2.6. Genotyping and paternity analyses
Paternity analyses were determined through microsatellite genotyping
and phenotype scoring. Red colour is controlled by a single
autosomal dominant allele, therefore offspring from a wild type
female sired by a wild type male should be all wild type unless both
parents were heterozygous for the bronze (blond) locus, where a
quarter of the offspring were expected to be blond (McAndrew et al.,
1988). On the other hand, offspring from a wild type female sired by a
red male should be all red. For offspring from wild type females, since
paternity confirmation could be based on phenotype scoring, a small
number of fry (minimum of 4 per batch) were also genotyped to
confirm the results based on colour phenotype. For offspring of red
females, a minimum of 10 fry per batch were taken randomly and
genotyped at between two to four loci until paternity could be
assigned without ambiguity.
Where both males contributed to a batch of fry from a single
female, the batch was allocated to the “primary” sire (i.e. the father of
the majority of the offspring in that batch) for the initial statistical
analysis (comparison of the mating success of wild type and red
males). In spawnings by wild type females even a single fry fathered
by the “secondary” male could be detected through phenotype
scoring. However, for red females, estimation of the contribution