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87 results for “trophic niche”

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dryad36/100

The bite force-gape relationship as an avenue of biomechanical adaptation to trophic niche in two salmonid fishes

All skeletal muscles produce their largest forces at a single optimal length, losing force when stretched or shortened. In vertebrate feeding systems, this fundamental force-length relationship translates to variation in bite force across gape, which affects the food types that can be eaten effectively. We measured the bite force-gape curves of two sympatric species: king salmon (Oncorhynchus tshawytscha) and pink salmon (O. gorbuscha). Cranial anatomical measurements are not significantly different between species, however, peak bite forces are produced at significantly different gapes. Maximum bite force is achieved at 67% of maximum gape for king salmon and 43% of maximum gape for pink salmon. This may allow king salmon to use greater force when eating large or elusive prey. In contrast, pink salmon do not require high forces at extreme gapes for filter feeding. Our results illustrate that the bite force-gape relationship is an important ecophysiological axis of variation.

opencc-zeroSep 2020View details →

dryad36/100

Data from: Spider webs, stable isotopes and molecular gut content analysis: multiple lines of evidence support trophic niche differentiation in a community of Hawaiian spiders

1. Adaptive radiations are typically characterized by niche partitioning among their constituent species. Trophic niche partitioning is particularly important in predatory animals, which rely on limited food resources for survival. 2. We test for trophic niche partitioning in an adaptive radiation of Hawaiian Tetragnatha spiders, which have diversified in situ on the Hawaiian Islands. We focus on a community of nine species belonging to two different clades, one web building and the other actively hunting, which co-occur in wet forest on East Maui. We hypothesize that trophic niches differ significantly both 1) among species within a clade, indicating food resource partitioning, and 2) between the two clades, corresponding with their differences in foraging strategy. 3. To assess niches of the spider species, we measure a) web architecture, the structure of the hunting tool, and b) site choice, the physical placement of the web in the habitat. We then test whether differences in these parameters translate into meaningful differences in trophic niche by measuring c) stable isotope signatures of carbon and nitrogen in the spiders' tissues, and d) gut content of spiders based on metabarcoding data. 4. We find significant interspecific differences in web architecture and site choice. Importantly, these differences are reflected in stable isotope signatures among the five web-building species, as well as significant isotopic differences between web-builders and active hunters. Gut content data also show interspecific and inter-clade differences. Pairwise overlaps of web architecture between species are positively correlated with overlaps of isotopic signature. 5. Our results reveal trophic niche partitioning among species within each clade, as well as between the web-building and actively hunting clades. Based on the correlation between web architecture and stable isotopes, it appears that the isotopic signatures of spiders' tissues are influenced by architectural differences among their webs. Our findings indicate an important link between web structure, microhabitat preference and diet in the Hawaiian Tetragnatha.

opencc-zeroDec 2018View details →

zenodo36/100

Data from: Trophic position and niche overlap of an Asian weatherfish (Misgurnus bipartitus), western tubenose goby (Proterorhinus semilunaris), and native benthic fish species

The dataset belonging to the paper "Trophic position and niche overlap of an Asian weatherfish (Misgurnus bipartitus), western tubenose goby (Proterorhinus semilunaris), and native benthic fish species" published in Aquatic Invasions (paper in press; doi link will be added later), is provided here. The dataset consists of δ13C and δ15N (‰) stable isotope ratios of taxa of fish, macroinvertebrates, plants, alga, and soil. If applicable, the length of the taxon was included. Below, methodological information is provided on the study site, the sampling process, the sampling preparation, and the stable isotope analysis. For references, see the published paper in Aquatic Invasions. Study siteThe study site concerned a section of the lowland brook Tungelroysebeek (51°14.38'N, 005°52.086'E – 51°14.26'N, 005°47.77'E) near the village Tungelroy in the Province of Limburg, the Netherlands. This brook of 35 km length has several tributaries before discharging into the River Meuse. Over most of its course, the brook was meandering and had a well-developed riparian and hydrophyte vegetation. During sampling the mean water temperature was 16.0 °C, conductivity 664 µS/cm, pH 7.3, water velocity 0.2 m/s, depth 70 cm, and Secchi depth 60 cm. The brook width ranged between 5-8 m and its bed substrate predominantly consisted of sand. SamplingSamples of fish, macroinvertebrates, macrophytes, dead organic material, and bottom soil substrate were collected in October 2019. The samples were collected in the stretch of the brook that is denoted in Fig. 1 of the paper. Fish were caught using handheld electrofishing equipment (Bretschneider EFGI 650). After catching, the fish were euthanized using a neutralized benzocaine solution of 100 mg l-1. Macroinvertebrates were collected using 70x55 cm dip nets with a mesh size of 1 mm. Helophytes, floating-leaved, and submerged aquatic macrophytes were collected by hand. Soil samples were collected by means of a hollow soil sampling tube with a diameter of 5 cm. A Nikon SMZ800 stereo microscope with a 10-63 magnification was used for the identification of small macroinvertebrates. Sample preparation All samples were transported to the laboratory and stored separately at -18° C until preparation. To obtain muscle samples a piece of 0.5-1 cm of the dorsal tissue of each fish was dissected. Muscle tissue samples were dissected from fish, crayfish, and unionid mussels. Other macroinvertebrates were stored alive for two days at 5 °C to empty their intestinal contents. Subsequently, these invertebrates were rinsed with tap water and then with demineralized water before processing. From unionid mussels, muscle tissue of a similar size was dissected. Of small mollusks, all soft body tissues were used. For small mollusks and other macroinvertebrates, individuals of the same species were pooled to obtain enough material (0.22-0.26 mg) for analyses. For crayfish, muscle tissue of the abdomen was used while the intestine was removed. The stems, leaves, and roots of individual plants were pooled. After preparation, all samples were stored at -80 °C until freeze drying. Freeze drying was carried out at -90 °C for 24-48 hours for fish and macroinvertebrate samples. Plant, dead organic material, and soil samples were freeze dried at least 48 hours. After freeze drying, the samples were grounded with aluminum balls, for 2 min at 30 rpm, using a Retsch MM 400. Subsequently, the grounded samples were weighted in tin cups (Elemental Microanalysis 8 x 5 mm) and prepared for isotope analyses. For the fish and invertebrate samples, 0.22-0.26 mg was weighted. For plants and soil, separate samples were weighted for carbon (10 mg) and nitrogen (40 mg) analyzes.  Stable isotope analysesCarbon and nitrogen stable isotopes were measured using a Thermo Scientific FLASH 2000 HT Elemental Analyzer with a Thermo Scientific DELTA V Advantage Next Generation Isotope Ratio mass spectrometer. Reference gasses were calibrated with the IAEA standards (IAEA-N-2 and IAEA-CH-6), with a maximum deviation of 0.15‰. As an internal standard control, caffeine was used and the 13C/12C and 15N/14N of every sample were determined (in ‰). The isotope ratios (R) δ13C and δ15N are relative to Vienna PDB and atmospheric N2 and were calculated by: δ13C or δ15N = (Rsample/Rstandard − 1) * 1000 Abstract Co-occurring and morphologically similar species have adapted to differential niches for minimizing competition. An invasive alien species can occupy an 'empty niche' in introduced ranges. Alternatively, the invader may occupy an overlapping niche and compete with native species to a certain degree. In a Western European lowland brook with high nutrient loads, we studied a benthic community of five fish species, including two alien species: an Asian weatherfish (Misgurnus bipartitus) and the western tubenose goby (Proterorhinus semilunaris). The native species concerned stone loach (Barbatula barbatula), spined loach (Cobitis taenia), and gudgeon (Gobio gobio). Because of the unknown effects of the invaders on native benthic fish species, the trophic position, isotopic niche overlap, and potential food competition among these species were identified using nitrogen and carbon stable isotopes. The trophic levels of the five fish species indicated that they are secondary consumers. Body size of native fish species correlated significantly negative with their δ15N (‰) signature, in contrast with the invaders indicating that the latter are generalists. Significant isotopic niche overlap was observed among all benthic species. The degree of niche overlap of M. bipartitus was the highest (91.8%) with the G. gobio. Proterorhinus semilunaris had the highest degree of niche overlap (91.2%) with the (B. barbatula. It was notable that the observed niche overlap between the native B. barbatula and C. taenia was high (99.2%). Overlap between M. bipartitus and P. semilunaris was low (8.9% overlap), indicating little resource competition between these alien species. Native species showed wider isotopic niches than the invaders. Bayesian mixing models revealed that native and alien species slightly differ in their main diet. The results suggest that the invaders are plastic in their resource use, leading to niche differentiation and promoting co-existence of benthic fish species.

opencc-by-4.0Nov 2023View details →

dryad36/100

Data for the article entitled: Linking sexual size dimorphism to trophic niche partitioning in a generalist predator

Sexual size dimorphism is a common phenomenon in mammals, and researchers have been trying to demonstrate the evolutionary causes leading to sexual dimorphism. Two main hypotheses emerged: (i) the sexual selection hypothesis and (ii) the sexual competition hypothesis (also called resource partitioning hypothesis). Here, we attempted to link sexual dimorphism in fishers (Pekania pennanti (Erxleben, 1777)) with their fall diet using stable isotope profiling and body and skull measurements. We used the carcasses of 39 fishers which were caught in eastern Québec during fall 2014 by volunteer trappers as well as several potential prey items ranging from small rodents to cervids. We expected minimal niche overlap between sexes, as males should be able to exploit different prey species than females. We also expected to observe an effect of age class (adults vs. juveniles) on trophic niche. As expected, we found great evidence of sexual dimorphism in both body mass and skull measurements: males were heavier and longer than females and had a larger zygomatic and intracanine width and a longer skull. While proportions of prey in diet according to sex and age did not vary greatly, we found some evidence of niche partitioning using Layman's metrics. Indeed, females tended to have a less diversified and more similar diet compared to one another, whereas males showed more diversified and contrasted diets. Despite our limited sample size, our findings provide partial support to the sexual competition hypothesis, as the difference in body and skull size based on sex could have evolved to lessen intraspecific competition in fishers.

opencc-zeroAug 2022View details →

dryad36/100

Temporal stability of polymorphic Arctic charr parasite communities reflect sustained divergent trophic niches

Polymorphic Arctic charr Salvelinus alpinus populations frequently display distinct differences in habitat use, diet and parasite communities. Changes to the relative species densities and composition of the wider fish community have the potential to alter the habitat-niche of sympatric Arctic charr populations. This study evaluated the temporal stability of the parasite community, diet and stable isotopes (δ13C, δ15N) of three sympatric Arctic charr morphs (piscivore, benthivore and planktivore) from Loch Rannoch, Scotland, in relation to changes to the fish community. All Arctic charr morphs displayed distinct differences parasite communities, diet and stable isotope signatures over time, despite the establishment of four new trophically transmitted parasite taxa, and increased fish and zooplankton consumption by the piscivorous and planktivore morphs respectively. Native parasite prevalence also increased in all Arctic charr morphs. Overall, Loch Rannoch polymorphic Arctic charr morph populations have maintained their distinct trophic niches and parasite communities through time despite changes in the fish community. This result indicates that restocking of a native fish species has the potential to induce shifts in the parasite community and diet of Arctic charr morphs.

opencc-zeroOct 2022View details →

dryad36/100

Data from: Variations of trophic structure and niche space in fish community along a highly regulated subtropical large river

The trophic interactions between consumers and resources play a vital role in the stability of communities. In river systems, fragmentation of natural habitats and environmental changes alters the energy basis and community composition, consequently leading to variations in the community's trophic structure and niche space. However, our understanding of how the trophic structure responds to environmental changes is still very limited. Here, based on stable isotope data, we explored and compared trophic positions (TPs), community-wide trophic metrics, and isotope niche space of fish communities in three reaches with different hydrogeomorphic conditions along a highly regulated subtropical river over three seasons. The community trophic structure and niche space showed notable spatiotemporal variations. Overall, the downstream reach had lower TPs and trophic diversity but higher trophic redundancy. The middle reach occupied a wider isotope niche space than other reaches, with the largest niche size during autumn. Furthermore, the niche overlap was relatively high in winter between reaches and in the downstream between seasons. The results implied a homogenization of feeding functional groups and energy flow pathways of species in the downstream community associated with the change of energy source and stability of hydrological conditions. The relationship between trophic structure and environmental factors suggested that the dam-induced alteration in hydrological-related aspects may drive the changes in the functional group composition, together with changes in energy basis, resulting in differences in the trophic structure of the community. The results of the present study deepen our understanding of how ecosystem functions respond to disturbance, thus contributing to an improved ability to conserve river ecosystems.

opencc-zeroOct 2022View details →

zenodo36/100

Cave amphipods reveal co-variation between morphology and trophic niche in a low-productivity environment

Datasets used to explore co-variation patterns between morphological traits and trophic niche in co-occurring Niphargus amphipods from five groundwater caves of the Dinaric Karst, Europe. We quantified gnathopod size and shape by means of morphometric measurements and assessed isotopic niche, trophic position, and carbon signatures using nitrogen (δ15N) and carbon (δ13C) stable isotopes. We provide morphometric and isotopic data for Niphargus specimens, and isotopic data for food resources sampled in the caves.

opencc-by-4.0Jun 2021View details →

dryad36/100

Predicting the competitive interactions and trophic niche consequences of a globally invasive fish with threatened native species

1. Novel trophic interactions between invasive and native species potentially increase levels of inter-specific competition in the receiving environment. However, theory on the trophic impacts of invasive fauna on native competitors is ambiguous, as while increased inter-specific competition can result in the species having constricted and diverged trophic niches, the species might instead increase their niche sizes, especially in omnivorous species. 2. The competitive interactions between an omnivorous invasive fish, common carp Cyprinus carpio, and a tropically analogous native and threatened fish, crucian carp Carassius carassius, were tested using comparative functional responses (CFRs). A natural pond experiment then presented the species in allopatry and sympatry, determining the changes in their trophic (isotopic) niche sizes and positions over four years. These predictive approaches were complemented by assessing their trophic relationships in wild populations. 3. CFRs revealed that compared to crucian carp, carp had a significantly higher maximum consumption rate. Coupled with a previous cohabitation growth study, these results predicted that competition between the species is asymmetric, with carp the superior competitor. 4. The pond experiment used stable isotope metrics to quantify shifts in the trophic (isotopic) niche sizes of the fishes. In allopatry, the isotopic niches of the two species were similar sized and diverged. Conversely, in sympatry, carp isotopic niches were always considerably larger than those of crucian carp and were strongly partitioned. Sympatric crucian carp had larger isotopic niches than allopatric conspecifics, a likely response to asymmetric competition from carp. However, carp isotopic niches were also larger in sympatry than allopatry. In the wild populations, the carp isotopic niches were always larger than crucian carp niches, and were highly divergent. 5. The superior competitive abilities of carp predicted in aquaria experiments were considered to be a process involved in sympatric crucian carp having larger isotopic niches than in allopatry. However, as sympatric carp also had larger niches than in allopatry, this suggests other ecological processes were also likely to be involved, such as those relating to fish prey resources. These results highlight the inherent complexity in determining how omnivorous invasive species integrate into food-webs and alter their structure.

opencc-zeroJul 2021View details →

dryad36/100