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Sommer GM, Njom SD, Indermaur A, Nyom ARB, Jandová K, Kukla J, Petrtýl M, Horká P, Musilova Z. Trophic ecology of the African riverine elephant fishes (Mormyridae). Ecol Evol 2024; 14:e70173. [PMID: 39206461 PMCID: PMC11349487 DOI: 10.1002/ece3.70173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 07/22/2024] [Accepted: 07/30/2024] [Indexed: 09/04/2024] Open
Abstract
Multiple species of the elephant fishes (Mormyridae) commonly coexist in sympatry in most African tropical rivers and lakes. In this study, we investigated the trophic ecology and potential trophic niche partitioning of eleven mormyrid fish species from the Sanaga River system in Cameroon using the stable isotope composition of carbon and nitrogen in the muscle samples. Albeit most mormyrids mainly feed on invertebrates, we found differences in isotope ratios, and we report signs of the trophic niche partitioning among species. We further found significant differences in isotopic signatures within the Mormyrus genus, suggesting ecological niche diversification among three closely related species. We have also evaluated differences in the isotopic signals between seasons in four species, which could be possibly caused by species migration and/or anthropogenic agricultural activities. To evaluate body shape, we applied geometric morphometric analyses, and we show that most of the species are clearly morphologically separated. We focused on the mormyrid ecomorphology to identify a possible interaction between shape and ecology, and we found a relationship between the δ13C (but not δ15N) isotopic signal and morphology, suggesting their interplay during mormyrid evolution. Overall, we present robust evidence of the trophic niche partitioning within the mormyrid species community, and we integrate trophic ecology with morphometrics, shedding light on the enigmatic evolutionary history of these fascinating African fishes.
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Affiliation(s)
- Gina Maria Sommer
- Department of Zoology, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Samuel Didier Njom
- Department of Biological SciencesUniversity of NgaoundéréNgaoundéréCameroon
| | | | - Arnold Roger Bitja Nyom
- Department of Biological SciencesUniversity of NgaoundéréNgaoundéréCameroon
- Department of Management of Fisheries and Aquatic EcosystemsUniversity of DoualaDoualaCameroon
| | - Kateřina Jandová
- Institute for Environmental Studies, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Jaroslav Kukla
- Institute for Environmental Studies, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Miloslav Petrtýl
- Department of Zoology and Fisheries, Faculty of Agrobiology, Food and Natural ResourcesCzech University of Life Sciences PragueSuchdolCzech Republic
| | - Petra Horká
- Institute for Environmental Studies, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Zuzana Musilova
- Department of Zoology, Faculty of ScienceCharles UniversityPragueCzech Republic
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Sporta Caputi S, Kabala JP, Rossi L, Careddu G, Calizza E, Ventura M, Costantini ML. Individual diet variability shapes the architecture of Antarctic benthic food webs. Sci Rep 2024; 14:12333. [PMID: 38811641 PMCID: PMC11137039 DOI: 10.1038/s41598-024-62644-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024] Open
Abstract
Antarctic biodiversity is affected by seasonal sea-ice dynamics driving basal resource availability. To (1) determine the role of intraspecific dietary variability in structuring benthic food webs sustaining Antarctic biodiversity, and (2) understand how food webs and the position of topologically central species vary with sea-ice cover, single benthic individuals' diets were studied by isotopic analysis before sea-ice breakup and afterwards. Isotopic trophospecies (or Isotopic Trophic Units) were investigated and food webs reconstructed using Bayesian Mixing Models. As nodes, these webs used either ITUs regardless of their taxonomic membership (ITU-webs) or ITUs assigned to species (population-webs). Both were compared to taxonomic-webs based on taxa and their mean isotopic values. Higher resource availability after sea-ice breakup led to simpler community structure, with lower connectance and linkage density. Intra-population diet variability and compartmentalisation were crucial in determining community structure, showing population-webs to be more complex, stable and robust to biodiversity loss than taxonomic-webs. The core web, representing the minimal community 'skeleton' that expands opportunistically while maintaining web stability with changing resource availability, was also identified. Central nodes included the sea-urchin Sterechinus neumayeri and the bivalve Adamussium colbecki, whose diet is described in unprecedented detail. The core web, compartmentalisation and topologically central nodes represent crucial factors underlying Antarctica's rich benthic food web persistence.
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Affiliation(s)
- Simona Sporta Caputi
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
- CoNISMa, National Inter-University Consortium for Marine Sciences, Piazzale Flaminio 9, 00196, Rome, Italy
| | - Jerzy Piotr Kabala
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
| | - Loreto Rossi
- CoNISMa, National Inter-University Consortium for Marine Sciences, Piazzale Flaminio 9, 00196, Rome, Italy.
| | - Giulio Careddu
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
- CoNISMa, National Inter-University Consortium for Marine Sciences, Piazzale Flaminio 9, 00196, Rome, Italy
| | - Edoardo Calizza
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
- CoNISMa, National Inter-University Consortium for Marine Sciences, Piazzale Flaminio 9, 00196, Rome, Italy
| | - Matteo Ventura
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
| | - Maria Letizia Costantini
- Department of Environmental Biology, Sapienza University of Rome, Via Dei Sardi 70, 00185, Rome, Italy
- CoNISMa, National Inter-University Consortium for Marine Sciences, Piazzale Flaminio 9, 00196, Rome, Italy
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Peña‐Villalobos I, Muñoz‐Pacheco CB, Escobar MAH, Jaksic FM, Sabat P. Living with voracious roommates: Factors that explain isotopic niche variation in a mixed colony of insectivorous bats. Ecol Evol 2024; 14:e10939. [PMID: 38500854 PMCID: PMC10945080 DOI: 10.1002/ece3.10939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 12/02/2023] [Accepted: 12/15/2023] [Indexed: 03/20/2024] Open
Abstract
Theory predicts that in resource-limited environments, coexisting species may overlap their niche dimensions but must differ in at least one to avoid competitive exclusion. Specifically, it has been suggested that the coexistence of competing species within a guild, could be sustained with mechanisms of resource partitioning, such as segregation along a trophic dimension. Among the most gregarious mammals are bats, which present diversification in their diet based on habitat choice and body size. Despite differences that could explain specialization in prey selection, there are insufficient studies that explore food overlap in mixed bat colonies and the factors that determine the selection of prey, both at intra- and inter-specific levels. To fill this gap, we analyzed the isotope signal (δ13C and δ15N) in feces collected in a mixed colony of Tadarida brasiliensis and Myotis chiloensis. To understand how several factors could influence these isotopic signals, intrinsic explanatory variables were analyzed, including body mass, body length, age, and sex. Also, extrinsic variables were analyzed, including monthly temporality and moonlight intensity. Our findings support age-dependent specialization in M. chiloensis, with a significant role of moonlight intensity and sex on δ15N. In T. brasiliensis, we identified a significant effect of size, sex, and ear length on δ15N. Our analysis indicates that both species of bats experience diverse degrees of overlap through austral summer months, affected by several factors that explain the variability in their fecal isotopic signals.
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Affiliation(s)
- Isaac Peña‐Villalobos
- Departamento de Ciencias Ecológicas, Facultad de CienciasUniversidad de ChileSantiagoChile
- Laboratorio de Células troncales y Biología del Desarrollo, Departamento de Biología, Facultad de CienciasUniversidad de ChileSantiagoChile
| | - Catalina B. Muñoz‐Pacheco
- Grupo de Ecología, Naturaleza y Sociedad (GENS), Departamento de Gestión Forestal y su Medio Ambiente, Facultad de Ciencias Forestales y de la Conservación de la NaturalezaUniversidad de ChileSantiagoChile
- Escuela de Arquitectura del PaisajeUniversidad Central de ChileSantiagoChile
| | - Martín A. H. Escobar
- Grupo de Ecología, Naturaleza y Sociedad (GENS), Departamento de Gestión Forestal y su Medio Ambiente, Facultad de Ciencias Forestales y de la Conservación de la NaturalezaUniversidad de ChileSantiagoChile
- Facultad de Ciencias de la NaturalezaUniversidad San SebastiánSantiagoChile
| | - Fabian M. Jaksic
- Center of Applied Ecology and Sustainability (CAPES)SantiagoChile
| | - Pablo Sabat
- Departamento de Ciencias Ecológicas, Facultad de CienciasUniversidad de ChileSantiagoChile
- Center of Applied Ecology and Sustainability (CAPES)SantiagoChile
- Millennium Nucleus of Patagonian Limit of Life (LiLi)ValdiviaChile
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Velarde-Garcéz DA, Mata VA, Beja P, da Silva LP. DNA metabarcoding, diversity partitioning and null models reveal mechanisms of seasonal trophic specialization in a Mediterranean warbler. Mol Ecol 2024; 33:e17245. [PMID: 38124452 DOI: 10.1111/mec.17245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 11/14/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023]
Abstract
Optimal Foraging Theory (OFT) predicts that a population's trophic niche expansion should occur in periods of food scarcity as individuals begin to opportunistically exploit sub-optimal food items. However, the Niche Variation Hypothesis (NVH) posits that niche widening may result from increased among-individual differentiation due to food partitioning to avoid competition. We tested these hypotheses through a DNA metabarcoding study of the Sardinian Warbler (Curruca melanocephala) diet over a year. We used null models and the decomposition of beta diversity on among-individual dietary differentiation to infer the mechanisms driving the population's niche variation. Warblers fed frequently on berries, with a peak in late summer and, to a lesser extent, in autumn. Their diet also included a wide range of arthropods, with their prevalence varying among seasons. Consistent with OFT, the population's niche width was narrower in spring/summer when the population was strongly specialized in berries. In winter, the population's niche expanded, possibly reflecting seasonal declines in food abundance. As predicted by NVH, among-individual differentiation tended to be higher in winter, but this was mainly due to increased differences in dietary richness rather than to the partitioning of resources. Overall, our results suggest that within-individual niche does not increase in lean periods, and instead, individuals adopt either a more opportunistic or more specialized foraging strategy. Increased competition in periods of scarcity may help explain such patterns, but instead of showing increased food partitioning as expected from NVH, it may reflect OFT mechanisms on individuals with differential competitive ability to access better food resources.
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Affiliation(s)
- Daniel A Velarde-Garcéz
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | - Vanessa A Mata
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | - Pedro Beja
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Instituto de Agronomia, Universidade de Lisboa, Lisboa, Portugal
| | - Luis P da Silva
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, Vairão, Portugal
- BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
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Vanessa DS, Davide C, Ilaria B, Chiara B, Stefano B, Mattia I, Silvia Z, Pietro V. Non-native fish assemblages display potential competitive advantages in two protected small and shallow lakes of northern Italy. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Vadeboncoeur Y, Moore MV, Stewart SD, Chandra S, Atkins KS, Baron JS, Bouma-Gregson K, Brothers S, Francoeur SN, Genzoli L, Higgins SN, Hilt S, Katona LR, Kelly D, Oleksy IA, Ozersky T, Power ME, Roberts D, Smits AP, Timoshkin O, Tromboni F, Zanden MJV, Volkova EA, Waters S, Wood SA, Yamamuro M. Blue Waters, Green Bottoms: Benthic Filamentous Algal Blooms Are an Emerging Threat to Clear Lakes Worldwide. Bioscience 2021; 71:1011-1027. [PMID: 34616235 PMCID: PMC8490932 DOI: 10.1093/biosci/biab049] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nearshore (littoral) habitats of clear lakes with high water quality are increasingly experiencing unexplained proliferations of filamentous algae that grow on submerged surfaces. These filamentous algal blooms (FABs) are sometimes associated with nutrient pollution in groundwater, but complex changes in climate, nutrient transport, lake hydrodynamics, and food web structure may also facilitate this emerging threat to clear lakes. A coordinated effort among members of the public, managers, and scientists is needed to document the occurrence of FABs, to standardize methods for measuring their severity, to adapt existing data collection networks to include nearshore habitats, and to mitigate and reverse this profound structural change in lake ecosystems. Current models of lake eutrophication do not explain this littoral greening. However, a cohesive response to it is essential for protecting some of the world's most valued lakes and the flora, fauna, and ecosystem services they sustain.
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Affiliation(s)
| | | | | | - Sudeep Chandra
- Biology Department and the Global Water Center, University of Nevada, Reno, Nevada, United States
| | - Karen S Atkins
- University of California, Davis, Davis, California, United States
| | - Jill S Baron
- US Geological Survey, Fort Collins, Colorado, United States
| | - Keith Bouma-Gregson
- California State Water Resources Control Board, Sacramento, California, United States
| | | | | | - Laurel Genzoli
- Flathead Lake Biological Station and the University of Montana, Missoula, Montana, United States
| | - Scott N Higgins
- International Institute for Sustainable Development, Experimental Lakes Area, with its head office in Winnipeg, Manitoba, Canada
| | - Sabine Hilt
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | | | | | | | - Ted Ozersky
- Large Lakes Observatory, University of Minnesota, Duluth, Minnesota, United States
| | - Mary E Power
- University of California, Berkeley, Berkeley, California, United States
| | - Derek Roberts
- San Francisco Estuary Institute, Richmond, California, United States
| | - Adrianne P Smits
- University of California, Davis, Davis, California, United States
| | - Oleg Timoshkin
- Siberian Branch of the Russian Academy of Sciences’ Limnological Institute, Irkutsk, Russian Federation
| | - Flavia Tromboni
- Biology Department and the Global Water Center, University of Nevada, Reno, Nevada, United States
| | - M Jake Vander Zanden
- Center for Limnology, University of Wisconsin—Madison, Madison, Wisconsin, United States
| | - Ekaterina A Volkova
- Siberian Branch of the Russian Academy of Sciences’ Limnological Institute, Irkutsk, Russian Federation
| | | | | | - Masumi Yamamuro
- Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
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