Figure 1From: Evolution of the nuclear ribosomal DNA intergenic spacer in four species of the Daphnia pulex complexTypical rDNA IGS from species in the Daphnia pulex complex. 28S = 28S rRNA gene. 18S = 18S rRNA gene. N1 = nonrepetitive region 1. N2 = nonrepetitive region 2. R = repetitive mid section composed of A (blue), B (green), and C (red) repeats. N2 contains the external transcribed spacer (ETS).Back to article page