referee)
This bachelor thesis is focused on the comparison of the two main glacial periods of the Phanerozoic, the Late Paleozoic Ice Age and the Cenozoic Ice Age including Pleistocene. The main goal of the thesis is to compare the factors of glaciation and their controlling mechanisms on short and long-term scales, and the basic features of the Earth's circulation. Last but not least, the evaluation of unresolved questions and consideration of the possibility of using data from the Cenozoic, which point to a very complex behaviour of the climate system components. In both periods compared, the main climate driver appears to be the atmospheric greenhouse gas content. Another common feature is the declining trend in temperature, manifested initially by a less significant and ephemeral glaciation during the Upper Devonian, Eocene and Oligocene. The transition to the coldest phases with the lowest average temperature and the largest ice volume is characteristic. Based on CO2 content, amplitude of glacioeustatic oscillations or Milankovitch cycles, a sequence of several glaciation events in the Serpukhovian to Sakmarian interval can be considered as an analogue of the Pleistocene. The difference from the Pleistocene glaciation is presence of a large number of glaciation centres in the Gondwana area. Some...
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Reconstructing the central sector of the Cordilleran Ice Sheet
Dulfer, Helen Elizabeth ; Margold, Martin (advisor) ; Ely, Jeremy (referee) ; Nývlt, Daniel (referee)
The Quaternary Period (last 2.6 Ma) was a time of increased climate oscillation that resulted in the repeated growth and decay of Northern Hemispheric ice sheets. During this period the Cordilleran Ice Sheet (CIS) repeatedly covered mountainous western North America and attained a volume and area similar to the present-day Greenland Ice Sheet. At the Last Glacial Maximum (LGM) the CIS formed part of the North American Ice Sheet Complex (NAISC), coalescing with the Laurentide Ice Sheet east of the Rocky Mountains. However, the high relief bed and remote location mean there are few empirical constraints pertaining to the nature of ice sheet build-up and retreat in the central region of the CIS, in northern British Columbia, making it one of the least understood ephemeral Pleistocene ice sheets. In this thesis I use glacial geomorphology and quantitative dating techniques to reconstruct the advance of the CIS to its LGM position and subsequent retreat. I use high resolution remotely sensed data to create a detailed map of glacial landforms for the central sector of the CIS, beneath the local LGM ice divide (55řN to 60řN; paper I). Seven landform categories were mapped: ice flow parallel lineations, moraines (CIS outlet glacier moraines, Late Glacial moraines and moraines of unknown origin), meltwater...
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Distribution and pattern morphology of pseudomorphs of thermal-conctraction-cracks features in Austria
Dufek, Jaroslav ; Křížek, Marek (advisor) ; Margold, Martin (referee)
During the cold Pleistocene episodes, the territory of Austria was at the forefront of nearby Alpine glaciation. The unglaciated area of Austria was part of the Central European periglacial zone, in which permafrost developed. The distribution of Upper Pleistocene permafrost, its character, but also its time classification in the western part of the Pannonian Basin is still unclear. It is also because ideas about the characteristics of Upper Pleistocene permafrost in this area have so far been based mainly on indirect biological or lithological records such as pollen grains, malacofauna snails, or loess-paleosol sequences. Until now, the evidence of direct geo-indicators of paleo-permafrost has been relatively limited, with unique relict frost-wedges, cryoturbations, or sporadic remains of thermokarst lakes depressions and pingos. The results present a new database of relict frost-wedges in Austria, which was created based on published literary sources, but mainly based on aerial imaginary available on Google Earth Pro. The results significantly expand (by hundreds of localities) the existing knowledge about the occurrence of relict frost-wedges, which have so far been located in Austria purely on the basis of excavated profiles and soil probes. The found polygons of frost-wedge pseudomorphs are an...
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The catalogue of the mammalian fauna of pleistocenne localities in Prague area
Havlová, Tereza ; Mazuch, Martin (advisor) ; Kadlecová, Eva (referee)
More than a hundred sites were in Prague in the past, where skeletal remains of Pleistocene mammals had been found. Most of these sites were brickyards or sand pits. These pits were in operation during the second half of the 19th century and first half of the 20th century. Many awards were found during construction works as well. Most of researchers attended only several most famous sites at the time of the findings. The catalog summarizes the basic known information about majority of Prague localities and includes a list of taxa wich were found there. Key words: Prague, locality, mammals, Pleistocene, brickyards, sand pits
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Quaternary insects and their significance for zoogeography, paleoclimatology and paleoecology
Moudrý, Jakub ; Prokop, Jakub (advisor) ; Říhová, Dagmar (referee)
The present thesis is a review of available published data on Quaternary insects. Research focused on Quaternary insects has been so far overlooked by the Czech scientists, even though there is potential to provide additional data for complex reconstruction of Quaternary deposits. Insect faunas allow to trace the dynamic development of areas across continents and serve for example as proof of migration routes. It is especially true for the Pleistocene, well known for prominent climatic oscillations. Thus, the insect species served as climatic indicators allowing estimations of average temperatures by application of the MCR method. Finally, these faunal changes reflect dynamic development of palaeoenvironments. The fact that the subfossil taxa correspond to the recent species allows broader reconstruction of the Quaternary deposits.
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Hamsters (Rodentia, Cricetinae) in the Quaternary fossil record of Czech Republic and Slovakia
Lebedová, Klára ; Horáček, Ivan (advisor) ; Wagner, Jan (referee)
1 Abstract The material of hamster remains in the Quaternary fossil assemblages from Czech Republic and Slovakia was analyzed in details with aid of biometric comparisons and contextual analyses focused on stratigraphic position of particular records and structure of the small mammals communities accompanying them. Cricetus as well as small hamsters (Allocricetus-Cricetulus) were recorded in all main Quaternary biozones (MN17-Q4). Yet Cricetus was recorded in few assemblages only mostly just with a single specimen only, except for several Q2 sites and those from the present glacial cycle (with peak abundance in preboreal and boreal). Despite obvious common trends (enlarging size from MN17 to Q3) all samples show roughly the same pattern of dental variation supporting a concept of Cricetus as a monotypic genus with a single species, C. cricetus covering all fossil forms separated as its subspecies. Correspondingly, our results support congeneric status of MN17-Q3 Allocricetus and Q4 Cricetulus, despite separating them as independent species, i.e., Cricetulus bursae and Cricetulus migratorius. Analysis of subrecent samples of C. migratorius from Turkey revealed a very broad span of phenotype variation in extant species covering both the variation framework of extant Phodopus sungorus and metric variation in a...
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Genus Sicista (Mammalia, Rodentia) in the fossil record of central Europe: phenotypic variation, taxonomic structure, range dynamics.
Lišková, Tereza ; Horáček, Ivan (advisor) ; Vohralík, Vladimír (referee)
Member of the genus Sicista rank among the rarest and the least known European mammals. They exhibit a number of outstanding specificities (hibernation, aestivation etc.) and extreme capability of a rare range dynamics. Their fossil record is fragmentary and associated with numerous controversies. The present thesis summarizes results of a detailed revision of the fossil record of Sicista from Czech Republic, Slovakia and some other countries. It comprises of about 150 items of the Holocene and Vistualian age as well as from the Middle and Early Pleistocene including earliest records from MN17/Q1 boundary and type material of S. praeloriger from Q1 Betfia. Compared to a sample of extant population, variation dynamics of both metrical and nonmetrical dental traits was examined in details with particular attention to phenotype patterns of particular fossil samples. The results demonstrated extensive amount of both within- and between-population variation and rather limited validity of commonly used discrimination criteria of extant clades. Nevertheless, we succeeded in species identification of considerable part of numerous Holocene and Vistulian records which revealed (i) a range expansion of S. subtilis s.l. during MIS 3 with persistent distribution in lowland regions of Central Europe in the Late...
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