Cytogenetics of the South-American Akodon Rodents (Cricetidae) VI polymorphism in Akodon dolores (Thomas)

✍ Scribed by N. O. Bianchi; Susana Merani; Martha Lizarralde

• Publisher: Springer Netherlands
• Year: 1979
• Tongue: English
• Weight: 398 KB
• Volume: 50
• Category: Article
• ISSN: 0016-6707
• DOI: 10.1007/bf00123284

✦ Synopsis

The cytogenetic analysis of 68 specimens of Akodon dolores (Rodentia: Cricetidae) collected in three different localities of the central region of Argentina showed the presence of chromosomal polymorphisrns of the Robertsonian type in chromosomes 1, 3, 4 and 5. The variability in chromosomes 3, 4 and 5 was correlated with the geographical area of collection. Animals with low chromosome numbers and two biarmed chromosomes in pairs 3, 4 and 5 were mainly found in the southern most area of collection (simple homozygous). Conversely, in the northern most locality forms with an increased frequency of acroeentrics and high modal numbers (double homozygous) predominated. The central part showed the highest con. centration of heterozygous specimens. It is speculated that Robertsonian rearrangements of chromosomes 3, 4 and 5 originated in the central area and that DH and SH animals migrated from there to the North and South respectively.

The polymorphism of chromosome 1 was not correlated with the geographical areas. In the three localities surveyed the frequency of double homozygous animals was very low while the frequency of heterozygous and simple homozygous specimens was high. It is assumed that the high frequency of heterozygous animals is maintained through positive selection. The possible correlation between the chromosome 1 polymorphism and the infection with virus Junin (ethio. logical agent of the haemorrhagic fever in Argentina) is discussed.