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Karyotype evolution and species differentiation in the genus <i>Rattus</i> of Manipur, India

D Chingangbam
JM Laishram
NB Singh
L Taibangjam
C Brajakishore


Rattus is the most studied genus all over the world but species of the genus are not thoroughly reported from Manipur. The present paper deals with the morphometric, cytotaxonomic and phylogenetic studies of Manipur, India. The different species of Rattus namely Rattus rattus, Rattus brunneusculus, Rattus tanezumi and Rattus nitidus were studied. Berylmys manipulus and Berylmys mackenziei were taken from the genus Berylmys. The studies of the species reveal that the polymorphic chromosomes in the genus Rattus were pair numbers that is, 1, 9, 10 and 13. The change of acrocentrics which are regarded as primitive/ancestral types of chromosomes into either subtelocentric or small metacentrics leads to speciation or simply new species particularly in Manipur. It is generally accepted cytologically that 2n=40 (Berylmys manipulus, B. mackenziei, R. kandianus etc) are derived from the 2n=42 through centric fusion/Robertsonian fusion, but the soft palate studies shows affinity of the species that is, B. manipulus  and B. mackenziei from Manipur towards Niviventer. The present study is the first step towards the understanding of the relationship between these two genera-Rattus and Berylmys.

Keywords: Rattus, Berylmys, Manipur

African Journal of Biotechnology, Vol 13(53) 4733-4744