Interannual changes in δ15N baseline in a lake–swamp–river food web: effects of summer precipitation in West Siberian forest steppe

The diversification of phenotypes and species has been a major concern in evolutionary biology. Both resource competition and predator-prey interactions have been suggested as mechanisms that drive phenotypic divergence and speciation, but the latter has attracted much less attention than the former. The Karaftohelix land snails in Northeast Asia provide an excellent model to investigate the effects of competition and predation on the divergence process. This is because (1) all species-especially Karaftohelix editha and Karaftohelix gainesi in northern Japan-are closely related and sometimes indistinguishable by genital morphologies and neutral nuclear and mitochondrial DNA markers, despite the distinct phenotypes among species; (2) two different anti-predatory strategies (i.e., passive and active defenses) are observed for each species in this group; and (3) multiple species have generally overlapping distributions and were often observed at exactly the same time and place. In this study, we conducted quantitative quadrat surveys and carbon/ nitrogen stable isotope analyses to compare the microhabitat and trophic niches among Karaftohelix land snails and estimated the cause of adaptive radiation in this taxon. All the results indicated that the differences in microhabitats and trophic niches among Karaftohelix land snails-especially between the most closely related sister species, K. editha and K. gainesi in northern Japanwere too small to promote the adaptive radiation in this group. Therefore, it is difficult to explain the extreme divergence of phenotypes and species among Karaftohelix land snails in Northeast Asia based on environmental adaptation through resource competition and/or reproductive interference.

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“…L‐alanine (AZ1Z0, Lot No. M5R9452, Shoko Science) was used as a working standard, that is,

R_{standard}

(see also Kanaya et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…L-alanine (AZ1Z0, Lot No. M5R9452, Shoko Science) was used as a working standard, that is, R standard (see also Kanaya et al, 2020). The δ 13 C and δ 15 N values of K. editha and K. gainesi were analyzed by generalized linear mixed models (GLMMs) with a Gaussian distribution with R version 4.0.2 (R Core Team, 2021).…”

Section: Stable Isotope Analysesmentioning

confidence: 99%

The habitat use and trophic niche comparisons among closely related land snails in Northeast Asia

et al. 2022

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“…The highest δ 15 N values for all basal resources and primary consumers (i.e., zooplankton) occurred in the lake mouth and river mouth. This probably reflects the inflow of 15 N-rich nutrients in the ecotone ecosystems through natural and anthropogenic activities (Kanaya et al, 2020).…”

Section: The Detritus-based Food Web Shifted To a Phytoplankton-based...mentioning

confidence: 99%

Spatial Heterogeneity of Food Webs in A River-Lake Ecotone under Flow Regulation – A Case Study in Northern China

Yang¹,

Fu²,

Li³

et al. 2023

J ENV INFORM

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The river–lake ecotone supports diverse aquatic life, but its food web structure and topology are poorly understood. Baiyangdian Lake, northern China’s largest shallow lake, depends on external environmental flows, of which the Fu River provides the most stable water supply. Here, we used stable isotopes and topological analysis to explore the food web structure along a spatial gradient using data from field surveys from 2018 to 2019. Carbon and nitrogen stable isotopes and the food web structure were associated with environmental factors for four ecosystem types (river, river mouth, lake mouth, lake). Detritus, phytoplankton, and zooplankton δ13C values became more depleted along the gradient from the river to the lake, whereas δ13C of submerged macrophytes was enriched in the ecotones compared to the river and lake. Higher δ15N values for basal resources and zooplankton occurred at the lake mouth and river mouth. The top consumers were omnivorous fish: Hemiculter leucisculus (trophic level [TL] = 3.85 ± 0.89) in the river and Pseudorasbora parva (TL = 4.54 ± 0.58) in the river mouth. Carnivorous Erythroculter dabryi occupied the highest TL (3.61 ± 0.36 and 4.46 ± 0.36, respectively) in the lake mouth and lake. These results together led to a change from a detritus-based to phytoplankton-based food web along the gradient from the river to the lake. The species richness, number of trophic links, link density, and mean food chain length all are greatest in the lake, followed by the lake mouth, and the lowest were in the river. Our results provide a holistic view of the ecotone ecosystem and its food web, suggesting that it supports a more diverse species assemblage and more complex food web structure than the adjacent river ecosystem, rather than the adjacent lake ecosystem. Therefore, management should emphasize the combined effects of altered hydrological regimes and poor water quality on the ecotone food webs to manage the river and lake more sustainably.

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Marine food webs, ecosystem models and stable isotopes

Xie

Zheng

et al. 2024

Treatise on Estuarine and Coastal Science (Second Edition)

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Interannual changes in δ15N baseline in a lake–swamp–river food web: effects of summer precipitation in West Siberian forest steppe

Cited by 6 publications

References 39 publications

The habitat use and trophic niche comparisons among closely related land snails in Northeast Asia

The habitat use and trophic niche comparisons among closely related land snails in Northeast Asia

Spatial Heterogeneity of Food Webs in A River-Lake Ecotone under Flow Regulation – A Case Study in Northern China

Marine food webs, ecosystem models and stable isotopes

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