Loss of nucleolar organizer regions during chromosomal evolution in the South American cricetid Graomys griseoflavus
Graomys griseoflavus is a South American phyllotine rodent having a remarkable Robertsonian polymorphism which may have produced reproductive isolation between 2n=42−41 and 2n=38−34 karyomorphs. Analysis of nucleolar organizer region (NOR) locations both by silver staining (Ag-NOR) and in situ hybri...
Guardado en:
| Autores principales: | , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
1996
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/140089 |
| Aporte de: |
| Sumario: | Graomys griseoflavus is a South American phyllotine rodent having a remarkable Robertsonian polymorphism which may have produced reproductive isolation between 2n=42−41 and 2n=38−34 karyomorphs. Analysis of nucleolar organizer region (NOR) locations both by silver staining (Ag-NOR) and in situ hybridization revealed that 2n=42 individuals exhibit highly variable Ag-NOR patterns, while specimens of the 2n=38−34 karyomorphic group showed a single Ag-NOR pattern. The latter animals underwent two NOR deletions in reference to the 2n=42 karyomorphs, one of which would be the consequence of a Robertsonian fusion and the other would be produced by the unequal crossing-over mechanism. The differential NOR homogenization supports the hypothesis that G. griseoflavus karyomorphs are evolving separately towards the acquisition of separate species status. |
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