|
|
Sexual incompatibility of protist cryptic species
Jelínková, Lucie ; Škaloud, Pavel (advisor) ; Urbánková, Pavla (referee)
The systematic and the evolutionary biology attempt to define a species category or a species taxon from the beginning of their existence. Specific taxons are considered species on the base of different criteria, so on the base of different species concepts. Most of these concepts emerged previous century. The biological species concept has been assumed to be most important species concept for dozens of times. It was based on a presence of the reproduction isolation of two species. However, its applicability was questioned by the existence of many asexual lineages and also the lineages with a large degree of hybridization between an approved species. This thesis is trying to give a description of the biological species concept and its changes during the time. And it is also trying to answer the question of its simultaneous usability for protist.
|
|
|
Sperm motility and postmating prezygotic isolation in two nightingale species
Baránková, Lucie ; Reifová, Radka (advisor) ; Frolíková, Michaela (referee)
The motility of male gametes (sperm) is one of the important factors influencing the reproductive success of males. Because sperms are often subjected to strong postmating sexual selection and even closely related species often differ in sperm morphology, sperm motility could also differ between species, which may contribute to reproductive isolation between species. As part of my diploma thesis, I studied sperm motility in two closely related species of songbirds, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia). These two species of nightingales are an ideal model system because the areas of these two species overlap in the secondary contact zone across Central and Eastern Europe, where they occasionally hybridize and thus allow the study of speciation mechanisms in the natural environment. Both species also differ greatly in total sperm length. As part of my diploma thesis, I studied the possible influence of different sperm morphology on their motility. I further tested whether the motility of nightingale sperm differs in the fluid from the cloaca of a female of the same species and a different species, which would demonstrate the presence of postmating prezygotic reproductive isolation between species. The results of my work showed that despite the...
|
|
|
Sexual incompatibility of protist cryptic species
Jelínková, Lucie ; Škaloud, Pavel (advisor) ; Urbánková, Pavla (referee)
The systematic and the evolutionary biology attempt to define a species category or a species taxon from the beginning of their existence. Specific taxons are considered species on the base of different criteria, so on the base of different species concepts. Most of these concepts emerged previous century. The biological species concept has been assumed to be most important species concept for dozens of times. It was based on a presence of the reproduction isolation of two species. However, its applicability was questioned by the existence of many asexual lineages and also the lineages with a large degree of hybridization between an approved species. This thesis is trying to give a description of the biological species concept and its changes during the time. And it is also trying to answer the question of its simultaneous usability for protist.
|
guest ::
