Why sex matters in phenological research

Males and females often desynchronise their mating activity during the breeding season (intersexual phenological asynchrony). This suggests that the two sexes differentially use environmental cues to initiate seasonal reproduction, and climate change may cause phenological shifts in a sex-specific manner, subsequently altering frequency distribution of mating attempts over time and influencing the emergence timing and recruitment success of juveniles. In this article, we tested these hypotheses through literature reviews and theoretical modelling. We found that the sex specificity of environmental cues and phenological shifts remain poorly understood in most sexually reproducing animal taxa because of sex-specific publication bias and data limitations. Meanwhile, our theoretical model predicted that the ecological consequences of phenological shifts are sexually asymmetric, with earlier mating onset of males having generally greater negative effects on population growth than that of females. We therefore suggest that further research is necessary to collect and incorporate sex-specific information on seasonal reproduction into the theory of phenological mismatch, for which previous work has mostly focused on interspecific trophic asynchrony. We also outline a future research agenda to better understand the consequences of sex-specific phenological shifts on seasonal population dynamics and long-term persistence of species.