Investigating isotopic functional indices to reveal changes in the structure and functioning of benthic communities

Rigolet, Carinne; Thiébaut, Éric; Brind’Amour, Anik; Dubois, Stanislas F.

doi:10.1111/1365-2435.12444

Cited by 57 publications

(62 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A number of metrics originally developed by functional ecologists to quantify trait functional diversity have been repurposed and applied in stable isotope ecology research (Rigolet et al, 2015;Comte et al, 2016). Like traditional traits, isotopic traits can be fit with a convex hull, the size of which has been extensively used as a proxy of the size of the trophic niche occupied by a group of individuals (Layman et al, 2007(Layman et al, , 2012Cucherousset and Villéger, 2015).…”

Section: Introductionmentioning

confidence: 99%

The Multidimensional Stoichiometric Niche

et al. 2017

View full text Add to dashboard Cite

The niche concept is essential to understanding how biotic and abiotic factors regulate the abundance and distribution of living entities, and how these organisms utilize, affect and compete for resources in the environment. However, it has been challenging to determine the number and types of important niche dimensions. By contrast, there is strong mechanistic theory and empirical evidence showing that the elemental composition of living organisms shapes ecological systems, from organismal physiology to food web structure. We propose an approach based on a multidimensional elemental view of the ecological niche. Visualizing the stoichiometric composition of individuals in multivariate space permits quantification of niche dimensions within and across species. This approach expands on previous elemental characterizations of plant niches, and adapts metrics of niche volume, overlap and nestedness previously used to quantify isotopic niches. We demonstrate the applicability of the multidimensional stoichiometric niche using data on carbon, nitrogen, and phosphorus of terrestrial and freshwater communities composed by multiple trophic groups. First, we calculated the stoichiometric niche volumes occupied by terrestrial and freshwater food webs, by trophic groups, by individual species, and by individuals within species, which together give a measure of the extent of stoichiometric diversity within and across levels of organization. Then we evaluated complementarity between these stoichiometric niches, through metrics of overlap and nestedness. Our case study showed that vertebrates, invertebrates, and primary producers do not overlap in their stoichiometric niches, and that large areas of stoichiometric space are unoccupied by organisms. Within invertebrates, niche differences emerged between freshwater and terrestrial food webs, and between herbivores and non-herbivores (detritivores and predators). These niche differences were accompanied by changes in the covariance structure of the three elements, suggesting fundamental shifts in organismal physiology and/or structure. We also demonstrate the sensitivity of results to sample size, and suggest that representative sampling is better than rarefaction in characterizing the stoichiometric niche occupied by food webs. Overall, our approach demonstrates that stoichiometric traits provide a common currency to estimate the dimensionality of stoichiometric niches, and help reduce and rationalize the number of axis required to characterize communities.

show abstract

Section: Introductionmentioning

confidence: 99%

The Multidimensional Stoichiometric Niche

et al. 2017

View full text Add to dashboard Cite

show abstract

“…; Rigolet et al . ). Building upon metrics designed to quantify the functional diversity of community (i.e.…”

Section: Introductionmentioning

confidence: 97%

“…), other more refined isotopic functional indices have since been applied to communities of freshwater fishes (Cucherousset & Villéger ) or marine invertebrates (Rigolet et al . ).…”

Section: Introductionmentioning

confidence: 97%

“…Then, many empirical studies have tried to grasp changes in community trophic structure based on community isotopic metrics, such as in African estuaries following the wet season (Abrantes, Barnett & Bouillon ), in coastal marine benthic habitats after colonization by an engineer species (Rigolet et al . ), in littoral fish communities following species invasions (Fanelli et al . ) or in several human‐created salt‐marches over a long‐term period (Nordstrom et al .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Are food web structures well represented in isotopic spaces?

et al. 2017

View full text Add to dashboard Cite

Summary Isotopic analyses are increasingly used to assess the structure of food webs and a series of isotopic functional indices have been proposed in the last decade to characterize this structure. These indices are based on the foundational assumption that proximity in the isotopic space informs on trophic similarity between species. While it has been recognized for long that this simplifying assumption should be used with caution, no formal evaluation of its domain of validity has been performed to date. We here simulate a large number (15 000) of food webs with varying characteristics to assess (i) whether isotopic distance is a good proxy of trophic dissimilarity; (ii) whether isotopic functional indices are good proxies of trophic functional properties; and (iii) how the quality of these two proxies depend on various species and food web properties. We first demonstrate that isotopic distance is moderately correlated with trophic similarity in simulated food webs. We find, however, that two isotopic community metrics investigated (Rao's index of functional divergence and nearest neighbour distance index of functional originality) are good indicators of community trophic structure, especially in food webs with large connectance, and when predators have low levels of diet specialization. We also find that isotopic functional indices are decreasingly reliable as they aim at characterizing more subtle functional patterns (such as standard deviation of nearest neighbour distance, an index of between species variation in originality). Taken together, our results suggest that the reliability of the isotopic mapping of consumers decreases with their number of potential prey species, but increases with their number of realized prey species. Consequently, isotopic reliability decreases in species‐rich food webs with low connectance, large vertical diversity and large incidence of omnivory. Our study highlights that researchers should not hope to grasp subtle patterns of food web structure based solely on widely used isotopic indices. They should instead envisage mobilizing such isotopic information in combination with complementary data types. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12895/suppinfo is available for this article.

show abstract

“…Trophic interactions within food webs (e.g., basal sources of energy, assimilated diet) can often be efficiently inferred by biochemical traits of species such as their carbon and nitrogen isotopic composition (Layman, Arrington, Montana, & Post, ; Newsome, del Rio, Bearhop, & Phillips, ; Rigolet, Thiébaut, Brind’Amour, & Dubois, ). Hence, the isotopic space, occupied by various members of a food web in a δ 15 N–δ 13 C biplot (i.e., isotopic niche), is a relevant descriptor of the total resource use of that community (Newsome et al., ).…”

Section: Introductionmentioning

confidence: 99%

Functional traits and environmental conditions predict community isotopic niches and energy pathways across spatial scales

et al. 2018

View full text Add to dashboard Cite

Despite ongoing research in food web ecology and functional biogeography, the links between food web structure, functional traits and environmental conditions across spatial scales remain poorly understood. Trophic niches, defined as the amount of energy and elemental space occupied by species and food webs, may help bridge this divide. Here, we ask how the functional traits of species, the environmental conditions of habitats and the spatial scale of analysis jointly determine the characteristics of trophic niches. We used isotopic niches as a proxy of trophic niches, and conducted analyses at spatial scales ranging from local food webs and metacommunities to geographically distant sites. We sampled aquatic macroinvertebrates from 104 tank bromeliads distributed across five sites from Central to South America and compiled the macroinvertebrates’ functional traits and stable isotope values (δ15N and δ13C). We assessed how isotopic niches within each bromeliad were influenced by the functional trait composition of their associated invertebrates and environmental conditions (i.e., habitat size, canopy cover [CC] and detrital concentration [DC]). We then evaluated whether the diet of dominant predators and, consequently, energy pathways within food webs reflected functional and environmental changes among bromeliads across sites. At last, we determined the extent to which the isotopic niches of macroinvertebrates within each bromeliad contributed to the metacommunity isotopic niches within each site and compared these metacommunity‐level niches over biogeographic scales. At the bromeliad level, isotopic niches increased with the functional richness of species in the food web and the DC in the bromeliad. The diet of top predators tracked shifts in prey biomass along gradients of CC and DC. Bromeliads that grew under heterogeneous CC displayed less trophic redundancy and therefore combined to form larger metacommunity isotopic niches. At last, the size of metacommunity niches depended on within‐site heterogeneity in CC. Our results suggest that the trophic niches occupied by food webs can predictably scale from local food webs to metacommunities to biogeographic regions. This scaling process is determined by both the functional traits of species and heterogeneity in environmental conditions. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13142/suppinfo is available for this article.

show abstract

Investigating isotopic functional indices to reveal changes in the structure and functioning of benthic communities

Cited by 57 publications

References 49 publications

The Multidimensional Stoichiometric Niche

The Multidimensional Stoichiometric Niche

Are food web structures well represented in isotopic spaces?

Functional traits and environmental conditions predict community isotopic niches and energy pathways across spatial scales

Contact Info

Product

Resources

About