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Earlier evolutionary dead-ends, now the creators of a reproductive strategy: the origin and reproduction of the all-male water frog lineage Pelophylax esculentus
Doležálková, Marie ; Choleva, Lukáš (advisor) ; Mikulíček, Peter (referee) ; Kratochvíl, Lukáš (referee)
Asexual modes of reproduction are usually based on the principle of copying (cloning) DNA from the female and passing it on to the offspring. For most asexually reproducing vertebrates the progeny develop from an unreduced and often unfertilised egg. This is driven by the mechanisms of parthenogenetic and gynogenetic reproduction. While in the former the clonal germ cell develops spontaneously and separately, in the latter a sexual partner is needed to activate the cleavage of the ovum, although without the fusion of the sperm and egg. Therefore in both cases there is no fertilization and the clonal progeny consist solely of daughters, hence the majority of previous studies have only focused on asexual female lineages. However, on rare occasions asexual clonal males can arise when the right fertilization occurs. Whilst these offspring are usually infertile, fertile diploid asexual males have been discovered in just three genera of hybrid origin in vertebrates. One of these unique cases is the European water frog complex of the genus Pelophylax, whose distribution includes the Czech Republic. In areas around the upper Odra River populations of hybrid males were recently discovered who form stable all-male lineages, similar to those formed by asexual females. The results of this study show that males produce...
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Earlier evolutionary dead-ends, now the creators of a reproductive strategy: the origin and reproduction of the all-male water frog lineage Pelophylax esculentus
Kaštánková, Marie
Asexual modes of reproduction are usually based on the principle of copying (cloning) DNA from the female and passing it on to the offspring. For most asexually reproducing vertebrates the progeny develop from an unreduced and often unfertilised egg. This is driven by the mechanisms of parthenogenetic and gynogenetic reproduction. While in the former the clonal germ cell develops spontaneously and separately, in the latter a sexual partner is needed to activate the cleavage of the ovum, although without the fusion of the sperm and egg. Therefore in both cases there is no fertilization and the clonal progeny consist solely of daughters, hence the majority of previous studies have only focused on asexual female lineages. However, on rare occasions asexual clonal males can arise when the right fertilization occurs. Whilst these offspring are usually infertile, fertile diploid asexual males have been discovered in just three genera of hybrid origin in vertebrates. One of these unique cases is the European water frog complex of the genus Pelophylax, whose distribution includes the Czech Republic. In areas around the upper Odra River populations of hybrid males were recently discovered who form stable all-male lineages, similar to those formed by asexual females. The results of this study show that males produce...
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Programmed DNA elimination in animals
Janáková, Šárka ; Reifová, Radka (advisor) ; Choleva, Lukáš (referee)
Programmed DNA elimination (PDE) is a process in which a part of genetic information is eliminated from the organisms genome. It can be found be found in both plants and animals. There is a difference in the genetic inormation eliminated depending on the species. There are some organisms that eliminate only parts of their chromosomes, others that eliminate whole chromosomes and in hybrid organisms one whole parental genome is eliminated. In somatic cells PDE usually takes place during early embryogenesis. If the genome being eliminated comes from the germline cells, PDE takes place during gametogenesis. The function and mechanisms of PDE differs inbetween the species. It is most often connected with soma and germ cell differentiation, sex determination in animals and haploid gamete production in hybrid species. Mechanisms frequently include epigenetic modifications of DNA destined for elimination or production of micronuclei (MN) with the eliminated DNA inside. This work summarizes these functions and mechanisms and provides examples. Key words: programmed DNA elimination, chromatin diminution, chromosomal elimination, hybridogenesis, micronuclei, epigenetic modifications, Germ1, GRC
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Earlier evolutionary dead-ends, now the creators of a reproductive strategy: the origin and reproduction of the all-male water frog lineage Pelophylax esculentus
Kaštánková, Marie
Asexual modes of reproduction are usually based on the principle of copying (cloning) DNA from the female and passing it on to the offspring. For most asexually reproducing vertebrates the progeny develop from an unreduced and often unfertilised egg. This is driven by the mechanisms of parthenogenetic and gynogenetic reproduction. While in the former the clonal germ cell develops spontaneously and separately, in the latter a sexual partner is needed to activate the cleavage of the ovum, although without the fusion of the sperm and egg. Therefore in both cases there is no fertilization and the clonal progeny consist solely of daughters, hence the majority of previous studies have only focused on asexual female lineages. However, on rare occasions asexual clonal males can arise when the right fertilization occurs. Whilst these offspring are usually infertile, fertile diploid asexual males have been discovered in just three genera of hybrid origin in vertebrates. One of these unique cases is the European water frog complex of the genus Pelophylax, whose distribution includes the Czech Republic. In areas around the upper Odra River populations of hybrid males were recently discovered who form stable all-male lineages, similar to those formed by asexual females. The results of this study show that males produce...
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Origin of species by interspecific hybridization in animals
Štiková, Jana ; Reifová, Radka (advisor) ; Choleva, Lukáš (referee)
Speciation mostly occur by splitting an ancestral species into two daughter species. Alternatively, new species may arise by hybridization, a phenomenon known as hybrid speciation. This type of speciation is frequent especially in plants, but recently, a growing number of example has been described also in animals. The aim of this thesis is to summarize the current knowledge about hybrid speciation and describe known examples of hybrid speciation in animals. Hybrid speciation in animals is mostly homoploid, e.g. without the change of number of chromosomes. I found 23 homoploid hybrid species in animals. Most of them belong to insects and fishes, but know examples are also among birds and mammals. Origin of species in animals by hybrid speciation seems to be more commons than was previously thought. Powered by TCPDF (www.tcpdf.org)
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Earlier evolutionary dead-ends, now the creators of a reproductive strategy: the origin and reproduction of the all-male water frog lineage Pelophylax esculentus
Doležálková, Marie ; Choleva, Lukáš (advisor) ; Mikulíček, Peter (referee) ; Kratochvíl, Lukáš (referee)
Asexual modes of reproduction are usually based on the principle of copying (cloning) DNA from the female and passing it on to the offspring. For most asexually reproducing vertebrates the progeny develop from an unreduced and often unfertilised egg. This is driven by the mechanisms of parthenogenetic and gynogenetic reproduction. While in the former the clonal germ cell develops spontaneously and separately, in the latter a sexual partner is needed to activate the cleavage of the ovum, although without the fusion of the sperm and egg. Therefore in both cases there is no fertilization and the clonal progeny consist solely of daughters, hence the majority of previous studies have only focused on asexual female lineages. However, on rare occasions asexual clonal males can arise when the right fertilization occurs. Whilst these offspring are usually infertile, fertile diploid asexual males have been discovered in just three genera of hybrid origin in vertebrates. One of these unique cases is the European water frog complex of the genus Pelophylax, whose distribution includes the Czech Republic. In areas around the upper Odra River populations of hybrid males were recently discovered who form stable all-male lineages, similar to those formed by asexual females. The results of this study show that males produce...
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