scholarly journals Isotopic Niche Partitioning and Individual Specialization in an Arctic Raptor Guild

2021 ◽  
Author(s):  
Devin L. Johnson ◽  
Michael T. Henderson ◽  
David L. Anderson ◽  
Travis L. Booms ◽  
Cory T. Williams
Keyword(s):  
Resource Availability ◽  
Niche Overlap ◽  
Niche Width ◽  
Foraging Strategies ◽  
Foraging Efficiency ◽  
Isotopic Niche ◽  
Individual Specialization ◽  
Niche Specialization ◽  
Niche Variation ◽  
Golden Eagles

Abstract Intra- and inter-specific resource partitioning within predator communities is a fundamental component of trophic ecology, and one proposed mechanism for how populations partition resources is through individual niche variation. The Niche Variation Hypothesis (NVH) predicts that interindividual trait variation leads to functional trade-offs in foraging efficiency, resulting in populations comprised of individual dietary specialists. A modified version of the NVH [mNVH] predicts niche specialization is plastic and responsive to fluctuating resource availability. We quantified niche overlap and tested the mNVH within an Arctic raptor guild, focusing on three species that employ different foraging strategies: Golden Eagles (generalists); Gyrfalcons (facultative specialists); and Rough-legged Hawks (specialists). Tundra ecosystems exhibit cyclic populations of arvicoline rodents (lemmings and voles), providing a unique system under which to examine interannual fluctuations in predator resource availability. Using blood δ13C & δ15N values from 189 raptor nestlings on Alaska’s Seward Peninsula (2014–2019), we calculated isotopic niche width and used Bayesian stable isotope mixing models (BSIMMs) to characterize individual specialization and test the mNVH. We observed a high degree of isotopic niche overlap between the three species and variable trophic responses to different stages of the arvicoline rodent cycle. Elevated arvicoline rodent abundance corresponded to reduced niche overlap among species and increased individual specialization in Golden Eagles and Gyrfalcons. Further, Gyrfalcons displayed a positive relationship between individual specialization and population niche width on an interannual basis consistent with the mNVH. Our findings suggest plasticity in niche specialization may reduce intra- and inter-specific resource competition under dynamic ecological conditions.

scholarly journals Isotopic niches of sympatric native and exotic fish species in a Neotropical floodplain

2015 ◽  
Vol 87 (2) ◽  
pp. 825-833 ◽  
Author(s):  
Juliana S. Philippsen ◽  
Marília Hauser ◽  
Evanilde Benedito
Keyword(s):  
Exotic Species ◽  
Fish Species ◽  
Intraspecific Competition ◽  
Native Species ◽  
Niche Overlap ◽  
Food Resources ◽  
Foraging Strategies ◽  
Isotopic Niche ◽  
Exotic Fish ◽  
Niche Concept

This study investigated the isotopic niches of two fish species, one exotic and one native. It was hypothesized that these species would show little or no isotopic niche overlap. This hypothesis was tested with the isotopic niche concept and the trophic Layman's metrics. A considerable isotopic niche overlap was observed between the species, mainly for the exotic that showed the greater percentage of overlapping, indicating an interspecific competition for food resources. Layman's metrics also showed this species probably exploits a more specific array of food resources when compared with the native species. The native species probably has the ability to exploit a wider array of resources, highlighted by the higher values given for the Layman's metrics. The juveniles and adults of native species showed minor overlapping between the isotopic niches. This indicates that they have probably adopted different foraging strategies, minimizing intraspecific competition. Evidences that the exotic species explores a narrower range of resources and that the native species has a greater isotopic niche and possibly suffer less intraspecific competition, indicates that the native species can tolerate the presence of the exotic species and promote survival and maintenance of its population even under possible competition effects imposed by the exotic species.

scholarly journals Trophic niches of native and nonnative fishes along a river-reservoir continuum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Casey A. Pennock ◽  
Zachary T. Ahrens ◽  
Mark C. McKinstry ◽  
Phaedra Budy ◽  
Keith B. Gido
Keyword(s):  
Resource Availability ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Nonnative Species ◽  
Fish Diversity ◽  
Isotopic Niche ◽  
Negative Consequences ◽  
Native Communities ◽  
River Reservoir ◽  
Lake Powell

AbstractInstream barriers can constrain dispersal of nonnative fishes, creating opportunities to test their impact on native communities above and below these barriers. Deposition of sediments in a river inflow to Lake Powell, USA resulted in creation of a large waterfall prohibiting upstream movement of fishes from the reservoir allowing us to evaluate the trophic niche of fishes above and below this barrier. We expected niche overlap among native and nonnative species would increase in local assemblages downstream of the barrier where nonnative fish diversity and abundance were higher. Fishes upstream of the barrier had more distinct isotopic niches and species exhibited a wider range in δ15N relative to downstream. In the reservoir, species were more constrained in δ15N and differed more in δ13C, representing a shorter, wider food web. Differences in energetic pathways and resource availability among habitats likely contributed to differences in isotopic niches. Endangered Razorback Sucker (Xyrauchen texanus) aggregate at some reservoir inflows in the Colorado River basin, and this is where we found the highest niche overlap among species. Whether isotopic niche overlap among adult native and nonnative species has negative consequences is unclear, because data on resource availability and use are lacking; however, these observations do indicate the potential for competition. Still, the impacts of diet overlap among trophic generalists, such as Razorback Sucker, are likely low, particularly in habitats with diverse and abundant food bases such as river-reservoir inflows.

scholarly journals Competition and resource breadth shape niche variation and overlap in multiple trophic dimensions

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190369 ◽  
Author(s):  
Raul Costa-Pereira ◽  
Márcio S. Araújo ◽  
Franco L. Souza ◽  
Travis Ingram
Keyword(s):  
Local Environment ◽  
Niche Overlap ◽  
Niche Width ◽  
Similar Species ◽  
Niche Theory ◽  
Extrinsic Factors ◽  
Population Total ◽  
Niche Variation ◽  
Multiple Dimensions ◽  
Frog Species

Competition plays a central role in the maintenance of biodiversity. A backbone of classic niche theory is that local coexistence of competitors is favoured by the contraction or divergence of species' niches. However, this effect should depend on the diversity of resources available in the local environment, particularly when resources vary in multiple ecological dimensions. Here, we investigated how available resource breadth (i.e. prey diversity) and competition together shape multidimensional niche variation (between and within individuals) and interspecific niche overlap in 42 populations of congeneric tropical frog species. We modelled realized niches in two key trophic dimensions (prey size and carbon stable isotopes) and sampled available food resources to quantify two-dimensional resource breadth. We found a 14-fold variation in multidimensional population niche width across populations, most of which was accounted for by within-individual diet variation. This striking variation was predicted by an interaction whereby individual niche breadth increased with resource breadth and decreased with the number of congeneric competitors. These ecological gradients also interact to influence the degree of niche overlap between species, which surprisingly decreased with population total niche width, providing novel insights on how similar species can coexist in local communities. Together, our results emphasize that patterns of exploitation of resources in multiple dimensions are driven by both competitive interactions and extrinsic factors such as local resource breadth.

scholarly journals Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

2021 ◽  
Author(s):  
Mayara P. Neves ◽  
Pavel Kratina ◽  
Rosilene L. Delariva ◽  
J. Iwan Jones ◽  
Clarice B. Fialho
Keyword(s):  
Seasonal Variation ◽  
Fish Species ◽  
Resource Availability ◽  
Seasonal Changes ◽  
Dry Season ◽  
Diet Overlap ◽  
Isotopic Niche ◽  
Neotropical Streams ◽  
Feeding Plasticity ◽  
The Impact

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

scholarly journals Isotopic niche variation in Tasmanian devils Sarcophilus harrisii with progression of devil facial tumor disease

2021 ◽  
Author(s):  
Olivia Bell ◽  
Menna E. Jones ◽  
Calum X. Cunningham ◽  
Manuel Ruiz‐Aravena ◽  
David G. Hamilton ◽  
...  
Keyword(s):  
Isotopic Niche ◽  
Niche Variation ◽  
Devil Facial Tumor Disease ◽  
Sarcophilus Harrisii

Intraspecific isotopic niche variation in broad-snouted caiman (Caiman latirostris)

2013 ◽  
Vol 49 (3) ◽  
pp. 325-335 ◽  
Author(s):  
Thiago S. Marques ◽  
Neliton R.F. Lara ◽  
Luis A.B. Bassetti ◽  
Carlos I. Piña ◽  
Plínio B. Camargo ◽  
...  
Keyword(s):  
Isotopic Niche ◽  
Niche Variation

A comparison of bryophyte species diversity and niche structure of montane streams and stream banks

1987 ◽  
Vol 65 (9) ◽  
pp. 1824-1837 ◽  
Author(s):  
Janice M. Glime ◽  
Dale H. Vitt
Keyword(s):  
New York ◽  
Species Diversity ◽  
Water Surface ◽  
Niche Overlap ◽  
Niche Width ◽  
Vertical Distance ◽  
Substrate Size ◽  
Species Cover ◽  
Montane Streams ◽  
Stream Substrate

Eleven alkaline western Canadian montane streams were sampled by transects to compare the bryophyte species cover, diversity, frequency, richness, niche width, and niche overlap in three vertical zones (relative to water level) with the same parameters in four acidic streams on Slide Mountain in the Adirondack Mountains of New York. Resources for niche width and overlap include vertical distance from water surface, aspect in stream, substrate size, and percent bare substrate. Species cover, richness, and diversity increase from the submerged zone 1 (< −5 cm) to the terrestrial zone 3 (10–30 cm). Brillouin species diversity increases from 1.98 to 3.03 (means per stream) along the same gradient. All species except one from zone 1 also occur in zone 3. The niche widths for aspect in stream, substrate size, and vertical distance from water surface are all negatively correlated with their chi-square values, indicating that the width values are most reliable for small widths and become increasingly less reliable for large niche widths. Niche overlap is high among most species for at least one resource parameter.

scholarly journals Temporal Variation in the Niche Partitioning of Lake Michigan Salmonines as it Relates to Alewife Abundance and Size Structure.

2021 ◽  
Author(s):  
Benjamin A. Turschak ◽  
Charles R. Bronte ◽  
Sergiusz J. Czesny ◽  
Brandon S. Gerig ◽  
Austin Happel ◽  
...  
Keyword(s):  
Ecological Niche ◽  
Lake Michigan ◽  
Nitrogen Isotopes ◽  
Size Structure ◽  
Prey Availability ◽  
Habitat Preferences ◽  
Niche Partitioning ◽  
Niche Overlap ◽  
Isotopic Niche ◽  
Resource Gradient

Stable isotope analyses offer a useful means for quantifying ecological niche dimensions, though few studies have examined isotopic response of an ecological community with respect to resource gradients such as fluctuations in prey availability. Stable carbon and nitrogen isotopes were measured for Lake Michigan salmonines and their prey collected from 2014 to 2016. Bayesian ellipse and mixing model analyses were used to quantify isotopic niche characteristics and diets, respectively, among species and years. During the three-year study period, abundance and size structure of preferred alewife prey changed substantially and offered an opportunity to explore predator isotopic niche response and diet shifts along a prey resource gradient. Results suggested increased reliance on alewives, especially small alewives, over the study period and were consistent with greater availability of this prey. However, differential use of alewife size classes and alternative prey sources by salmonine predators was apparent, which suggested possible resource partitioning. Characterization of ecological niche overlap using stable isotopes likely requires consideration of shared resource availability as well as specific prey and habitat preferences.

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