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Selected aspects of biology of the invasive species \kur{Pectinatella magnifica}
JEŽKOVÁ, Eva
Pectinatella magnifica, invazní organismus, statoblast, rozmnožování, laboratorní kultivace SUMMARY Pectinatella magnifica is an invasive organism transfered to Czech republic from the USA with the international boat transport. Here it poses a lot of potencial threats toour native species, as well as to submerged technical constructions. It is a species of freshwater Bryozoan that is able to create colonies of considerable sizes. On the surface of a gelatinuous matrix there are small living indiviuals called the zooids. These can reproduce both sexually and asexually, which gives them a huge competitive potential. The dormant asexual spores, e.g. statoblasts, are extremely resistant towards various natural conditions and have characteristics enabling them to spread to substantial distances. This thesis aimed to identify and describe several life aspects of Pectinatella magnifica, especially reproduction and spreading strategy. I monitored the organism in the nature, as well as in a number of laboratory experiments. I was able to succesfully transfer the colonies of Pectinatella from the ponds into a special aquarium system. Under the laboratory conditions, 80 % of statoblasts germinated within five to eight days, depending on the water temperature. Then the zooids emerged and survived for around eight weeks, enabling me to observe different development and behaviour. Obtained photo and viceodocumentation shows details of a sexual reproduction of zooids, proving that it occurs even in our environment. The most prefered natural conditions seem to be the flooded mezotrophic sand quarries and protected and recreational ponds with a low fishing stock (without a massive algeae presence, fluctuating oxygen levels, etc.) The results do not suggest that Pectinatella magnifica is currently a significant competitor to our native Bryozoan species.
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The impact of hand-rearing of the Psittaciformes chicks on their future breeding behaviour and reproduction abilities.
BALABÁN, Michal
Hand-breeding of Psittaciformes is an important theme in connection with potential problems in the reproduction of such reared individuals. This also affects the future survival of some endangered species in the wild. This theme is not very developed in the literature and many breeders are of the opinion that artificially fed birds could cause problems in breeding. Literary research on the given theme, elaboration of 54 anonymous questionnaires filled in by breeders and three interviews with breeders who encountered the issue of inclusion of artificially fed individuals in breeding are chosen as the methodology. During the literature search, evaluation of questionnaires and from the conducted interviews, it was found that mainly the method, resp. the course of artificial breeding, determines the characteristics and abilities of parrots for their future life. The course of hand breeding depends on the decision of the breeder, for what purpose the parrot is intended, whether for breeding or as a domestic companion. Depending on the circumstances and conditions, the hand breeding parrot is able to be of the same quality for breeding as a naturally bred individual or to be a perfect pet. The results of this work contribute to the view that endangered populations of some captive species, which are very difficult to reproduce naturally, can be supplemented under the right conditions by reintroduction of hand-breeding parrots. Artificially bred individuals can also be placed in captivity. If the right process of socialization has taken place, such birds have the same ability to reproduce as naturally bred individuals.
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Reproduction and hybridization in ferns
HORNYCH, Ondřej
This thesis studies several aspects of fern reproduction and hybridization. Aspects of multiple stages in the fern life cycle are analyzed. Specifically, rates of spore abortion and antheridiogen usage are assessed and compared between various groups. Own cultivation and spore assessment data are compared extensively with existing literature. Finally, the rate of hybridization in natural populations and the symmetry of hybridization is analyzed in buckler ferns (Dryopteris carthusiana group).
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Interakce spermií a jiker u sladkovodních ryb: vliv prostředí na fertilizační proces
KHOLODNYY, Vitaliy
Fertilization of fresh water fish occurs in an environment which may affect negatively the gametes, therefore the fish male gametes should reach their counterpart, the female gamete, as soon as possible because spermatozoa become damaged within minutes or less due to osmotic shock. Existence of specific mechanism triggering, supporting and guiding the encounter of gametes would be highly expedient in these conditions. The eggs of many externally fertilizing freshwater fish species are released into the external milieu surrounded by a coat of ovarian fluid (OF) with a composition ideal for supporting and protecting eggs and sperm against the deleterious effect of freshwater. The existing data support the idea that the properties of OF and/or the specific compounds contained in it or released by the eggs could significantly affect the behavior of male gametes and consequently influence the outcome of fertilization in terms of the number of fertilized oocytes. The mechanisms which facilitate and trigger gametes' encounter are also highly demanded in terms of natural selection. It was found that presence of OF affected significantly the behavior of rainbow trout spermatozoa, in particular, their motility traits: higher velocity was supported for longer time and trajectories were straightened, comparing to those observed in water. In the microcapillary spermatozoon accumulation test (test of chemotactic response) the rainbow trout OF showed a trapping effect on activated male gametes which depended on osmotic properties of the activating media. Different molecular weight fractions from OF affected the tactic behavior of the cells in a various way. The most significant trapping effect was rendered by low molecular fraction and the possible chemotactic agent was found to be thermostable. The trapped cells showed specific turn-and-run behavior accompanied by asymmetric bending of flagella and burst-like increase of calcium concentration in the bended area. The in vitro fertilization test revealed the enhancement of spermatozoa performance, especially in the samples from the related individuals, which led to the higher embryo development rate. Presence of particular concentration of ovarian fluid (30% solution in water) had inhibiting effect on sterlet spermatozoa motility initiation. Lower concentrations of the ovarian fluid improved the longevity of spermatozoa and did not affect their trajectories. Test of chemotactic response showed no effect of ovarian fluid on spermatozoa behavior, while at the same time the attracting effect of egg conditioned medium was evident (i.e. due to some substances released from the eggs during their contact with fresh water). The results of in vitro fertilization test showed that presence of ovarian fluid prevented the eggs from losing the fertilizing ability due to the contact with water, as well as promoted the spermatozoa to fertilize the eggs during longer period of time. Presence of common carp ovarian fluid in the activation medium caused the decrease of the velocity of spermatozoa comparing to the OF-free medium and significantly altered the motility pattern from straightforward motility observed in the water to the tumbling in the medium with high OF content (50%). Introduction of OF (in the sperm accumulation test) entailed immediate and prominent chemotactic-like reaction of spermatozoa. The environmental conditions which accompany the encounter of gametes, in particular presence of OF, calcium ion content and osmolarity, significantly affect the performance of male gametes in spermatozoa in rainbow trout, sterlet and common carp in terms of changes in velocity, path linearity and ability to response to the external signals, e.g. attractants. The conducted study allowed to conclude that way how the ovarian fluid affects the behavior of spermatozoa in these species may be associated with their reproduction (spawning) strategy.
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Seasonality in reproduction and abundance of birds in African savannas
Kučminová, Veronika ; Hořák, David (advisor) ; Remeš, Vladimír (referee)
Seasonality of climate is a crucial factor that determines the existence of African savannas. Especially, the rainfall seasonality is a key factor in the abundance and reproduction of bird species of the savannas. Precipitation determines the timing of reproduction directly, but mainly indirectly through the influence of the environment, phenology, and productivity of plants. The vegetation determines the availability of resources and shelters. However, the widespread distribution of the savannas across the continent means that the seasonality and consequently the environment varies considerably from one area to another due to the different timing, size, and duration of wet and dry seasons. Breeding, as well as the abundance of savanna birds, is clearly influenced by the availability of food, which is determined by seasonal rainfall. For most species, the rainy season is an ideal time for reproduction, but there are also other groups of birds, that prefer a dry season for breeding and nesting. The birds must cope with unfavourable conditions outside the breeding season or leave their breeding areas. The abundance of birds in savannas is also significantly affected by the presence of palearctic migrants. Migration is therefore an important factor of the seasonal abundance of the savanna avifauna....
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Breeding of White Cockatoos in the Czech Republic and their Rearing and Breeding Administration
Kašíková, Petra ; Vančata, Václav (advisor) ; Řezníček, Jan (referee)
Background: This thesis deals about breeding and rearing white cockatoo in the Czech Republic. The work was conducted through a questionnaire about terms of compiling breeding pair, breeding and breeding conditions, additional feeding methods and kinds of mixtures for feeding and additional feeding. For the research part was used an electronic questionnaire where was collected 34 answers. This thesis includes research and comparison about rearing of 9 own white cockatoos. Objectives: The aim of this work was to describe breeding of white cockatoo in the Czech Republic to give an idea about this kind of parrots to the breeders of exotic parrots. As the first work about breeding and rearing fledgling based on questionnaires, which is complemented by administrative data on hand-rearing several fledglings of white cockaoo. Methods: Data were collected by using structured questionnaire for breeders of white cockatoo in the Czech Republic. The questionnarie was about breeding and rearing this kind of Cockatoo. For the analysis of the development and weight gain of the fledglings was used an administrative monitoring of own breed of white cockatoo. Results: From the research is clear that the fledglings which were additionaly feeded by mixture NutriBird and Kaytee we now know that fledglings which were...
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Physiological basis of extended longevity in termite kings and queens - is activation of telomerase mechanism linked with extended longevity of termites?
Pangrácová, Marie ; Hanus, Robert (advisor) ; Kodrík, Dalibor (referee)
- Extended longevity and high fecundity are two phenomena typical for reproductive castes (queens, eventually kings) of eusocial insects. In my thesis, we explore the hypothesis that the longevity of reproductives in the termite Prorhinotermes simplex is linked with the activation of the telomerase enzyme complex. Telomerase is well known for its life-extension functions, due especially to its capacity to prolong the telomeric ends of chromosomes. Therefore, we studied here the gene expression of: (1) the gene TERT coding for the catalytic subunit of the telomerase and (2) the genes of the main endocrine regulatory pathways, known to be responsible for the control of reproduction and longevity in insects. Expression dynamics of these genes were measured in sterile and reproductive castes of P. simplex during their development and sexual maturation. Based on our results obtained from the TERT expression analyses and their comparison with telomerase enzyme activities, we assume that the telomerase action in the long-lived reproductive individuals is regulated at a post-transcription level. Furthermore, we observed in reproductive castes a simultaneous upregulation of some transcription variants of vitellogenin and the genes for insulin signalling pathways. We can, therefore, conclude that in...
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Impact of river system structure on the genetic diversity of reed populations
Fuxová, Gabriela ; Fér, Tomáš (advisor) ; Kubátová, Barbora (referee)
Many plant species are closely related to river biotopes or to biotopes influenced by rivers. River systems create important linear corridors in ecosystems and directly or non-directly influence spatial spread of species in these environments. This offer many questions about species spread in this system. We can answer these questions by using molecular methods. Using 10 microsatellite (SSRs) primers, 202 individuals of Phragmites australis from 60 populations were analysed. Those analyses allowed reveal kinship of individuals, obtain information about spatial spread of populations and about spreading of common reed. Phragmites australis creates both - monoclonal and polyclonal - populations. Dependence of rate of clonality on environment was revealed. Populations from river banks are more monoclonal, populations from pond shores are more polyclonal. Populations are isolated. The highest percentage of variability was explained on among-population level. This is common for anemochoric species. Communication between populations is present, more on shorter distances. Evidence for vegetative spread was found on short distance. Generative spread is much more common. Long-distance spreading is mediated by generative diaspores - seeds. This spreading includes within-river spread, among-river spread and spreading...
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Physiological and hormonal mechanisms influencing ejaculate quality in birds
Mojžišová, Kateřina ; Tomášek, Oldřich (advisor) ; Svobodová, Jana (referee)
Sexual selection is an important mechanism of evolution. In addition to precopulatory sexual selection, arising when males compete for female partners, there is also postcopulatory sexual selection (sperm competition), when females copulate with more males. Even though most avian species are socially monogamous, most of them are also partially promiscuous. In such species, sperm competition is an important factor increasing variability in reproductive success between males. Male's success in sperm competition is primarily determined by sperm concentration, total sperm count and morphology and motility of spermatozoa. My bachelor thesis summarizes knowledge about the hormonal a physiological mechanisms that influence semen quality. This is especially the effect of sex and other hormones, physiological and oxidative stress, environmental conditions, antioxidant mechanism and composition of sperm cell membrane. Besides evaluating their influence on ejaculate quality on intraspecific level, I also describe their differences between avian species with respect to the differences of sperm competition.
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