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Interspecific hybridization in birds: lessons for conservation
Štěpánková, Klára ; Reif, Jiří (advisor) ; Vokurková, Jana (referee)
Interspecific hybridization is quite common in recent years. Favorable factors are rarity of a species, limited time for partner selection, misdirected preference in mating partner selection of females, preference for males with more pronounced sexually selected traits, greater body size and habitat destruction. Factors which lead to the artificially interspecific hybridization due to habitat destruction include deforestation, fragmentation of the territory, urbanization, abandoning agricultural areas, as well as translocation of species into the regions where they did not originally occur. These species can later interbreed with the native species and if the latter are rare and the former aggressive, it can result in increased threat potentially leading to extinction of indigenous populations. Exceptionally, interbreeding can lead to the emergence of a new species; however, this type of origination of a new species is not common in animals. Hybridization is a natural phenomenon important for the evolution. Nevertheless, anthropogenically induced or assisted hybridization represents a serious problem for the species conservation. Finding a solution to overcome the negative impacts of such interspecific hybridization is difficult and there is no exact and universally applied methodology to date. Key...
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Predictors of global threat in bird sister species
Štěpánková, Klára ; Reif, Jiří (advisor) ; Storchová, Lenka (referee)
Despite the threat of extinction in many bird species, it still not sufficiently known what are the biological characteristics related to this threat. This thesis tries to answer this question by analyzing the database of sister species, when we compare the traits of the threatened and unthreatened species within each species pair. This pairwise comparison should benefit from factoring, out the effects of traits shared within a given pair of species. In my thesis I use a global threat level from the IUCN classification and I relate it to latitudinal position of species geographic ranges, migration strategy, body size, habitat type and diet. I always take into account the effect of geographic range size. The range size is, often considered during the classification of threat and can also influence and the effects of other traits. Results show, besides the trivial effect of range size, when species with smaller ranges have a higher degree of threat, that the migration strategy is the only trait significantly related to the degree of threat at the global scale. Species, migrating for longer distances were more threatened than species migrating for shorter distances, probably because the former face more frequently the risks encountering many different environments and regions.
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Interspecific hybridization in birds: lessons for conservation
Štěpánková, Klára ; Reif, Jiří (advisor) ; Vokurková, Jana (referee)
Interspecific hybridization is quite common in recent years. Favorable factors are rarity of a species, limited time for partner selection, misdirected preference in mating partner selection of females, preference for males with more pronounced sexually selected traits, greater body size and habitat destruction. Factors which lead to the artificially interspecific hybridization due to habitat destruction include deforestation, fragmentation of the territory, urbanization, abandoning agricultural areas, as well as translocation of species into the regions where they did not originally occur. These species can later interbreed with the native species and if the latter are rare and the former aggressive, it can result in increased threat potentially leading to extinction of indigenous populations. Exceptionally, interbreeding can lead to the emergence of a new species; however, this type of origination of a new species is not common in animals. Hybridization is a natural phenomenon important for the evolution. Nevertheless, anthropogenically induced or assisted hybridization represents a serious problem for the species conservation. Finding a solution to overcome the negative impacts of such interspecific hybridization is difficult and there is no exact and universally applied methodology to date. Key...
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