The overdominance effects in both traits, fish size and cold tolerance, can be seen in Figs. 2–4, as fish heterozygous for each marker were more cold tolerant and smaller than homozygous fish.
The marker UNH879 was linked to the fish gender with difference in gender ratio between fish bearing the parental (homozygous) genotypes (29 females and 19 males) andthe hybrid (heterozygous) genotype (14 females and 38 males). Although both cold tolerance and fish gender were linked to UNH879, there was no significant correlation
between the two traits.
Genotype frequencies for three markers (UNH907, UNH130 and UNH180) exhibited significant distortion from the expected Mendelian segregation ratios (Table 2).