Reanalysis of Caswell's Neutral Models

Ugland, Karl I.; Gray, J. S.

doi:10.2307/1939979

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…Comparing against older but less flexible models such as the logseries or geometric which are known to fail to fit many datasets is weaker. Multiple mechanisms: Any given mathematical formulation of an SAD can be created by many different mechanisms, so fit to data cannot possibly be ultimate proof of a particular mechanism (Pielou 1975; McGill 2003a). For example, Cohen (1968) showed that multiple mechanisms lead to the broken stick, Boswell & Patil (1971) showed that multiple mechanisms lead to the logseries while Ugland & Gray (1983) showed that either niche‐based competition or neutrality can lead to neutral patterns and processes. It is well known to philosophers of science that similarity in pattern does not imply similarity in process, but ecologists seem to frequently forget it.…”

Section: Theoretical Developments In Sadsmentioning

confidence: 99%

Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework

et al. 2007

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Species abundance distributions (SADs) follow one of ecologyÕs oldest and most universal laws -every community shows a hollow curve or hyperbolic shape on a histogram with many rare species and just a few common species. Here, we review theoretical, empirical and statistical developments in the study of SADs. Several key points emerge. (i) Literally dozens of models have been proposed to explain the hollow curve. Unfortunately, very few models are ever rejected, primarily because few theories make any predictions beyond the hollow-curve SAD itself. (ii) Interesting work has been performed both empirically and theoretically, which goes beyond the hollow-curve prediction to provide a rich variety of information about how SADs behave. These include the study of SADs along environmental gradients and theories that integrate SADs with other biodiversity patterns. Central to this body of work is an effort to move beyond treating the SAD in isolation and to integrate the SAD into its ecological context to enable making many predictions. (iii) Moving forward will entail understanding how sampling and scale affect SADs and developing statistical tools for describing and comparing SADs. We are optimistic that SADs can provide significant insights into basic and applied ecological science.

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Section: Theoretical Developments In Sadsmentioning

confidence: 99%

Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework

et al. 2007

View full text Add to dashboard Cite

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“…(2) Multiple mechanisms: Any given mathematical formulation of an SAD can be created by many different mechanisms, so fit to data cannot possibly be ultimate proof of a particular mechanism (Pielou 1975;McGill 2003a). For example, Cohen (1968) showed that multiple mechanisms lead to the broken stick, Boswell & Patil (1971) showed that multiple mechanisms lead to the logseries while Ugland & Gray (1983) showed that either niche-based competition or neutrality can lead to neutral patterns and processes. It is well known to philosophers of science that similarity in pattern does not imply similarity in process, but ecologists seem to frequently forget it.…”

Section: Causes Of the Proliferationmentioning

confidence: 99%

The zero-sum assumption in neutral biodiversity theory

Etienne

Alonso

McKane

2007

Journal of Theoretical Biology

107

139

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The neutral theory of biodiversity as put forward by Hubbell in his 2001 monograph has received much criticism for its unrealistic simplifying assumptions. These are the assumptions of functional equivalence among different species (neutrality), the assumption of point mutation speciation, and the assumption that resources are continuously saturated, such that constant resource availability implies constant community size (zero-sum assumption). Here we focus on the zero-sum assumption. We present a general theory for calculating the probability of observing a particular species-abundance distribution (sampling formula) and show that zero-sum and non-zero-sum formulations of neutral theory have exactly the same sampling formula when the community is in equilibrium. Moreover, for the non-zero-sum community the sampling formula has this same form, even out of equilibrium. Therefore, the term "zero-sum multinomial (ZSM)" to describe species abundance patterns, as coined by Hubbell [2001. The Unified Neutral Theory of Biodiversity and Biogeography, Princeton University Press, Princeton, NJ], is not really appropriate, as it also applies to non-zero-sum communities. Instead we propose the term "dispersal-limited multinomial (DLM)", thus making explicit one of the most important contributions of neutral community theory, the emphasis on dispersal limitation as a dominant factor in determining species abundances.

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“…It should be noted that there has been some debate about whether certain models are truly neutral (e.g. Ugland & Gray 1983, Caswell 1983): we defer comment at this point. Here we are simply interested in the neutral model as an alternative, relatively sample-size independent measure of diversity.…”

Section: Introductionmentioning

confidence: 97%

Neutral modelanalysis of patterns of marine benthic species diversity

Piatt¹,

Lambshead²

1985

Mar. Ecol. Prog. Ser.

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Caswell (1976) proposed a neutral model which calculates a theoretical diversity for a sample of a given number of individuals and species assuming no biological interactions between species. Disagreement with the neutral model predictions have been suggested as a method of detecting disturbance or stress. To test these theoretical considerations, 98 samples of marine benthic organisms were subjected to neutral model analysis. Deviation from the predicted diversity was generally found to be negative -less diverse than expected. Where disturbance was known to have occurred, spatial or temporal variations in the degree of dev~ation were in accordance with a hypothesis of diversity based on a combination of the Intermediate Disturbance Hypothesis (Connell 1978) and the General Hypothesis of Diversity (Huston 1979). Artificially created log-normal patterns of species abundance distribution gave a diversity greater than that predicted by the neutral model. But in no cases where the diversity of actual samples exceeded the neutral model prediction were the species abundance distributions log-normal.

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Reanalysis of Caswell's Neutral Models

Cited by 5 publications

References 5 publications

Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework

Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework

The zero-sum assumption in neutral biodiversity theory

Neutral modelanalysis of patterns of marine benthic species diversity

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