MATERNAL EFFECTS ON UNIFORMITY OF GROWTH IN A HYBRID FINFISH

Thomas A. Delomas* and Konrad Dabrowski
 
School of Environment and Natural Resources
The Ohio State University
Columbus, OH 43210
delomas.1@osu.edu
 

Uniformity of growth is an economically important trait, as it allows farmers to produce a consistent product and reduces or eliminates the need for labor intensive practices such as grading and multiple harvests. Additionally, uniformity of growth can reduce aggressive behavior between different size classes, thereby reducing stress and increasing the growth and health of fish. We show that in hybrids of zebrafish Danio rerio ♀ x pearl danio Danio albolineatus ♂ uniformity of growth is influenced by a maternal effect gene.

Fig 2. Coefficient of variation of weight at 21 dpf of hybrid families produced by F1 dams (n=15 fish/family)

Fig 1. Coefficient of variation (CV) of weight at 21 days post-fertilization (dpf) of hybrid families (n=10 fish/family)

We first obtained hybrids by crossing five zebrafish dams with one pearl danio (sire 1). Dam 1 produced a family with highly uniform growth, while dams 2-5 produced families with high variability in growth rate (Fig 1). Dams 1 and 2 were crossed with two additional sires (sires 2 and 3) and this difference in uniformity was consistent between sires. Dams 1 and 2 were crossed to an unrelated zebrafish male to produce F1 females (no difference in uniformity of growth was evident between the two F1 families). These F1 females were mated to pearl danio sires and uniformity of the resulting offspring was measured. All five F1 females derived from dam 2 produced highly variable families (Fig 2). Of ten F1 females derived from dam 1, four produced highly variable families and six produced uniform families (not different from 1:1, Chi-square test p > 0.10). This suggests Mendelian inheritance of a maternal effect gene that influences the uniformity of growth rate in hybrid offspring. Based on our observations, the allele which leads to uniformity of growth is likely dominant, although we cannot eliminate the possibility that it is recessive and the zebrafish sire of the F1 generation was heterozygous for this allele. Crosses that will discriminate between these possibilities are being evaluated and these results will be presented.