GEOGRAPHIC VARIATION IN GENOME SIZE OFGRAOMYS GRISEOFLAVUS(RODENTIA: MURIDAE)

Abstract

Abstract Studies on Thomomys and Peromyscus, among others, have confirmed that karyotypic variation in mammals is often reflected in genome size variation. We used flow cytometry to estimate genome sizes from 91 individuals of the karyotypically variable Graomys griseoflavus complex from Argentina. Our samples represented 16 populations and included 2 ostensibly reproductively isolated forms. The mean genome size (2C value) for all populations, 5.72 pg ± 0.34 SD of DNA, was low for mammals, and the range was greater than observed in previous studies on Geomys, Thomomys, and bats. Two groups of populations were identified that differed in mean genome size. A high–genome-size group consisted of 2 populations in San Juan Province with a mean genome size of 7.38 ± 0.53 pg. These populations occupied the most arid part of the Monte Desert. A small–genome-size group included the remaining 14 populations that mostly occupied a broadly distributed, continuous habitat and possessed lower genome sizes with a mean o...