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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Morfologie spermií v sekundární kontaktní zóně slavíka obecného a slavíka tmavého / Sperm morphology in the secondary contact zone of Common Nightingale and Thrush Nightingale

Opletalová, Kamila January 2017 (has links)
The male gametes (sperms) are under strong sexual selection and are therefore very diverse in their morphology and often differ even amongst closely related species. Sperms are thus assumed to play very important role in reproductive isolation between species, due to their fast evolution in morphology. In my master thesis, I have studied the possible role of sperm morphology divergence in reproductive isolation in two sister species of passerine birds, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (L. luscinia). The areas of these species overlap in secondary contact zone running across central and Eastern Europe, where they occasionally hybridize. I have compared sperm morphology of males of both species originating in allopatric and sympatric localities as well as interspecies hybrids. The results showed significant differences in total sperm length which is approximately 20 % longer in the common nightingale. That is caused by great interspecies divergence in midpiece (containing mitochondria) length. Interspecific hybrids showed sperms with intermediate length but despite expectations completely morphologically normal. This outcome corresponds with observed fertility in F1 hybrid males. What I consider to be an essential finding is a significant divergence in head...

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