Beyond species: why ecological interaction networks vary through space and time

Poisot, Timothée; Stouffer, Daniel B.; Gravel, Dominique

doi:10.1101/001677

Cited by 92 publications

(156 citation statements)

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“…However, most populations are heterogeneous mixtures of individuals that vary in their phenotypes, and there is growing evidence that this intraspecific variation is an important factor governing the assembly of ecological communities (4)(5)(6). Consequently, there is a clear need to account for the role of intraspecific variation in structuring ecological networks (7).…”

mentioning

confidence: 99%

Genetic specificity of a plant–insect food web: Implications for linking genetic variation to network complexity

Barbour

Fortuna

Bascompte

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Theory predicts that intraspecific genetic variation can increase the complexity of an ecological network. To date, however, we are lacking empirical knowledge of the extent to which genetic variation determines the assembly of ecological networks, as well as how the gain or loss of genetic variation will affect network structure. To address this knowledge gap, we used a common garden experiment to quantify the extent to which heritable trait variation in a host plant determines the assembly of its associated insect food web (network of trophic interactions). We then used a resampling procedure to simulate the additive effects of genetic variation on overall food-web complexity. We found that trait variation among host-plant genotypes was associated with resistance to insect herbivores, which indirectly affected interactions between herbivores and their insect parasitoids. Direct and indirect genetic effects resulted in distinct compositions of trophic interactions associated with each host-plant genotype. Moreover, our simulations suggest that food-web complexity would increase by 20% over the range of genetic variation in the experimental population of host plants. Taken together, our results indicate that intraspecific genetic variation can play a key role in structuring ecological networks, which may in turn affect network persistence.species interactions | ecological networks | evolutionary ecology | community genetics N etwork theory has provided both a conceptual and a quantitative approach for mapping interactions between species and making predictions about how the gain or loss of species will affect the structure and dynamics of ecological networks (1-3). Representing a network at the species level, however, makes the implicit assumption that each species consists of a homogenous population of individuals, all of which interact equally with individuals of different species. However, most populations are heterogeneous mixtures of individuals that vary in their phenotypes, and there is growing evidence that this intraspecific variation is an important factor governing the assembly of ecological communities (4-6). Consequently, there is a clear need to account for the role of intraspecific variation in structuring ecological networks (7).Genetic variation is a key driver of intraspecific variation and many studies have now demonstrated direct and indirect genetic effects on species interactions (8-10) and the composition of communities across multiple trophic levels (11)(12)(13)(14). This prior work forms a clear expectation that intraspecific genetic variation is capable of scaling up to affect the structure of an ecological network. In particular, we expect that network structure will be affected by genetic variation through at least two different mechanisms. For a food web (network of trophic interactions), genetic variation in the quality of a basal resource may alter the (i) abundances or (ii) phenotypes of consumer species or both (15). These direct genetic effects on consumers may then have cascadi...

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mentioning

confidence: 99%

Genetic specificity of a plant–insect food web: Implications for linking genetic variation to network complexity

Barbour

Fortuna

Bascompte

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…optimal temperature, habitat requirements), as they are not directly involved in the trophic interactions and food web dynamics. They should nonetheless be kept in mind, as they influence the co-distribution of predators and preys over environmental gradients and consequently the occurrence of an interaction [50], they could condition interaction rates [51], as well as temporal dynamics. We also ignored trait-mediated interactions, which are well known to impact community dynamics and ecosystem functioning [52].…”

Section: Classifying Traits In Food Websmentioning

confidence: 99%

“…We also ignored trait-mediated interactions, which are well known to impact community dynamics and ecosystem functioning [52]. Some interactions impact the expression of species traits, and indirectly affect other interactions [51]. Trait-mediated interactions are susceptible to affect all three categories of traits we described here.…”

Section: Classifying Traits In Food Websmentioning

confidence: 99%

“…Abundance and prevalence consequently have a fundamental importance to food web structure [51]. Neutral models of trophic structure are exclusively based on the law of mass action; they propose that the frequency of an interaction happening and the strength of that interaction should be proportional to the product of abundances between pairs of species [88].…”

Section: Relating Trait Structure To Network Topologymentioning

confidence: 99%

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The meaning of functional trait composition of food webs for ecosystem functioning

Gravel

Albouy

Thuiller

2016

Phil. Trans. R. Soc. B

Self Cite

145

160

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One contribution of 17 to a theme issue 'Biodiversity and ecosystem functioning in dynamic landscapes'. There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the everincreasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and topdown control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with welldefined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists.

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“…On the other hand, theoretical works for different interaction types lack multiple tasks in the single interaction strategy (Kopp & Gavrilets, 2006), or lack mechanistic perspective (Eklöf et al, 2013;Bastazini et al, 2017;Ovaskainen et al, 2017). To our knowledge, only two frameworks for the occurrence of interactions appear able to incorporate all four features, although they lack an explicit reference to alternative interaction strategies (Poisot et al, 2015;Bartomeus et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Incorporating trait-based mechanisms, alternative interaction modes and forbidden links increases the minimum trait dimensionality of ecological networks

Boddy

Eastwood

et al. 2017

Preprint

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Trait-based approaches in direct intraspecific and interspecific interactions address proximate and evolutionary questions across biological systems. However, interest in particular questions or systems has led to specialised descriptions of how interactions occur. We propose a generalised description in which interactions can be: defined by goals (e.g. consumption, parasitism, pollination); charted systematically (with logic statements); and explained by performance inequalities (comparing traits of individuals). Consequently, goal failures ('forbidden links') are interaction outcomes; alternative strategies to goal success exist; and matching traits are reformulated as difference traits. To illustrate, we introduce a new network measure: minimum mechanistic dimensionality, the minimum number of traits for the mechanistic explanation of the outcomes. Our dimensionality offers alternative explanations for intransitive networks. We show that previous approaches underestimate the dimensionality of 658 published empirical ecological networks (animal dominance, food webs, pollination, parasitism, seed dispersal) by omitting concepts emerging from the framework (mechanistic perspective, trait-mediated goal failures, generalisation to alternative interaction strategies). Such underestimation can prevent models from generating networks at the interaction outcome level. The framework provides a common mechanistic basis for proximate and evolutionary questions, inspiring hypotheses and trait-based models of social network dynamics, antagonistic or mutualistic community assembly or invasion, and coevolution.

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Beyond species: why ecological interaction networks vary through space and time

Cited by 92 publications

References 97 publications

Genetic specificity of a plant–insect food web: Implications for linking genetic variation to network complexity

Genetic specificity of a plant–insect food web: Implications for linking genetic variation to network complexity

The meaning of functional trait composition of food webs for ecosystem functioning

Incorporating trait-based mechanisms, alternative interaction modes and forbidden links increases the minimum trait dimensionality of ecological networks

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