Species richness increases fitness differences, but does not affect niche differences

Spaak, Jürg W.; Carpentier, Camille; Laender, Frederik De

doi:10.1111/ele.13877

Cited by 19 publications

(9 citation statements)

References 79 publications

(144 reference statements)

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“…2). This is consistent with previous theoretical studies arguing that increasing species richness decreases stability (Spaak et al ., 2021b; Allesina & Tang, 2015). However, it differs from previous empirical findings that the inclusion of a predator only affects fitness differences of the basal species, not however their niche differences (Petry et al ., 2018; Terry et al ., 2021).…”

Section: Discussionsupporting

confidence: 93%

“…2F & L and Appendix D). Intuitively, niche differences are a weighted average of the pair-wise niche differences a species has with the other species (Spaak et al ., 2021b), which is not affected by species richness for the basal species. In contrast, fitness differences species richness is the weighted sum of the pair-wise fitness differences (Spaak et al ., 2021d), which increases with increasing species richness as the sum has more terms.…”

Section: Resultsmentioning

confidence: 99%

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Multitrophic assembly: a perspective from modern coexistence theory

Song

Spaak

2023

Preprint

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Ecological communities encompass rich diversity across multiple trophics. While modern coexistence theory has been useful in understanding community assembly, its traditional formalism only allows for the study of assembly within a single trophic level. Here, using an expanded definition of niche and fitness differences applicable to multi-trophic communities, we study how diversity within and across trophics affect species coexistence. Specifically, we investigate how assembly in one trophic level impacts the coexistence of three types of communities: (1) the single-trophic subcommunity with species at that level, (2) the single-trophic subcommunity with species at an adjacent level, and (3) the entire multitrophic community. We find that while coexistence mechanisms are similar for single-trophic communities, they differ for multitrophic ones. We also find that fitness differences primarily constrain diversity in lower-level tropics, while niche differences primarily constrain diversity in higher-level tropics. Empirical data corroborates our predictions about multitrophic structures. Our work provides needed theoretical expectation of multitrophic communities within modern coexistence theory.

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Section: Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Multitrophic assembly: a perspective from modern coexistence theory

Song

Spaak

2023

Preprint

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“…Second, diverse communities have a higher probability of interactions (exclusion or facilitation) of any pair of native and exotic species due to sampling effects. As species richness increases fitness differences (Spaak et al, 2021), there is an increased turnover of species‐specific identities within diverse communities, which increases biotic sorting for exotic species. So, resident species and potential exotic invaders will vary in their resource use similarity and how intensely they compete (MacDougall et al, 2009; Young et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Native diversity contributes to composition heterogeneity of exotic floras

et al. 2023

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Variation in species composition among sites (beta diversity) is generally thought to be driven by environmental filtering and dispersal limitation, but the role of biotic interactions has not been sufficiently addressed. Specifically, the early species in a local community may contribute to subsequent beta diversity patterns. Exotic assemblages within native communities provide a unique opportunity to study biotic interaction mechanisms. In this study, we conducted a field survey of plants over an approximately 1800‐km transect in the middle and lower Yangtze River valley in China to study how native communities influence exotic beta diversity. The survey included 459 plots in 51 local plant communities with 40 exotic species and 103 co‐occurring native species. We also investigated how 11 environmental factors involving climate conditions, soil properties, and human activity regulate the interaction between native and exotic plants. The results showed that native diversity (Shannon–Wiener index) increased exotic beta diversity. Environmental conditions, especially monthly minimum temperature, influenced exotic beta diversity indirectly through native diversity rather than directly. Our results suggest that lower native diversity driven by environmental conditions, especially warmer temperatures, led to a decrease in composition heterogeneity of the exotic flora. Our results will help to incorporate biotic interactions into the framework of beta diversity mechanisms for local community assembly.

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“…At the same time, if divergence of niche positions results in a decrease in the growth rate of phenotypes situated further from the resource optimum, this should generate greater fitness differences. Increasing richness in a given resource space should on the other hand increase niche overlap [30] as well as fitness differences [42]. We therefore expect that effects of evolution on coexistence and productivity may vary depending on the environmental and temporal scales considered.…”

Section: Introductionmentioning

confidence: 99%

Robustness versus productivity during evolutionary community assembly: short-term synergies and long-term trade-offs

Lepori,

Loeuille,

Rohr

2024

Proc. R. Soc. B.

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The realization that evolutionary feedbacks need to be considered to fully grasp ecological dynamics has sparked interest in the effect of evolution on community properties like coexistence and productivity. However, little is known about the evolution of community robustness and productivity along diversification processes in species-rich systems. We leverage the recent structural approach to coexistence together with adaptive dynamics to study such properties and their relationships in a general trait-based model of competition on a niche axis. We show that the effects of coevolution on coexistence are two-fold and contrasting depending on the time scale considered. In the short term, evolution of niche differentiation strengthens coexistence, while long-term diversification leads to niche packing and decreased robustness. Moreover, we find that coevolved communities tend to be on average more robust and more productive than non-evolutionary assemblages. We illustrate how our theoretical predictions echo in observed empirical patterns and the implications of our results for empiricists and applied ecologists. We suggest that some of our results such as the improved robustness of Evolutionarily Stable Communities could be tested experimentally in suitable model systems.

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Species richness increases fitness differences, but does not affect niche differences

Cited by 19 publications

References 79 publications

Multitrophic assembly: a perspective from modern coexistence theory

Multitrophic assembly: a perspective from modern coexistence theory

Native diversity contributes to composition heterogeneity of exotic floras

Robustness versus productivity during evolutionary community assembly: short-term synergies and long-term trade-offs

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