|
|
Glycerolipids and carotenoids in microalgae: the implications in ecophysiology and applied phycology
Střížek, Antonín ; Nedbalová, Linda (advisor) ; Brányiková, Irena (referee) ; Barreira, Luísa (referee)
Lipids are basic biomolecules found in all organisms. They have a key function as structural molecules forming cell membranes, and, in the form of fats and oils, energy is also stored. There are a huge number of lipid types that have other functions, for example, in cell signaling, enzyme support, protection against stress, and others. Microscopic algae are the main primary producers in both freshwater and marine ecosystems. Therefore, algal biosynthesis has a fundamental effect on the trophic networks of aquatic ecosystems and ultimately on humans. The environment affects the ecophysiology of algae, which is reflected in their biochemical composition, i.e. in the composition of their lipids. This work is focused on two groups of lipids, namely glycerolipids, which consist of fatty acids, and carotenoids, which are photosynthetic pigments with antioxidant and photoprotective properties. In these groups of lipids, the target substances were further selected, namely polyunsaturated fatty acids and the carotenoid fucoxanthin belonging to xanthophylls. These substances are important not only in the ecophysiology of algae, but they are valuable substances that have positive effects on the human organism and, with the help of optimized cultivation, could be obtained from algae for industrial production...
|
|
|
Butterfly thermoregulation across habitats and climates
LAIRD-HOPKINS, Benita Carmen
Global warming, through rising temperatures and changing precipitation patterns, is placing major stress on species and ecosystems. Understanding how species respond to temperature and the mechanisms underpinning thermoregulation can help us predict which species are most vulnerable in the face of warming. In this thesis, I explore how butterflies across different habitats and climates thermoregulate and the mechanisms, including morphology and behaviour, underlaying thermoregulatory ability. Firstly, when comparing the buffering ability of neotropical and temperate butterflies I found that tropical butterflies were able to maintain more stable body temperatures than temperate butterflies, and this was likely driven by their morphology. I also found that temperate butterflies used postural means to raise their body temperature more than neotropical species, likely an adaptation to the cooler air temperatures they experience. Secondly, I showed the importance of butterflies' thermoregulatory abilities at the community level, by comparing thermoregulation of European butterflies across geographic regions and climatic zones. This study highlighted that behavioural thermoregulation, including the use of microclimates and postural means, drives regional differences in butterflies' thermoregulatory abilities. Finally, I utilised the Müllerian mimicry exhibited in Heliconius butterflies to untangle the contributions of morphology and phylogeny in butterfly thermoregulation, investigating thermal traits, including buffering ability, take-off temperature and heating rate. I found that morphology, not phylogeny, was the main driver of thermoregulation in these butterflies. Further, I investigated differences in the thermoregulatory ability of Heliconius butterflies from different habitats. I found that species from colder habitats were able to maintain a more stable body temperature and took off at a lower temperature than those from hotter habitats, suggesting there is local adaptation or acclimation in thermal traits. Overall, this work highlights that species have their own unique thermoregulatory abilities, as a result of the thermal environment they experience, and that thermoregulation is driven by morphology, behaviour and physiology. My findings have important consequences for predicting the impacts of climate change on ectotherms, by highlighting variation in thermal ability which makes some populations and species more vulnerable, while others more resilient. This thesis lays the groundwork for future studies comparing species' thermal traits across climates and habitats, increasing our understanding of how species cope with climate and land-use change.
|
|
|
Condition dependence of sexually selected ornaments in birds
Tomášek, Oldřich ; Albrecht, Tomáš (advisor) ; Verhulst, Simon (referee) ; Šálek, Miroslav (referee)
Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...
|
|
| |
|
| |
|
|
Condition dependence of sexually selected ornaments in birds
Tomášek, Oldřich ; Albrecht, Tomáš (advisor) ; Verhulst, Simon (referee) ; Šálek, Miroslav (referee)
Sexual ornaments important for mating success in many species are often assumed to evolve as condition-dependent signals of individual quality. Ornament expression can be associated with age and survival, thereby signalling individual viability. Here, we have tested viability signalling function of tail streamers and their importance for within-pair and extra-pair fertilisation success in the European barn swallow (Hirundo rustica rustica). In contrast to previous studies on this subspecies, our data suggest that tail length is not associated with fertilisation success in our population. Instead, the most important predictors of within-pair and extra-pair fertilisation success were female and male age, respectively. Our data supported viability signalling function of male tail streamers, as documented by age-related within- individual increase in their length. There was no evidence for senescence in this trait. Contrary to some previous studies, the viability signalling function of tail streamers was further supported by observed selective disappearance of males with shorter tails. Several physiological mechanisms have been proposed as maintaining signalling honesty. Among them, oxidative stress from highly reactive species (RS), including free radicals, attracted a considerable attention. Given...
|
|
|
Ecophysiological differentiation of Synura petersenii cryptic species (Synurophyceae)
Jelínková, Lucie ; Škaloud, Pavel (advisor) ; Elster, Josef (referee)
Synura petersenii represents a complex of pseudo-cryptic species. These are planktonic colonial organisms belonging to the class Chrysophyceae. The species are abundant in spring and autumn, when they produce golden-brown blooms in oligo-mesotrophic waters. In this thesis, I focused on investigating the effect of temperature to growth parameters of four selected species: S. petersenii, S. americana, S. glabra and S. conopea. Several temperature experiments were performed and statistically analyzed. According to growth curves the temperature 25 žC was mostly stressful for these organisms. Only S. petersenii sensu stricto was sometimes able to growth at this temperature. In general, the significant differences in growth rates were detected between S. petersenii and S. americana. In all experiments, S. petersenii had the lowest growth rate. This ubiquitous species probably acts as a K-strategist. S. americana grew generally very quickly, especially at temperature 13 žC that is obviously optimal for it. Further, I observed a significant strain specificity, which is largely a well-known phenomenon in the ecophysiology. Significant differences in growth rates were noted between temperatures 13 žC and 16 žC, where all tested species grew best, as well. This is in accordance with a general recognition of...
|
|
|
Comparative anatomy of genus Lasiocephalus - from tropical mountain forest to páramo
Ježková, Barbora ; Soukup, Aleš (advisor) ; Lhotáková, Zuzana (referee)
South American genus Lasiocephalus colonized high altitudes of the tropical Andes, the so called páramo, from lower elevations of the Andean forest. Páramo is a specific high-altitude environment characterised by pronounced diurnal changes in temperature, growing season over the entire year, low average temperatures, generally high humidity, and intense solar radiation. These specific environmental conditions are reflected by anatomical characters of the species. Given the known phylogeny of the group it was possible to observe anatomical adaptations along steep gradient of environmental conditions from forest to páramo. The hypothesis about adaptive changes that occurred during the colonization of the páramo habitats was confirmed. Observed characteristics were, for example, leaf area and thickness, epidermal cells cuticle and cell wall thickness, epidermal cells lumen height, ratio of palisade and spongy parenchyma, stomatal area, stomata length and width, stomata pore length and sieve elements average area. Results suggest that the anatomy of the plants reflect the environmental conditions of the habitats rather than the species phylogeny.
|
|
| |
|
| |
guest ::
