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Gondwanian element of Latin American Flora
Potůčková, Anna ; Stančík, Daniel (advisor) ; Kvaček, Jiří (referee)
The concept of plate tectonics accepted during 20th century fundamentally changed general opinion on the origin of Latin American flora. It was found, that South America formed a part of the ancient continent Gondwana. This continent was covered by a unique flora until 100 million years ago. Actual disjunction of widely distributed tropical taxa present in South America originated after disruption of that original flora distribution. It was deduced that the separation of South America from Gondwana finished about 100 million years ago and led to the isolation of their flora until the formation of the Isthmus of Panama about 3 million years ago. However, recent studies based on molecular clock approaches shows that the exchange of biota between South America and rest of the World was possible several times in different ways before the closure of the Isthmus of Panama. The reevaluation of our opinion about the gondwanan origin of Latin American flora based on advanced molecular analysis is the aim of this work.
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Reconstruction of palaeo-environmental conditions of a former lake Šúr during the late-glacial and Holocene using macrofossil analysis
Potůčková, Anna ; Žáčková, Pavla (advisor) ; Hájková, Petra (referee)
The Danubian Plain is nothern part of the Pannonian Plain and in terms of palaeobotanical research it is an entirely unexplored area. However, this region is assumed to contain cryptic glacial refugia and migration routes of thermophilous biota northward after the Last Glacial Maximum. The late-glacial and Holocene natural long-term succession and temporal changes in the composition of plant communities of lowland lakes in the Slovakia is unknown. Šúr, a National Nature Reserve is a former lake, presently overgrown by alder carr forest. Successional development since the late-glacial was studied along two profiles. Macrofossil analysis was carried out on lake sediments extending to the Middle Pleniglacial (OIS 3). Using knowledge of the modern ecological requirements of taxa, past environmental conditions were reconstructed. The historical biogeography of selected plant species in Europe during the late- glacial and Holocene is also discussed. During the Middle Pleniglacial Myriophyllum spicatum and Chara sp. grew in the lake. During the late-glacial shallow basin contained a calcareous, meso- to eutrophic lake with Potamogeton filiformis, P. praelongus, Ranunculus subgen. Batrachium etc. During the early Holocene these elements disappeared and thermophilous plants immigrated, such as the...
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Gondwanian element of Latin American Flora
Potůčková, Anna ; Stančík, Daniel (advisor) ; Kvaček, Jiří (referee)
The concept of plate tectonics accepted during 20th century fundamentally changed general opinion on the origin of Latin American flora. It was found, that South America formed a part of the ancient continent Gondwana. This continent was covered by a unique flora until 100 million years ago. Actual disjunction of widely distributed tropical taxa present in South America originated after disruption of that original flora distribution. It was deduced that the separation of South America from Gondwana finished about 100 million years ago and led to the isolation of their flora until the formation of the Isthmus of Panama about 3 million years ago. However, recent studies based on molecular clock approaches shows that the exchange of biota between South America and rest of the World was possible several times in different ways before the closure of the Isthmus of Panama. The reevaluation of our opinion about the gondwanan origin of Latin American flora based on advanced molecular analysis is the aim of this work.
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