2005 Volume 70 Issue 3 Pages 243-248
This study evaluated and compared the chromosomes of 2 populations of Peromyscus difficilis felipensis which has a broad but discontinuous distribution. One population occurs throughout the central highlands of Mexico, 2000 m above sea level, where the population range extends through the States of Mexico and Morelos; the second population is found in a locality called Cerro San Felipe, State of Oaxaca. The chromosomes were obtained from bone marrow cells, and their classification is described here. The diploid chromosome number (2n) found is 48 and the fundamental number (fn) is 76 for both populations. The principal differences reside in one pair of the morphology of biarmed chromosomes. The chromosomic formula for the population in the States of Mexico and Morelos is 1M+1SM+13ST+8T, and for the population in the southeast of Oaxaca is 2M+13ST+8T. In both populations, the X chromosome is subtelocentric and the Y chromosome is metacentric. Several comparisons with other subspecies are presented here, as well as the description of a karyotype of Peromyscus difficilis felipensis which is different from other reported subspecies.
