Abstract
Offspring sex ratio has been proposed as an indicator of the risk of developing certain cancers in humans, but offspring sex ratio may also be a consequence of the disease. In this study, we investigate this subject using the zebrafish, Danio rerio, as a model system. First, we explore whether inducing skin cancer at an early stage of the host's life (embryonic stage) has the potential to influence sex determination and/or sex-specific mortality. Second, we investigate whether the sex ratio in offspring produced by tumor-bearing adult females differs from that of healthy females. Third, we compare the survival (until sexual maturity) of offspring produced by cancerous and non-cancerous females. We found that skin cancer did not influence sex determination and the sex ratio of the offspring. However, consistent with previous studies on other model systems, the survival of offspring was higher when mothers were cancerous, suggesting that diseased females allocate more resources to current reproductive effort compared to their healthy counterparts. This study makes a significant contribution to our understanding of the ecological and evolutionary consequences of host-tumor interactions in animals.