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Emergent niche structuring leads to increased differences from neutrality in species abundance distributions
Author(s) -
Rael Rosalyn C.,
D'Andrea Rafael,
Barabás György,
Ostling Annette
Publication year - 2018
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1002/ecy.2238
Subject(s) - niche , ecological niche , abundance (ecology) , ecology , biology , coexistence theory , competition (biology) , relative species abundance , neutral theory of molecular evolution , niche segregation , relative abundance distribution , population , niche differentiation , trait , evolutionary biology , habitat , biochemistry , demography , sociology , gene , computer science , programming language
Species abundance distributions must reflect the dynamic processes involved in community assembly, but whether and when specific processes lead to distinguishable signals is not well understood. Biodiversity and species abundances may be shaped by a variety of influences, but particular attention has been paid to competition, which can involve neutral dynamics, where competitor abundances are governed only by demographic stochasticity and immigration, and dynamics driven by trait differences that enable stable coexistence through the formation of niches. Key recent studies of the species abundance patterns of communities with niches employ simple models with pre‐imposed niche structure. These studies suggest that species abundance distributions are insensitive to the relative contributions of niche and neutral processes, especially when diversity is much higher than the number of niches. Here we analyze results from a stochastic population model with competition driven by trait differences. With this model, niche structure emerges as clumps of species that persist along the trait axis, and leads to more substantial differences from neutral species abundance distributions than have been previously shown. We show that heterogeneity in “between‐niche” interaction strength (i.e., in the strength of competition between species in different niches) plays the dominant role in shaping the species abundances along the trait axis, acting as a biotic filter favoring species at the centers of niches. Furthermore, we show that heterogeneity in “within‐niche” interactions (i.e., in the competition between species in the same niche) counteracts the influence of heterogeneity in “between‐niche” interactions on the SAD to some degree. Our results suggest that competitive interactions that produce niches can also influence the shapes of SAD s.