Diet composition and foraging success in generalist predators: Are specialist individuals better foragers?

Terraube, Julien; Guixé, David; Arroyo, Beatriz

doi:10.1016/j.baae.2014.08.008

Cited by 39 publications

(30 citation statements)

References 37 publications

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“…Furthermore, the observed seasonal change could also be related to a seasonal variation in the activity of S. strinatii, in terms of time spent foraging, driven by climatic conditions. In fact, there is some evidence that the most specialized individuals are also more efficient in terms of hunting success (Terraube et al 2014).…”

Section: Discussionmentioning

confidence: 99%

Trophic specialization at the individual level in a terrestrial generalist salamander

et al. 2015

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Information on individual trophic specialization may be relevant to better understand the ecological adaptation of populations to their environment and the evolution of their realized trophic niche. In this study, we analysed the trophic specialization at the individual level in a population of the plethodontid Northwest Italian Cave Salamander (Speleomantes strinatii (Aellen, 1958)), a terrestrial generalist predator. Salamanders were sampled in northwestern Italy on the forest floor in autumn (n = 49) and spring (n = 47) along with their available prey. In autumn, when trophic resources showed a twofold reduction in abundance, the population trophic niche width (TNW = 2.58) was significantly broader than during spring (TNW = 2.25), and in both seasons, individual specialization (IS) was significantly higher than expected by chance (P = 0.001). There were no sexual or ontogenetic differences in IS within each season, but IS in autumn was significantly higher than in spring (IS = 0.34 and IS = 0.41, respectively; P = 0.01). These findings are in accordance with the niche variation hypothesis, which predicts a positive relationship between TNW and IS. Therefore, while the population became more generalist, individual salamanders shifted towards a more specialized diet by adapting their feeding behaviour to changes in prey availability.Résumé : La connaissance de la spécialisation trophique à niveaux individuelle peut permettre de mieux comprendre l'adaptation des populations à leur milieux et l'évolution de leur niche trophique réalisée. Dans cette étude, nous avons analysé la spécialisation trophique individuelle dans une population de la salamandre terrestre Speleomantes strinatii (Aellen, 1958), qui est un prédateur generaliste. Nous avons échantillonnées les salamandres, au même temps que leur disponibilité en proies, en un milieu forestier de l'Italie du nord-ouest, au cours de l'automne (n = 49) et du printemps (n = 47). En automne, quand la disponibilité en proies est réduite, l'ampleur de niche trophique de la population est majeure (TNW = 2,58) qu'au printemps (TNW = 2,25). Toutefois, dans les deux saisons, la spécialisation individuelle (IS) est significativement majeur de celle attendue par chance (P = 0,001). Il n'y a pas des différences de spécialisation trophique individuelle à niveau du sexe ou d'age entre saison, mais en automne l'IS est majeur qu'au printemps (respectivement IS = 0,34 et IS = 0,41, P = 0,01). Ces résultats sont en accord avec l'hypothèse de la variation de niche, la quelle prédit une relation positive entre TNW et spécialisation à niveau individuel. Dans notre cas, lorsque la population entière devienne plus generaliste, les individus assument une diète plus spécialisée en s'adaptant aux changement des proies disponibles.Mots-clés : Spélerpès de Strinati, écologie trophique, spécialisation individuelle, Speleomantes strinatii, comportement trophique, variation de la niche trophique.

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Section: Discussionmentioning

confidence: 99%

Trophic specialization at the individual level in a terrestrial generalist salamander

et al. 2015

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“…Across all herbivorous insects, it is estimated that less than 10% feed on plants in more than three different plant families (Bernays & Graham, 1988). Moreover, controlling for body mass, specialist feeders have larger home ranges than generalists as their food sources are less abundant and hence require larger foraging areas (Terraube, Guixé & Arroyo, 2014).…”

Section: (4) Imbalance Between Generalist and Specialist Insect Populmentioning

confidence: 99%

How do herbivorous insects respond to drought stress in trees?

2019

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Increased frequency and severity of drought, as a result of climate change, is expected to drive critical changes in plant–insect interactions that may elevate rates of tree mortality. The mechanisms that link water stress in plants to insect performance are not well understood. Here, we build on previous reviews and develop a framework that incorporates the severity and longevity of drought and captures the plant physiological adjustments that follow moderate and severe drought. Using this framework, we investigate in greater depth how insect performance responds to increasing drought severity for: (i) different feeding guilds; (ii) flush feeders and senescence feeders; (iii) specialist and generalist insect herbivores; and (iv) temperate versus tropical forest communities. We outline how intermittent and moderate drought can result in increases of carbon‐based and nitrogen‐based chemical defences, whereas long and severe drought events can result in decreases in plant secondary defence compounds. We predict that different herbivore feeding guilds will show different but predictable responses to drought events, with most feeding guilds being negatively affected by water stress, with the exception of wood borers and bark beetles during severe drought and sap‐sucking insects and leaf miners during moderate and intermittent drought. Time of feeding and host specificity are important considerations. Some insects, regardless of feeding guild, prefer to feed on younger tissues from leaf flush, whereas others are adapted to feed on senescing tissues of severely stressed trees. We argue that moderate water stress could benefit specialist insect herbivores, while generalists might prefer severe drought conditions. Current evidence suggests that insect outbreaks are shorter and more spatially restricted in tropical than in temperate forests. We suggest that future research on the impact of drought on insect communities should include (i) assessing how drought‐induced changes in various plant traits, such as secondary compound concentrations and leaf water potential, affect herbivores; (ii) food web implications for other insects and those that feed on them; and (iii) interactions between the effects on insects of increasing drought and other forms of environmental change including rising temperatures and CO2 levels. There is a need for larger, temperate and tropical forest‐scale drought experiments to look at herbivorous insect responses and their role in tree death.

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“…Finally, even considering that we focused on three different aspects of the ecology of cuckoos (parasitism, breeding distribution range, and body mass), aspects which can play a role in the foraging strategy of species, we prefer to be cautious about any interpretation linking these aspects as a causal association. Many other factors or variables were not explored in this study, and they could be significantly conditioning the level of diet specialization of birds, even much more than the three aspects that were the object of the present study (Garvey & Whiles, 2019; Terraube, Guixé, & Arroyo, 2014). Thus, we have preferred to follow a descriptive approach rather than trying to explain any causal relationship between diet specialization and brood parasitism of cuckoos.…”

Section: Discussionmentioning

confidence: 99%

“…Another potential drawback of the index used in this study could be related to the fact that the degree of diet specialization can change even within species. In some cases, species considered overall generalists could be characterized as strongly specialist individuals (Terraube et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Diet specialization and brood parasitism in cuckoo species

Morelli

Benedetti

Møller

2020

Ecology and Evolution

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Brood parasitism is a breeding strategy adopted by many species of cuckoos across the world. This breeding strategy influences the evolution of life histories of brood parasite species. In this study, we tested whether the degree on diet specialization is related to the breeding strategy in cuckoo species, by comparing brood parasite and nonparasite species. We measured the gradient of diet specialization of cuckoos, by calculating the Gini coefficient, an index of inequality, on the multiple traits describing the diet of species. The Gini coefficient is a measure of statistical dispersion on a scale between 0 and 1, reflecting a gradient from low to high specialization, respectively. First, we tested the strength of the phylogenetic signal of diet specialization index among cuckoo species worldwide. Then, we ran phylogenetic generalized least square (PGLS) models to compare diet specialization, distribution range, and body mass of parasitic and nonparasitic cuckoo species, considering the phylogenetic signal of data. After adjusting for the phylogenetic signal of the data and considering both, species distribution range and species body mass, brood parasitic cuckoos were characterized by higher diet specialization than nonbrood parasitic species. Brood parasitic species were also characterized by a larger breeding distribution range than nonparasitic species. The findings of this study provide an additional understanding of the cuckoos’ ecology, relating diet and breeding strategies, information that could be important in conservation ecology.

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Diet composition and foraging success in generalist predators: Are specialist individuals better foragers?

Cited by 39 publications

References 37 publications

Trophic specialization at the individual level in a terrestrial generalist salamander

Trophic specialization at the individual level in a terrestrial generalist salamander

How do herbivorous insects respond to drought stress in trees?

Diet specialization and brood parasitism in cuckoo species

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