This blog post on ‘Competition’ is part of the BES ‘Key Concepts in Ecology’ series, designed to help ecologists in learning the key topics in ecology! Take a look at the full series for a list of key topics you might typically find in an ecology textbook, each providing a quick introduction to the topic, and a list of suggested papers for students to refer to.  

Across natural ecosystems, communities host an incredible and complex combination of species interactions playing out at various scales, from a continuum of amensalism to commensalism, to a whole suite of mutualists, all the way down to species competing for resources and space, intertwined with various blends of parasites, consumers, and predators. Embracing this complexity methodologically and conceptually enables ecologists to map the relative importance of interactions, such as competition, and refine the quantification of interaction webs (Carrara et al. 2015). And this can be achieved through accurate and consistent measurement of competition (Hart et al. 2018), and/or the development of standardised interaction indices (Díaz-Sierra et al. 2017), and/or by linking models and experimental studies to quantify when competition promotes species coexistence (Terry et al. 2021). 

Deciphering how species interact is a top priority for ecologists as it holds the key for effective conservation and ecosystem management (Gilmartin 2022) and for unlocking the complexity of natural communities, especially competitive interactions. Notably, Prior et al. (2020) demonstrated the importance of quantifying competition in understanding the dynamics of seed dispersal and plant community assembly in mesocosms, while Singer et al. (2017) quantified resource partitioning between predatory birds and ants based on prey traits, offering valuable insights into how competition shapes ecological communities. 

Merging the predictions of the Theory of Island Biogeography and competition theory, Si et al. (2017) identified the disproportionate role of functional traits and evolutionary history in structuring island bird communities. By developing new statistical methods, Teller et al. (2016) also paved the way to efficiently integrate and simulate climate drivers with various competition levels to understand population dynamics. However, practical challenges persist in predicting species abundance, necessitating a trade-off between model complexity and generality (Clark et al. 2020). 

In conclusion, the continuous integrating of theory, experimentation, and empirical studies is perhaps critical for advancing our understanding of competition and its impacts on ecosystems, as well as conservation and management strategies. 

Introduction written by Nicolas Lecomte (Senior Editor, Methods in Ecology and Evolution). Reading list curated by the BES journal Editors.  

References and suggested reading 

Intra- and interspecific competition 

• Clark, A.T. et al. (2020), Predicting species abundances in a grassland biodiversity experiment: Trade-offs between model complexity and generality. Journal of Ecology, 108:774–787 .  

• Hart, S.P. et al. (2018), How to quantify competitive ability. Journal of Ecology, 106:1902–1909.   

• Prior, K.M. et al. (2020), Interactions between seed-dispersing ant species affect plant community composition in field mesocosms. Journal of Animal Ecology, 89:2485–2495.   

• Si, X. et al. (2017), Functional and phylogenetic structure of island bird communities. Journal of Animal Ecology, 86:532-542.   

• Singer, M.S.  et al. (2017), Predatory birds and ants partition caterpillar prey by body size and diet breadth. Journal of Animal Ecology; 86:1363–1371.   

Lotka-Voltera competition models 

• Carrara, F. et al. (2015), Inferring species interactions in ecological communities: a comparison of methods at different levels of complexity. Methods in Ecology and Evolution, 6:895-906.   

Types of competition 

• Díaz-Sierra, R. et al. (2017), A new family of standardised and symmetric indices for measuring the intensity and importance of plant neighbour effects. Methods in Ecology and Evolution, 8:580-591.   

• Gilmartin, E. (2022), Evidence review: how do woodland creation approaches give rise to differences in woodland structure? Woodland Trust, 20220033027.   

• Teller, B.J. et al. (2016), Linking demography with drivers: climate and competition. Methods in Ecology and Evolution, 7:171-183.   

Context-dependent competition 

• Terry, J.C.D. et al. (2021), Natural enemies have inconsistent impacts on the coexistence of competing species. Journal of Animal Ecology, 90:2277–2288.