The importance of paternal effects in heatwaves

As the threat of climate change and associated heatwaves grows, we need to
understand how natural populations will respond. Inter-generational
non-genetic inheritance may play a key role in rapid adaptation, but
whether such mechanisms are truly adaptive and sufficient to protect wild
populations is unclear. The contribution of paternal effects in particular
is not fully understood, even though the male reproductive system may be
highly sensitive to heatwaves. We used the zebrafish Danio rerio to
investigate the effects of heatwaves on male fertility and assess
potential adaptive benefits to their offspring in a number of large-scale
heatwave experiments. Heatwave conditions had negative effects on male
fertility by reducing gamete quality and fertilisation success, and we
found indications of an adaptive effect on hatching in offspring produced
by heatwave-exposed males. Our findings highlight the importance of
including male and female fertility when determining species ability to
cope with extreme conditions and suggest that parental effects provide
limited adaptive benefits.