Ecosystem ecology: size-based constraints on the pyramids of life

Trebilco, Rowan; Baum, Julia K.; Salomon, Anne K.; Dulvy, Nicholas K.

doi:10.1016/j.tree.2013.03.008

Cited by 308 publications

(446 citation statements)

References 67 publications

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“…The competitive exclusion from resources is therefore not necessarily the exclusion from an abundant and widespread resource that can maintain a large population, but more importantly the exclusion from a resource that is easy for the individuals to exploit for energy and other essential components. The resources that are exploited by the larger species are therefore not necessarily the resources that can sustain the largest biomass (Makarieva, Gorshkov, & Li, 2004; Trebilco, Baum, Salomon, & Dulvy, 2013). It is for similar resources that we expect the straight forward allometric relations where biomass (

n w \propto w^{1 / 2 d}

) increases with mass and the energy (

n w β \propto w^{0}

) that is metabolized by the population is invariant of mass.…”

Section: Discussionmentioning

confidence: 99%

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

Witting

2017

Ecology and Evolution

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I show that the natural selection of metabolism and mass can select for the major life‐history and allometric transitions that define lifeforms from viruses, over prokaryotes and larger unicells, to multicellular animals. The proposed selection is driven by a mass‐specific metabolism that is selected as the pace of the resource handling that generates net energy for self‐replication. An initial selection of mass is given by a dependence of mass‐specific metabolism on mass in replicators that are close to a lower size limit. A sublinear maximum dependence selects for virus‐like replicators, with no intrinsic metabolism, no cell, and practically no mass. A superlinear dependence selects for prokaryote‐like self‐replicating cells, with asexual reproduction and incomplete metabolic pathways. These self‐replicators have selection for increased net energy, and this generates a gradual unfolding of population‐dynamic feed‐back selection from interactive competition. The incomplete feed‐back selects for larger unicells with more developed metabolic pathways, and the completely developed feed‐back for multicellular animals with sexual reproduction. This model unifies the natural selection of lifeforms from viruses to multicellular animals, and it provides a parsimonious explanation where allometries and major life histories evolve from the natural selection of metabolism and mass.

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n w \propto w^{1 / 2 d}

) increases with mass and the energy (

n w β \propto w^{0}

) that is metabolized by the population is invariant of mass.…”

Section: Discussionmentioning

confidence: 99%

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

Witting

2017

Ecology and Evolution

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“…The natural history of temperate reefs suggests that energetic subsidies are the most likely explanation for the mismatch between the observed pattern of community structure and the underlying process of size-based energy flow [3,41]. Processes that are likely to subsidize the fish communities in this study system and facilitate IBPs include the movement, foraging and aggregation of mobile consumers across habitats, seasonally pulsed inputs of production at small body sizes, and multiple energy sources, some of which potentially enter the community at large body sizes.…”

Section: Discussionmentioning

confidence: 99%

“…However, the plausibility of such top-heavy configurations has been debated [2,3]. Recent work demonstrating the equivalence of biomass pyramids and biomass spectra highlights that, in size-structured assemblages, where trophic-level increases with body size, biomass distributions should be 'stacks' or bottom-heavy pyramids, and not strongly inverted [3]. Furthermore, natural history suggests that fish communities tend to be strongly size-structured because indeterminate growth and gape-limited size-selective predation predominate among fishes [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…[16]), although in such situations the relationship between trophic-level and body size is more appropriately expressed as a consumer-to-resource mass ratio (CRMR) rather than PPMR. Biomass pyramids and biomass spectra are equivalent and interchangeable; negative biomass spectrum slopes correspond to bottom-heavy pyramids, positive slopes correspond to inverted pyramids, and slopes of zero ('flat' spectra) represent biomass stacks or columns [3]. Hence the ecological processes, summarized by TE and PPMR, that determine the slopes of biomass spectra also determine ecological pattern-the shapes of biomass pyramids.…”

Section: Introductionmentioning

confidence: 99%

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The paradox of inverted biomass pyramids in kelp forest fish communities

et al. 2016

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Theory predicts that bottom-heavy biomass pyramids or 'stacks' should predominate in real-world communities if trophic-level increases with body size (mean predator-to-prey mass ratio (PPMR) more than 1). However, recent research suggests that inverted biomass pyramids (IBPs) characterize relatively pristine reef fish communities. Here, we estimated the slope of a kelp forest fish community biomass spectrum from underwater visual surveys. The observed biomass spectrum slope is strongly positive, reflecting an IBP. This is incongruous with theory because this steep positive slope would only be expected if trophic position decreased with increasing body size (consumer-to-resource mass ratio, less than 1). We then used d 15 N signatures of fish muscle tissue to quantify the relationship between trophic position and body size and instead detected strong evidence for the opposite, with PPMR % 1650 (50% credible interval 280-12 000). The natural history of kelp forest reef fishes suggests that this paradox could arise from energetic subsidies in the form of movement of mobile consumers across habitats, and from seasonally pulsed production inputs at small body sizes. There were four to five times more biomass at large body sizes (1-2 kg) than would be expected in a closed steady-state community providing a measure of the magnitude of subsidies.

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“…2014), scientists now acknowledge the potential benefits of individual‐level data in understanding the dynamics and functioning of ecosystems (e.g., Trebilco et al. 2013). An important body of work has emerged that relates community‐level responses of size spectra (the distribution of biomass across size classes: a method that links individual‐level data to communities and ecosystems) to environmental change and ecosystem functioning (Dossena et al.…”

Section: Introductionmentioning

confidence: 99%

Disentangling the influences of mean body size and size structure on ecosystem functioning: an example of nutrient recycling by a non‐native crayfish

Fritschie

Olden

2015

Ecology and Evolution

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Body size is a fundamental functional trait that can be used to forecast individuals' responses to environmental change and their contribution to ecosystem functioning. However, information on the mean and variation of size distributions often confound one another when relating body size to aggregate functioning. Given that size‐based metrics are used as indicators of ecosystem status, it is important to identify the specific aspects of size distributions that mediate ecosystem functioning. Our goal was to simultaneously account for the mean, variance, and shape of size distributions when relating body size to aggregate ecosystem functioning. We take advantage of habitat‐specific differences in size distributions to estimate nutrient recycling by a non‐native crayfish using mean‐field and variance‐incorporating approaches. Crayfishes often substantially influence ecosystem functioning through their omnivorous role in aquatic food webs. As predicted from Jensen's inequality, considering only the mean body size of crayfish overestimated aggregate effects on ecosystem functioning. This bias declined with mean body size such that mean‐field and variance‐incorporating estimates of ecosystem functioning were similar for samples at mean body sizes >7.5 g. At low mean body size, mean‐field bias in ecosystem functioning mismatch predictions from Jensen's inequality, likely because of the increasing skewness of the size distribution. Our findings support the prediction that variance around the mean can alter the relationship between body size and ecosystem functioning, especially at low mean body size. However, methods to account for mean‐field bias performed poorly in samples with highly skewed distributions, indicating that changes in the shape of the distribution, in addition to the variance, may confound mean‐based estimates of ecosystem functioning. Given that many biological functions scale allometrically, explicitly defining and experimentally or statistically isolating the effects of the mean, variance, and shape of size distributions is necessary to begin generalizing relationships between animal body size and ecosystem functioning.

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Ecosystem ecology: size-based constraints on the pyramids of life

Cited by 308 publications

References 67 publications

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

The paradox of inverted biomass pyramids in kelp forest fish communities

Disentangling the influences of mean body size and size structure on ecosystem functioning: an example of nutrient recycling by a non‐native crayfish

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