Miikka Benjami Laine, Dominik Martin-Creuzburg, Jaakko J. Litmanen, Sami J. Taipale
Essential biomolecules can critically influence the performance of consumers. A deficiency in dietary sterols has been shown to constrain the food quality of prokaryotic food sources for aquatic consumers. Here, we assessed the importance of dietary cholesterol for life history traits (survival, growth and egg production) of the freshwater herbivore Daphnia magna in supplementation experiments with various sterol-containing eukaryotic phytoplankton diets (dinoflagellates, diatoms, and golden algae). We combined cholesterol supplementation via liposomes with 13C-labelling of the phytoplankton diets and traced the origin of cholesterol in Daphnia using compound-specific stable isotope analysis. All phytoplankton strains used here were rich in polyunsaturated fatty acids (PUFA) but differed in their phytosterol composition. We show that growth and reproduction of D. magna can be limited by sterols even when feeding on sterol-containing eukaryotic phytoplankton diets. The impact of cholesterol supplementation on growth and reproduction of D. magna differed among phytoplankton diets (strains). The positive effect of cholesterol supplementation was most pronounced on diatom diets. Estimation of source proportions using stable isotopes revealed that D. magna preferentially assimilated the supplemented cholesterol rather than synthesizing it from dietary phytosterols. Our experiments suggest that the different responses to cholesterol supplementation on the various phytoplankton diets were unrelated to the suitability of dietary phytosterols to serve as cholesterol precursors but were caused by other biochemical or morphological food quality constraints. The combination of methods applied here could be very useful for uncovering nutritional constraints and thus for assessing the importance of essential biomolecules for the performance of herbivorous consumers.
{"title":"Sterol limitation of Daphnia on eukaryotic phytoplankton: a combined supplementation and compound-specific stable isotope labeling approach","authors":"Miikka Benjami Laine, Dominik Martin-Creuzburg, Jaakko J. Litmanen, Sami J. Taipale","doi":"10.1111/oik.10359","DOIUrl":"https://doi.org/10.1111/oik.10359","url":null,"abstract":"Essential biomolecules can critically influence the performance of consumers. A deficiency in dietary sterols has been shown to constrain the food quality of prokaryotic food sources for aquatic consumers. Here, we assessed the importance of dietary cholesterol for life history traits (survival, growth and egg production) of the freshwater herbivore <i>Daphnia magna</i> in supplementation experiments with various sterol-containing eukaryotic phytoplankton diets (dinoflagellates, diatoms, and golden algae). We combined cholesterol supplementation via liposomes with <sup>13</sup>C-labelling of the phytoplankton diets and traced the origin of cholesterol in <i>Daphnia</i> using compound-specific stable isotope analysis. All phytoplankton strains used here were rich in polyunsaturated fatty acids (PUFA) but differed in their phytosterol composition. We show that growth and reproduction of <i>D. magna</i> can be limited by sterols even when feeding on sterol-containing eukaryotic phytoplankton diets. The impact of cholesterol supplementation on growth and reproduction of <i>D. magna</i> differed among phytoplankton diets (strains). The positive effect of cholesterol supplementation was most pronounced on diatom diets. Estimation of source proportions using stable isotopes revealed that <i>D. magna</i> preferentially assimilated the supplemented cholesterol rather than synthesizing it from dietary phytosterols. Our experiments suggest that the different responses to cholesterol supplementation on the various phytoplankton diets were unrelated to the suitability of dietary phytosterols to serve as cholesterol precursors but were caused by other biochemical or morphological food quality constraints. The combination of methods applied here could be very useful for uncovering nutritional constraints and thus for assessing the importance of essential biomolecules for the performance of herbivorous consumers.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rivers form meta‐ecosystems, in which disturbance and connectivity control biodiversity, ecosystem functioning and their interactions across the river network, but also across connected instream and riparian ecosystems. This aquatic–terrestrial linkage is modified by drying, a disturbance that also naturally fragments river networks and thereby modifies organism dispersal and organic matter (OM) transfers across the river network. However, little evidence of the effects of drying on river network‐scale OM cycling exists. Here, we assessed the effects of fragmentation by drying at the river meta‐ecosystem scale by monitoring leaf resource stocks, invertebrate communities and decomposition rates, across three seasons and 20 sites, in the instream and riparian habitats of a river network naturally fragmented by drying. Although instream leaf resource quantity and quality increased, leaf‐shredder invertebrate richness and abundance decreased with flow intermittence. Decomposition was, however, mainly driven by network‐scale fragmentation and connectivity. Shredder richness and invertebrate‐driven decomposition both peaked at sites with intermediate amounts of intermittent reaches upstream, suggesting that upstream drying can promote the biodiversity and functioning of downstream ecosystems. Shredder richness, however, had a negative effect on decomposition in perennial sites, likely due to interspecific competition. Leaf quantity, invertebrate communities and invertebrate‐driven decomposition became more similar between instream and riparian habitats as drying frequency increased, likely due to homogenization of environmental conditions between both habitats as the river dried. Our study demonstrates the paramount effects of drying on the dynamics of resources, communities and ecosystem functioning in rivers and presents evidence of one of the first network‐scale examples of the co‐drivers of ecosystem functions across terrestrial–aquatic boundaries.
{"title":"Drying and fragmentation drive the dynamics of resources, consumers and ecosystem functions across aquatic‐terrestrial habitats in a river network","authors":"Romain Sarremejane, Teresa Silverthorn, Angélique Arbaretaz, Amélie Truchy, Nans Barthélémy, Naiara López‐Rojo, Arnaud Foulquier, Laurent Simon, Hervé Pella, Gabriel Singer, Thibault Datry","doi":"10.1111/oik.10135","DOIUrl":"https://doi.org/10.1111/oik.10135","url":null,"abstract":"Rivers form meta‐ecosystems, in which disturbance and connectivity control biodiversity, ecosystem functioning and their interactions across the river network, but also across connected instream and riparian ecosystems. This aquatic–terrestrial linkage is modified by drying, a disturbance that also naturally fragments river networks and thereby modifies organism dispersal and organic matter (OM) transfers across the river network. However, little evidence of the effects of drying on river network‐scale OM cycling exists. Here, we assessed the effects of fragmentation by drying at the river meta‐ecosystem scale by monitoring leaf resource stocks, invertebrate communities and decomposition rates, across three seasons and 20 sites, in the instream and riparian habitats of a river network naturally fragmented by drying. Although instream leaf resource quantity and quality increased, leaf‐shredder invertebrate richness and abundance decreased with flow intermittence. Decomposition was, however, mainly driven by network‐scale fragmentation and connectivity. Shredder richness and invertebrate‐driven decomposition both peaked at sites with intermediate amounts of intermittent reaches upstream, suggesting that upstream drying can promote the biodiversity and functioning of downstream ecosystems. Shredder richness, however, had a negative effect on decomposition in perennial sites, likely due to interspecific competition. Leaf quantity, invertebrate communities and invertebrate‐driven decomposition became more similar between instream and riparian habitats as drying frequency increased, likely due to homogenization of environmental conditions between both habitats as the river dried. Our study demonstrates the paramount effects of drying on the dynamics of resources, communities and ecosystem functioning in rivers and presents evidence of one of the first network‐scale examples of the co‐drivers of ecosystem functions across terrestrial–aquatic boundaries.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Naoto Shinohara, Yuta Kobayashi, Keita Nishizawa, Kohmei Kadowaki, Akira Yamawo
Biogeographical variation in community assembly processes forms the basis of the latitudinal gradient of biodiversity by driving β‐diversity. Classical studies on community assembly predict environmental filtering affecting β‐diversity more strongly at higher latitudes, where productivity is lower and abiotic stress is stronger. Contrary to this prediction, recent evidence indicates that plant community composition at higher latitudes exhibits more spatially clustered distributions independently of background environments, suggesting the importance of spatial processes, such as priority effects. In this study, we propose a hypothesis that resolves this paradox by considering plant–soil feedback and biogeographic variations in the dominant mycorrhizal type: we predict that the increasing prevalence of ectomycorrhizal (EcM) trees with latitude contributes to the spatially clustered distribution of plants, as EcM trees tend to exhibit positive plant–soil feedback. We analyzed a large‐scale standardized dataset of Japanese forests covering a latitudinal gradient of >10° and found that 1) the proportion of EcM trees was higher at higher latitudes, and 2) EcM tree‐rich communities exhibited more spatially clustered distributions likely due to positive plant–soil feedback. Consequently, 3) tree species composition at higher latitudes was better explained by spatial variables suggesting the importance of priority effects. Consistent with the predictions of the plant–soil feedback theory, these patterns were more pronounced in understory than in canopy communities. Taken together, our results lend support to our hypothesis that biogeographic variation in tree community assembly patterns is defined by mycorrhizal types and plant–soil feedback, thereby resolving a paradox in the latitudinal gradient of plant community assembly. Our work highlights that plant mycorrhizal type underlies the determinants of β‐diversity which is a critical component of the latitudinal gradient of diversity.
{"title":"Plant–mycorrhizal associations may explain the latitudinal gradient of plant community assembly","authors":"Naoto Shinohara, Yuta Kobayashi, Keita Nishizawa, Kohmei Kadowaki, Akira Yamawo","doi":"10.1111/oik.10367","DOIUrl":"https://doi.org/10.1111/oik.10367","url":null,"abstract":"Biogeographical variation in community assembly processes forms the basis of the latitudinal gradient of biodiversity by driving β‐diversity. Classical studies on community assembly predict environmental filtering affecting β‐diversity more strongly at higher latitudes, where productivity is lower and abiotic stress is stronger. Contrary to this prediction, recent evidence indicates that plant community composition at higher latitudes exhibits more spatially clustered distributions independently of background environments, suggesting the importance of spatial processes, such as priority effects. In this study, we propose a hypothesis that resolves this paradox by considering plant–soil feedback and biogeographic variations in the dominant mycorrhizal type: we predict that the increasing prevalence of ectomycorrhizal (EcM) trees with latitude contributes to the spatially clustered distribution of plants, as EcM trees tend to exhibit positive plant–soil feedback. We analyzed a large‐scale standardized dataset of Japanese forests covering a latitudinal gradient of >10° and found that 1) the proportion of EcM trees was higher at higher latitudes, and 2) EcM tree‐rich communities exhibited more spatially clustered distributions likely due to positive plant–soil feedback. Consequently, 3) tree species composition at higher latitudes was better explained by spatial variables suggesting the importance of priority effects. Consistent with the predictions of the plant–soil feedback theory, these patterns were more pronounced in understory than in canopy communities. Taken together, our results lend support to our hypothesis that biogeographic variation in tree community assembly patterns is defined by mycorrhizal types and plant–soil feedback, thereby resolving a paradox in the latitudinal gradient of plant community assembly. Our work highlights that plant mycorrhizal type underlies the determinants of β‐diversity which is a critical component of the latitudinal gradient of diversity.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Blanca Arroyo‐Correa, Ignasi Bartomeus, Pedro Jordano
Indirect interactions among species within ecological communities govern ecological and evolutionary processes as much as, or even more, than direct effects. In insect‐pollinated plant communities, indirect interactions between plants can be mediated by shared pollinators, and may influence plant fitness, population growth and community structure. As individuals are the entities actually interacting in nature, rather than species, downscaling a hierarchical level (i.e. from species to individuals) is essential to understand the underlying processes promoting these indirect interactions. We combined empirical data on plant–pollinator interactions collected in Mediterranean shrublands with a novel modelling framework to assess how the patterns of heterospecific and conspecific pollinator sharing between plant individuals are generated and their fitness implications. We found that the effects of flowering synchrony on pollinator sharing among conspecific and heterospecific plant individuals outperformed those of spatial distance. Our results revealed that plant individuals that shared more pollinators with conspecifics were also involved in a higher pollinator sharing with heterospecifics. For most plant species, the sharing of pollinator species between heterospecific plant individuals produced positive mean fitness outcomes, as long as plants did not share many pollinator interactions, which had negative effects on their fitness. At the level of plant individuals, we found that specific combinations of conspecific and heterospecific pollinator sharing lead to distinct reproductive outcomes that placed each individual along a competition–facilitation continuum. Interestingly, most plant species included a higher proportion of individuals likely experiencing competition compared to those potentially involved in facilitation processes. Our contribution provides novel insights into the factors responsible for local‐scale indirect interactions within communities and their individual‐level functional consequences. Such intricate patterns of indirect interactions have far‐reaching implications, as the transitions of plant individuals along competitive or facilitative processes mediated by shared mutualists may contribute significantly to the functioning and coexistence of ecological communities.
{"title":"Flowering synchrony modulates pollinator sharing and places plant individuals along a competition–facilitation continuum","authors":"Blanca Arroyo‐Correa, Ignasi Bartomeus, Pedro Jordano","doi":"10.1111/oik.10477","DOIUrl":"https://doi.org/10.1111/oik.10477","url":null,"abstract":"Indirect interactions among species within ecological communities govern ecological and evolutionary processes as much as, or even more, than direct effects. In insect‐pollinated plant communities, indirect interactions between plants can be mediated by shared pollinators, and may influence plant fitness, population growth and community structure. As individuals are the entities actually interacting in nature, rather than species, downscaling a hierarchical level (i.e. from species to individuals) is essential to understand the underlying processes promoting these indirect interactions. We combined empirical data on plant–pollinator interactions collected in Mediterranean shrublands with a novel modelling framework to assess how the patterns of heterospecific and conspecific pollinator sharing between plant individuals are generated and their fitness implications. We found that the effects of flowering synchrony on pollinator sharing among conspecific and heterospecific plant individuals outperformed those of spatial distance. Our results revealed that plant individuals that shared more pollinators with conspecifics were also involved in a higher pollinator sharing with heterospecifics. For most plant species, the sharing of pollinator species between heterospecific plant individuals produced positive mean fitness outcomes, as long as plants did not share many pollinator interactions, which had negative effects on their fitness. At the level of plant individuals, we found that specific combinations of conspecific and heterospecific pollinator sharing lead to distinct reproductive outcomes that placed each individual along a competition–facilitation continuum. Interestingly, most plant species included a higher proportion of individuals likely experiencing competition compared to those potentially involved in facilitation processes. Our contribution provides novel insights into the factors responsible for local‐scale indirect interactions within communities and their individual‐level functional consequences. Such intricate patterns of indirect interactions have far‐reaching implications, as the transitions of plant individuals along competitive or facilitative processes mediated by shared mutualists may contribute significantly to the functioning and coexistence of ecological communities.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140002441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The determinants of food chain length (FCL), a crucial aspect of biodiversity due to its effects on ecosystem functioning, have long been debated. Previous studies proposed resource availability, disturbance, and ecosystem size as environmental drivers. However, studies using stable isotope approaches have shown inconsistent results, indicating missing links between environmental drivers and FCL. Here, we hypothesized that species richness and motifs (i.e. three‐species subgraphs) modulated environmental effects on FCL. Combining empirical food webs with our N‐species food web model, we found that FCL disproportionately changed at low species richness, with saturation at high species richness. This functional response was essential to the interdependent effects of disturbance and ecosystem size in our model. Disturbance more strongly regulated FCL in smaller ecosystems, where species richness was low. Similarly, increasing ecosystem size enhanced FCL under strong, but not weak, disturbance regimes. Our study suggests that internal food web structure should deepen our understanding of how FCL changes over environments.
{"title":"Food web complexity modulates environmental impacts on food chain length","authors":"Shota Shibasaki, Akira Terui","doi":"10.1111/oik.10331","DOIUrl":"https://doi.org/10.1111/oik.10331","url":null,"abstract":"The determinants of food chain length (FCL), a crucial aspect of biodiversity due to its effects on ecosystem functioning, have long been debated. Previous studies proposed resource availability, disturbance, and ecosystem size as environmental drivers. However, studies using stable isotope approaches have shown inconsistent results, indicating missing links between environmental drivers and FCL. Here, we hypothesized that species richness and motifs (i.e. three‐species subgraphs) modulated environmental effects on FCL. Combining empirical food webs with our <jats:italic>N</jats:italic>‐species food web model, we found that FCL disproportionately changed at low species richness, with saturation at high species richness. This functional response was essential to the interdependent effects of disturbance and ecosystem size in our model. Disturbance more strongly regulated FCL in smaller ecosystems, where species richness was low. Similarly, increasing ecosystem size enhanced FCL under strong, but not weak, disturbance regimes. Our study suggests that internal food web structure should deepen our understanding of how FCL changes over environments.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alyssa R. Cirtwill, Helena Wirta, Riikka Kaartinen, Gavin Ballantyne, Graham N. Stone, Helen Cunnold, Mikko Tiusanen, Tomas Roslin
Most animal pollination results from plant–insect interactions, but how we perceive these interactions may differ with the sampling method adopted. The two most common methods are observations of visits by pollinators to plants and observations of pollen loads carried by insects. Each method could favour the detection of different species and interactions, and pollen load observations typically reveal more interactions per individual insect than visit observations. Moreover, while observations concern plant and insect individuals, networks are frequently analysed at the level of species. Although networks constructed using visitation and pollen‐load data have occasionally been compared in relatively specialised, bee‐dominated systems, it is not known how sampling methodology will affect our perception of how species (and individuals within species) interact in a more generalist system. Here we use a Diptera‐dominated high‐Arctic plant–insect community to explore how sampling approach shapes several measures of species' interactions (focusing on specialisation), and what we can learn about how the interactions of individuals relate to those of species. We found that species degrees, interaction strengths, and species motif roles were significantly correlated across the two method‐specific versions of the network. However, absolute differences in degrees and motif roles were greater than could be explained by the greater number of interactions per individual provided by the pollen‐load data. Thus, despite the correlations between species roles in networks built using visitation and pollen‐load data, we infer that these two perspectives yield fundamentally different summaries of the ways species fit into their communities. Further, individuals' roles generally predicted the species' overall role, but high variability among individuals means that species' roles cannot be used to predict those of particular individuals. These findings emphasize the importance of adopting a dual perspective on bipartite networks, as based on the different information inherent in insect visits and pollen loads.
{"title":"Flower‐visitor and pollen‐load data provide complementary insight into species and individual network roles","authors":"Alyssa R. Cirtwill, Helena Wirta, Riikka Kaartinen, Gavin Ballantyne, Graham N. Stone, Helen Cunnold, Mikko Tiusanen, Tomas Roslin","doi":"10.1111/oik.10301","DOIUrl":"https://doi.org/10.1111/oik.10301","url":null,"abstract":"Most animal pollination results from plant–insect interactions, but how we perceive these interactions may differ with the sampling method adopted. The two most common methods are observations of visits by pollinators to plants and observations of pollen loads carried by insects. Each method could favour the detection of different species and interactions, and pollen load observations typically reveal more interactions per individual insect than visit observations. Moreover, while observations concern plant and insect individuals, networks are frequently analysed at the level of species. Although networks constructed using visitation and pollen‐load data have occasionally been compared in relatively specialised, bee‐dominated systems, it is not known how sampling methodology will affect our perception of how species (and individuals within species) interact in a more generalist system. Here we use a Diptera‐dominated high‐Arctic plant–insect community to explore how sampling approach shapes several measures of species' interactions (focusing on specialisation), and what we can learn about how the interactions of individuals relate to those of species. We found that species degrees, interaction strengths, and species motif roles were significantly correlated across the two method‐specific versions of the network. However, absolute differences in degrees and motif roles were greater than could be explained by the greater number of interactions per individual provided by the pollen‐load data. Thus, despite the correlations between species roles in networks built using visitation and pollen‐load data, we infer that these two perspectives yield fundamentally different summaries of the ways species fit into their communities. Further, individuals' roles generally predicted the species' overall role, but high variability among individuals means that species' roles cannot be used to predict those of particular individuals. These findings emphasize the importance of adopting a dual perspective on bipartite networks, as based on the different information inherent in insect visits and pollen loads.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Maglianesi, I. Varassin, Gerardo Ávalos, L. Jorge
Specialisation in food resource use is a crucial process that fosters species coexistence in plant–animal networks, contributing to the maintenance of biodiversity, ecological complexity, and community stability. Notably, although there is a vast literature on ecological specialisation in pollination systems, the evolutionary similarity among the plant species visited by particular pollinators has been largely ignored. Here, we apply a robust phylogenetic approach to analyse whether the evolutionary relatedness of plant species is a significant factor in mediating pollinator visits and how it relates to the morphology of interacting species. We quantified ecological and clade specialisation of hummingbird and insect species in three mutualistic networks from the Costa Rican highlands and associated these metrics with species traits. We found that hummingbirds were overall ecologically more specialised than insects (i.e. visited a less diverse set of plant species). However, when evaluating the phylogenetic relatedness among the visited plant species, all hummingbird species and most insects had overdispersed diets, which indicates they visited phylogenetically distant plant species in the community. Moreover, a great proportion of these clade generalists visited plant species with a great variation in corolla length, showing a lack of preference for this morphological trait. Altogether, our results demonstrate that by incorporating plant phylogeny to network analysis, pollinator species were generalists and that corolla length weakly influences plant–pollinator interactions in the three studied networks. A phylogenetic perspective should occupy a central role in the study of specialisation since it contributes to understanding the interplay between ecological and evolutionary processes in mutualistic networks. Future research should focus on evaluating whether the phylogenetic structure of animal diets mediates patterns of interactions in different types of mutualisms and environmental contexts, linking these patterns to other floral traits. This knowledge may be valuable for deepening our comprehension of the underlying mechanisms shaping ecological networks.
{"title":"A phylogenetic perspective on ecological specialisation reveals hummingbird and insect pollinators have generalist diets","authors":"M. Maglianesi, I. Varassin, Gerardo Ávalos, L. Jorge","doi":"10.1111/oik.10208","DOIUrl":"https://doi.org/10.1111/oik.10208","url":null,"abstract":"Specialisation in food resource use is a crucial process that fosters species coexistence in plant–animal networks, contributing to the maintenance of biodiversity, ecological complexity, and community stability. Notably, although there is a vast literature on ecological specialisation in pollination systems, the evolutionary similarity among the plant species visited by particular pollinators has been largely ignored. Here, we apply a robust phylogenetic approach to analyse whether the evolutionary relatedness of plant species is a significant factor in mediating pollinator visits and how it relates to the morphology of interacting species. We quantified ecological and clade specialisation of hummingbird and insect species in three mutualistic networks from the Costa Rican highlands and associated these metrics with species traits. We found that hummingbirds were overall ecologically more specialised than insects (i.e. visited a less diverse set of plant species). However, when evaluating the phylogenetic relatedness among the visited plant species, all hummingbird species and most insects had overdispersed diets, which indicates they visited phylogenetically distant plant species in the community. Moreover, a great proportion of these clade generalists visited plant species with a great variation in corolla length, showing a lack of preference for this morphological trait. Altogether, our results demonstrate that by incorporating plant phylogeny to network analysis, pollinator species were generalists and that corolla length weakly influences plant–pollinator interactions in the three studied networks. A phylogenetic perspective should occupy a central role in the study of specialisation since it contributes to understanding the interplay between ecological and evolutionary processes in mutualistic networks. Future research should focus on evaluating whether the phylogenetic structure of animal diets mediates patterns of interactions in different types of mutualisms and environmental contexts, linking these patterns to other floral traits. This knowledge may be valuable for deepening our comprehension of the underlying mechanisms shaping ecological networks.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139778858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Maglianesi, I. Varassin, Gerardo Ávalos, L. Jorge
Specialisation in food resource use is a crucial process that fosters species coexistence in plant–animal networks, contributing to the maintenance of biodiversity, ecological complexity, and community stability. Notably, although there is a vast literature on ecological specialisation in pollination systems, the evolutionary similarity among the plant species visited by particular pollinators has been largely ignored. Here, we apply a robust phylogenetic approach to analyse whether the evolutionary relatedness of plant species is a significant factor in mediating pollinator visits and how it relates to the morphology of interacting species. We quantified ecological and clade specialisation of hummingbird and insect species in three mutualistic networks from the Costa Rican highlands and associated these metrics with species traits. We found that hummingbirds were overall ecologically more specialised than insects (i.e. visited a less diverse set of plant species). However, when evaluating the phylogenetic relatedness among the visited plant species, all hummingbird species and most insects had overdispersed diets, which indicates they visited phylogenetically distant plant species in the community. Moreover, a great proportion of these clade generalists visited plant species with a great variation in corolla length, showing a lack of preference for this morphological trait. Altogether, our results demonstrate that by incorporating plant phylogeny to network analysis, pollinator species were generalists and that corolla length weakly influences plant–pollinator interactions in the three studied networks. A phylogenetic perspective should occupy a central role in the study of specialisation since it contributes to understanding the interplay between ecological and evolutionary processes in mutualistic networks. Future research should focus on evaluating whether the phylogenetic structure of animal diets mediates patterns of interactions in different types of mutualisms and environmental contexts, linking these patterns to other floral traits. This knowledge may be valuable for deepening our comprehension of the underlying mechanisms shaping ecological networks.
{"title":"A phylogenetic perspective on ecological specialisation reveals hummingbird and insect pollinators have generalist diets","authors":"M. Maglianesi, I. Varassin, Gerardo Ávalos, L. Jorge","doi":"10.1111/oik.10208","DOIUrl":"https://doi.org/10.1111/oik.10208","url":null,"abstract":"Specialisation in food resource use is a crucial process that fosters species coexistence in plant–animal networks, contributing to the maintenance of biodiversity, ecological complexity, and community stability. Notably, although there is a vast literature on ecological specialisation in pollination systems, the evolutionary similarity among the plant species visited by particular pollinators has been largely ignored. Here, we apply a robust phylogenetic approach to analyse whether the evolutionary relatedness of plant species is a significant factor in mediating pollinator visits and how it relates to the morphology of interacting species. We quantified ecological and clade specialisation of hummingbird and insect species in three mutualistic networks from the Costa Rican highlands and associated these metrics with species traits. We found that hummingbirds were overall ecologically more specialised than insects (i.e. visited a less diverse set of plant species). However, when evaluating the phylogenetic relatedness among the visited plant species, all hummingbird species and most insects had overdispersed diets, which indicates they visited phylogenetically distant plant species in the community. Moreover, a great proportion of these clade generalists visited plant species with a great variation in corolla length, showing a lack of preference for this morphological trait. Altogether, our results demonstrate that by incorporating plant phylogeny to network analysis, pollinator species were generalists and that corolla length weakly influences plant–pollinator interactions in the three studied networks. A phylogenetic perspective should occupy a central role in the study of specialisation since it contributes to understanding the interplay between ecological and evolutionary processes in mutualistic networks. Future research should focus on evaluating whether the phylogenetic structure of animal diets mediates patterns of interactions in different types of mutualisms and environmental contexts, linking these patterns to other floral traits. This knowledge may be valuable for deepening our comprehension of the underlying mechanisms shaping ecological networks.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139838693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Plants and insect herbivores are two of the most diverse multicellular groups in the world, and both are strongly influenced by interactions with the belowground soil microbiome. Effects of reciprocal rapid evolution on ecological interactions between herbivores and plants have been repeatedly demonstrated, but it is unknown if (and how) the soil microbiome could mediate these eco-evolutionary processes on a shared host plant. We tested the role of a plant-beneficial soil bacterium Acidovorax radicis in altering eco-evolutionary interactions between different aphid genotypes (Sitobion avenae, genotypes Sickte and Fescue) feeding on barley Hordeum vulgare. We measured fecundity, longevity and population growth of two aphid genotypes reared separately or together (population mixture) on three different barley varieties that were inoculated with or without A. radicis. Results showed that across all plant varieties A. radicis increased plant growth and suppressed aphid populations via reduced longevity and fecundity. The strength of effect was dependent on aphid genotype and barley variety, while the direction of effect was altered by aphid population mixture. Using Lotka–Volterra modelling, we demonstrated that while A. radicis inoculation decreased growth rates for both aphid genotypes it increased the competitiveness of one genotype against the other. In general, in the presence of A. radicis, the Fescue aphid genotype became more inhibitory of Sickte aphids, while Sickte aphids facilitated the growth of Fescue aphids. Our work demonstrates that plant rhizosphere microbiomes exert community-level influences by mediating eco-evolutionary interactions between herbivores and host plants. By altering competitive interaction outcomes among aphids and thus impacting processes such as rapid evolution, soil microbes contribute to the short- and long-term structure and functioning of terrestrial habitats.
{"title":"Microbe-induced plant resistance alters aphid inter-genotypic competition leading to rapid evolution with consequences for plant growth and aphid abundance","authors":"Xinqiang Xi, Andrew Dean, Sharon E. Zytynska","doi":"10.1111/oik.10426","DOIUrl":"https://doi.org/10.1111/oik.10426","url":null,"abstract":"Plants and insect herbivores are two of the most diverse multicellular groups in the world, and both are strongly influenced by interactions with the belowground soil microbiome. Effects of reciprocal rapid evolution on ecological interactions between herbivores and plants have been repeatedly demonstrated, but it is unknown if (and how) the soil microbiome could mediate these eco-evolutionary processes on a shared host plant. We tested the role of a plant-beneficial soil bacterium <i>Acidovorax radicis</i> in altering eco-evolutionary interactions between different aphid genotypes (<i>Sitobion avenae</i>, genotypes Sickte and Fescue) feeding on barley <i>Hordeum vulgare</i>. We measured fecundity, longevity and population growth of two aphid genotypes reared separately or together (population mixture) on three different barley varieties that were inoculated with or without <i>A. radicis</i>. Results showed that across all plant varieties <i>A. radicis</i> increased plant growth and suppressed aphid populations via reduced longevity and fecundity. The strength of effect was dependent on aphid genotype and barley variety, while the direction of effect was altered by aphid population mixture. Using Lotka–Volterra modelling, we demonstrated that while <i>A. radicis</i> inoculation decreased growth rates for both aphid genotypes it increased the competitiveness of one genotype against the other. In general, in the presence of <i>A. radicis</i>, the Fescue aphid genotype became more inhibitory of Sickte aphids, while Sickte aphids facilitated the growth of Fescue aphids. Our work demonstrates that plant rhizosphere microbiomes exert community-level influences by mediating eco-evolutionary interactions between herbivores and host plants. By altering competitive interaction outcomes among aphids and thus impacting processes such as rapid evolution, soil microbes contribute to the short- and long-term structure and functioning of terrestrial habitats.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139765764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Pérez-Toledo, M. Cuautle, C. Castillo-Guevara, J. G. Miguelena
Biodiversity is declining at various scales due to habitat simplification. Nevertheless, there is scarce information on how the biotic and abiotic changes linked to simplification affect several diversity dimensions, such as taxonomic, functional, and phylogenetic diversities. This study investigated whether transforming natural oak forests into induced grasslands affected species diversity, functional group structure, and phylogenetic diversity of ant assemblages inhabiting a temperate forest in central Mexico. We placed over 1000 pitfall traps in five sampling events covering a ten-year period. We used Hill numbers to evaluate species diversity differences between vegetation types and patterns over time. Ant species were classified into stress-related functional groups, which were analyzed for their association with vegetation types and changes to their proportional abundance over time. We calculated the standardized effect size of the mean nearest taxon distance to quantify the evolutionary history and test for non-random patterns within vegetation types and sampling years. Species richness did not differ between vegetation types, yet grasslands showed greater diversity for the q = 1 and q = 2 orders. , We also found three ant species as bioindicators for each type of vegetation. Regarding functional structure, cold climate specialists were associated with oak forests. In contrast, generalist species were predominant in induced grasslands. Higher phylogenetic diversity with an overdispersed structure was associated with oak forest, whereas lower phylogenetic diversity and a clustered pattern were found in induced grassland. These results indicate that habitat simplification may not affect the number of ant species, but rather increases their relative abundance and reorganizes the functional and phylogenetic structure in the ecosystem, particularly shifting towards the dominance of evolutionary closely related species and broad-stress-tolerant groups. These results highlight the importance of integrating further dimensions of diversity to properly evaluate the reassembly dynamics after habitat simplification, and understand the mechanisms driving this biodiversity loss.
{"title":"Habitat simplification affects functional group structure along with taxonomic and phylogenetic diversity of temperate-zone ant assemblages over a ten-year period","authors":"G. Pérez-Toledo, M. Cuautle, C. Castillo-Guevara, J. G. Miguelena","doi":"10.1111/oik.10472","DOIUrl":"https://doi.org/10.1111/oik.10472","url":null,"abstract":"Biodiversity is declining at various scales due to habitat simplification. Nevertheless, there is scarce information on how the biotic and abiotic changes linked to simplification affect several diversity dimensions, such as taxonomic, functional, and phylogenetic diversities. This study investigated whether transforming natural oak forests into induced grasslands affected species diversity, functional group structure, and phylogenetic diversity of ant assemblages inhabiting a temperate forest in central Mexico. We placed over 1000 pitfall traps in five sampling events covering a ten-year period. We used Hill numbers to evaluate species diversity differences between vegetation types and patterns over time. Ant species were classified into stress-related functional groups, which were analyzed for their association with vegetation types and changes to their proportional abundance over time. We calculated the standardized effect size of the mean nearest taxon distance to quantify the evolutionary history and test for non-random patterns within vegetation types and sampling years. Species richness did not differ between vegetation types, yet grasslands showed greater diversity for the q = 1 and q = 2 orders. , We also found three ant species as bioindicators for each type of vegetation. Regarding functional structure, cold climate specialists were associated with oak forests. In contrast, generalist species were predominant in induced grasslands. Higher phylogenetic diversity with an overdispersed structure was associated with oak forest, whereas lower phylogenetic diversity and a clustered pattern were found in induced grassland. These results indicate that habitat simplification may not affect the number of ant species, but rather increases their relative abundance and reorganizes the functional and phylogenetic structure in the ecosystem, particularly shifting towards the dominance of evolutionary closely related species and broad-stress-tolerant groups. These results highlight the importance of integrating further dimensions of diversity to properly evaluate the reassembly dynamics after habitat simplification, and understand the mechanisms driving this biodiversity loss.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139766061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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