Patterns of Competitive Exclusion in the Mammalian Fossil Record

Due to recentRecent common ancestry, species belonging to the same genus are expected to be more similar with respect to their phenotype, and hence exhibit less niche divergence, than species belonging to different genera. Consequently, congenericCongeneric species are expected to compete more intensely for resources, and therefore to be more segregated in space. Yet, despite the longstanding history of this hypothesis of congenericCongeneric competitive exclusionCompetitiveexclusion, empirical evidence in support of it is at best limited. Here, we analyze co-occurrence patterns of species that belong to the same genera in the mammalian fossil record kept in the NOW database, separately considering Europe during the Neogene, and North America during the Oligocene–Neogene. We assess co-occurrence patterns in comparison to baselines where competitive exclusionCompetitiveexclusion is obfuscated through randomizationRandomization. We find that congenericCongeneric species occur together notably less than would be expected at random, with large herbivoresHerbivore/herbivorous being more segregated than large carnivorans[aut]Carnivora (carnivorans) and small mammals.