Individual variation in early life-history traits in brown trout

We studied the variability of early life history traits in individually raised progeny of brown trout Salmo trutta L. Eggs from two dams were each fertilized with sperm from 10 sires, producing 20 full-sib families. Each individual progeny was followed from fertilization until death without exogenous food. Egg size was positively correlated with a number of life-history traits, especially length and yolk sac volume at hatching and length at death, and these traits were strongly influenced by maternal effects. We found significant additive genetic variance for growth rate, length at death and life span without external food. Thus these early life-history traits may be modulated by natural selection. We found positive phenotypic and genetic correlations between most early life-history traits. However, life span without external food was negatively correlated with growth rate, indicating a genetic trade-off.