Keystone Species

Mello, Marco A. R.

doi:10.1093/obo/9780199830060-0213

Cited by 3 publications

(2 citation statements)

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“…We used a set of centrality metrics to assess the relative importance of each species to the chorus structure. This approach is commonly used in ecological studies to assess the relative importance of species (or keystoneness, Mello, 2019) to the structure of interaction networks (Cirtwill et al., 2018; Mello et al., 2015). Centrality is defined as the relative position of a node (here a species) within a network and the number and distribution of its links (here species co‐signalling) between different regions of the network (Barabasi, 2016).…”

Section: Methodsmentioning

confidence: 99%

Structure and dynamics of mixed‐species choruses in a tropical anuran assemblage: insights from network analysis

et al. 2021

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Males of a wide variety of vertebrates aggregate in mixed‐species choruses to attract females and signal territory occupancy. It is often assumed that species within these choruses co‐signal, interact and compete for the acoustic space, although few studies have tested this assumption, particularly in tropical and highly diverse environments. Using a novel combination of passive acoustics and network analysis, we monitored calling activity of a tropical anuran assemblage for an entire year and examined the structure and dynamics of mixed‐species choruses. Species composition was determined at 1‐min resolution on 288 recording hours and then used to estimate a set of centrality metrics (degree, strength and eigenvector) that characterize the species roles within the acoustic network. The studied assemblage formed a dynamic network comprising eight species during the rainy season and four during the dry season. These species showed distinct roles within the network, ranging from central species (those co‐signalling frequently and with many species) to peripheral species (those barely co‐signalling and with few species). Our results shed light on the species interactions in acoustic communities and challenge the general assumption of an equal contribution of species to the mixed‐species choruses. While in the rainy season the territorial frogs Boana albopunctata and B. faber exhibit the most prominent role within the network (with a higher degree, strength and eigenvector centrality), all of the species calling in the dry season co‐signalled with equal number of species, with only another territorial species, B. lundii, showing a higher rate of co‐signalling events (higher strength and eigenvector centrality). This suggests that territorial behaviour may favour increased calling activity and hence central roles in acoustic networks. These findings contribute to a better understanding of chorus dynamics in tropical assemblages and have crucial implications for the study of species interactions and the evolutionary hypotheses of acoustic divergence.

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Section: Methodsmentioning

confidence: 99%

Structure and dynamics of mixed‐species choruses in a tropical anuran assemblage: insights from network analysis

et al. 2021

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“…The keystone species concept is one of the most successful theoretical frameworks in ecology (Mello, 2019). Since its inception in the mid-20th century (Paine, 1966(Paine, , 1969, it has opened many avenues for research.…”

Section: Introductionmentioning

confidence: 99%

A new centrality index designed for multilayer networks

Lotfi,

Requejo,

Rodrigues

et al. 2023

Methods Ecol Evol

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Since its inception, the keystone species concept has become a central theoretical framework in ecology. Among many approaches, keystones have been operationalized in natural and human environments using centrality metrics applied to monolayer networks. Despite the great success of this approach, as species make several types of interactions, recent studies on keystones moved from monolayer to multilayer networks. To help fulfil the need for a centrality metric designed for multilayer networks, here we introduce Gnorm. We tested the performance of our new metric using in silico data in addition to an empirical data set of frugivory and nectarivory interactions between bats and plants in the Neotropics. A comparison between the results obtained with different random and scale‐free networks demonstrates the performance of our new metric. First, a modularity analysis based on the multilayer version of the Louvain algorithm enables the modules to be composed of nodes from different layers. Second, by setting the coupling parameter () and the resolution parameter (), module identity changes gradually, from single‐ to multiple‐node modules and from mono‐ to multilayer composition. Third, we check the number of modules from different layers to which a node belongs (G) at different levels of and . Finally, by observing how average G decreases with and , it is possible to calculate Gnorm and detect which nodes are most resistant to change in these two parameters. Those resistant nodes are identified as central in the multilayer structure. After applying this new analysis to the bat–plant network, we observed that it identified a different set of potential keystone species compared to previous analyses performed separately for each layer or the aggregated network. In conclusion, our new metric opens a new way of operationalizing the keystone species concept in multilayer networks. It may help identify keystone species involved in different interaction types.

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Searching for keystone plant resources in fruit‐frugivore interaction networks across the Neotropics

et al. 2020

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Identifying keystone plant resources (KPR) is a contentious issue in ecology and conservation. Despite recent advances provided by mutualistic networks, we still lack studies addressing large-scale identification of keystone plants. We developed a novel quantitative framework for the large-scale identification of KPR that combines centrality and effects of simulated removals on networks properties. We built a database with 38 fruit-frugivore networks comprising 6,180 pairwise interactions from Neotropical forest and non-forest ecosystems ranging from sea level to 2,500 m a.s.l.. Effects of random removal simulations and removal of keystone taxa candidates on nestedness, modularity and niche overlap were assessed. Furthermore, we tested whether changes in network descriptors responded to both latitudinal and elevational gradients. From a total of 373 genera on networks, only species in six genera were ranked as keystone candidates. The simulated removal of species in Miconia (Melastomataceae), Cecropia (Urticaceae) and Byrsonima (Malpighiaceae) led to significant changes in nestedness, modularity and niche overlap, suggesting that these plants play important roles in maintaining the structure of Neotropical fruit-frugivore interaction networks, regardless of latitude or elevation. Our results confirm the keystone role of previously recognized taxa, recognize overlooked ones, providing support for their role at a biogeographical scale, and partially challenge taxa traditionally identified as keystone resources for frugivores. Our study has implications for conservation and restoration of Neotropical ecosystems and provides a new framework for large-scale identification of keystones in other types of ecological networks.

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Keystone Species

Cited by 3 publications

References 0 publications

Structure and dynamics of mixed‐species choruses in a tropical anuran assemblage: insights from network analysis

Structure and dynamics of mixed‐species choruses in a tropical anuran assemblage: insights from network analysis

A new centrality index designed for multilayer networks

Searching for keystone plant resources in fruit‐frugivore interaction networks across the Neotropics

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