Measuring Individual-Level Resource Specialization

Bolnick, Daniel I.; Yang, Louie H.; Fordyce, James A.; Davis, Jeremy M.; Svanbäck, Richard

doi:10.1890/0012-9658(2002)083[2936:milrs]2.0.co;2

Cited by 536 publications

(210 citation statements)

References 29 publications

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“…rspb.royalsocietypublishing.org Proc R Soc B 280: 20131481 (a) Estimating isotopic niche width Stable isotope ratios from tooth or bone can provide a relative measure of the long-term average consumption of different prey resources and variance in these isotopic ratios among individuals can be a useful proxy of the population's niche width [33,34]. We only included bone collagen and tooth dentin from animals estimated, based on size to be older than the post-weaning age of 4 years [35] and avoided sampling the enamel crown and outer dentin growth layers deposited during nursing.…”

Section: Methodsmentioning

confidence: 99%

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Foote

Newton²,

Ávila-Arcos

et al. 2013

Proc. R. Soc. B.

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Niche variation owing to individual differences in ecology has been hypothesized to be an early stage of sympatric speciation. Yet to date, no study has tracked niche width over more than a few generations. In this study, we show the presence of isotopic niche variation over millennial timescales and investigate the evolutionary outcomes. Isotopic ratios were measured from tissue samples of sympatric killer whale Orcinus orca lineages from the North Sea, spanning over 10 000 years. Isotopic ratios spanned a range similar to the difference in isotopic values of two known prey items, herring Clupea harengus and harbour seal Phoca vitulina. Two proxies of the stage of speciation, lineage sorting of mitogenomes and genotypic clustering, were both weak to intermediate indicating that speciation has made little progress. Thus, our study confirms that even with the necessary ecological conditions, i.e. among-individual variation in ecology, it is difficult for sympatric speciation to progress in the face of gene flow. In contrast to some theoretical models, our empirical results suggest that sympatric speciation driven by among-individual differences in ecological niche is a slow process and may not reach completion. We argue that sympatric speciation is constrained in this system owing to the plastic nature of the behavioural traits under selection when hunting either mammals or fish.

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Section: Methodsmentioning

confidence: 99%

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Foote

Newton²,

Ávila-Arcos

et al. 2013

Proc. R. Soc. B.

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“…This has been aided by novel approaches to the partitioning of variation in empirical studies [45]. Incorporating individual variability in body size of animals into food web models has already been discussed above.…”

Section: Linking Individuals To Food Webs To Ecosystem Functionmentioning

confidence: 99%

Food webs: reconciling the structure and function of biodiversity

Thompson

Brose

Dunne

et al. 2012

Trends in Ecology & Evolution

575

500

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The global biodiversity crisis concerns not only unprecedented loss of species within communities, but also related consequences for ecosystem function. Community ecology focuses on patterns of species richness and community composition, whereas ecosystem ecology focuses on fluxes of energy and materials. Food webs provide a quantitative framework to combine these approaches and unify the study of biodiversity and ecosystem function. We summarise the progression of foodweb ecology and the challenges in using the food-web approach. We identify five areas of research where these advances can continue, and be applied to global challenges. Finally, we describe what data are needed in the next generation of food-web studies to reconcile the structure and function of biodiversity.Reconciling the study of biodiversity and ecosystem function We are experiencing two interrelated global ecological crises. One is in biodiversity, with unprecedented rates of species loss across all major ecosystems, combined with greatly accelerated biotic exchange between landmasses [1]. Consequently, spatial and temporal patterns of species occurrence are being fundamentally altered by extinction and invasion. The second crisis concerns the regulation of ecological processes and the ecosystem services they provide. Processes such as primary production and nutrient cycling have been severely altered by human activities [1].Our understanding of biodiversity comes largely from a sound theoretical and empirical basis provided by community ecology, including core concepts such as niche segregation [2] and Island Biogeography [3,4]. Early studies of individual species' habitat preferences and physiological tolerances have been complemented by studies of interspecific interactions from field surveys and experiments. Applications such as conservation management depend largely on mapping of community patterns and studies of habitat occupancy and preferences. More recently, habitat models have been applied, and the advent of simple and cheap molecular markers has allowed quantification of important community assembly (see Glossary) processes such as dispersal [5]. In community ecology the unit of study is the individual, population, or species, consistent with other sub-disciplines such as behavioural and population biology. Review GlossaryAssembly: the set of processes by which a food web is rebuilt after disturbance or the creation of new habitat. Bioenergetics: the flow and transformation of energy in and between living organisms and between living organisms and their environment. Cascade model: a food-web model which assumes hierarchical feeding along a single niche axis, with each species allocated a probability of feeding on taxa below it in the hierarchy. Community web: a food web intended to include all species and trophic links that occur within a defined ecological community. 'Species' in this sense might involve various degrees of aggregation or division of biological species. Compartmentalisation: the property by which one subset of sp...

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“…Population diet breadth was determined for each year using the Shannon-Wiener index (H; Levins, 1968), which is maximized when the population uses more prey more evenly (Colwell and Futuyama, 1971). Likewise, the degree of individual diet specialization was determined using the index of individual specialization (IS; Bolnick et al, 2002), which declines towards zero when individuals use smaller subsets of the population diet and equals 1 when all individuals consume the full set of population diet. Estimates for both indices were obtained using bootstrapped 95% confidence intervals (1000 permutations).…”

mentioning

confidence: 99%

Long term patterns in the late summer trophic niche of the invasive pumpkinseed sunfishLepomis gibbosus

Gkenas

Magalhães

Domingos

et al. 2016

Knowl. Manag. Aquat. Ecosyst.

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-Quantifying the trophic dynamics of invasive species in novel habitats is important for predicting the success of potential invaders and evaluating their ecological effects. The North American pumpkinseed sunfish Lepomis gibbosus is a successful invader in Europe, where it has caused negative ecological effects primarily through trophic interactions. Here, we quantified variations in the late summer trophic niche of pumpkinseed during establishment and integration in the mainstem of the Guadiana river, using stomach content analyses over a period of 40 years. Pumpkinseed showed a shift from trophic specialization during establishment to trophic generalism during integration. These results were concomitant with an increase in diet breadth that was accompanied by higher individual diet specialization particularly in large individuals. Irrespective of their drivers, these changes in trophic niche suggest that the potential ecological effects of pumpkinseed on recipient ecosystems can vary temporally along the invasion process.Key-words: invasive species / trophic niche / diet shift / diet breadth / individual diet specialization Résumé -Tendances à long terme de la niche trophique estivale de la perche soleil Lepomis gibbosus invasive. La quantification de la dynamique trophique des espèces envahissantes dans leur aire d'introduction est importante pour prédire leur succès d'invasion et évaluer leurs potentiels effets écologiques. La perche soleil − Lepomis gibbosus − est une espèce originaire d'Amérique du Nord qui a été largement introduite en Europe où elle induit des effets écologiques négatifs principalement par des interactions trophiques. Dans cette étude, nous avons quantifié les variations de niche trophique de la perche soleil en fin d'été pendant les phases d'établissement et d'intégration dans le cours principal de la rivière Guadiana (Portugal) en comparant des contenus stomacaux sur une période de 40 ans. Nos résultats ont permis de démontrer que la perche soleil a modifié son régime alimentaire durant cette période en passant d'un régime spécialiste pendant la phase d'établissement à un régime généraliste pendant la phase d'intégration. En parallèle, nous avons également observé une augmentation de la taille de la niche trophique de la population qui était accompagnée d'une augmentation de la spécialisation trophique individuelle, notamment chez les individus les plus grands. Indépendamment des causes induisant ces changements de niche trophique, nos résultats suggèrent donc que les effets écologiques potentiels de la perche soleil sur les écosystèmes aquatiques peuvent varier pendant le processus d'invasion biologique.Mots-clés : espèce envahissante / niche trophique / régime alimentaire / spécialisation trophique individuelle

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Measuring Individual-Level Resource Specialization

Cited by 536 publications

References 29 publications

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Tracking niche variation over millennial timescales in sympatric killer whale lineages

Food webs: reconciling the structure and function of biodiversity

Long term patterns in the late summer trophic niche of the invasive pumpkinseed sunfishLepomis gibbosus

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