Sex-specific variation in species interactions matters in ecological communities.

Biological sex affects the morphology, physiology, behaviour, and distribution of organisms and populations. Integrating intraspecific variation of biological traits into community dynamics has improved our understanding of food web and ecosystem dynamics and stability. However, biological sex is rarely considered. The inclusion of sex-specific variation in theoretical models has highlighted that sex-based differences can significantly influence community dynamics, but empirical tests are limited. Methodological and logistical challenges often prevent the consideration of organisms' sex in the field, limiting our understanding of the role of sex in community functioning. Where these limitations have been overcome, field studies highlighted sex-based species interactions and their cascading ecological outcomes in marine, freshwater, and terrestrial ecosystems. Understanding how natural communities and ecosystems are structured and respond to anthropogenic pressures in a rapidly changing world is key to successful management and conservation. A fundamental but often overlooked biological characteristic of organisms is sex. Sex-based responses are often considered when conducting studies at organismal and population levels, but are rarely investigated in community ecology. Focusing on kelp forests as a model system, and through a review of other marine and terrestrial ecosystems, we found evidence of widespread sex-based variation in species interactions. Sex-based variation in species interactions is expected to affect ecosystem structure and functioning via multiple trophic and nontrophic pathways. Understanding the drivers and consequences of sex-based variation in species interactions can inform more effective management and restoration. [ABSTRACT FROM AUTHOR]