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Hybridisation of cyprinid fishes in the Czech Republic: genetic and morphometric analysis of the subfamily Leuciscinae
Kaufman, Vít ; Musilová, Zuzana (advisor) ; Choleva, Lukáš (referee)
Hybridization is a process when two interspecific individuals mate and spawn. When backcrossing it often goes hand in hand with admixing unrelated genome into the genome of a species. Nowadays it is well established that hybridization is not as uncommon as it was believed. Especially in vertebrates fish are quite common in such phenomena. In Leuciscids, the family of order Cypriniformes is relatively frequent. It is a rife family in the European freshwater systems. Factors that contribute to such frequent hybridization are extraneous fertilization, sympatric occurrence, competition for spawning grounds, and other ecophysiological traits. It was known since the second half of 20th century that this is an ongoing phenomenon in many species of this family. Previous research was focused mainly on morphological traits. The relative pinnacle of such research was based on allozymic analysis. The goal of our project was to evaluate the level of hybridization in the main water bodies of the Czech Republic with the main focus on the detection of involved hybrid species, the level of such hybridization, and the phenotypic characterization of hybrid individuals. For that reason, it was sampled over 400 specimens giving a dataset of 381 individuals. Tissue samples were sampled for DNA isolation and each of the...
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Use of stable isotopes in feeding ecology of fish
Inquort, Vít ; Horká, Petra (advisor) ; Musilová, Zuzana (referee)
Cyprinidae is an important family of fish as far as ecological and economical aspects are considered. Studying feeding ecology of this family in aquatic ecosystems and integration of the findings into the overall image of trophic relationships are the fundamental prerequisite for the right interpretation of its ecological role. Stable isotope analysis is one of the methods capable of elucidating such relationships. In this thesis currently used methods and approaches in applications of stable isotope analysis in feeding ecology of fish are summarized. These vary among individual authors and include sampling of different fish tissues and different methods of preparation of samples before analysis, e.g. lipid extraction or carbonate removal. Certain mechanisms and phenomena which need to be taken into account to avoid biased results are also outlined in this thesis, among all tissue turnover and isotopic routing in particular. In the thesis current findings on food resources, trophic level and trophic niche of cyprinid fishes in freshwater ecosystems based on stable isotope analysis were summarized as well. Despite such findings being partial to date and the potential of the method not yet being fully exploited in many species, stable isotope analysis provide an important and useful tool alongside...
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Hormonal stimulation of ovulation of grass carp (Ctenopharyngodon idella)
MUSIL, Martin
Hormonal stimulation of ovulation in grass carp (Ctenopharyngodon idella) In 2015, an experiment with hormonal stimulation of ovulation in grass carpwas performed using dopamine inhibition of secretion luteinizing hormone (LH) by mGnRHa ([D-Tle6, Pro9, NEt] -mGnRH), with or without metoclopramide. Three experimental groups of females were injected with the following hormonal preparations: group A - mGnRHa (12.5 mikrog.kg-1) + metoclopramide (20 mg.kg-1), group B - mGnRHa (12.5 mikrog.kg- 1) Group C - 0.9% NaCl. For group A injected mGnRHa with metoclopramide, ovulation only achieved one of the females (14.28%), the fecundity index was 5.66% and the fertility was only 0.1%. The luteinizing hormone concentration peaked after application of the hormonal preparation and, unlike group B, declined with imminent ovulation. In Group B, the application of pure synthetic mGnRH induced ovulation in 57.14% of injected females. Fecundity index was 11.25 +- 4.77% and average fertility reached 60.25 +- 11.22%. The level of luteinizing hormone reached its peak only at the time just before ovulation itself. The results of the experiment did not demonstrate the use of mGnRHa with metoclopramide as the most effective. However, LH levels have shown a strong dopamine inhibition of LH secretion in this species.
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The effect of posthodiplostomosis on the cyprinid fish fry
Ondračková, Markéta ; Dyková, Iva ; Gelnar, M. ; Jurajda, Pavel
Posthodiplostomosis, called also black-spot disease, is caused by metacercariae of Posthodiplostomum cuticola (Trematoda, Diplostomatidae). These parasites were studied on the cyprinid fish in floodplain area of the River Dyje in South Moravia. Twelve species from 16 totally explored Cyprinids were infected by metacercariae of P. cuticola during 1998, 1999 and 2001. Roach (Rutilus rutilus), rudd (S. erythrophthalmus), silver bream (B. bjoerkna), common bream (A. brama), bitterling (R. sericeus) and Prussian carp (C. auratus gibelio) were infected in all followed seasons. These species were histologicaly examined. During the cyst development the progressive maturation of connective tissue in outer layer of the cyst and infiltration of pigment cells were observed. Production of black pigment around the parasite cyst was chacteristic host reaction. Mainly melanocytes and in a small measure iridocytes took part in the pigmentation. The metacercariae of P. cuticola caused in the juvenile fish spine and body deformation. By high invasion the tissue dystrophy was observed.
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