Abstract:

Background & Aims Interactions between organisms, especially competitive interactions, are of central importance to species coexistence and biodiversity maintenance. Previous studies focused primarily on pairwise competition amongst species, which often failed to explain the maintenance of biodiversity in communities. Intransitive competition, similar to the ‘rock-paper-scissors’ game, is acknowledged as an important alternative mechanism of species coexistence and biodiversity and has recently garnered the attention of researchers.

Progress First, we reviewed the development of defining intransitive competition from traditional interspecific intransitive triplets to weak, pairwise, and intraspecific intransitive competition. We introduced different forms of intransitive competition networks including simple intransitive triplets and nested competitive networks. Second, we introduced the measurements of intransitivity based on a competitive outcomes matrix and invasive population growth rate and compared their performances. Third, we demonstrated the prevalence of intransitive competition in natural communities of different taxonomic groups (such as plants, animals, and microorganisms) and its underlying mechanisms such as resource access, life stage cycle, behavioral tradeoffs, tradeoffs between resource consumption and growth rate, and allelopathy. Finally, we discussed recent research that explores the effects of intransitive competition on biodiversity and ecosystem functioning.

Prospect Intransitive competition is essentially combinations of pairwise interactions of a single interaction type. Future research should focus its effects on the relationship between biodiversity, ecosystem functioning, and community stability, the effects of environments and higher-order interactions on intransitive competition, and move away from competitive networks to ecological networks consisting of multiple types of interactions. Advances in research on intransitive competition will improve our understanding of species coexistence and biodiversity maintenance, as well as provide guidance in biodiversity conservation and restoration.

Key words: intransitive competition, interaction chain, indirect interaction, biodiversity, ecological network