preliminary survey of chromosomes in populations of the Chilean burrowing octodont rodent Spalacopus cyanus Molina (Caviomorpha, Octodontidae)

• Published in: Biological journal of the Linnean Society Vol. 4; no. 1; pp. 29 - 38
• Main Authors: REIG, OSVALDO A, SPOTORNO O., ANGEL, FERNANDEZ D., RAUL
• Format: Journal Article
• Language: English
• Published: Blackwell Publishing Ltd 01.03.1972
• Subjects: Baccharis; Centaurea; chromosomes; dimorphism; gene flow; karyotyping; rodents; spleen; surveys; testes; Chile; Andes region
• ISSN: 0024-4066; 1095-8312
• DOI: 10.1111/j.1095-8312.1972.tb00689.x

Chromosomes obtained from bone-marrow, spleen and testes were studied in samples from five populations of Spalacopus cyanus of Central Chile. Animals of four low-land coastal localities and animals of a high Andean valley showed a karyotype of 2n = 58 chromosomes, with almost no variation, either in number or in structure, both within each population or among the various populations. This karyotype was found to be very similar to that of Octodon degus, but very different to those in species of Ctenomys. The evolutionary and systematic significance of these results is discussed. The lack of karyotypic variation found in Spalacopus is correlated with its taxonomic uniformity, and both could be the result of the high vagility of the populations of this rodent, suggested by previous studies. This high capacity of dispersal is supposed to have enhanced gene flow, and therewith chromosome uniformity and low taxonomic diversification. The occurrence of a case of dimorphism for the presence of a secondary constriction in one of the autosome pairs is reported and discussed.