Dataset Information

Novel tri-isotope ellipsoid approach reveals dietary variation in sympatric predators.

ABSTRACT: Sympatric species may partition resources to reduce competition and facilitate co-existence. While spatial variation and specialization in feeding strategies may be prevalent among large marine predators, studies have focussed on sharks, birds, and marine mammals. We consider for the first time the isotopic niche partitioning of co-occurring, teleost reef predators spanning multiple families. Using a novel tri-isotope ellipsoid approach, we investigate the feeding strategies of seven of these species across an atoll seascape in the Maldives. We demonstrate substantial spatial variation in resource use of all predator populations. Furthermore, within each area, there was evidence of intraspecific variation in feeding behaviors that could not wholly be attributed to individual body size. Assessing species at the population level will mask these intraspecific differences in resource use. Knowledge of resource use is important for predicting how species will respond to environmental change and spatial variation should be considered when investigating trophic diversity.

SUBMITTER: Skinner C

PROVIDER: S-EPMC6936247 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Novel tri-isotope ellipsoid approach reveals dietary variation in sympatric predators.

Skinner Christina C Mill Aileen C AC Newman Steven P SP Newton Jason J Cobain Matthew R D MRD Polunin Nicholas V C NVC

Ecology and evolution 20191104 23

Sympatric species may partition resources to reduce competition and facilitate co-existence. While spatial variation and specialization in feeding strategies may be prevalent among large marine predators, studies have focussed on sharks, birds, and marine mammals. We consider for the first time the isotopic niche partitioning of co-occurring, teleost reef predators spanning multiple families. Using a novel tri-isotope ellipsoid approach, we investigate the feeding strategies of seven of these sp ...[more]

PMID: 31893024

Similar Datasets

Project description:1. Competition among sympatric wild herbivores is reduced by different physiological, morphological, and behavioral traits resulting in different dietary niches. Wild equids are a rather uniform group of large herbivores which have dramatically declined in numbers and range. Correlative evidence suggests that pasture competition with livestock is one of the key factors for this decline, and the situation may be aggravated in areas where different equid species overlap. 2. The Dzungarian Gobi is currently the only place where two wild equid species coexist and share the range with the domesticated form of a third equid species. In the arid and winter cold Gobi, pasture productivity is low, highly seasonal, and wild equids additionally face increasing livestock densities. 3. We used stable isotope chronologies of tail hairs to draw inferences about multi-year diet seasonality, isotopic dietary niches, and physiological adaptations in the Asiatic wild ass (khulan), reintroduced Przewalski's horse, and domestic horse in the Mongolian part of the Dzungarian Gobi. 4. Our results showed that even in the arid Gobi, both horse species are predominantly grazers, whereas khulan are highly seasonal, switching from being grazers in summer to mixed feeders in winter. The isotopic dietary niches of the two horse species were almost identical, did not vary with season as in khulan, and were narrower than in the latter. Higher δ15N values point towards higher water use efficiency in khulan, which may be one reason why they can exploit pastures further away from water. 5. Synthesis and applications: The high degree of isotopic dietary niche overlap in the two horses points towards a high potential for pasture competition during the critical nutritional bottleneck in winter and highlights the need to severely restrict grazing of domestic horses on the range of the Przewalski's horses. Khulan are less constrained by water and seem more flexible in their choice of diet or less successful in exploiting grass dominated habitats in winter due to human presence. Providing additional water sources could increase the competition between khulan and livestock, and should therefore be only done following careful consideration.

Project description:BackgroundSmall fishes play fundamental roles in pelagic ecosystems, channelling energy and nutrients from primary producers to higher trophic levels. They support globally important fisheries in eastern boundary current ecosystems like the Humboldt Current System (HCS) of the SE Pacific (Chile and Peru), where fish catches are the highest in the world (per unit area). This production is associated with coastal upwelling where fisheries target small pelagic fishes including the Peruvian anchovy (Engraulis ringens). The elevated biomass attained by small pelagics is thought to reflect their low trophic position in short/simple food chains. Despite their global importance, large gaps exist in our understanding of the basic ecology of these resources. For instance, there is an ongoing debate regarding the relative importance of phytoplankton versus animal prey in anchovy diet, and ecosystem models typically assign them a trophic position (TP) of ∼2, assuming they largely consume phytoplankton. Recent work based on both relative energetic content and stable isotope analysis (SIA) suggests that this value is too low, with δ 15N values indicating that anchovy TP is ca. 3.5 in the Peruvian HCS.MethodsWe characterised the trophic ecology of adult anchovies (n = 30), their putative prey and carnivorous jack mackerel (n = 20) captured from N Chile. SIA (δ 13C and δ 15N) was used to estimate the relative contribution of different putative prey resources. δ 15N was used to estimate population level trophic position.ResultsAnchovies showed little variability in δ 13C (-18.7 to -16.1‰) but varied greatly in δ 15N (13.8 to 22.8‰)-individuals formed two groups with low or high δ 15N values. When considered as a single group, mixing models indicated that anchovy diet was largely composed of zooplankton (median contribution: 95% credibility limits), with major contributions of crustacean larvae (0.61: 0.37-0.77) and anchovy (preflexion) larvae (0.15: 0.02-0.34), and the assimilation of phytoplankton was negligible (0.05: 0-0.22). The modal (95% credibility limits) estimate of TP for the pooled anchovy sample was 3.23 (2.93-3.58), overlapping with recent SIA-based estimates from Peru. When the two δ 15N groups were analysed separately, our results indicate that the lower δ 15N group largely assimilated materials from crustacean larvae (0.73: 0.42-0.88), with a TP of 2.91 (2.62-3.23). Mixing models suggested high δ 15N anchovies were cannibalistic, consuming anchovy preflexion larvae (0.55: 0.11-0.74). A carnivorous trophic niche was supported by high TP (3.79: 3.48-4.16), mirroring that of carnivorous juvenile jack mackerel (Trachurus murphyi; 3.80: 3.51-4.14). Our results support recent conclusions regarding high TP values of anchovy from Peru and reveal new insights into their trophic behaviour. These results also highlight the existence of cryptic trophic complexity and ecosystem function in pelagic food webs, classically considered as simple.

Project description:Models that predict changes in the abundance and distribution of fauna under future climate change scenarios often assume that ecological niche and habitat availability are the major determinants of species' responses to climate change. However, individual species may have very different capacities to adapt to environmental change, as determined by intrinsic factors such as their dispersal ability, genetic diversity, generation time and rate of evolution. These intrinsic factors are usually excluded from forecasts of species' abundance and distribution changes. We aimed to determine the importance of these factors by comparing the impact of the most recent climate regime change, the late Pleistocene glacial-interglacial transition, on two sympatric, ice-dependent meso-predators, the emperor penguin (Aptenodytes forsteri) and Weddell seal (Leptonychotes weddellii).We reconstructed the population trend of emperor penguins and Weddell seals in East Antarctica over the past 75,000 years using mitochondrial DNA sequences and an extended Bayesian skyline plot method. We also assessed patterns of contemporary population structure and genetic diversity.Despite their overlapping distributions and shared dependence on sea ice, our genetic data revealed very different responses to climate warming between these species. The emperor penguin population grew rapidly following the glacial-interglacial transition, but the size of the Weddell seal population did not change. The expansion of emperor penguin numbers during the warm Holocene may have been facilitated by their higher dispersal ability and gene flow among colonies, and fine-scale differences in preferred foraging locations.The vastly different climate change responses of two sympatric ice-dependent predators suggests that differing adaptive capacities and/or fine-scale niche differences can play a major role in species' climate change responses, and that adaptive capacity should be considered alongside niche and distribution in future species forecasts.

Dataset Information

Novel tri-isotope ellipsoid approach reveals dietary variation in sympatric predators.

Publications

Novel tri-isotope ellipsoid approach reveals dietary variation in sympatric predators.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets