Secondary extinctions in ecological networks: Bottlenecks unveiled

Allesina, Stefano; Bodini, Antonio; Bondavalli, Cristina

doi:10.1016/j.ecolmodel.2005.10.016

Cited by 64 publications

(55 citation statements)

References 18 publications

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“…If y goes extinct, so does x: y is a bottleneck in energy delivery from the producers to x. Single-node dominators have been extensively used in computer science (Alstrup et al 1999) and have been recently introduced in ecology (Allesina & Bodini 2004;Allesina et al 2006). This concept can be extended to detect sets of nodes that collectively dominate a given node.…”

Section: Methodsmentioning

confidence: 99%

“…The relationship between network structure and robustness has been recently addressed by research on scale-free networks in which hubs hold the majority of connections and their removal causes major disruption (Albert et al 2000;Newman 2003). The same approach has been applied to the extinction of species in food webs (Dunne et al 2002(Dunne et al , 2004Montoya & Sole 2002;Allesina & Bodini 2004;Ebenman & Jonsson 2005;Allesina et al 2006;Montoya et al 2006) and other ecological networks (Memmott et al 2004), emphasizing the role of the most connected species. Many studies (Dunne et al 2002(Dunne et al , 2004Montoya & Sole 2002) have concentrated on hubs, implicitly assuming that these are the critical players in maintaining network structure (keystone species, Power et al 1996;Raffaelli 2004;Zavaleta & Hulvey 2004;Christianou & Ebenman 2005), and therefore, robustness.…”

Section: Introductionmentioning

confidence: 99%

“…All previous studies (Dunne et al 2002(Dunne et al , 2004Montoya & Sole 2002;Allesina & Bodini 2004;Allesina et al 2006;Montoya et al 2006;Srinivasan et al 2007) share a common approach: they consider how the loss of species cascades into the further loss of biodiversity. The importance of the species is predicted on the basis of their topological properties, especially their number of connections.…”

Section: Introductionmentioning

confidence: 99%

“…For example, we could examine weighted food webs, in which flows of energy between species are quantified, and consider that a predator that has lost most of its prey could go extinct when the remaining prey provide an insufficient flow of energy (e.g. Allesina et al 2006). However, even in this case, a predator with no prey will go extinct.…”

Section: Introductionmentioning

confidence: 99%

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Functional links and robustness in food webs

Allesina

Bodini

Pascual

2009

Phil. Trans. R. Soc. B

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The robustness of ecosystems to species losses is a central question in ecology, given the current pace of extinctions and the many species threatened by human impacts, including habitat destruction and climate change. Robustness from the perspective of secondary extinctions has been addressed in the context of food webs to consider the complex network of species interactions that underlie responses to perturbations. In-silico removal experiments have examined the structural properties of food webs that enhance or hamper the robustness of ecosystems to species losses, with a focus on the role of hubs, the most connected species. Here we take a different approach and focus on the role of the connections themselves. We show that trophic links can be divided into functional and redundant based on their contribution to robustness. The analysis of empirical webs shows that hubs are not necessarily the most important species as they may hold many redundant links. Furthermore, the fraction of functional connections is high and constant across systems regardless of size and interconnectedness. The main consequence of this scaling pattern is that ecosystem robustness can be considerably reduced by species extinctions even when these do not result in any secondary extinctions. This introduces the possibility of tipping points in the collapse of ecosystems.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Functional links and robustness in food webs

Allesina

Bodini

Pascual

2009

Phil. Trans. R. Soc. B

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“…These applications consider directed graphs, and the application of 'net status' was the first case when species were ranked according to their quantified importance (as early as in 1961). A related approach is to quantify dominator trees in binary (Allesina & Bodini 2004), and weighted (Allesina et al 2006), directed food webs, providing information on the structurally most important nodes.…”

Section: Quantifying Positional Importance (A) the Network Perspectivementioning

confidence: 99%

Keystone species and food webs

Jordán

2009

Phil. Trans. R. Soc. B

219

194

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Different species are of different importance in maintaining ecosystem functions in natural communities. Quantitative approaches are needed to identify unusually important or influential, 'keystone' species particularly for conservation purposes. Since the importance of some species may largely be the consequence of their rich interaction structure, one possible quantitative approach to identify the most influential species is to study their position in the network of interspecific interactions. In this paper, I discuss the role of network analysis (and centrality indices in particular) in this process and present a new and simple approach to characterizing the interaction structures of each species in a complex network. Understanding the linkage between structure and dynamics is a condition to test the results of topological studies, I briefly overview our current knowledge on this issue. The study of key nodes in networks has become an increasingly general interest in several disciplines: I will discuss some parallels. Finally, I will argue that conservation biology needs to devote more attention to identify and conserve keystone species and relatively less attention to rarity.

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Multitrophic diversity effects of network degradation

Nichols

Peres

Hawes

et al. 2016

Ecology and Evolution

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Predicting the functional consequences of biodiversity loss in realistic, multitrophic communities remains a challenge. No existing biodiversity–ecosystem function study to date has simultaneously incorporated information on species traits, network topology, and extinction across multiple trophic levels, while all three factors are independently understood as critical drivers of post‐extinction network structure and function. We fill this gap by comparing the functional consequences of simulated species loss both within (monotrophic) and across (bitrophic) trophic levels, in an ecological interaction network estimated from spatially explicit field data on tropical fecal detritus producer and consumers (mammals and dung beetles). We simulated trait‐ordered beetle and mammal extinction separately (monotrophic extinction) and the coextinction of beetles following mammal loss (bitrophic extinction), according to network structure. We also compared the diversity effects of bitrophic extinction models using a standard monotrophic function (the daily production or consumption of fecal detritus) and a unique bitrophic functional metric (the proportion of daily detritus production that is consumed). We found similar mono‐ and bitrophic diversity effects, regardless of which species traits were used to drive extinctions, yet divergent predictions when different measures of function were used. The inclusion of information on network structure had little apparent effect on the qualitative relationship between diversity and function. These results contribute to our growing understanding of the functional consequences of biodiversity from real systems and underscore the importance of species traits and realistic functional metrics to assessments of the ecosystem impacts of network degradation through species loss.

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Secondary extinctions in ecological networks: Bottlenecks unveiled

Cited by 64 publications

References 18 publications

Functional links and robustness in food webs

Functional links and robustness in food webs

Keystone species and food webs

Multitrophic diversity effects of network degradation

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