A Karyological Study of Two Intraspecific Taxa in Japanese Eothenomys (Mammalia: Rodentia)
1988 年 13 巻 2 号 p. 93-104
詳細
1988 年 13 巻 2 号 p. 93-104
Karyological studies of two Japanese Eothenomys species, E. smithii and E. kageus, were carried out using conventional, G- and C-band stainings. Their G- and C-banded karyotypes (2n=56, FN=60) were essentially indentical with each other in band patterns, except for a difference in size of the totally heterochromatic Y chromosomes, which is attributable to quantitative alteration of constitutive hetero-chromatin. Considering the karyotypes of both species and the doubtful taxonomic validity of E. kageus, it is reasonable to construe the above difference in the Y chromosome as a variation or a polymorphism within E. smithii. A pair matching of G-banded karyotypes between Eothenomys smithii and Clethrionomys glareolus (2n= 56, FN= 56) showed no detectable difference in band patterns, with the exception of two pairs of autosomes (nos. 1 and 2) and the X chromosome (ST-elements in Eothenomys and A-elements in Clethrionomys for all elements concerned) . Furthermore, the difference in shape and size was noticed in entirely heterochromatic Y chromosomes. Therefore, taking the phylogenetic, relationship based on morphological characters between both genera into consideration, it is suggested that the karyotype of E. smithii has differentiated from Clethrionomys-like one by pericentric inversions and addition of heterochromatin.
