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Abundance and habitat use of reintroduced populations of the Hermit (Chazara briseis) in the Czech Republic
Pešová, Lucie ; Sedláček, Ondřej (advisor) ; Vrba, Pavel (referee)
The Hermit (Chazara briseis) belongs to the critically endangered species in the Czech Republic. Its last population survived until recently in the NPR Raná in the České středohoří Protected Landscape Area, but it has gradually declined. The specie's habitat is short-stemmed grasslands, which are maintained mainly by extensive grazing and management. Currently, these sites are declining, traditional management has changed and the sites are gradually becoming overgrown. Therefore, the reconstruction of the butterfly's habitats has been undertaken in selected localities that the butterfly used to inhabit in the past, in the České středohoří Protected Landscape Area (PR Číčov, Dlouhá hora, PP Radobýl) and in the Český kras Protected Landscape Area (Třesina, Radotín). Reintroduction of eggs and caterpillars took place in these sites in 2020-2021. The aim of the thesis was to evaluate the population abundance and habitat use of the Chazara briseis at these sites immediately after reintroduction. I estimated the size of the populations using the mark-capture-recapture method in 2020 and 2021. The size of the populations in the Lonské středohoří (Dlouhá hora and Číčov) was around 400-500 individuals with a fairly balanced sex ratio. Overflights were also recorded between these sites, which may indicate...
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Induction and potential use of monosex populations of pikeperch (Sander lucioperca) in intensive farming
ŠVEJDA, Pavel
The aim of this study was to induce monosex populations of pikeperch using the method of direct masculinization and direct feminization in order to change sex and evaluate the production parameters and body indices of the treated groups of pikeperch. For direct masculinization, 17 -methyltestosterone was used at a dose of 30 or 50 mg.kg-1 for 30 or 60 days. For direct feminization, 17 -estradiol was used at a dose of 30 mg.kg-1 feed for 30 days. Individuals of pikeperch with TL = 51.52 +- 4.19 mm and W = 1.23 +- 0.26 g, FC = 0.9 +- 0.3 were used for the experiment. In the experiment, direct feminization achieved a sex ratio 98.3 % of females and 1.7 % of males. This is the first record of an almost all-female population induced with 17 -estradiol. The highest level of masculinization of the tested individuals was achieved in the group exposed to 17 -methyltestosterone at a dose of 30 mg.kg-1 feed for 60 days. In this population, 75 % of individuals with male genital tissue were found, of which 21.7 % were individuals whose testicular sperm could be used to produce an all-female population. In groups treated with 17 -methyltestosterone for 60 days, the presence of "neomales" and intersex (hermaphrodite) individuals was observed. The experiment revealed that the use of the hormones 17 -methyltestosterone and 17 -estradiol can temporarily cause growth suppression, particularly during and shortly after exposure of individuals to these hormones. However, it does not have a lethal effect on individuals in the doses we applied. The higher growth rate of pikeperch females was not confirmed in the test. Females treated with 17 -estradiol did not show higher weight gains compared to the control group. A significant difference in the achieved final weight was not observed between both sexes in the control group at the end of the experiment.
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Sex ratios in reptiles according to the type of sex determination
Palata, Tomáš ; Kratochvíl, Lukáš (advisor) ; Rehák, Ivan (referee)
There are many factors influencing sex ratios in reptile populations and these factors can differ among sex ratios in different developmental stages. The observed ratio is the result of many complex processes. One of the key factors is the mechanism of sex determination. In reptiles we distinguish two mechanisms of sex determination. The first is genotypic sex determination (GSD), where sex is determined during the fusion of gametes. Species with GSD show just little variation in sex ratios after birth or hatching and during adulthood there is a higher mortality rate of the heterogametic sex. Secondarily, there are reptiles possesing environmental sex determination (ESD). The sex of the developing individual of this species is influenced by incubation temperature during the thermosensitive phase of development. Reptiles with ESD show much greater variability in sex ratios after hatching and this variability may persist to adulthood. This thesis focuses mainly on the differences in sex ratios between GSD and ESD species. One of its interests is also the question of vulnerability of reptiles with ESD in terms of skewed sex ratios during contemporary climate change. Key words: sex ratio, reptiles, sex determination, GSD, ESD, climate change
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Surviving of Northern Lapwing (Vanellus vanellus) chicks in agriculture landscape
Kubelka, Vojtěch ; Šálek, Miroslav (advisor) ; Cepák, Jaroslav (referee)
The variability of egg-size within a bird species reflects different reproductive investments and, besides the intrinsic constraints and particular female quality, it can be affected by environmental factors, too. Moreover, the egg-size predetermines the chick performance. The knowledge of factors influencing precocial chick survival is crucial for better understanding of life-history strategies as well as for endangered species conservation. The Northern Lapwing (Vanellus vanellus) represents a suitable model species for investigation of climate variables effects on egg-size and also to study factors influencing chick survival. Eggs in a total of 714 nests were measured during 13 breeding seasons over period 1988-2014 in South Bohemia and 293 lapwing chicks from 100 broods in 37 localities were monitored in 2013-2014. The mean egg-size through the whole season is positively affected by March precipitation, March clutches also negatively by minus temperatures in March. The higher intensity of rainfall there is during March, the bigger eggs are laid in March and the steeper is slope of decline in mean egg-size during season. This decline is more profound with lower rainfall in April. The effect of habitat is not significant. The body mass and condition of hatchlings is positively correlated with the...
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Can birds manipulate sex ratio of their offspring?
Tomiška, Lubomír ; Kratochvíl, Lukáš (advisor) ; Fuchs, Roman (referee)
The aim of this study is a summary of existing knowledge about skewed sex ratio in birds. This controversial topic represents one of the most important questions of evolutionary ecology. We still miss consistence in finding ultimate causes just as proximate mechanisms although there was an expansion of experimental studies already in the last decade of the 20th century which was caused by an invention of the new technology in sex determination. On the other hand, there are many convincing proofs of skewed primary, secondary, tertiary and even quartenary sex ratio so the facultative manipulation or obligatory sex ratio bias is presumable. My Bachelor's thesis compares studies focused on the similar ultimate causes and tries to point out their deficiencies together with contributions to research of this topic. Observation of sex ratio includes many specifics which are mentioned in theoretical introduction. The second part offers potencial proximate mechanisms which could be responsible for sex ratio manipulation. Within the analysis of studies I found sex ratio manipulation of the first egg in clutch as common trend which could fit to selective ovum resorption as a proximate mechanism.
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Analýza poměru pohlaví a věkové struktury vybraných populací prasete divokého a zhodnocení vlivu loveckých aktivit
Svoboda, Tomáš
In three locations in the Czech Republic an analysis of sex ratio and age structure of selected populations of wild boar was conducted in order to assess age and sex structure of hunted game. The analysis was conducted in 2016-2018 during organised hunts without distinction of sex and age. Altogether, 665 wild boars were assessed, out of which 384 were females and 281 males. Sex was identified with each head, so was their age – according to teeth development, and their weight – using scales. According to the results, the sex ratio is deteriorating with growing age, leaving more females; examined locations show poor structure of game from the point of view of both age and sex. Although farrowing was at its highest in spring, it is happening all year round.
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Analýza reprodukčního potenciálu dospělých samic prasete divokého
Podlipná, Jiřina
Diploma Thesis focuses on adult wild boar females and analysis of their reproductive potential based on data obtained on drives during main reproduction period (August to January) at 30 areas of interest throughout the Czech Republic in years 2014–2017. Average value detection of Gonadosomatic Index (GSI) out of gravid female wild boars 0,0097 and out of all samples 0,0071. Rut period based on the age of fetuses is from October to January and expected dates of birth are determined by shifting the length of pregnancy towards the rut period with a peak in March. The litter size has just low correlation with the weight and very low with the age, average litter size in adult wild boar females is 6,1 youngsters for hoggets and 6,3 youngsters for wild sows. Average embryonic mortality reaches 13 %. The total sex ratio of piglets is 1:1,08 (M:F), the sex ratio of piglets for hoggets is 1:1,13 and for wild sows 1:1. The resulting finding of this analysis is, that there is no significant difference between the average litter size of hoggets and wild sows, so it is recommended to regulate the number of adult wild boar females year-round irrespective of age of the individuals.
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Toxoplasma and Host's Reproductive Function
Hlaváčová, Jana ; Kaňková, Šárka (advisor) ; Kodym, Petr (referee)
Toxoplasma gondii (Apicomplexa) is probably one of the most common human parasite in developed countries. It has a wide range of hosts including a variety of warm-blooded animals as well as humans. In this bachelor thesis you can find review of literature focusing on an influence of T. gondii on host's reproductive functions. Toxoplasmosis is accompanied by hormonal changes which may be one reason for the negative effect on host's fertility. Throughout the thesis are mentioned immunosuppression and reduced quality control of embryos associated with T. gondii. Both of these phenomena probably affect pregnancy, prenatal and postnatal development of the offsprings of mothers with latent toxoplasmosis. And these also play a role in shifting of sex ratio in infected hosts.
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Surviving of Northern Lapwing (Vanellus vanellus) chicks in agriculture landscape
Kubelka, Vojtěch ; Šálek, Miroslav (advisor) ; Cepák, Jaroslav (referee)
The variability of egg-size within a bird species reflects different reproductive investments and, besides the intrinsic constraints and particular female quality, it can be affected by environmental factors, too. Moreover, the egg-size predetermines the chick performance. The knowledge of factors influencing precocial chick survival is crucial for better understanding of life-history strategies as well as for endangered species conservation. The Northern Lapwing (Vanellus vanellus) represents a suitable model species for investigation of climate variables effects on egg-size and also to study factors influencing chick survival. Eggs in a total of 714 nests were measured during 13 breeding seasons over period 1988-2014 in South Bohemia and 293 lapwing chicks from 100 broods in 37 localities were monitored in 2013-2014. The mean egg-size through the whole season is positively affected by March precipitation, March clutches also negatively by minus temperatures in March. The higher intensity of rainfall there is during March, the bigger eggs are laid in March and the steeper is slope of decline in mean egg-size during season. This decline is more profound with lower rainfall in April. The effect of habitat is not significant. The body mass and condition of hatchlings is positively correlated with the...
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