Coalescent dynamics of planktonic communities

Martín, Paula Villa; Koldaeva, Anzhelika; Pigolotti, Simone

doi:10.1103/physreve.106.044408

Cited by 2 publications

(1 citation statement)

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“…The unified neutral theory of biodiversity, based on the interchangeability of individuals regardless of species identity, predicts a power-law tail of the SAD with exponent one ( 3 , 56 ). To approach the empirical value, previous studies augmented neutral theory with nonlinear growth rates ( 12 ) or chaotic mixing ( 71 ) to find an exponent dependent on the model parameters. However, for large census sizes such as that of plankton communities, neutral theories predict astronomically large turnover timescales ( 72 , 73 ), inconsistent with observation.…”

Section: Discussionmentioning

confidence: 99%

Chaotic turnover of rare and abundant species in a strongly interacting model community

Mallmin,

Traulsen,

De Monte

2024

Proc. Natl. Acad. Sci. U.S.A.

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The composition of ecological communities varies not only between different locations but also in time. Understanding the fundamental processes that drive species toward rarity or abundance is crucial to assessing ecosystem resilience and adaptation to changing environmental conditions. In plankton communities in particular, large temporal fluctuations in species abundances have been associated with chaotic dynamics. On the other hand, microbial diversity is overwhelmingly sustained by a “rare biosphere” of species with very low abundances. We consider here the possibility that interactions within a species-rich community can relate both phenomena. We use a Lotka–Volterra model with weak immigration and strong, disordered, and mostly competitive interactions between hundreds of species to bridge single-species temporal fluctuations and abundance distribution patterns. We highlight a generic chaotic regime where a few species at a time achieve dominance but are continuously overturned by the invasion of formerly rare species. We derive a focal-species model that captures the intermittent boom-and-bust dynamics that every species undergoes. Although species cannot be treated as effectively uncorrelated in their abundances, the community’s effect on a focal species can nonetheless be described by a time-correlated noise characterized by a few effective parameters that can be estimated from time series. The model predicts a nonunitary exponent of the power-law abundance decay, which varies weakly with ecological parameters, consistent with observation in marine protist communities. The chaotic turnover regime is thus poised to capture relevant ecological features of species-rich microbial communities.

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