Genome Size of Bisexual and Unisexual Poeciliopsis

Abstract

We used flow cytometry to examine the genome size of bisexual and unisexual fishes in the genus Poeciliopsis. Two bisexual species, P. monacha and P. lucida, had genome sizes of 1.45–1.47 pg DNA and 1.37 pg DNA, respectively. These are small genomes for a vertebrate. Hemiclones of the unisexual hybrid P. mona-cha-lucida had genome sizes intermediate to those of P. monacha and P. lucida, its sexual progenitors. The triploid unisexuals P. 2 monacha-lucida and P. monacha-2 lucida had genome sizes equal to the sum of their three haploid components. No ploidy mosaics were observed among the unisexuals. Their genome size has not changed over time from that of the parental species that hybridized and produced them.