|
|
Karyotype analysis of selected representatives of two pedipalpid orders, Amblypygi and Uropygi
Sember, Alexandr ; Král, Jiří (advisor) ; Ráb, Petr (referee)
Karyotype analysis of selected species from arachnid orders Amblypygi and Uropygi Whip spiders (Amblypygi) and whip scorpions (Uropygi) represent relict arachnid orders which has been found already at Upper Carboniferous strata. Although cytogenetic data from amblypygids and uropygids might be important to reconstruct karyotype evolution of arachnids, cytogenetics of these orders is almost unknown. Presented study is aimed in analysis of karyotype and meiosis in 16 species of Amblypygi and 4 species of Uropygi. Both groups are characterized by considerable range of diploid chromosome numbers (2n = 24 - 86 in Amblypygi and 36 - 66 in Uropygi). Analysed species does not exhibit morfologically differentiated sex chromosomes. Differentiation of sex chromosomes on molecular level was revealed in amblypygid Paraphrynus mexicanus by comparative genome hybridization. Obtained data indicate XY/XX sex chromosome system in this species. Comparison of karyotype data indicates reduction of chromosome numbers during evolution of both orders. In Amblypygi, this reduction was accompanied by increase of number of biarmed chromosomes. This trend is not apparent in Uropygi. Karyotypes of most analysed amblypygids and uropygids are also characterized by low amount of heterochromatin. Most studied species exhibit two pairs...
|
|
|
Karyotype analysis of selected groups of tetrapulmonate arachnids
Reyes Lerma, Azucena Claudia ; Sember, Alexandr (advisor) ; Johnson Pokorná, Martina (referee) ; de Bello Cioffi, Marcelo (referee)
Arachnids are a highly speciose group of arthropods with about 130 000 extant species from 12 orders. Some arachnid species are of economic and medical interest. They also offer various opportunities to study the link between genome and karyotype variability and morphological and ecological diversification, evolution and adaptation. The knowledge about arachnid karyotypes and genomes is, however, still limited. The available data show wide range of diploid chromosome numbers (2n), monocentric or holocentric chromosomal structure, variability in sex chromosome systems (especially in spiders) and modifications of meiosis. The main objective of this doctoral thesis was to study by conventional and molecular cytogenetic methods the mechanisms of karyotype evolution in haplogyne spiders (with monocentric and holocentric chromosomes), and further in two families (Charinidae and Phrynidae) from the closely related order Amblypygi. The selected groups offer unique insights into fundamental karyotype traits of the arachnid clade Tetrapulmonata, and they also enable to analyse the role of polyploidy in arachnid karyotype evolution and the evolutionary mechanisms behind the emergence of holocentric chromosomes. Our data suggest that holocentric chromosomes are an autoapomorphy for the haplogyne superfamily...
|
|
|
Karyotype analysis of selected representatives of two pedipalpid orders, Amblypygi and Uropygi
Sember, Alexandr ; Král, Jiří (advisor) ; Ráb, Petr (referee)
Karyotype analysis of selected species from arachnid orders Amblypygi and Uropygi Whip spiders (Amblypygi) and whip scorpions (Uropygi) represent relict arachnid orders which has been found already at Upper Carboniferous strata. Although cytogenetic data from amblypygids and uropygids might be important to reconstruct karyotype evolution of arachnids, cytogenetics of these orders is almost unknown. Presented study is aimed in analysis of karyotype and meiosis in 16 species of Amblypygi and 4 species of Uropygi. Both groups are characterized by considerable range of diploid chromosome numbers (2n = 24 - 86 in Amblypygi and 36 - 66 in Uropygi). Analysed species does not exhibit morfologically differentiated sex chromosomes. Differentiation of sex chromosomes on molecular level was revealed in amblypygid Paraphrynus mexicanus by comparative genome hybridization. Obtained data indicate XY/XX sex chromosome system in this species. Comparison of karyotype data indicates reduction of chromosome numbers during evolution of both orders. In Amblypygi, this reduction was accompanied by increase of number of biarmed chromosomes. This trend is not apparent in Uropygi. Karyotypes of most analysed amblypygids and uropygids are also characterized by low amount of heterochromatin. Most studied species exhibit two pairs...
|
guest ::
