The Unified Neutral Theory of Biodiversity and Biogeography: Reply

Hubbell, Stephen P.; Borda‐de‐Água, Luís

doi:10.1890/04-0808

Cited by 630 publications

(902 citation statements)

References 9 publications

(15 reference statements)

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“…Low y is skewed by its heavily populated two-clusters. The plots for high y show the log-normal form observed in many real ecosystems and in other ecological models (McKane et al, 2000;Hubbell, 2001). They appear to become more log-normal as time increases with the dip between four and eight individuals falling, even though the diversity is rising.…”

Section: Species Abundancementioning

confidence: 65%

“…There has lately been much interest in the neutral theory of biodiversity (Hubbell, 2001;Bell, 2001). Despite making assumptions that are anathema to traditional niche models (all individuals are the same and adaptations to specific environmental niches are essentially unimportant) it has been successful in making predictions about real world ecologyalthough its effectiveness in modelling the species abundance has recently been called into question (McGill, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Technically, Tangled Nature is also neutral if J ¼ 0 for all time, but this is obviously not the case in this paper. Further, unlike the models in Hubbell (2001), we have no spatial aspect: we deal with only one large metacommunity as opposed to aggregating many local communities to form the metacommunity.…”

Section: Discussionmentioning

confidence: 99%

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Network properties, species abundance and evolution in a model of evolutionary ecology

Anderson

2005

Journal of Theoretical Biology

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We study the evolution of the network properties of a populated network embedded in a genotype space characterized by either a low or a high number of potential links, with particular emphasis on the connectivity and clustering. Evolution produces two distinct types of network. When a specific genotype is only able to influence a few other genotypes, the ecosystem consists of separate noninteracting clusters (i.e. isolated compartments) in genotype space. When different types may influence a large number of other sites, the network becomes one large interconnected cluster. The distribution of interaction strengths-but not the number of connections-changes significantly with time. We find that the species abundance is only realistic for a high level of species connectivity. This suggests that real ecosystems form one interconnected whole in which selection leads to stronger interactions between the different types. Analogies with niche and neutral theory and assembly models are also considered. r

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Section: Species Abundancementioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

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Network properties, species abundance and evolution in a model of evolutionary ecology

Anderson

2005

Journal of Theoretical Biology

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“…Alternatively, both solar and productive energy availability may influence speciation/extinction rates indirectly through variables such as body size and reproductive rates. The unified neutral theory also predicts that larger populations, which may occur in high-energy areas (see Section III.2), may promote faster evolutionary rates (Hubbell, 2001). …”

Section: (D ) Summarymentioning

confidence: 99%

Species–energy relationships at the macroecological scale: a review of the mechanisms

2005

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Correlations between the amount of energy received by an assemblage and the number of species that it contains are very general, and at the macro-scale such species-energy relationships typically follow a monotonically increasing curve. Whilst the ecological literature contains frequent reports of such relationships, debate on their causal mechanisms is limited and typically focuses on the role of energy availability in controlling the number of individuals in an assemblage. Assemblages from high-energy areas may contain more individuals enabling species to maintain larger, more viable populations, whose lower extinction risk elevates species richness. Other mechanisms have, however, also been suggested. Here we identify and clarify nine principal mechanisms that may generate positive species-energy relationships at the macro-scale. We critically assess their assumptions and applicability over a range of spatial scales, derive predictions for each and assess the evidence that supports or refutes them. Our synthesis demonstrates that all mechanisms share at least one of their predictions with an alternative mechanism. Some previous studies of species-energy relationships appear not to have recognised the extent of shared predictions, and this may detract from their contribution to the debate on causal mechanisms. The combination of predictions and assumptions made by each mechanism is, however, unique, suggesting that, in principle, conclusive tests are possible. Sufficient testing of all mechanisms has yet to be conducted, and no single mechanism currently has unequivocal support. Each may contribute to species-energy relationships in some circumstances, but some mechanisms are unlikely to act simultaneously. Moreover, a limited number appear particularly likely to contribute frequently to species-energy relationships at the macro-scale. The increased population size, niche position and diversification rate mechanisms are particularly noteworthy in this context.

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“…Thus, we present a specieslevel model such as those traditionally used in ecological networks (see Pimm, 2002). Consequently, the model ignores features such as the number of individuals of each species that may markedly affect sampling and ecological patterns and processes (Hubbell, 2001). However, because of its simplicity, the model allows exploring the effects of processes that lead to different species richness in mutualistic networks in the absence of complicating factors.…”

Section: The Modelmentioning

confidence: 99%

Build-up mechanisms determining the topology of mutualistic networks

Guimarães

Machado

Aguiar

et al. 2007

Journal of Theoretical Biology

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The frequency distribution of the number of interactions per species (i.e., degree distribution) within plant-animal mutualistic assemblages often decays as a power-law with an exponential truncation. Such a truncation suggests that there are ecological factors limiting the frequency of supergeneralist species. However, it is not clear whether these patterns can emerge from intrinsic features of the interacting assemblages, such as differences between plant and animal species richness (richness ratio). Here, we show that high richness ratios often characterize plant-animal mutualisms. Then, we demonstrate that exponential truncations are expected in bipartite networks generated by a simple model that incorporates build-up mechanisms that lead to a high richness ratio. Our results provide a simple interpretation for the truncations commonly observed in the degree distributions of mutualistic networks that complements previous ones based on biological effects. r

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The Unified Neutral Theory of Biodiversity and Biogeography: Reply

Cited by 630 publications

References 9 publications

Network properties, species abundance and evolution in a model of evolutionary ecology

Network properties, species abundance and evolution in a model of evolutionary ecology

Species–energy relationships at the macroecological scale: a review of the mechanisms

Build-up mechanisms determining the topology of mutualistic networks

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