Z chromosome features. (a) Map of the Z chromosome. Loci that had 0% recombination with other markers are shown adjacent to the marker used in the construction of the map. The Z-specific markers are shown in green. Asterisks (*P < 0.01, **P < 0.005, ***P < 0.001, ****P < 0.0005, *****P < 0.0001) indicate significance of deviation from Mendelian expectations, where brackets show recombination hotspots in the female meioses (recombination frequencies for each sex are listed next to the brackets). (b) Meiotic metaphase spreads from females showing the Z and W bivalents. This figure illustrates the non-recombining region between the Z and W chromosomes. The dark staining regions are heterochromatin of the W chromosome and the large black arrows mark chiasmata. Scale bars are 10 μm. (c) Fluorescent in situ hybridization (FISH) showing the hybridization position of bacterial artificial chromosome (BACs; names at lower left of each panel) that BLAST to scaffolds with mapped microsatellite markers. The white arrowheads show BAC hybridization and the white dash is the centromere. Scale bar is 10 μm. The inset for BAC 15B20 is the W chromosome, on which 15B20 does not hybridize (that is, it is Z-specific). The genetic map position of the markers on these BACs is shown in blue text in (a). FISH allows assignment of linkage groups to physical chromosomes (see also Additional data file 4 and Figure 3).