DESCRIPCION DEL CARIOTIPO Y LOS PATRONES DE BANDEOS C Y NOR DE Pheucticus aureoventris (PASSERIFORMES: CARDINALIDAE)

LEDESMA MARIO; MARTÍNEZ PABLO; CALDERÓN PABLO; BOERIS JUAN; MERILES JOSÉ

Posadas, Misiones, Argentina

Jornada; III Jornadas Científico Tecnológicas de la UNaM y V de la Facultad de Ciencias Exactas Químicas y Naturales; 2005

The black-backed grosbeak (Pheucticus aureoventris) is one of the species in risk of extinction due to human pressure on its habitat. It is mainly distributed in the pre-mountaine areas of Andes (between 1700 to 3700 mts). Although the order Passeriformes presents the largest amount of karyotyped species, none of the six species of the genus Pheucticus have been previously studied. The objective of the present work was to determine the diploid number and the C and NOR bands patterns of P. aureoventris. Three females and two males were collected in General Belgrano department, Province of Jujuy, Argentina. The chromosomes were obtained from direct cultures of bone marrow. Seventy metaphases were analyzed for each individual in order to establish the diploid number. Conventional and differential staining techniques (C and NOR bands) were used. The diploid number was 2n = 78. The pair one and the Z chromosome were submetacentrics, the pairs two, three, five and the W chromosome were subtelocentric, and the remaining elements of the complement were telocentric. C banding showed that the heterochromatin is located mainly in the centromeric regions of the microchromosomes, and that the W chromosome is completely heterochromatic. Among the macrochromosomes, tenuous centromeric marks were observed, as well as interstitial bands in the largest pairs. The analysis of the nucleolar organizer regions showed positive marks in two microchromosome pairs. The data here presented provides an initial step for the understanding of the karyotype evolution of the genus Pheucticus.