Citogenética Clássica e Molecular em Espécies da Família Tyrannidae (aves, Passeriformes)

Abstract

In the bird’s class, the Tyrannidae Family is one of the most diversified and numerous in numbers of species, however, few have been karyotyped and for this, only conventional staining was used. Despite of few cytogenetic researches, interesting results about this family were related in the literature, for example, the high morphology and diploid number variability. Hence, four species of Tyrannidae: Elaenia spectabilis, Megarynchus pitangua, Tolmomyias flaviventris e Corythopis delalandi were studied by conventional staining and chromosome painting with the use of whole chromosome probes derived from Gallus gallus and Leucopternis albicollis. The species E. spectabilis, was also cytogenetically characterized by G- and C-banding, Ag-NORs e 18S rDNA. Cytogenetic analysis in the four species studied in this work showed a large chromosomal variability. The species E. spectabilis and M. pitangua retained chromosomal complements similar to the putative avian ancestral karyotype, with diploid number relatively high (approximately 80 chromosomes), many pairs of microchromosomes and a few pairs of macrochromosomes. On the other hand, the species T. flaviventris and C. delalandi have atypical karyotypes among birds, with a low diploid number (approximately 60 chromosomes). We identified a paracentric inversion and fission of ancestral chromosome 1 of Gallus gallus (GGA1) as derived chromosomal characteristics shared between the species E. spectabilis, M. pitangua and T. flaviventris. The chromosomal inversion mentioned was found on ancestor chromosome 1q (GGA1q). In species T. flaviventris chromosomal fusions, which led to lower diploid number of this species, were found. The results presented and discussed in this dissertation show some of chromosomal rearrangements that occurred along the karyotype evolution of the representatives of the Tyrannidae family. We discuss the evolutionary status of the species studied in relation to the ancestral karyotype of birds.