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Speciation rate
Leščinskij, Artem ; Storch, David (advisor) ; Macháč, Antonín (referee)
Speciation rate is a frequency at which an original species splits into two species per unit of time. Since this rate cannot be directly determined, it must be inferred from the fossil record or a reconstructed phylogeny using appropriate diversification model or nodes and branches of a phylogenetic tree. The homogeneous birth-death process is the basic method upon which other models, such as time-dependent or density-dependent models, are based. Non-model methods such as DR statistics, node-density metrics or inverstion length of terminal branches, are methods depend on reconstructed phylogenetic trees. More complex methods include MEDUSA, BAMM, CLaDS, MTBD, or trait-dependant models. Protracted-speciation models are biologically more plausible and describe speciation as a gradual process. These methods can detect more complex diversification regimes. Tip rate determines expected species-specific rate of speciation and is less dependent on the rates of extinction and diversification; rather, it corresponds to the rate of speciation. Model identifiability is a fundamental problem limiting the estimation of the speciation rate, but this limitation can be partially overcome by new techniques such as pulled rates. Keywords: speciation rate, phylogeny, diversification, evolution, model
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The Current Extinction of species
Schätz, Filip ; Storch, David (advisor) ; Hulva, Pavel (referee)
This bachelor thesis deals with the current process of species extinction. The main aim of the thesis is to answer the question how we can accurately describe this process. The understanding of this process is based on the limited sample of extinct species known to us, provided by the IUCN Red List. The sheer number of extinct species is affected by the use of different species concepts, the synonymy of binomial names and the difficulty of tracking individual extinction events. The Red List sample is subject to strong selection bias, so currently there are only reliable records of extinctions of groups of birds and mammals. These extinctions are mainly associated with their occurrence on islands. For other taxa, records of extinctions are sporadic, so the status of the current extinction process in these groups is unknown. It is not possible in most cases to relate to these groups the knowledge resulting from the study of different taxa. Estimates that attempt to describe the process beyond our knowledge also suffer from shortcomings. While the problems of expressing actual extinction rates stem from our ignorance of biodiversity, the inaccuracies of the SAR curve back-extrapolation method are mainly due to the attempt to generalise the overly complex effect of range loss on species numbers. The...
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Factors influencing intraspecific scaling of metabolic rate
Trubelová, Zuzana ; Starostová, Zuzana (advisor) ; Storch, David (referee)
The relationship between metabolic rate and animal body size of the animal has been studied for more than hundred years. Recently, attention of scientists moved from the interspecific to the intraspecific level. The work focuses on the intraspecific scaling of metabolism. When plotting the metabolic rate against body mass during ontogeny the resulting line often exhibits one or more breaks. Why these breaks (and thus reduction the metabolic rate) occur hasn't been fully explained. It is assumed that can be due to certain factors that affect an individual during development. Some of these factors came from the most famous of several hypotheses attempting to explain the scaling of metabolic rate. These hypotheses include the Metabolic Theory of Ecology (MTE), the Metabolic Level Boundaries (MLB), the Cell model and the Dynamic Energy Budget (DEB) hypothesis. There are several factors that could affect individuals during ontogeny. These include internal factors, which result from the internal processes within the body. These factors are often interrelated with each other in different ways; therefore, it is unlikely to choose only one particular factor which affects metabolic rate. The most frequently studied factors are changes of cell size and changes in the proportion of metabolically active...
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Relationships between functional traits, home range sizes, and dispersal abilities in birds
Holubová, Kateřina ; Storch, David (advisor) ; Sedláček, Ondřej (referee)
Avian movements through the landscape involving dispersal and routine movements within home-range or territory are one of the basic but due to a high mobility of birds also one of the least understood processes of bird ecology, especially on the interspecific level. Not only is dispersal a fundamental mechanism of species' spreading into new areas, but also, together with home-range size, it shows the scale on which species perceive the landscape and how they can deal with habitat changes. Dispersal ability, represented by dispersal distances, is determined by a few species specific traits like body size, migratory status, wing and bill morphology, diet type, preferred habitat type or some life-history traits. On the contrary, home-range size variability is determined primarily by energetic demands of the species, given by its body size and trophic level, and by the productivity of the environment. There is a positive relationship between home-range size or territory size, respectively, and dispersal distances of birds that can be attributed to species vagility or their spatial requirements determined especially by their food preference. Nevertheless, further research mainly on interspecific level is necessary for a deeper insight into this issue.
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Population dynamics of Red-crested Pochard (Netta rufina)
Poláková, Klára ; Musil, Petr (advisor) ; Storch, David (referee)
This study is aimed at analysis of long-term and short-term changes in numbers of Red-crested Pochard (Netta rufina) in Třeboň region. This species is increasing in long-term period and it is also spreading into new localities in the Czech Republic. There were recorded two waves of arrival of Red-crested Pochard arrive, i.e. in April and in May. The total numbers were decreasing at the end of breeding season (from the beginning of July) in study area. The water surface area and area of littoral vegetation were found to be the most important factors affecting preference of individual ponds in pre-breeding season. Furthermore, water transparency seems to be important factor affecting numbers of broods, ducklings and adults in post-breeding season. Low numbers of broods per 1 female were recorded in years with high numbers of Red- crested Pochard at the start of breeding season. However, the frequency of brood parasitism was higher in these years. Key words: Netta rufina, Red-crested Pochard, population dynamics, ducks, breeding, numbers, brood parasitism, south Bohemia
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The relationships between diversity patterns and community abundance
Dlouhá, Hana ; Storch, David (advisor) ; Keil, Petr (referee)
Increase in the number of species with area is one of the most studied ecological patterns. There is a considerable amount of literature devoted to this question. The rate of increase in the species diversity with area isn't equal at all the spatial scales, as shown by empirical studies. On the finest and coarsest scales, there is distinctively higher rate of increase than on the middle (regional) scales. These distinctions were attributed to many characteristics of environment, taxon etc. There is a possibility to explain the variability of this particular rate by mean species abundance. This work focuses on summarizing the relationships between the rate of increase in biodiversity with area, factors that influence it and mean species abundance.
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More-individuals hypothesis
Bohdalková, Eliška ; Storch, David (advisor) ; Sedláček, Ondřej (referee)
Gradients in species richness are often explained by variation in energy availability. Positive relationship between energy and number of species may be caused by many mechanisms. One of them is the 'more individuals' hypothesis (MIH). According to it greater energy availability enable more individuals to coexist and more individuals can be divided into more species with viable populations. However, authors do vary in exact formulation of the MIH and so they vary in predictions that they test. Review of literature has also revealed that studies are fundamentally different in the approach to testing MIH. Some studies examine whether mechanism of MIH can operate in real assemblages and they often give a positive answer. Other studies ask whether MIH is able to explain spatial patterns of species richness. The answer is mostly negative. Number of species is often closely related to energy without the mediating effect of the number of individuals. There is also the question whether the number of individuals really determines number of species, and not vice versa. However, these two variables are certainly linked. Therefore, regardless of the causality, the relationship between the number of individuals and number of species is worth exploring.
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Diversity dynamics across scales
Macháč, Antonín ; Storch, David (advisor) ; Remeš, Vladimír (referee) ; Ricklefs, Robert (referee)
Charles University, Prague Diversity dynamics across scales Antonin Machac 2018 Abstract Diversity dynamics remain controversial. It has been suggested that the dynamics are expansionary, such that the number of species across regions and clades increases constantly. However, the opposite has also been suggested, namely that species numbers are relatively stable, following equilibrial dynamics. Both views (expansionary and equilibrial) have been supported by compelling phylogenetic, biogeographic, and fossil evidence and, currently, it remains largely unclear how the two seemingly conflicting views could be reconciled. My dissertation addresses this question, based on the premise that diversity dynamics change systematically with scale. Specifically, I hypothesize that expansionary dynamics typify regionally distributed, small, and young clades whose diversity tends to expand, driven by a variety of regionally relevant factors (e.g. habitat-level adaptation, biotic interactions, or montane shifts leading to ecological divergence and speciation). Conversely, equilibrial dynamics typify large, ancient, and globally distributed clades, whose diversity is environmentally limited (e.g. by the total amount of resources that can sustain only a limited number of populations and species). Consequently, it seems...
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Macroecological analysis of economy
Krupička, Jan ; Storch, David (advisor) ; Petrusek, Adam (referee) ; Kratochvíl, Lukáš (referee)
Abstract: Brown et al. (2011) proposed a fundamental similarity between organisms and the economies of nationstates based on the distribution networks necessary for the functioning of the metabolism / economics and limitations arising from them according to the Metabolic theory of ecology. This work is primarily intended to investigate whether these limitations figure even within individual sectors of the economy and their relation to some other macroeconomic and demographic indicators. Key words: ecology, macroecology, metabolic theory of ecology, economy, energy
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