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Morphological, behavioural and physiological adaptations of island-dwelling birds
Krpcová, Alena ; Albrecht, Tomáš (advisor) ; Mikula, Ondřej (referee)
Morphological, behavioural and physiological adaptations of island-dwelling birds Alena Krpcová prof. Tomáš Albrecht, Ph.D. Abstract Islands represent a model system of evolutionary biology. They are isolated environments in which specific ecological conditions often operate differently than on the mainland. In this context, island taxa develop unique morphological, physiological and behavioural adaptations, collectively referred to as island syndromes, through convergent evolution. This thesis aims to provide an overview of selected island syndromes that have been detected in a large group of vertebrates typically inhabiting islands, the birds (Aves). Attention is paid to body size, wing length and associated flightlessness, as well as changes in life strategies (life span, offspring care, clutch size and egg size), antipredatory behaviour and island tameness, and finally the relationship between the above-mentioned island syndromes and the extinction of island species caused by humans and the invasive organisms that accompany them. Factors operating in island environments that may influence the evolution of selected island syndromes are discussed, and it is suggested that reduced predation pressure on islands and an energetic trade-offs between investments in survival, defence and reproduction could be...
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Latest Ludlow chitinozoans from the Prague Basin: significanec for correlations and succession during Kozlowskii/Lau extinction events
Vodička, Jakub ; Fatka, Oldřich (advisor) ; Štorch, Petr (referee)
Two sections, Všeradice and Kosov, represent continuous sedimentary succession situated in the Prague Basin. No detailed research on stratigraphical level equal the N. kozlowskii graptolite zone focusing on chitinozoans, has not yet been conducted in the Prague Basin and is also very scarce globally. Limestone beds, examined for chitinozoans, were not very productive. Chitinozoan reaction on extinction is visible, if we compile data from both sections. The pre-extinct chitinozoan fauna is characterized by the Conochitinidae family. Samples from the post-extinct interval contained no chitinozoas. The interval of fauna recovery is characterized mainly by the Eisenackitina genera. In this interval, global zone for the uppermost Ludfordian, represented by E. barrandei, can be confirmed. In agreement with all the published literature, we have not found E. philipi, index taxa of the former global zone in the Prague Basin. E. lagenomorpha appears stratigraphically only slightly below E. barrandei and therefore it cannot substitute E. philipi, as it is used in Baltika region. chitinozoa, Prague Basin, Kozlowskii, Lau, extinction, Ludfordian, stratigraphy
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Development of the mammal assemblages during Quaternary climatic changes
Havlová, Tereza ; Mazuch, Martin (advisor) ; Nývltová Fišáková, Miriam (referee)
During the Quaternary there was a cyclical alternation of warm and cold periods - interglacials and glacials. Over the past 2.5 million years there was eighteen or twenty these cycles. These climate changes influenced by, except other, Milankovic cycles caused at sea level, extent of glaciation or distribution of vegetation zones. All these factors affected the communities of mammals, their distribution, migration and extinction of some groups of mammals. Area of continental and mountain glaciers expanded as well as levels of the ocean decreased during the glacials. Many species of mammals penetrated into new territory with the emergence of land-bridges a mammals from isolated areas could interact during cold periods. There was a retreat of glaciers and sea level rise and the migration routes through the land bridges was interrupted during the interglacials. Many, mostly island, populations were isolated and they were often developed to new endemic species. Key words: glacial, interglacial, climate changes, distribution, migration, extinction
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Extinction risk and population size
Váňová, Lenka ; Storch, David (advisor) ; Reif, Jiří (referee)
There is generally accepted assumption that the probability of extinction risk increases with decreasing population size. But it's not sure at all, to what extent does this relation really work in real populations. The amount of studies dealing with this topic is on the increase, but still it's necessary to carry on researching. Previous results indicate that inspected connection is indeed true in many populations, in other words, preferential extinction of less abundant populations functions properly. Yet the dependence isn't as unambiguous and strong as expected. Many exceptions are known as well, which demonstrate that low number of individuals doesn't always have to be a disadvantage in terms of survival chance. Such deviations can be found both in paleontological papers and among current populations. For example, mass extinctions represent that kind of a special exception because each of them was probably driven by a different mechanism, so in one case the abundance could be an advantageous trait, whereas in another it was rather disadvantage. In my work, I briefly mention themes referring to extinction in general and subsequently I try to summarize findings about the phenomenon of population size and its connection to extinction risk. On the basis of explorers' ideas and by means of...
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Latest Ludlow chitinozoans from the Prague Basin: significanec for correlations and succession during Kozlowskii/Lau extinction events
Vodička, Jakub ; Fatka, Oldřich (advisor) ; Štorch, Petr (referee)
Two sections, Všeradice and Kosov, represent continuous sedimentary succession situated in the Prague Basin. No detailed research on stratigraphical level equal the N. kozlowskii graptolite zone focusing on chitinozoans, has not yet been conducted in the Prague Basin and is also very scarce globally. Limestone beds, examined for chitinozoans, were not very productive. Chitinozoan reaction on extinction is visible, if we compile data from both sections. The pre-extinct chitinozoan fauna is characterized by the Conochitinidae family. Samples from the post-extinct interval contained no chitinozoas. The interval of fauna recovery is characterized mainly by the Eisenackitina genera. In this interval, global zone for the uppermost Ludfordian, represented by E. barrandei, can be confirmed. In agreement with all the published literature, we have not found E. philipi, index taxa of the former global zone in the Prague Basin. E. lagenomorpha appears stratigraphically only slightly below E. barrandei and therefore it cannot substitute E. philipi, as it is used in Baltika region. chitinozoa, Prague Basin, Kozlowskii, Lau, extinction, Ludfordian, stratigraphy
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Development of the mammal assemblages during Quaternary climatic changes
Havlová, Tereza ; Mazuch, Martin (advisor) ; Nývltová Fišáková, Miriam (referee)
During the Quaternary there was a cyclical alternation of warm and cold periods - interglacials and glacials. Over the past 2.5 million years there was eighteen or twenty these cycles. These climate changes influenced by, except other, Milankovic cycles caused at sea level, extent of glaciation or distribution of vegetation zones. All these factors affected the communities of mammals, their distribution, migration and extinction of some groups of mammals. Area of continental and mountain glaciers expanded as well as levels of the ocean decreased during the glacials. Many species of mammals penetrated into new territory with the emergence of land-bridges a mammals from isolated areas could interact during cold periods. There was a retreat of glaciers and sea level rise and the migration routes through the land bridges was interrupted during the interglacials. Many, mostly island, populations were isolated and they were often developed to new endemic species. Key words: glacial, interglacial, climate changes, distribution, migration, extinction
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