Biología Pesquera 19: 3-8, 1990
ISSN N" 0067 - 8767 
POLIMORFISMO CROMOSOMICO DE DOS POBLACIONES DE LA TRUCHA ARCOIRIS, ONCORHYNCHUS MYKISS (WALBAUM) DE LA ZONA CENTRAL DE CHILE
TWO POPULATIONS CHROMOSOME POLYMORPHISM OF RAINBOW TROUT, ONCORHYNCHUS MYKISS (WALBAUM) FROM CENTRAL CHILE

Alberto Veloso, Patricia Iturra1, Nelson Colihueque, Nelson Díaz y Francisco Estay.

Abstract

There are differences in the chromosome polymorphism found in two populations oí fish farm and introduced Oncorhynchus mykkis. Diploid numbers correspond to 2n = 58 to 2n = 61 and 2n = 60 to 2n = 63 respectively. Arm number (NF) in all individuals was 104. It was possible to identified chromosomes by chromosome measurements. C and AgAsNOR banding. There are correspondences between chromosomic and somatic sex (XX/XY system). The distributional pattern of constitutive heterochromatin makes easy to recognize certain homologs. Active DNAR cistrons are located in a small metacentric pair. in correspondence with a secondary constriction. Intraindividual polymorphism was found in 15% of the sampled individuals. The results suggest that the polymorphism is determined by robertsonian rearrangements berween larger metacentric and telocentric chromosomes. The polymorphism range in the introduced rainbow trout suggest its European origin.
Keywords: Citogenetics, chromosome. Exotic species 
Departamento de Ciencias Ecológicas. Facultad de Ciencias. Universidad de Chile. Casilla 653. Santiago. Chile.

1 Departamento de Biología Celular y Genética. Facultad de Medicina. Universidad de Chile. Casilla 70061. Santiago. Chile.