A new method to analyse species abundances in space using generalized dimensions

Saravia, Leonardo A.

doi:10.1111/2041-210x.12417

Cited by 6 publications

(8 citation statements)

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“…It has been assumed that the features of fractal structures are present in the patterns of community ecology (Saravia, 2015;Våge and Thingstad, 2015). Cases of power law dependency have been detected in rank-abundance distributions of microbial communities (Feranchuk et al, 2018a), as it is shown in Fig.…”

Section: Detection Of Power-law Distributions Inmentioning

confidence: 99%

Microevolution processes in Baikal are detected in symbiotic microbiomes of Baikal sponges by the methods of fractal theory

Feranchuk

Potapova

Chernogor

et al. 2018

LFWB

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In recent years, a large scale ecological crisis has been observed in the Lake Baikal ecosystem. It is clearly shown by several signs, including the mass disease of sponges in the coastal zone. To investigate the causes of the crisis, the composition of symbiotic communities in sponges was investigated in 2015 by sequencing of the 16S rRNA gene in three locations of the lake. The methods of fractal theory were adopted in order to detect a fractal structure in the distribution of the sequencing reads, being considered as fragments of the 16S rRNA gene for individual bacteria within the collected samples. The fractal-like distributions were constructed for the seven most abundant phylotypes, and the observed properties of the distributions reflect microevolution processes within the selected genera and species. The values of the fractal dimension, evaluated for the distributions, are observed to correlate with an anthropogenic load at the place of sample collection, for the Flavobacterium and Synechococcus genera. The sampling sites were also observed to be associated with the properties of the distributions for chloroplasts of Trebouxiophyceae algae, the endosymbiont of Lubomirskia baicalensis sponge.The long-scale time dependency of fractal dimension was also evaluated for the data from temperature detectors in four locations of Lake Baikal. The values of the fractal dimension for fluctuations of temperature are also observed to be associated with an anthropogenic load in the place of measurement. The consistency of both approaches validates the usefulness of fractal-based methods in the interpretation of the experiments designed to study the ecological crisis in Lake Baikal.

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Section: Detection Of Power-law Distributions Inmentioning

confidence: 99%

Microevolution processes in Baikal are detected in symbiotic microbiomes of Baikal sponges by the methods of fractal theory

Feranchuk

Potapova

Chernogor

et al. 2018

LFWB

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“…It was demonstrated that neutral and niche mechanisms could produce the same RAD (Volkov et al , Chisholm and Pacala ), so it might not be useful for determining the proximity to the critical point. We found that there is a change in the RAD when the critical point is approached but these changes are small and will probably go undetected (Saravia ). The shape of the RAD is highly dependent on the metacommunity, which is difficult to estimate as a baseline, and thus there is no RAD characteristic of a community near the critical point.…”

Section: Discussionmentioning

confidence: 77%

“…Our criteria to stop enlarging the scale is that the species abundance distribution (SAD) of the discretized lattice should not be statistically different from the original SAD. To test this we use the Anderson‐Darling statistic with a randomization procedure using the R package kSamples (Scholz and Zhu ); this statistic has proven powerful to detect different kinds of communities using SAD (Saravia ). With this procedure we obtained a scale of 1 m, and thus used a lattice of 1000 × 500 sites.…”

Section: Methodsmentioning

confidence: 99%

“…Here we study the phase transition between neutral and niche dynamics from a spatial point of view by applying methods of percolation theory. We will use a spatially explicit neutral model where niche dynamics is represented as a competitive hierarchy (Saravia ). Our first objective is to demonstrate the existence of the phase transition in our spatial neutral‐niche model triggered by competition intensity; we show that the phase transition is determined by the geometric characteristics of the species patches, and that the niche state that emerges after the critical point has lower species diversity and richness.…”

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confidence: 99%

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Biodiversity collapse and early warning indicators in a spatial phase transition between neutral and niche communities

Saravia

Momo

2017

Oikos

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The dynamics of ecological communities have been described by neutral and niche theories that are now increasingly integrated into unified models. It is known that a critical transition exists between these two states, but the spatial aspect of this transition has not been studied. Our aim is to study the spatial aspect of the transition and propose early warning signals to detect it. We used a stochastic, spatially explicit model that spans a continuum from neutral to niche communities, and is driven by the intensity of hierarchical competition. The transition is indicated by the emergence of a large patch formed by one species that connects the whole area. The properties of this patch can be used as early warning indicators of a critical transition. If competition intensity increases beyond the critical point, our model shows a sudden decrease of the Shannon diversity index and a gentle decline in species richness. The critical point occurs at a very low value of competitive intensity, with the rate of migration from the metacommunity greatly influencing the position of this critical point. As an example, we apply our new method of early warning indicators to the Barro Colorado Tropical forest, which, as expected, appears to be far from a critical transition. Low values of competitive intensity were also reported by previous studies for different high-diversity real communities, suggesting that these communities are located before the critical point. A small increase of competitive interactions could push them across the transition, however, to a state in which diversity is much lower. Thus this new early warnings indicator could be used to monitor high diversity ecosystems that are still undisturbed.

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“…Here we study the phase transition between neutral and niche dynamics from a spatial point of view by applying methods of percolation theory. We will use a spatially explicit neutral model where niche dynamics is represented as a competitive hierarchy (Saravia 2015). Our first objective is to demonstrate the existence of the phase transition in our spatial neutral-niche model triggered by competition intensity; we show that the phase transition is determined by the geometric characteristics of the species patches, and that the niche state that emerges after the critical point has lower species diversity and richness.…”

Section: Introductionmentioning

confidence: 99%

Biodiversity collapse and early warning indicators in a spatial phase transition between neutral and niche communities

Saravia

Momo

2017

Preprint

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1The dynamics of ecological communities have been described by neutral and niche theories that are now 2 increasingly integrated into unified models. It is known that a critical transition exists between these two 3 states, but the spatial aspect of this transition has not been studied. Our aim is to study the spatial aspect of 4 the transition and propose early warning signals to detect it. We used a stochastic, spatially explicit model 5 that spans a continuum from neutral to niche communities, and is driven by the intensity of hierarchical 6 competition. The transition is indicated by the emergence of a large patch formed by one species that 7 connects the whole area. The properties of this patch can be used as early warning indicators of a critical interactions could push them across the transition, however, to a state in which diversity is much lower. 16Thus this new early warnings indicator could be used to monitor high diversity ecosystems that are still 17 undisturbed. 18Short title: A spatial phase transition between neutral and niche communities

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A new method to analyse species abundances in space using generalized dimensions

Cited by 6 publications

References 58 publications

Microevolution processes in Baikal are detected in symbiotic microbiomes of Baikal sponges by the methods of fractal theory

Microevolution processes in Baikal are detected in symbiotic microbiomes of Baikal sponges by the methods of fractal theory

Biodiversity collapse and early warning indicators in a spatial phase transition between neutral and niche communities

Biodiversity collapse and early warning indicators in a spatial phase transition between neutral and niche communities

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