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Bird diversity and diversification: Different processes converging to the same pattern?
Černá, Vladimíra ; Storch, David (advisor) ; Hulva, Pavel (referee)
Latitudinal diversity gradient is one of the oldest known trends in the distribution of life on the Earth. Scientists have been trying to find causes of its formation for more than two hundred years. There are several hypotheses suggested to explain this gradient. Recently, it is one of the main themes of discussion among ecologists and evolutionary biologists. By this Thesis, I will try to contribute to understanding of processes that generate the latitudinal diversity gradient. Particularly, I study if there is a relationship between ambient temperature and diversification rate. Is this relationship different for individual groups of animals? I choose birds as a model group. Specifically, these six families of birds: Accipitridae, Columbidae, Furnariidae, Picidae, Psittacidae and Strigidae. These groups include more than 1500 species. Each of them has the same universal gradient of diversity, with the highest diversity concentrated in the tropics. My objective was to find out, whether the universal gradients of bird's diversity had been shaped by the same historical processes. Or alternatively, whether different evolutionary trajectories had converged to the same gradients. The main outcome of my work is a discovery that some of the selected families diversified faster in warmer climates...
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Bird diversity and diversification: Different processes converging to the same pattern?
Černá, Vladimíra ; Storch, David (advisor) ; Hulva, Pavel (referee)
Latitudinal diversity gradient is one of the oldest known trends in the distribution of life on the Earth. Scientists have been trying to find causes of its formation for more than two hundred years. There are several hypotheses suggested to explain this gradient. Recently, it is one of the main themes of discussion among ecologists and evolutionary biologists. By this Thesis, I will try to contribute to understanding of processes that generate the latitudinal diversity gradient. Particularly, I study if there is a relationship between ambient temperature and diversification rate. Is this relationship different for individual groups of animals? I choose birds as a model group. Specifically, these six families of birds: Accipitridae, Columbidae, Furnariidae, Picidae, Psittacidae and Strigidae. These groups include more than 1500 species. Each of them has the same universal gradient of diversity, with the highest diversity concentrated in the tropics. My objective was to find out, whether the universal gradients of bird's diversity had been shaped by the same historical processes. Or alternatively, whether different evolutionary trajectories had converged to the same gradients. The main outcome of my work is a discovery that some of the selected families diversified faster in warmer climates...
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The factors affecting evolutionary diversification
Černá, Vladimíra ; Storch, David (advisor) ; Kratochvíl, Lukáš (referee)
The number of species on the Earth is estimated to lie between five to ten millions. All these species originated from a common ancestor, which appeared on our planet 3,5 bilion years ago. Speciation and extinction are responsible for the current species richness. Evolutionary diversification is the difference between speciation and extinction. There are several methods used to obtain the values of speciation, extinction and diversification rates. I will briefly explain some of these methods, outline the advantages and disadvantages of them. The aim of this paper is to summarize current knowledge of evolutionary diversification and factors that may affect it. In this search I focused on the studies dealing with factors that may affect several groups of organisms. Although many determinants of diversification were found, most of them affect only one group of organisms. Here I did not find any factor that would be common for the majority of taxa. Evolutionary diversification is probably influenced by different factors in different evolutionary lineages. Key words: diversification, speciation, radiation, diversity gradient
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