Between-individual variation drives the seasonal dynamics in the trophic niche of a Neotropical marsupial

Pires, Mathias M.; Martins, Eduardo G.; Araújo, Márcio S.; Reis, Sérgio Furtado dos

doi:10.1111/aec.12011

Cited by 19 publications

(20 citation statements)

References 43 publications

(59 reference statements)

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“…The contrast between our results at the intra-specific level and those of Tinker et al (2008) and Pires et al (2013) on how TNW varies when food availability decreases may be due to (1) differences in how generalist species under study are and (2) the number of food resources available as alternative diet during restricted food periods. In our study, the availability of food resources is particularly low during winter due to snow cover and plant senescence, which may explain why, for example, we obtained opposite results to Tinker et al (2008) and Pires et al (2013). More studies on species with differing ranking on the generalist-specialist gradient over a range of restriction in food availability would be needed to understand the temporal dynamics of TNW.…”

Section: Response Of Inter-individual Variation To Seasonal Variationcontrasting

confidence: 99%

“…During these periods, several mechanisms may reinforce inter-individual variation in diets, such as local intra-specific competition (in mouflon, for instance), but also individual rank preferences (Araújo et al 2011), foraging behavior, physiological requirements, or experience (Bolnick et al 2003). The contrast between our results at the intra-specific level and those of Tinker et al (2008) and Pires et al (2013) on how TNW varies when food availability decreases may be due to (1) differences in how generalist species under study are and (2) the number of food resources available as alternative diet during restricted food periods. In our study, the availability of food resources is particularly low during winter due to snow cover and plant senescence, which may explain why, for example, we obtained opposite results to Tinker et al (2008) and Pires et al (2013).…”

Section: Response Of Inter-individual Variation To Seasonal Variationcontrasting

confidence: 66%

“…Some studies (Tinker et al 2008;Pires et al 2013) showed that a reduction in resource diversity led to an increase in the total niche width, due to the decline of preferred resources. In such cases, individuals may indeed expand their niche width by adding new prey to their diet, or by shifting, independently of each other, to different available resources.…”

Section: Response Of Inter-individual Variation To Seasonal Variationmentioning

confidence: 99%

“…In such cases, individuals may indeed expand their niche width by adding new prey to their diet, or by shifting, independently of each other, to different available resources. For instance, when resource diversity was low, TNW increased both in marsupials (Pires et al 2013) and sea otters (Tinker et al 2008), due to an increase of inter-individual variation in diet. We found the contrary: TNW was lowest in winter and highest in summer when the diversity in resource availability was at its maximum.…”

Section: Response Of Inter-individual Variation To Seasonal Variationmentioning

confidence: 99%

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Upscaling the niche variation hypothesis from the intra- to the inter-specific level

et al. 2015

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The "niche variation hypothesis" (NVH) predicts that populations with wider niches should display higher among-individual variability. This prediction originally stated at the intra-specific level may be extended to the inter-specific level: individuals of generalist species may differ to a greater extent than individuals of a specialist species. We tested the NVH at intra- and inter-specific levels based on a large diet database of three large herbivore feces collected in the field and analyzed using DNA metabarcoding. The three herbivores (roe deer Capreolus capreolus, chamois Rupicapra rupicapra and mouflon Ovis musimon) are highly contrasted in terms of sociality (solitary to highly gregarious) and diet. The NVH at the intraspecific level was tested by relating, for the same population, diet breadth and inter-individual variation across the four seasons. Compared to null models, our data supported the NVH both at the intra- and inter-specific levels. Inter-individual variation of the diet of solitary species was not larger than in social species, although social individuals feed together and could therefore have more similar diets. Hence, the NVH better explained diet breadth than other factors such as sociality. The expansion of the population niche of the three species was driven by resource availability, and achieved by an increase in inter-individual variation, and the level of inter-individual variability was larger in the generalist species (mouflon) than in the specialist one (roe deer). This mechanism at the base of the NVH appears at play at different levels of biological organization, from populations to communities.

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Section: Response Of Inter-individual Variation To Seasonal Variationcontrasting

confidence: 99%

Section: Response Of Inter-individual Variation To Seasonal Variationcontrasting

confidence: 66%

Section: Response Of Inter-individual Variation To Seasonal Variationmentioning

confidence: 99%

Section: Response Of Inter-individual Variation To Seasonal Variationmentioning

confidence: 99%

See 2 more Smart Citations

Upscaling the niche variation hypothesis from the intra- to the inter-specific level

et al. 2015

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“…Details on fecal analysis can be found in other studies based on the same database that we used in the present study (Camargo et al, ; Camargo, Ribeiro, Camargo, & Vieira, ). Fecal analysis is considered an effective method for assessing the diet of Neotropical marsupials (Araújo et al, ; e.g., Pires, Martins, Araujo, & Reis, ; Camargo et al, ), despite some intrinsic limitations of the method, such as differential digestibility of food items, potential problems for the identification of food items at lower taxonomic level (e.g., family or genus), and difficulty in estimating the relative importance of each food item (Araújo et al, ). Differently of other studies that estimated the number of items consumed based on small fecal remains (the number of insects consumed based on the number of leg pieces, or the number of fruits based on seed and fiber count; Anthony & Kunz, ; Mallet‐Rodrigues, ; Pires et al, ), we opted for a conservative approach of considering only the occurrence of each food category.…”

Section: Methodsmentioning

confidence: 99%

Availability of food resources and habitat structure shape the individual‐resource network of a Neotropical marsupial

Camargo

Oliveira

Ribeiro

et al. 2019

Ecology and Evolution

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Spatial and temporal variation in networks has been reported in different studies. However, the many effects of habitat structure and food resource availability variation on network structures have remained poorly investigated, especially in individual‐based networks. This approach can shed light on individual specialization of resource use and how habitat variations shape trophic interactions. To test hypotheses related to habitat variability on trophic interactions, we investigated seasonal and spatial variation in network structure of four populations of the marsupial Gracilinanus agilis in the highly seasonal tropical savannas of the Brazilian Cerrado. We evaluated such variation with network nestedness and modularity considering both cool‐dry and warm‐wet seasons, and related such variations with food resource availability and habitat structure (considered in the present study as environmental variation) in four sites of savanna woodland forest. Network analyses showed that modularity (but not nestedness) was consistently lower during the cool‐dry season in all G. agilis populations. Our results indicated that nestedness is related to habitat structure, showing that this metric increases in sites with thick and spaced trees. On the other hand, modularity was positively related to diversity of arthropods and abundance of fruits. We propose that the relationship between nestedness and habitat structure is an outcome of individual variation in the vertical space and food resource use by G. agilis in sites with thick and spaced trees. Moreover, individual specialization in resource‐rich and population‐dense periods possibly increased the network modularity of G. agilis . Therefore, our study reveals that environment variability considering spatial and temporal components is important for shaping network structure of populations.

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Exploring the Impacts of Methylmercury‐Induced Behavioral Alterations in Larval Yellow Perch in Lake Michigan Using an Individual‐Based Model

et al. 2020

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The inclusion of sublethal behavioral effects in population models has predicted lower estimates of cohort abundance and survival. Methylmercury, a persistent contaminant in the Great Lakes, has been shown to alter foraging and predator avoidance behaviors of larval Yellow Perch Perca flavescens, which may have indirect effects on recruitment. Poor recruitment of Yellow Perch in Lake Michigan has been associated with changes in trophic structure and adverse habitat conditions, but the potential effects of contaminants have not been fully explored. To test this, we adapted existing larval fish individual-based models to incorporate laboratory-derived methylmercury behavioral impairments on a larval Yellow Perch cohort in Lake Michigan. Overall, swimming speed reductions following methylmercury exposure did not drastically affect cohort survival. In contrast, the impairment to prey capture success resulted in an additional 8, 45, and 28% starvation of the cohort in simulations with tissue concentrations of 0.21, 0.95, and 3.14 μg/g total mercury whole-embryo wet weight, respectively. While our experimental methylmercury concentrations were higher than those typically found in Lake Michigan, our findings suggest that contaminants could be an additional factor impacting recruitment of Yellow Perch in systems highly contaminated with mercury.

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Between-individual variation drives the seasonal dynamics in the trophic niche of a Neotropical marsupial

Cited by 19 publications

References 43 publications

Upscaling the niche variation hypothesis from the intra- to the inter-specific level

Upscaling the niche variation hypothesis from the intra- to the inter-specific level

Availability of food resources and habitat structure shape the individual‐resource network of a Neotropical marsupial

Exploring the Impacts of Methylmercury‐Induced Behavioral Alterations in Larval Yellow Perch in Lake Michigan Using an Individual‐Based Model

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