Laboratory studies on embryos of salmonids, such as the brown trout ( Salmo trutta ), have been extensively used to study environmental stress and how responses vary within and between natural populations. These studies are based on the implicit assumption that early life‐history traits are relevant for stress tolerance in the wild. Here we test this assumption by combining two data sets from studies on the same 60 families. T...

Inbreeding depression, that is, the reduction of health and vigour in individuals with high inbreeding coefficients, is expected to increase with environmental, social, or physiological stress. It has therefore been predicted that sexual selection and the associated stress usually lead to higher inbreeding depression in males than in females. However, sex‐specific differences in life history may reverse that pattern during cer...

Fish often spawn eggs with ovarian fluids that have been hypothesized to support the sperm of some males over others (cryptic female choice). Alternatively, sperm reactions to ovarian fluids could reveal male strategies. We used wild‐caught lake char ( Salvelinus umbla ) to experimentally test whether sperm react differently to the presence of ovarian fluid, and whether any differential sperm reaction could be predicted by mal...