Paternal-effects in a terrestrial ectotherm are temperature dependent but no evidence for adaptive effects

1. Global rising of average temperatures and increase in extreme climatic events may largely impact animal survival and reproduction. Yet, how variation in temperature may affect male fertility, in particular ejaculate traits, and whether this can in turn affect offspring fitness, is seldom addressed. Paternal effects may be of key importance as they could impact the rate and direction of evolutionary change in response to climate change. 2. We tested the effects of temperature experienced by males on sperm traits, and asked whether the paternal environmental temperature affected offspring phenotype. We further explored the potential for paternal effects to be adaptive, which would occur when offspring fitness increased under the same environmental conditions experienced by the fathers. We exposed male field crickets to high or low temperatures at two life stages, either throughout development or as adults, and tested sperm traits (number and quality) and offspring fitness (hatching suc...