Kryokonzervace rybího spermatu: kvalita versus kvantita
SOTNIKOV, Anatolii
2024 - anglický Kryokonzervaci spermatu ryb můžeme považovat za slibně se vyvíjející technologii s velkým potenciálem pro rozšíření účinnosti programů zachování genetické rozmanitosti u ohrožených a ekonomicky významných ryb. Kryokonzervace spermatu ryb se vyvíjela v průběhu let a byla zkoušena řada přístupů. Dnes je zřejmé, že se protokoly kryokonzervace spermatu podstatně liší podle taxonu a specifických vlastností spermatu ryb. A aby byla aplikace kryokonzervovaného spermatu co nejúčinnější, měly by použité protokoly zohlednit i praktické aspekty. S ohledem k základním vlastnostem spermatu ryb jako kryobiologických objektů je zřejmé, že protokoly poskytující nejlepší výsledky nejsou vždy vhodné pro rybářskou praxi, kdy se objem a forma jednotlivých dávek kryokonzervovaného materiálu, stejně tak jako snadná manipulace s dávkami, stávají klíčovými parametry pro praxi. Proto bylo jedním z cílů této práce vyvinout spolehlivý protokol kryokonzervace spermatu kapra obecného vhodný pro rybářskou praxi. Tento cíl byl dosažen vyvinutím specifické metody orientované na akvakulturu pro kryokonzervaci spermatu kapra. Druhým cílem bylo určit optimální, druhově specifické podmínky kryokonzervace spermatu jeseterů s různými ploidními úrovněmi. Tento cíl byl zvolen proto, protože druhově specifické rozdíly ve velikosti spermií spojené s ploidní úrovní by mohly mít vliv např. na optimální koncentraci spermatu při kryokonzervaci. Tento aspekt by mohl být klíčový pro použití kryokonzervace spermatu jeseterů v rybářské praxi a pro programy uchování genofondu. Třetím cílem bylo ověřit možnost třídění spermií v rozmrazeném spermatu jako nástroje k odhalení a k eliminaci kryokonzervací poškozených spermií a tím v budoucnu zabránit negativnímu účinku kryokonzervace spermatu na potomstvo. Práce obsahuje následující kapitoly. První kapitola představuje úvod do problému. Druhá kapitola této práce diskutuje vhodnou koncentraci spermií a skutečnost, že při vysokých koncentracích spermií během kryokonzervace dosahujeme nišší pohyblivosti spermií v rozmražených vzorcích. I přes nižší dosahovanou pohyblivost snižuje kryokonzervace vysoce koncentrovaných vzorků spermatu potřebu skladovacího prostoru v kryobankách a objem vzorků potřebných pro pokusy o umělé oplodnění. Třetí kapitola této práce ukazuje, že použití 4,5 ml kryozkumavek ve spojení s konkrétním kryomédiem, rychlostmi zmrazování a rozmrazování poskytuje vhodnou metodu pro kryokonzervaci koncentrovaného spermatu kapra obecného, vhodnou pro rybářskou praxi. Čtvrtá kapitola této práce ukázala, že rozdíly ve velikostech spermií různých druhů jeseterů nejsou spojeny pouze s ploidní úrovní. Navíc ploidní úroveň není určujícím faktorem optimální koncentrace spermatu pro kryokonzervaci u zkoumaných druhů, a proto se různé druhy jeseterů vyznačují poměrně podobnou optimální koncentrací spermatu při zmrazení a mohou být zmrazeny podobným postupem kryokonzervace. Pátá kapitola popisuje použitelnost dvou technik frakcionace spermatu pro kryokonzervované sperma u taxonomicky vzdálených druhů ryb. Použití separace pomocí Percoll gradientu umožňuje oddělení populace spermatu s významně zvýšeným procentem pohyblivých buněk u kapra obecného, jeseterů malého a sibiřského a pstruha duhového. Použití mikrofluidní akustické separace spermatu bylo vhodné pro jesetery malého a sibiřského a pro pstruha duhového, ale bylo neúčinné pro kapra obecného. Důležité je, že obě tyto metody zlepšují kvalitu potomstva získaného z kryokonzervovaného spermatu z hlediska procenta abnormálně se vyvíjejících larev. Sperm cryopreservation is considered a well-developed technology with a big potential for expanding the effectiveness of conservation programs preserving genetic diversity in endangered and economically important fishes. Fish sperm cryopreservation has developed over the years, and numerous approaches have been explored. Nowadays, it is evident that sperm cryopreservation protocols vary essentially according to taxa-specific properties of fish sperm, and to make the application of cryopreserved sperm the most effective, these protocols should be oriented toward practical requests. Due to the basic properties of fish sperm as cryobiological objects, it is clear that the protocols providing the best outcomes are not always appropriate for fisheries practice when cryopreserved material volume and easy-to-use packaging become vital parameters for the practice. That is why developing a sperm cryopreservation protocol suitable for fisheries practice in common carp is one of the primary goals of the current thesis. This goal was accomplished by developing a specific, aquaculture-oriented method for carp sperm cryopreservation. The second goal was to determine the optimal species-specific conditions for cryopreservation sperm in sturgeon possessing different ploidy levels. This goal was set because, specific to sturgeons, differences in sperm size associated with ploidy level could influence the optimal sperm concentration at cryopreservation. This aspect could be crucial for applying sturgeon sperm cryopreservation in fisheries practice and conservation programs. The third goal was set based on the necessity of a basic understanding of sperm sorting after unfreezing, which could help to reveal sperm cryopreservation damages in future studies and to avoid the negative effect of sperm cryopreservation on offspring performance. The thesis contains the following chapters. The first chapter represents an introduction to the problem. The second chapter of this thesis discusses that high spermatozoa concentration during cryopreservation decreases thawed samples' motility. Nevertheless, even with decreased motility, the cryopreservation of highly concentrated sperm samples reduces storage space in cryobanks and the volume of samples needed for artificial fertilization trials. The third chapter of this thesis shows that using 4.5 ml cryotubes in combination with specific cryomedium, freezing, and thawing rates gives an appropriate for fisheries practice method for cryopreservation of concentrated common carp sperm. Chapter four of this thesis showed that differences in spermatozoa sizes of different sturgeon species are not solely connected with ploidy level. Moreover, ploidy level is not a determinant of optimal sperm concentration for sperm cryopreservation in investigated species, and therefore, different sturgeon species are characterized by quite similar optimal sperm concentration at freezing and could be frozen by a similar cryopreservation approach. Chapter five describes the applicability of two sperm fractionation techniques for cryopreserved sperm in taxonomically distant fishes. Using Percoll gradient separation allows the separation of the sperm population with a significantly increased percentage of motile cells in common carp, sturgeons, and rainbow trouts. The use of microfluidic acoustic sperm separation was appropriate for sterlet, Siberian sturgeon, and rainbow trout but was ineffective for common carp. Importantly, both of these methods improve the quality of offspring obtained from cryopreserved sperm in terms of the percentage of abnormally developing larvae. Klíčová slova: pohyblivost spermií; počítačově asistovaná analýza spermatu; kryokonzervace; Cypriniformes; Acipenseridae; umělá reprodukce Plné texty jsou dostupné v digitálním repozitáři JČU. Kryokonzervace rybího spermatu: kvalita versus kvantita

Kryokonzervaci spermatu ryb můžeme považovat za slibně se vyvíjející technologii s velkým potenciálem pro rozšíření účinnosti programů zachování genetické rozmanitosti u ohrožených a ekonomicky ...

SOTNIKOV, Anatolii
Jihočeská univerzita v Českých Budějovicích, 2024

Potravní efektivita a kapacita nepůvodního hlaváče černoústého (Neogobius melanostomus) v různých biotických podmínkách
FRANTA, Pavel
2024 - anglický Plné texty jsou dostupné v digitálním repozitáři JČU. Potravní efektivita a kapacita nepůvodního hlaváče černoústého (Neogobius melanostomus) v různých biotických podmínkách

FRANTA, Pavel
Jihočeská univerzita v Českých Budějovicích, 2024

Studie kompatibility zárodečných buněk po transplantaci příjemci
NAYAK, Rigolin
2024 - anglický Náhradní produkce pomocí transplantace zárodečných kmenových buněk je novou biotechnologií, která má zefektivnit akvakulturu a základní výzkum týkající se reprodukční biologie ryb. Zárodečné kmenové buňky odebrané dárci v embryonálním nebo dospělém stadiu se transplantují geneticky kompatibilním sterilním příjemcům. U transplantovaných zárodečných buněk je méně pravděpodobné, že budou příjemcem odmítnuty, pokud je genetická příbuznost na úrovni druhu. Produkce zárodečných chimér se však snižuje v případě fylogeneticky vzdálených druhů. Xenogenní transplantace je často zaměřena na zlepšení určitých vlastností dárcovského druhu, jako je zrychlení doby pohlavního dozrávání, odbourání environmentálních překážek při chovu v zajetí, zachování genetických zdrojů ohrožených druhů a zvýšení produkce gamet prostřednictvím náhradního rodičovství. Transplantace zárodečných buněk mezi těmito vzdálenými druhy často selhávala kvůli menší genetické kompatibilitě a dalším faktorům, jako je stupeň sterility a kmenovost transplantovaných zárodečných buněk. Další ústřední otázka týkající se náhradní produkce se týká epigenetických změn v gametách a potomstvu pocházejícím od dárce, které dosud nebyly zkoumány. Je známo, že epimutace (ztráta nebo zisk metylace DNA) způsobují funkční změny, které jsou dědičné pro mnoho generací. Metylace DNA je nejlépe prozkoumanou epigenetickou značkou, která reguluje genovou expresi. Zárodečné buňky jsou během izolace podrobeny několika mechanickým a enzymatickým úpravám. Proliferace a diferenciace se řídí somatickými buňkami hostitelské gonády, které se nepochybně liší od mikroprostředí dárcovské gonády. Tyto změny mohou ovlivnit metylom dárcovské zárodečné linie, a tím způsobit buněčné a funkční změny, které mohou přetrvávat po generace. Byla provedena xenogenní transplantace mezi zebřičkami a daniem malabarským s cílem zvýšit množství gamet zebřiček prostřednictvím náhradních rodičů dania malabarského. Byl sekvenován dean end gen (dnd) dania malabarského a byly navrženy morfolinové sekvence, které účinně znemožňují vývoj zárodečných buněk. Transplantací spermatogonií vznikly zárodečné chiméry dania malabarského produkující spermie zebřičky, které byly desetkrát koncentrovanější než spermie dárce. Podobnou metodu lze v budoucnu použít i u jiných druhů ke zvýšení produkce gamet prostřednictvím většího náhradního rodiče. Pomocí dvou typů náhradních rodičů bylo provedeno podrobné zkoumání epimutací a jejich funkčních změn. Studie odhalila, že spermie a potomstvo obou náhradních rodičů jsou ve srovnání se spermiemi a potomstvem dárce hypermetylované v celém genomu. Porušená hypermetylace neměla vliv na změny genové exprese ani na fenotypové abnormality potvrzené analýzami genové exprese a fenotypovými vyšetřeními. Částečná gonadektomie u dvou malých druhů ryb, zebřiček a halančíků, poskytla účinnou metodu izolace zárodečných buněk bez nutnosti usmrcení dárce, která se může uplatnit i u jiných druhů pro náhradní reprodukci. Údaje z této studie poskytnou lepší vhled do budoucích studií transplantace zárodečných buněk a epigenetické srovnávací studie otevírají prostor pro podrobnou analýzu gamet odvozených od dárce z fylogeneticky vzdálených náhradních spermií a kryokonzervovaných zárodečných kmenových buněk. Surrogate production by germline stem cell transplantation is new-age biotechnology to improve aquaculture and basic research pertaining to reproductive biology in fishes. Germ stem cells harvested from the donor at the embryonic or adult stage are transplanted into genetically compatible sterile recipients. The transplanted germ cells are less likely to be rejected by the recipient when the genetic relationship is at the species level. However, the germline chimera production decreases in the case of the phylogenetically distant species. Xenogenic transplantation is often targeted to improve certain traits in the donor species, such as speeding up sexual maturation time, removing the environmental barriers to captive rearing, preserving the genetic resources of threatened species, and boosting gamete production via surrogacy. Germ cell transplantation between those distant species often failed due to less genetic compatibility and other factors, such as the degree of sterility and the stemness of the transplanted germ cell. Another central question about surrogate production concerns the epigenetic changes in donor-derived gametes and progeny, which remain to be unveiled. Epimutations (loss or gain of DNA methylation) are known to cause functional changes that are heritable to many generations. DNA methylation is the best-studied epigenetic mark that regulates gene expression. The germ cells undergo several mechanical and enzymatic treatments during their isolation. Proliferation and differentiation are guided by the host gonadal somatic cells that undoubtedly differ from the donor gonadal microenvironment. Those changes can influence the methylome of the donor germline and, thereby, cause cellular and functional changes that may persist over generations. Xenogenic transplantation was performed between zebrafish and giant danio to increase the amount of zebrafish gametes via giant danio surrogates. The giant danio dead end (dnd) gene was sequenced, and morpholino sequences were designed to deplete germ cell development in giant danio effectively. Spermatogonial transplantation was optimized to produce giant danio germline chimera with ten times more concentrated zebrafish donor-derived sperm than the donor. A similar method can be applied to other species in the future to increase gamete production via a bigger surrogate. A thorough investigation of epimutations and their functional changes was assessed using two kinds of surrogates. The study revealed that the sperm and progeny from both surrogates are genome-wide hypermethylated compared to the donor sperm and progeny. The perturbed hypermethylation did not influence gene expression changes or phenotypical abnormalities confirmed by gene expression analyses and phenotypical investigations. Partial gonadectomy in two small species, zebrafish and killifish, provided an effective method for germ cell isolation without sacrificing the donor, which may apply to other species for surrogate production. The data from the current study will provide greater insight into future germ cell transplantation studies, and the epigenetic comparative studies set the stage for in-depth analysis of donor-derived gametes from phylogenetically distant surrogates and the cryopreserved germ stem cells. Klíčová slova: Náhradní reprodukce; Zárodečné buňky; DNA metylace; Epigenetická remodelace; Transplantace zárodečných buněk; Částečná gonadektomie Plné texty jsou dostupné v digitálním repozitáři JČU. Studie kompatibility zárodečných buněk po transplantaci příjemci

Náhradní produkce pomocí transplantace zárodečných kmenových buněk je novou biotechnologií, která má zefektivnit akvakulturu a základní výzkum týkající se reprodukční biologie ryb. Zárodečné kmenové ...

NAYAK, Rigolin
Jihočeská univerzita v Českých Budějovicích, 2024

Thin Nanostructured Film with Bioapplication Potential
KUMAR, Sanjay
2024 - anglický The Ph.D. thesis aims to investigate, develop, and fabricate advanced nanostructured surfaces for (bio)sensors and detection applications. The primary outcome of the research is the development of a functional sensor transducer for the detection of specific anti-DbpA antibodies, typically produced by a living organism in response to Lyme disease infection, as well as for detecting live Borreliosis pathogens. The developed sensor is based on AgNPs/C:H:N:O plasma polymer nanocomposites. Silver (Ag) nanoparticles, generated by a gas aggregation source, are incorporated into a C:H:N:O plasma polymer matrix, which is deposited by magnetron sputtering of nylon 6.6. The surface of the AgNPs/C:H:N:O nanocomposite is functionalized with amino-rich -NH2 grafts and specific antibodies to achieve high specificity in detection. Anchored Ag nanoparticles propagate localized surface plasmon resonance (LSPR), optically responding to changes caused by immobilized targets near the nanoparticles. The sensitivity of the sensor transducer is enhanced by incorporating Cu nanoparticles, which contribute to Cu-Ag coupling modes responsible for the modulation of the LSPR bands. The achieved results pave the way for rapid, low-cost, sensitive platforms for detecting not only the antibodies/pathogens studied here but also potentially other targets. The Ph.D. thesis aims to investigate, develop, and fabricate advanced nanostructured surfaces for (bio)sensors and detection applications. The primary outcome of the research is the development of a functional sensor transducer for the detection of specific anti-DbpA antibodies, typically produced by a living organism in response to Lyme disease infection, as well as for detecting live Borreliosis pathogens. The developed sensor is based on AgNPs/C:H:N:O plasma polymer nanocomposites. Silver (Ag) nanoparticles, generated by a gas aggregation source, are incorporated into a C:H:N:O plasma polymer matrix, which is deposited by magnetron sputtering of nylon 6.6. The surface of the AgNPs/C:H:N:O nanocomposite is functionalized with amino-rich -NH2 grafts and specific antibodies to achieve high specificity in detection. Anchored Ag nanoparticles propagate localized surface plasmon resonance (LSPR), optically responding to changes caused by immobilized targets near the nanoparticles. The sensitivity of the sensor transducer is enhanced by incorporating Cu nanoparticles, which contribute to Cu-Ag coupling modes responsible for the modulation of the LSPR bands. The achieved results pave the way for rapid, low-cost, sensitive platforms for detecting not only the antibodies/pathogens studied here but also potentially other targets. Klíčová slova: plasma polymer; plasma polymerization; C:H:N:O thin film; nylon; nanoparticles (Ag; Cu); nanostructures; nanocomposite; surface functionalization; magnetron sputtering; annealing; adhesion; immobilization; sensors; antibacterial; Lyme disease; Borrelia; plasmonic absorption; localized surface plasmon resonance (LSPR); plasma-assisted deposition; enhanced detection Plné texty jsou dostupné v digitálním repozitáři JČU. Thin Nanostructured Film with Bioapplication Potential

The Ph.D. thesis aims to investigate, develop, and fabricate advanced nanostructured surfaces for (bio)sensors and detection applications. The primary outcome of the research is the development of a ...

KUMAR, Sanjay
Jihočeská univerzita v Českých Budějovicích, 2024

Population genomics of parasite adaptation: New insights into diversification and speciation of parasites
NAZARIZADEH DEHKORDI, Masoud
2024 - anglický This thesis investigates the ecological and genetic dynamics of parasitic species, primarily focusing on Ligula intestinalis tapeworms and Cimex bedbugs, aiming to enhance our understanding of their evolutionary biology, genetics, and adaptation mechanisms. In Chapter I, it elucidates the prevalence and population genetic structure of L. intestinalis plerocercoids in various cyprinoid fish species across Czech water bodies, focusing on how different hosts and environments influence genetic diversity and distribution. Chapter II explores the historical dispersal and host-switching events that have shaped the evolutionary history of the L. intestinalis species complex on a global scale. This includes identifying major evolutionary lineages, their host specificity, and the influence of biogeographic and demographic events on lineage diversity. Chapter III provides a highly contiguous genome assembly for L. intestinalis and examines RNA transcription patterns to understand the regulation of biological functions during its life cycle, establishing a comprehensive reference transcriptome for both plerocercoid and adult stages. Chapter IV explores the mechanisms underlying possible ecological speciation in L. intestinalis, particularly under a sympatric setting, to determine whether host specificity influences population structure in the absence of geographical separation. Chapter V shifts focus to the establishment of the tropical bedbug, Cimex hemipterus, in Central Europe, using genetic analyses to reveal limited mtDNA variability and the presence of pyrethroid resistance mutations. Finally, Chapter VI investigates genetic and transcriptomic divergence in C. lectularius populations associated with human and bat hosts, exploring how host switching influences genetic diversity and adaptation. This genomic and transcriptomic approach provides valuable insights into the evolutionary dynamics and adaptive strategies of parasitic species. Klíčová slova: Population genomics; Phylogeography; Historical biogeography; Ligula intestinalis; bedbugs Plné texty jsou dostupné v digitálním repozitáři JČU. Population genomics of parasite adaptation: New insights into diversification and speciation of parasites

This thesis investigates the ecological and genetic dynamics of parasitic species, primarily focusing on Ligula intestinalis tapeworms and Cimex bedbugs, aiming to enhance our understanding of their ...

NAZARIZADEH DEHKORDI, Masoud
Jihočeská univerzita v Českých Budějovicích, 2024

Tuning carotenoid photophysics by changes in structure and local environment
ÖZCAN, Emrah
2024 - anglický This thesis investigates the complex dynamics of excited states in carotenoids, focusing on the origins and properties of certain dark states and how they are affected by external disturbances such as metal interactions, pH changes, applied voltage, and chemical modifications. Paper I demonstrates the creation of stable astaxanthin-metal complexes and their altered excited-state dynamics, revealing shortened lifetimes and enhanced ICT bands due to metal-ion interactions. Paper II explores the effect of external voltage on 8-apo--carotenal, showing that applied voltage can control the ICT state amplitude and extend its lifetime. Paper III examines pH-dependent effects on crocin, finding significant pH-induced shifts and stabilization at basic pH levels. Paper IV presents the synthesis and analysis of bis-phenylhydrazone astaxanthin, highlighting its modified excited-state dynamics and the potential for organic modification to study new effects. These findings enhance our understanding of carotenoid excited states and suggest new research approaches. This thesis investigates the complex dynamics of excited states in carotenoids, focusing on the origins and properties of certain dark states and how they are affected by external disturbances such as metal interactions, pH changes, applied voltage, and chemical modifications. Paper I demonstrates the creation of stable astaxanthin-metal complexes and their altered excited-state dynamics, revealing shortened lifetimes and enhanced ICT bands due to metal-ion interactions. Paper II explores the effect of external voltage on 8-apo--carotenal, showing that applied voltage can control the ICT state amplitude and extend its lifetime. Paper III examines pH-dependent effects on crocin, finding significant pH-induced shifts and stabilization at basic pH levels. Paper IV presents the synthesis and analysis of bis-phenylhydrazone astaxanthin, highlighting its modified excited-state dynamics and the potential for organic modification to study new effects. These findings enhance our understanding of carotenoid excited states and suggest new research approaches. Klíčová slova: Carotenoids; Metal complexes; Ultrafast spectroscopy; Charge transfer state; Cyclic voltammetry; 8'-apo--carotenal; Spectroelectrochemistry; Crocin; pH-dependence. Plné texty jsou dostupné v digitálním repozitáři JČU. Tuning carotenoid photophysics by changes in structure and local environment

This thesis investigates the complex dynamics of excited states in carotenoids, focusing on the origins and properties of certain dark states and how they are affected by external disturbances such as ...

ÖZCAN, Emrah
Jihočeská univerzita v Českých Budějovicích, 2024

Consumptive and non-consumptive effect of predators and food quality on arthropod herbivores
KOLLROSS, Jan
2024 - anglický Top-down and bottom-up controls are crucial mechanisms that shape ecosystems and biodiversity. In this thesis, I investigate both bottom-up and top-down forces, their interplay and specific effects on arthropod communities, herbivores, and their behaviour across vertical forest gradients. The thesis consists of four chapters. The first chapter explores the top-down regulation of arthropods and the resulting herbivore damage across a vertical forest gradient in a Japanese temperate forest, focusing on the effect of three groups of insectivorous predators. In my second chapter, I attempt to compare the relative impact of bottom-up and top-down control. I studied their relative effects on arthropods and herbivore damage by manipulating nutrient availability and access of predators to trees in a temperate forest in the Czech Republic. In my third chapter, I focused on one of the most important insect orders, the Coleoptera. I investigated the Coleoptera communities and the influence of predators on them along the vertical forest gradient in two different temperate sites: in Japan and Germany. Finally, I examined the nonlethal effect of predators on herbivore prey, testing the effect of bird presence on locust behavior and their stress hormone levels. Overall, my thesis examines the complexity of tri-trophic interactions between plants, herbivorous arthropods, and their insectivorous predators. It highlights the importance of nutrient availability, and the access of insectivorous predators to plants, for the functioning and result of multi-trophic interactions. It also discusses lethal as well as nonlethal effects separately. Top-down and bottom-up controls are crucial mechanisms that shape ecosystems and biodiversity. In this thesis, I investigate both bottom-up and top-down forces, their interplay and specific effects on arthropod communities, herbivores, and their behaviour across vertical forest gradients. The thesis consists of four chapters. The first chapter explores the top-down regulation of arthropods and the resulting herbivore damage across a vertical forest gradient in a Japanese temperate forest, focusing on the effect of three groups of insectivorous predators. In my second chapter, I attempt to compare the relative impact of bottom-up and top-down control. I studied their relative effects on arthropods and herbivore damage by manipulating nutrient availability and access of predators to trees in a temperate forest in the Czech Republic. In my third chapter, I focused on one of the most important insect orders, the Coleoptera. I investigated the Coleoptera communities and the influence of predators on them along the vertical forest gradient in two different temperate sites: in Japan and Germany. Finally, I examined the nonlethal effect of predators on herbivore prey, testing the effect of bird presence on locust behavior and their stress hormone levels. Overall, my thesis examines the complexity of tri-trophic interactions between plants, herbivorous arthropods, and their insectivorous predators. It highlights the importance of nutrient availability, and the access of insectivorous predators to plants, for the functioning and result of multi-trophic interactions. It also discusses lethal as well as nonlethal effects separately. Klíčová slova: Bottom-up control; top-down control; arthropod communities; herbivory; vertical forest gradient; nutrient availability; predator presence; trophic cascades; ecosystem dynamics; nonlethal predator effects; Coleoptera; temperate forests Plné texty jsou dostupné v digitálním repozitáři JČU. Consumptive and non-consumptive effect of predators and food quality on arthropod herbivores

Top-down and bottom-up controls are crucial mechanisms that shape ecosystems and biodiversity. In this thesis, I investigate both bottom-up and top-down forces, their interplay and specific effects on ...

KOLLROSS, Jan
Jihočeská univerzita v Českých Budějovicích, 2024

Impact of water deficit stress on leaf quality, predator and herbivore communities in Ficuses
XIAO, Xue
2024 - anglický This thesis addresses the mechanism by which drought affects tropical plant-insect interactions via leaf traits, focusing on Ficus species. I discovered that both drought intensity and duration indirectly influenced the leaf palatability of Ficus through changes in leaf mechanical traits such as leaf water content and specific leaf area. Furthermore, my research revealed that drought increased leaf herbivory by altering leaf latex outflow, without affecting insect communities. Additionally, I observed that drought enhanced Ficus indirect defense through changes in herbivore-induced plant volatiles. My findings suggest that the impact of drought on Ficus-insect interactions may vary between greenhouse and tropical rainforest environments and may be species-specific. This work underscores the importance and urgency of researching tropical plant-insect interactions under climate change. Klíčová slova: drought; herbivores; leaf mechanical traits; leaf secondary metabolites; leaf volatile; predators; tropical ecosystem Plné texty jsou dostupné v digitálním repozitáři JČU. Impact of water deficit stress on leaf quality, predator and herbivore communities in Ficuses

This thesis addresses the mechanism by which drought affects tropical plant-insect interactions via leaf traits, focusing on Ficus species. I discovered that both drought intensity and duration ...

XIAO, Xue
Jihočeská univerzita v Českých Budějovicích, 2024

Patrnosti v polinačních systémech podél geografických gradientů
JACKWERTH, Karolína
2024 - anglický The general aim of the thesis is to shed light on invertebrate herbivory and pollination in relation to the changing environment. Several experiments were conducted on meadow communities in the temperate region, and we combined manipulative and experimental approaches during data collection. The first chapter of the thesis investigated the change of invertebrate herbivory across one season affected by phylogeny and plant functional traits. The second chapter emphasized the impact of range-shifting plants, driven by increasing temperature as a proxy for global warming, on herbivory damage. Similarly, the third chapter focused on plant-pollinator turnover on range-shifting plants, driven by increasing temperature as a proxy for global warming. The last fourth chapter examined the effect of increasing temperature as a proxy for global warming on pollen viability of widespread forb. Klíčová slova: invertebrate herbivory; insect pollination; range-shifting plants; elevation Plné texty jsou dostupné v digitálním repozitáři JČU. Patrnosti v polinačních systémech podél geografických gradientů

The general aim of the thesis is to shed light on invertebrate herbivory and pollination in relation to the changing environment. Several experiments were conducted on meadow communities in the ...

JACKWERTH, Karolína
Jihočeská univerzita v Českých Budějovicích, 2024

Enhancement of fish communities, improvement of sampling and stock assessment in lakes and reservoirs.
RIBEIRO DE MORAES, Karlos
2024 - anglický This Ph.D. thesis focuses on fish habitats, how we can improve their natural complexity, and how we can improve techniques to survey these habitats. With increasing human activities affecting freshwater ecosystems due to human population growth and industrial expansion, it is crucial to study environmental changes, their impacts, and ways to mitigate damage. As many biotic and abiotic factors can influence the health and diversity of the community, for our study, we focused on habitat definition and complexity, and the effect of fishery management. Paper (I) focuses on the transition between littoral (shallow areas) and pelagic (open water) habitats and their impact on fish communities. The littoral zone, typically the most intricate segment of a water body, serves as the primary habitat for a significant portion of the fish community and species diversity. However, its spatial extent is very limited. Littoral delimitation is important for obtaining a true picture of the fish community composition and for its sustainable management decisions. Paper (II) investigated the impact of protected areas on fish populations in the Lipno reservoir in the Czech Republic, specifically focusing on the abundance, biomass, standard length, and diversity indices. Protected areas have legislation that reduces or stops certain anthropological impacts to help recover the ecosystem. These areas are normally linked to spawning areas, feeding grounds, or rare species and are vital for the restoration and proliferation of specific environments. In our case, we revealed more and larger predatory fish in protected and low anthropological impact areas. Paper (III) tests the introduction of artificial habitats, which are man-made structures or environments created to provide additional habitats and support for various organisms. Despite efforts to restore habitats to their natural states, there are instances where complete restoration is challenging. In particular, water bodies are subjected to significant anthropogenic alterations, such as reservoirs. In such instances, the introduction of artificial habitats has emerged as a solution to rapidly enhance the complexity of these environments. In Lipno reservoir, artificial floating islands attracted young-of-the-year of common species. Klíčová slova: Fish management; Anthropogenic impact; Spatial distribution; Habitat use; Habitat restoration; Stock enhancement; Protected areas; Artificial Habitat Plné texty jsou dostupné v digitálním repozitáři JČU. Enhancement of fish communities, improvement of sampling and stock assessment in lakes and reservoirs.

This Ph.D. thesis focuses on fish habitats, how we can improve their natural complexity, and how we can improve techniques to survey these habitats. With increasing human activities affecting ...

RIBEIRO DE MORAES, Karlos
Jihočeská univerzita v Českých Budějovicích, 2024