The Geography of Sexual Conflict: A Synthetic Review*

Sexual conflict is a mechanism of selection driven by the divergent fitness interests between females and males. This disagreement can be great enough to promote antagonistic/defensive traits and behaviors. Although the existence of sexual conflict has been identified in many species, less research has explored the conditions that initially promote sexual conflict in animal mating systems. In previous work in Opiliones, we observed that morphological traits associated with sexual conflict occurred only in species from northern localities. We hypothesized that by shortening and compartmentalizing time periods optimal for reproduction, seasonality represents a geographic condition sufficient to promote sexual conflict. We conducted a systematic review of the literature on reproductive traits and behaviors. Using standardized criteria, we reviewed publications to identify whether subjects occurred in a temperate (high-seasonality) or tropical (low-seasonality) biome. After identifying and adjusting for a publication bias toward temperate research, we identified no significant difference in the strength of sexual conflict between temperate and tropical study systems. A comparison between the distribution of taxa studied in sexual conflict articles and articles focused on general biodiversity indicates that species with conflict-based mating systems more accurately represent the distribution of terrestrial animal species. These findings contribute to ongoing efforts to characterize the origins of sexual conflict as well as life history traits that covary with sexual conflict.