The Pantophysin gene and its relationship with survival in Atlantic cod

Distinction between highly migratory Northeast Arctic cod and stationary
Norwegian Coastal cod represents an important management issue. They
overlap on the same spawning grounds where they are harvested, but display
highly different abundences. This necessitates alternative management
strategies. The bi-allelic genetic marker, pantophysin (Pan I), has been
widely used as a diagnostic marker to discriminate between these two
stocks. However, it has been proposed that this locus, or another gene(s)
on chromosome 1 where it is located, may be under strong divergent
selection between these two stocks. In order to address this, we compared
relative survival rates between different Pan I genotypes in common garden
pedigree-controlled experiments conducted in a temperature-controlled
laboratory facility, and mesocosms. We found no evidence of departure from
the expected 1:2:1 mendelian ratio for any of the three genotypes during
the egg stage, while both the 6 and 12 °C temperature regimes in the
laboratory experiment weakly favoured the Pan IAA genotype thereafter. No
difference was observed between genotype survival in the mesocosm
experiments. These results demonstrate that there are no clear advantages
of certain Pan I genotypes under the experimental conditions observed.