National Repository of Grey Literature 5 records found  Search took 0.01 seconds. 
Evolution of brain size in birds
Straková, Barbora ; Němec, Pavel (advisor) ; Remeš, Vladimír (referee)
Vertebrates show dramatic interspecific variation in the size of their brains. The complexity of brains is considered to be the key factor of evolutionary success in Vertebrates, and therefore an evolutionary trend towards increasing brain size and coplexity is assumed. Large and complex brains evolved independently in birds and mammals. Birds have brains that are comparable in their relative size to the brains of mammals. However, in stark contrast to mammals, there is no general trend towards increase of brain size in birds. Relatively large brains have evolved independently in many avian lineages. Highly encephalised orders are parrots (Psittaciformes), woodpeckers and relatives (Piciformes), hornbills, hoopoe and wood hoopoes (Bucerotiformes), owls (Strigiformes), storks (Ciconiiformes) and several families of songbirds (Passeriformes), mainly bowerbirds (Ptilorhynchidae) and corvids (Corvidae). Otherhighlyencephalizedgroupsarenon-parasiticcuckoos(genusCentropus,Phaenicophaeus and Coua) and family Diomeidea and genus Pelecanus belonging to the clade water birds. Less encephalized groups include the basal lineages such as paleognaths and fowl (Galloanserae), and also pigeons (Columbiformes) and swifts, treeswifts and hummingbirds (Apodiformes). We suggest that this mosaic evolution is result of...
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...
Sexual size dimorphism and related phenomena in ungulates
Polák, Jakub ; Frynta, Daniel (advisor) ; Remeš, Vladimír (referee) ; Sedláček, František (referee)
Sexual size dimorphism (SSD) defined by differences in body size of a conspecific male and female are widespread phenomenon in the animal kingdom and ungulates belong among the most dimorphic mammals. In most species males are the larger sex which is often explained by differing sex-specific reproductive roles. While parental investment is predominantly left to females which are the selective sex, males have to fight for access to receptive mates in intensive combats where body size, strength, and condition are often critical. The relationship between male body size and reproductive success varies according to a mating system with the highest SSD being achieved by harem and promiscuous species. Even though several compilation studies of SSD have been done on ungulates it is rare that systematic research is closely concentrated on a well-defined specialised homogenous group where detailed knowledge on its life-history traits is also available. I have focused on subfamily Caprinae and Bovinae with the objective to conduct a detailed analysis of their SSD and its evolutionary traits. Using advanced phylogenetic methods I could reconstruct the ancestral state in wild goats and sheep that was characterised by medium SSD which then took two different routes of evolution depending on a type of habitat and...
Geographical variation in functional traits of European birds
Kopsová, Lenka ; Hořák, David (advisor) ; Remeš, Vladimír (referee)
Each species has specific adaptations to its environment, and since environmental parameters reveal geographic trends, it is reasonable to expect the existence of geographic trends in species characteristics as well. The aim of this study has been to evaluate the effect of environmental conditions on geographic variability of functional traits of European birds. I have analysed the effect of temperature, precipitation, productivity, altitude and habitat type (forest, open habitats, bush, settlements, wetlands) on clutch size, number of clutches per breeding season, egg size, incubation length, age of maturity, body mass, wing, tail, bill and tarsus length. I have used data from the European breeding bird atlas, so that I have calculated mean values of all the traits for quadrats 50x50 km, and then related them to environmental characteristics using OLS and GLS. Clutch size increases with temperature, whereas the number of clutches decreases with it, indicating possible trade-off between clutch size and the number of clutches, whose result is determined by the length of breeding season. Egg size decreases with temperature, possibly due to higher survival of large eggs (and consequently juveniles) in cold regions. Incubation length increases with both temperature and environmental productivity,...
Investment in reproduction and nest defense in waterfowl
Javůrková, Veronika ; Albrecht, Tomáš (advisor) ; Remeš, Vladimír (referee) ; Weidinger, Karel (referee)
Investment in reproduction is considered to be crucial component of life history traits. Reproductive success is however constrained by generally unpredictable environmental conditions. Based on "bet hedging" theory, individuals are forced to eliminate such unpredictability via the mixed strategy to maximize their long-term fitness. Predation represents underlying factor affecting individual reproductive success, and it undoubtedly lies behind the evolution of alternative reproductive strategies such as extra-pair paternity and conspecific brood parasitism. Behavioral mechanisms related to nest defense are thought to be investment in reproduction in accordance with trade-off between actual and residual reproductive value. Despite the extensive interest in the principles associated with parental investment into the nest defense, studies describing in detail the pattern of particular antipredator strategies are rare. Similarly, mechanisms responsible for maintenance of egg- viability during prolonged egg-laying period in species delayed the onset of incubation are poorly understood. In accordance with mentioned themes, this thesis includes publications aimed at aspects of reproductive biology and antipredator behavior in Mallards (Anas platyrhynchos). Particular publications concretely documented: a)...

See also: similar author names
1 Remeš, Vlastislav
2 Remeš, Vojtěch
3 Remeš, Václav
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