Morphological, chromosomal, and genic differences between sympatric Rattus rattus and Rattus satarae in South India

• Published in: Journal of Mammalogy
• Main Authors: Pagès, Marie, Corbet, Gordon, Orth, Annie, Volobouev, Vitaly, Michaux, Johan, Catzeflis, François
• Format: Article in Journal/Newspaper
• Language: English
• Published: Allen Press Publishing Services Inc. 2011
• Subjects: cryptic species; Rattus; rodent; South India; Life sciences; Zoology; Sciences du vivant; Zoologie; Rattus rattus
• Online Access: https://orbi.uliege.be/handle/2268/139320; https://doi.org/10.1644/10-MAMM-A-033.1

peer reviewed Two morphological forms of black rats (Rattus cf. rattus) were found living in sympatry in high-altitude dense forests of the Nilgiri Mountains, South India. The 1st one, often brown- or gray-bellied, also is found commensal in lowland settlements and represents Rattus rattus cf. rufescens (Gray 1837), with a diploid number (2N) of 38 chromosomes. The 2nd form, which has most often a pure white belly, has 2N 5 42 chromosomes and is referable to Rattus r. satarae Hinton, 1918, based on morphological comparison with the holotype. A multidisciplinary study indicates that these 2 forms are characterized by clear-cut differences in biochemistry (electrophoresis of homologous isozymes), molecular sequences (mitochondrial and nuclear DNA), and chromosomes (detailed banding analysis). All these data, coupled to diagnostic morphological characteristics, support the hypothesis that Rattus satarae and Rattus rattus are separate, sympatric species, with no gene flow between them. Their similar external morphology is interpreted as the result of convergence through occupying the same ecological niche.