Fig. 2
XY sex determination in Hydractinia. A Early and late stages of development of female gonozooids. B Early and late stages of development of male gonozooids. C Image of colony 339–116 on the day the first female gonophores were identified. D Close-up of boxed area in C. m, gonozooid bearing male gonophores. f, gonozooid bearing female gonophores. Scale bars in C and D are 1 mm. E LOD chart of QTL for sex in the maternal linkage map. F LOD chart of QTL for sex in the paternal linkage map. (G) Detail of LOD chart for linkage group 4 from the paternal linkage map. In E–G, significance thresholds of p = 0.05 and p = 10−5 are denoted in red and blue, respectively. H Recombination map of linkage group 4. Plot depicts genotype segregation pattern of pseudo-testcross markers (rows) in the F1 progeny (columns). Genotypes: AA: white; AB, gray. An example of a recombinant progeny is illustrated to the right of the plot. Observed sex of each F1 progeny is displayed above the plot. Genotypes in red box show perfect correlation with sex phenotype. I Recombination map of linkage group 4 in two animals with sexual chimerism