Lance T. Vermeire, Kurt O. Reinhart, Jacqueline Ott
Disturbance seasonality and return interval can create complex interactions of direct and indirect effects on species and ecosystems. Fire is a key grassland disturbance, yet long‐term research examining seasonality and return intervals is limited. A 15‐year experiment testing combinations of fire seasonality (summer, fall, spring) and return interval (2, 3, 6‐year) plus non‐burned controls was conducted in northern mixed prairie to evaluate effects on the plant community. Hesperostipa comata is a native C3 bunchgrass and dominant species in northern mixed prairie and previously observed to be fire‐sensitive. Current‐year aboveground biomass results were generally counter to expectations based on short‐term research. Fire increased H. comata biomass with a strong, rhythmic response pattern to a specific fire seasonality‐return‐interval combination (fall fire at 3‐year return intervals) that periodically increased biomass to more than three times that with no fire. Through the first four post‐fire growing seasons, biomass with summer, fall and spring fire across return intervals was 41, 89 and 93% of that with no fire. Afterward, no fire combination produced less biomass than no fire and recurring patterns emerged with large increases in biomass, particularly with fall fire at 3‐year intervals. Peak biomass years were regularly two growing seasons after 3‐year fall fire and occurred across wet, near‐average and dry conditions. We hypothesize that productivity responses were driven by the combination of demographic processes of seedling recruitment and synchronization of multiple tiller age classes. Because short‐term negative effects were reversed and regular patterns only emerged 5 years after study initiation, more long‐term research evaluating fire regimes is recommended to expand upon tests of individual factors over short periods. This suggestion is based on fire research, but likely applies to multiple forms of disturbance and demonstrates how demographic processes can inform responses for individual species and larger ecosystem functions, such as productivity.
{"title":"Do plants respond to multi‐year disturbance rhythms and are we missing the beat?","authors":"Lance T. Vermeire, Kurt O. Reinhart, Jacqueline Ott","doi":"10.1111/oik.10791","DOIUrl":"https://doi.org/10.1111/oik.10791","url":null,"abstract":"Disturbance seasonality and return interval can create complex interactions of direct and indirect effects on species and ecosystems. Fire is a key grassland disturbance, yet long‐term research examining seasonality and return intervals is limited. A 15‐year experiment testing combinations of fire seasonality (summer, fall, spring) and return interval (2, 3, 6‐year) plus non‐burned controls was conducted in northern mixed prairie to evaluate effects on the plant community. <jats:italic>Hesperostipa comata</jats:italic> is a native C<jats:sub>3</jats:sub> bunchgrass and dominant species in northern mixed prairie and previously observed to be fire‐sensitive. Current‐year aboveground biomass results were generally counter to expectations based on short‐term research. Fire increased <jats:italic>H. comata</jats:italic> biomass with a strong, rhythmic response pattern to a specific fire seasonality‐return‐interval combination (fall fire at 3‐year return intervals) that periodically increased biomass to more than three times that with no fire. Through the first four post‐fire growing seasons, biomass with summer, fall and spring fire across return intervals was 41, 89 and 93% of that with no fire. Afterward, no fire combination produced less biomass than no fire and recurring patterns emerged with large increases in biomass, particularly with fall fire at 3‐year intervals. Peak biomass years were regularly two growing seasons after 3‐year fall fire and occurred across wet, near‐average and dry conditions. We hypothesize that productivity responses were driven by the combination of demographic processes of seedling recruitment and synchronization of multiple tiller age classes. Because short‐term negative effects were reversed and regular patterns only emerged 5 years after study initiation, more long‐term research evaluating fire regimes is recommended to expand upon tests of individual factors over short periods. This suggestion is based on fire research, but likely applies to multiple forms of disturbance and demonstrates how demographic processes can inform responses for individual species and larger ecosystem functions, such as productivity.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255123","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}
Forest productivity is a crucial integrator of ecosystem functions and services. Although the effects of landscape structure on species richness and stand structure have been extensively studied, how landscape structures affect forest productivity and their interactions with stand‐level attributes, especially in the context of considerable land use change, remain unclear. In this study, we investigated the effects of landscape structures (fragmentation, complexity, and heterogeneity) and their interactions with stand‐level attributes on forest productivity in the conterminous United States across three spatial scales (1–3 km), using an extensive forest inventory dataset from the national forest inventories (NFI) plots. Our results revealed that all landscape indices around selected forest plots significantly increased from 2006 to 2016. Across three scales, forest productivity and stand‐level attributes (number of trees, tree species richness, and structural diversity) exhibited unimodal relationships with landscape fragmentation and complexity, while generally showed positive correlations with landscape heterogeneity. The interactions between landscape structures and stand attributes enhanced the explanatory power of forest productivity. Landscape complexity directly or indirectly reduced forest productivity by decreasing the number of trees and tree species richness, whereas landscape fragmentation and heterogeneity had the opposite effects. Furthermore, landscape heterogeneity and stand age had relatively stronger total effects (the sum of direct and indirect effects) on forest productivity, and their strength increased modestly with spatial scales. However, tree species richness consistently had the lowest total effects. Our study elucidates the complex driving mechanisms of landscape patterns on forest productivity across spatial scales, providing a deeper understanding of ecosystem complexity and responses to accelerating land use changes.
{"title":"Landscape structures and stand attributes jointly regulate forest productivity","authors":"Hengchao Zou, Huayong Zhang","doi":"10.1111/oik.10749","DOIUrl":"https://doi.org/10.1111/oik.10749","url":null,"abstract":"Forest productivity is a crucial integrator of ecosystem functions and services. Although the effects of landscape structure on species richness and stand structure have been extensively studied, how landscape structures affect forest productivity and their interactions with stand‐level attributes, especially in the context of considerable land use change, remain unclear. In this study, we investigated the effects of landscape structures (fragmentation, complexity, and heterogeneity) and their interactions with stand‐level attributes on forest productivity in the conterminous United States across three spatial scales (1–3 km), using an extensive forest inventory dataset from the national forest inventories (NFI) plots. Our results revealed that all landscape indices around selected forest plots significantly increased from 2006 to 2016. Across three scales, forest productivity and stand‐level attributes (number of trees, tree species richness, and structural diversity) exhibited unimodal relationships with landscape fragmentation and complexity, while generally showed positive correlations with landscape heterogeneity. The interactions between landscape structures and stand attributes enhanced the explanatory power of forest productivity. Landscape complexity directly or indirectly reduced forest productivity by decreasing the number of trees and tree species richness, whereas landscape fragmentation and heterogeneity had the opposite effects. Furthermore, landscape heterogeneity and stand age had relatively stronger total effects (the sum of direct and indirect effects) on forest productivity, and their strength increased modestly with spatial scales. However, tree species richness consistently had the lowest total effects. Our study elucidates the complex driving mechanisms of landscape patterns on forest productivity across spatial scales, providing a deeper understanding of ecosystem complexity and responses to accelerating land use changes.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255162","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 importance of fine‐root diameter for ecosystem functioning is increasingly recognized, yet much remains to be learned about the variation in fine‐root diameter at large scales. We conducted an analysis of fine‐root diameter for five root orders for 1163 plant species to detect patterns in relation to resource availability (e.g. carbon, nitrogen, water and net primary production (NPP)), stress intensity (e.g. plant/soil biodiversity and soil bulk density) and temperature. First‐ to fourth‐order root diameters showed non‐linear relationships with mean annual temperature (except for first‐order root diameter) and/or with latitude. The diameters of the five root orders decreased with increasing mean annual precipitation, but increased with greater NPP, which was the strongest determinant of fine‐root diameter. Increasing soil biodiversity was associated with decreasing diameters of fourth‐ and fifth‐order roots, while greater plant biodiversity was associated with decreasing diameters of first‐ to third‐order roots. Soil total nitrogen concentration had a positive effect on first‐order root diameter but a negative effect on fourth‐ and fifth‐order root diameters. The patterns reversed for soil total phosphorus concentration. First‐ to third‐order and fifth‐order root diameters increased with greater soil bulk density. Second‐ to fourth‐order root diameters increased with higher soil pH. Overall, the variables related to climatic, biological and edaphic factors explained 44–63% of the total variance in the diameters of the different root orders. The unique patterns of plasticity observed in fine‐root diameter across root orders in response to varying environmental conditions contributes to a diversification of plant strategies for nutrient/water acquisition and transport under climate change.
{"title":"Linking fine‐root diameter across root orders with climatic, biological and edaphic factors in the Northern Hemisphere","authors":"Wei Guo, Cunguo Wang, Ivano Brunner, Qinrong Tang, Junni Wang, Yingtong Zhou, Mai‐He Li","doi":"10.1111/oik.10763","DOIUrl":"https://doi.org/10.1111/oik.10763","url":null,"abstract":"The importance of fine‐root diameter for ecosystem functioning is increasingly recognized, yet much remains to be learned about the variation in fine‐root diameter at large scales. We conducted an analysis of fine‐root diameter for five root orders for 1163 plant species to detect patterns in relation to resource availability (e.g. carbon, nitrogen, water and net primary production (NPP)), stress intensity (e.g. plant/soil biodiversity and soil bulk density) and temperature. First‐ to fourth‐order root diameters showed non‐linear relationships with mean annual temperature (except for first‐order root diameter) and/or with latitude. The diameters of the five root orders decreased with increasing mean annual precipitation, but increased with greater NPP, which was the strongest determinant of fine‐root diameter. Increasing soil biodiversity was associated with decreasing diameters of fourth‐ and fifth‐order roots, while greater plant biodiversity was associated with decreasing diameters of first‐ to third‐order roots. Soil total nitrogen concentration had a positive effect on first‐order root diameter but a negative effect on fourth‐ and fifth‐order root diameters. The patterns reversed for soil total phosphorus concentration. First‐ to third‐order and fifth‐order root diameters increased with greater soil bulk density. Second‐ to fourth‐order root diameters increased with higher soil pH. Overall, the variables related to climatic, biological and edaphic factors explained 44–63% of the total variance in the diameters of the different root orders. The unique patterns of plasticity observed in fine‐root diameter across root orders in response to varying environmental conditions contributes to a diversification of plant strategies for nutrient/water acquisition and transport under climate change.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255122","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}
Jorge A. Martínez‐Villegas, Irene Pisanty, Carlos Martorell, Mariana Hernández‐Apolinar, Teresa Valverde, Luisa A. Granados‐Hernández, Mariana Rodríguez‐Sánchez, J. Jaime Zúñiga‐Vega
Detection of plant individuals is imperfect. Not accounting for this issue can result in biased estimates of demographic parameters as important as population growth rates. In mobile organisms, a common practice is to explicitly account for detection probability during the estimation of most demographic parameters, but no study in plant populations has examined the consequences of ignoring imperfect detectability on the estimation of population growth rates. The lack of accounting for detection probability occurs because plant demographers have frequently assumed that detection is perfect, and because there is a scarcity of studies that formally compare the performance of estimation methods that incorporate detection probabilities with respect to methods that ignore detectabilities. Based on field data of five plant species and data simulations, we compared the performance of three methods that estimate population growth rates, two that do not estimate detection probabilities (direct counts of individuals and the minimum‐number‐alive method) and the other that explicitly accounts for detection probabilities (temporal symmetry models). Our aims were 1) to estimate detection probabilities, and 2) to evaluate the performance of these three methods by calculating bias, accuracy, and precision in their estimates of population growth rates. Our five plant species had imperfect detection. Estimates of population growth rates that explicitly incorporate detectabilities had better performance (less biased estimates, with higher accuracy and precision) than those obtained with the two methods that do not calculate detection probabilities. In these latter methods, bias increases as detection probability decreases. Our findings highlight the importance of using robust analytical methods that account for detection probability of plants during the estimation of critical demographic parameters such as population growth rates. In this way, estimates of plant population parameters will reliably indicate their actual status and quantitative trends.
{"title":"Importance of accounting for imperfect detection of plants in the estimation of population growth rates","authors":"Jorge A. Martínez‐Villegas, Irene Pisanty, Carlos Martorell, Mariana Hernández‐Apolinar, Teresa Valverde, Luisa A. Granados‐Hernández, Mariana Rodríguez‐Sánchez, J. Jaime Zúñiga‐Vega","doi":"10.1111/oik.10708","DOIUrl":"https://doi.org/10.1111/oik.10708","url":null,"abstract":"Detection of plant individuals is imperfect. Not accounting for this issue can result in biased estimates of demographic parameters as important as population growth rates. In mobile organisms, a common practice is to explicitly account for detection probability during the estimation of most demographic parameters, but no study in plant populations has examined the consequences of ignoring imperfect detectability on the estimation of population growth rates. The lack of accounting for detection probability occurs because plant demographers have frequently assumed that detection is perfect, and because there is a scarcity of studies that formally compare the performance of estimation methods that incorporate detection probabilities with respect to methods that ignore detectabilities. Based on field data of five plant species and data simulations, we compared the performance of three methods that estimate population growth rates, two that do not estimate detection probabilities (direct counts of individuals and the minimum‐number‐alive method) and the other that explicitly accounts for detection probabilities (temporal symmetry models). Our aims were 1) to estimate detection probabilities, and 2) to evaluate the performance of these three methods by calculating bias, accuracy, and precision in their estimates of population growth rates. Our five plant species had imperfect detection. Estimates of population growth rates that explicitly incorporate detectabilities had better performance (less biased estimates, with higher accuracy and precision) than those obtained with the two methods that do not calculate detection probabilities. In these latter methods, bias increases as detection probability decreases. Our findings highlight the importance of using robust analytical methods that account for detection probability of plants during the estimation of critical demographic parameters such as population growth rates. In this way, estimates of plant population parameters will reliably indicate their actual status and quantitative trends.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255124","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}
Oliver Mitesser, Florian Menzel, Susanne Foitzik, Thomas Schmitt, Thomas Hovestadt
Nestmate recognition is a widespread phenomenon and evolutionary important trait in the social insects. Yet evidence accumulates that the responses to non‐nestmates varies more than previously thought. We present a simple frequency‐dependent cost‐benefit model of nestmate recognition to understand conditions that might or might not favor the evolution of nestmate recognition that is based on cuticular hydrocarbon (CHC) profiles. Costs accounted for are costs for 1) maintaining a functional recognition system and 2) keeping a CHC profile that may be sub‐optimal regarding other functionalities like desiccation control, whereas the benefit of recognition is the prevention of nest raiding by other colonies. Unsurprisingly, the model indicates that recognition systems only evolve if costs are sufficiently low and benefits sufficiently high. In addition, the model suggests that nestmate recognition is more likely to evolve if colony turnover is fast (colony life‐expectancy is low). Our model creates evolutionary cycles that are typically longest under parameter combinations that just allow the evolution of recognition systems at all; the system expresses attributes of a rock‐paper‐scissors game. The model shows that a breakdown of nestmate recognition may occur under changing ecological situations, e.g. as a result of reduced intraspecific competition or increased abiotic stress. We speculate that such effects may be involved in the formation of supercolonies during invasions. Nestmate recognition may have evolved more to prevent interspecific predation or parasitism by antagonists that managed to mimic their host's CHC profile than as a mechanism to prevent exploitation by conspecific colonies.
{"title":"Evolutionary cycles in a model of nestmate recognition","authors":"Oliver Mitesser, Florian Menzel, Susanne Foitzik, Thomas Schmitt, Thomas Hovestadt","doi":"10.1111/oik.10509","DOIUrl":"https://doi.org/10.1111/oik.10509","url":null,"abstract":"Nestmate recognition is a widespread phenomenon and evolutionary important trait in the social insects. Yet evidence accumulates that the responses to non‐nestmates varies more than previously thought. We present a simple frequency‐dependent cost‐benefit model of nestmate recognition to understand conditions that might or might not favor the evolution of nestmate recognition that is based on cuticular hydrocarbon (CHC) profiles. Costs accounted for are costs for 1) maintaining a functional recognition system and 2) keeping a CHC profile that may be sub‐optimal regarding other functionalities like desiccation control, whereas the benefit of recognition is the prevention of nest raiding by other colonies. Unsurprisingly, the model indicates that recognition systems only evolve if costs are sufficiently low and benefits sufficiently high. In addition, the model suggests that nestmate recognition is more likely to evolve if colony turnover is fast (colony life‐expectancy is low). Our model creates evolutionary cycles that are typically longest under parameter combinations that just allow the evolution of recognition systems at all; the system expresses attributes of a rock‐paper‐scissors game. The model shows that a breakdown of nestmate recognition may occur under changing ecological situations, e.g. as a result of reduced intraspecific competition or increased abiotic stress. We speculate that such effects may be involved in the formation of supercolonies during invasions. Nestmate recognition may have evolved more to prevent interspecific predation or parasitism by antagonists that managed to mimic their host's CHC profile than as a mechanism to prevent exploitation by conspecific colonies.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215583","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}
Charles W. Davison, Carsten Rahbek, Naia Morueta‐Holme
Our understanding of how human activities impact biodiversity comes largely from space‐for‐time substitutions. However, spatial gradients are a poor surrogate for changes through time as they do not account for dynamic processes such as delayed extinction debts. Here we contribute towards filling this research gap by assessing the trajectories of local avian assemblages over 40+ years of climate and land‐use change. Using four decades of volunteer observations in Denmark we investigated long‐term trends of local bird richness, community structure, function, abundance, and biomass to better understand their anthropogenic drivers. Between 1976 and 2020, volunteers recorded ~ 2.4 million birds at 378 routes spanning a median of 15 years (range: 10–44). At the local level, we found a restructuring of bird communities over time (6% change per decade) and declines in abundance (−7% per decade), but stability in biomass, functional diversity, and spatial turnover. Local species richness showed a shallow decline on average. These results provide evidence that temporal turnover and loss of individuals are the most prominent features of recent ecological change in these communities. We found that the rate of local warming was positively associated with trends of species richness and functional diversity, suggesting a potential redistribution of warm‐adapted species. Meanwhile, communities that were becoming more spatially homogenous were associated with urban and farmland areas. In space, environmental changes are often distinct and recognisable, e.g. between forest and farmland. Through time, however, changes can be infrequent, gradual, and non‐linear. Despite these challenges, our results illustrate the power of spatially replicated, long‐term biodiversity monitoring programs for detecting the trends and attributing drivers of local biodiversity change.
{"title":"Changes in Danish bird communities over four decades of climate and land‐use change","authors":"Charles W. Davison, Carsten Rahbek, Naia Morueta‐Holme","doi":"10.1111/oik.10697","DOIUrl":"https://doi.org/10.1111/oik.10697","url":null,"abstract":"Our understanding of how human activities impact biodiversity comes largely from space‐for‐time substitutions. However, spatial gradients are a poor surrogate for changes through time as they do not account for dynamic processes such as delayed extinction debts. Here we contribute towards filling this research gap by assessing the trajectories of local avian assemblages over 40+ years of climate and land‐use change. Using four decades of volunteer observations in Denmark we investigated long‐term trends of local bird richness, community structure, function, abundance, and biomass to better understand their anthropogenic drivers. Between 1976 and 2020, volunteers recorded ~ 2.4 million birds at 378 routes spanning a median of 15 years (range: 10–44). At the local level, we found a restructuring of bird communities over time (6% change per decade) and declines in abundance (−7% per decade), but stability in biomass, functional diversity, and spatial turnover. Local species richness showed a shallow decline on average. These results provide evidence that temporal turnover and loss of individuals are the most prominent features of recent ecological change in these communities. We found that the rate of local warming was positively associated with trends of species richness and functional diversity, suggesting a potential redistribution of warm‐adapted species. Meanwhile, communities that were becoming more spatially homogenous were associated with urban and farmland areas. In space, environmental changes are often distinct and recognisable, e.g. between forest and farmland. Through time, however, changes can be infrequent, gradual, and non‐linear. Despite these challenges, our results illustrate the power of spatially replicated, long‐term biodiversity monitoring programs for detecting the trends and attributing drivers of local biodiversity change.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215622","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}
Host–parasite interactions are influenced by present and past eco‐evolutionary interactions and the local environment. An ecological community defines the potential host range of each parasite and the potential parasite diversity of each host species. Past and present processes translate potential to realised interaction niches of parasite and host species. Host–parasite interactions are antagonistic, which may slow the saturation of their interaction niches. Intervality, a property of bipartite networks, measures saturation of interaction niches. Intervality of a community increases as the interaction niches of species of one guild (e.g. hosts) become saturated for their interactions with another guild (e.g. parasites). Characteristics driving intervality in host and parasite communities are largely unknown, as well as the effect of environmental change on intervality of these communities. In our study, we assess if the characteristics ‘phylogenetic relatedness' and ‘overlap in ecological interactions' explain intervality of rodent host–helminth parasite communities. In addition, we contrast intervality of these communities from habitats that differ in their history of human‐driven modification. We performed the analyses for the interaction niches of both parasites and hosts, independently. Our results indicated that host and parasite communities were non‐interval or significantly less interval than expected by chance. Phylogenetic relatedness and overlap in ecological interactions did not explain the maximum values of intervality. We speculate that antagonistic coevolution in host–parasite communities may hinder communities to reach saturation, which would explain why it is difficult to find the characteristics that explain intervality of a community. Interestingly, intervality of the interaction niche of parasites (host range) increased with habitat modification (i.e. saturation increased), whereas intervality of the interaction niche of hosts (parasite diversity) decreased as habitat modification increased. These opposite trends suggest that interaction niches of parasites and hosts respond differently to habitat modification.
{"title":"Host and parasite intervality in differentially human‐modified habitats","authors":"Cristina Llopis‐Belenguer, Frida Feijen, Serge Morand, Kittipong Chaisiri, Alexis Ribas, Jukka Jokela","doi":"10.1111/oik.10446","DOIUrl":"https://doi.org/10.1111/oik.10446","url":null,"abstract":"Host–parasite interactions are influenced by present and past eco‐evolutionary interactions and the local environment. An ecological community defines the potential host range of each parasite and the potential parasite diversity of each host species. Past and present processes translate potential to realised interaction niches of parasite and host species. Host–parasite interactions are antagonistic, which may slow the saturation of their interaction niches. Intervality, a property of bipartite networks, measures saturation of interaction niches. Intervality of a community increases as the interaction niches of species of one guild (e.g. hosts) become saturated for their interactions with another guild (e.g. parasites). Characteristics driving intervality in host and parasite communities are largely unknown, as well as the effect of environmental change on intervality of these communities. In our study, we assess if the characteristics ‘phylogenetic relatedness' and ‘overlap in ecological interactions' explain intervality of rodent host–helminth parasite communities. In addition, we contrast intervality of these communities from habitats that differ in their history of human‐driven modification. We performed the analyses for the interaction niches of both parasites and hosts, independently. Our results indicated that host and parasite communities were non‐interval or significantly less interval than expected by chance. Phylogenetic relatedness and overlap in ecological interactions did not explain the maximum values of intervality. We speculate that antagonistic coevolution in host–parasite communities may hinder communities to reach saturation, which would explain why it is difficult to find the characteristics that explain intervality of a community. Interestingly, intervality of the interaction niche of parasites (host range) increased with habitat modification (i.e. saturation increased), whereas intervality of the interaction niche of hosts (parasite diversity) decreased as habitat modification increased. These opposite trends suggest that interaction niches of parasites and hosts respond differently to habitat modification.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215584","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}
Matthias Pilecky, Aatu Turunen, Mohammad S. Sohrabi, Sadikshya Ghimire, Timo Ilo, Petri Kesti, Simon Vitecek, Lena Fehlinger, Jarkko Akkanen, Sami J. Taipale, Anssi Vainikka, Kimmo K. Kahilainen, Martin J. Kainz, Ursula Strandberg
Chironomids are keystone primary benthic consumers with semi‐aquatic life cycles. They support aquatic and terrestrial consumers at higher trophic levels by conveying dietary nutrients, such as fatty acids. In this study, we combined field sampling and laboratory experiments to examine the effects of environmental parameters, including diet, on fatty acid composition and metabolism in chironomid larvae and imagines. Results from 53 lakes showed that lake size, depth, dissolved organic carbon (DOC) concentrations, and trophic state had only marginal effects on the content of long‐chain polyunsaturated fatty acids (LC‐PUFA) in chironomids. Compound‐specific stable hydrogen isotope analyses confirmed that chironomids actively bioconvert dietary fatty acid precursors to LC‐PUFA in all lake types, independent of nutrient or DOC concentrations. Moreover, fatty acid‐specific stable carbon isotope data indicated that the diet of chironomids was subsidized, particularly in oligotrophic lakes in spring, by terrestrial C18 fatty acid precursors that were converted to LC‐PUFA. Data from feeding experiments further confirmed that decreased dietary availability of LC‐PUFA enhanced the conversion of dietary short‐chain precursors to LC‐PUFA. These results suggest that chironomids are PUFA regulators that can sustain LC‐PUFA levels under varying environmental conditions. Furthermore, our results indicate that they bioconvert terrestrial low‐quality material to high‐quality resources, which, via chironomid emergence, support terrestrial food webs. Chironomids are abundant and widespread, and thus, the trophic transfer of LC‐PUFA can have significant implications for the fitness and production of upper trophic level consumers in both aquatic and terrestrial ecosystems.
{"title":"Chironomids regulate long‐chain polyunsaturated fatty acid levels independent of lake nutrient or dissolved organic carbon concentrations","authors":"Matthias Pilecky, Aatu Turunen, Mohammad S. Sohrabi, Sadikshya Ghimire, Timo Ilo, Petri Kesti, Simon Vitecek, Lena Fehlinger, Jarkko Akkanen, Sami J. Taipale, Anssi Vainikka, Kimmo K. Kahilainen, Martin J. Kainz, Ursula Strandberg","doi":"10.1111/oik.10816","DOIUrl":"https://doi.org/10.1111/oik.10816","url":null,"abstract":"Chironomids are keystone primary benthic consumers with semi‐aquatic life cycles. They support aquatic and terrestrial consumers at higher trophic levels by conveying dietary nutrients, such as fatty acids. In this study, we combined field sampling and laboratory experiments to examine the effects of environmental parameters, including diet, on fatty acid composition and metabolism in chironomid larvae and imagines. Results from 53 lakes showed that lake size, depth, dissolved organic carbon (DOC) concentrations, and trophic state had only marginal effects on the content of long‐chain polyunsaturated fatty acids (LC‐PUFA) in chironomids. Compound‐specific stable hydrogen isotope analyses confirmed that chironomids actively bioconvert dietary fatty acid precursors to LC‐PUFA in all lake types, independent of nutrient or DOC concentrations. Moreover, fatty acid‐specific stable carbon isotope data indicated that the diet of chironomids was subsidized, particularly in oligotrophic lakes in spring, by terrestrial C<jats:sub>18</jats:sub> fatty acid precursors that were converted to LC‐PUFA. Data from feeding experiments further confirmed that decreased dietary availability of LC‐PUFA enhanced the conversion of dietary short‐chain precursors to LC‐PUFA. These results suggest that chironomids are PUFA regulators that can sustain LC‐PUFA levels under varying environmental conditions. Furthermore, our results indicate that they bioconvert terrestrial low‐quality material to high‐quality resources, which, via chironomid emergence, support terrestrial food webs. Chironomids are abundant and widespread, and thus, the trophic transfer of LC‐PUFA can have significant implications for the fitness and production of upper trophic level consumers in both aquatic and terrestrial ecosystems.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215585","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}
Niraj Meisuria, Emma E. Spencer, Rhys J. Cairncross, Mathew S. Crowther, Thomas M. Newsome
Apex scavengers can perform an important ecosystem service by rapidly removing carrion, in turn regulating nutrient cycling linked to carcass decomposition. Yet, our understanding of the biotic and abiotic factors that influence rates of apex scavenging and their behaviour around carrion remains limited, in part because of the absence of replicated studies across different bioregions, habitats and seasons. Here, we examine the use of carrion by one of Australia's apex scavengers, the wedge‐tailed eagle Aquila audax, and uncover the extent and consequences of their social interactions at carrion. We applied a standardised design to monitor 120 kangaroo (Family: Macropodidae) carcasses using camera traps across contrasting bioregions (desert, forest and alpine), habitats (open and closed canopy) and seasons (warm and cool). We predicted that wedge‐tailed eagles would discover carcasses quicker in open habitats, and that intrinsic carrion value (ICV), or the desirability of carrion, would be related to dietary stress as a function of productivity and season (i.e. we expected to see increased carcass use by eagles in the less productive desert bioregion and in cooler seasons). Across all bioregions, we found that wedge‐tailed eagles discovered carcasses in open habitats 2.7 times faster than in closed habitats and 5.3 times faster in cool seasons compared with warm seasons. Scavenging was less likely to occur in open environments, was more frequent in cool seasons and in the desert bioregion. ICV largely governed social interactions; there were more aggressive encounters between wedge‐tailed eagles during cool seasons and in the desert bioregion. Our results highlight how bioregional, habitat, and seasonal variation can drive scavenging rates and social interactions between conspecific apex scavengers. Further studies considering both carrion use and corresponding behavioural interactions will enhance our understanding of how carrion contributes to shaping interactions between and within species groups as well as scavenger communities more broadly.
{"title":"Scavenging and social interaction of an apex avian scavenger is governed by bioregional and seasonal variation","authors":"Niraj Meisuria, Emma E. Spencer, Rhys J. Cairncross, Mathew S. Crowther, Thomas M. Newsome","doi":"10.1111/oik.10826","DOIUrl":"https://doi.org/10.1111/oik.10826","url":null,"abstract":"Apex scavengers can perform an important ecosystem service by rapidly removing carrion, in turn regulating nutrient cycling linked to carcass decomposition. Yet, our understanding of the biotic and abiotic factors that influence rates of apex scavenging and their behaviour around carrion remains limited, in part because of the absence of replicated studies across different bioregions, habitats and seasons. Here, we examine the use of carrion by one of Australia's apex scavengers, the wedge‐tailed eagle <jats:italic>Aquila audax</jats:italic>, and uncover the extent and consequences of their social interactions at carrion. We applied a standardised design to monitor 120 kangaroo (Family: Macropodidae) carcasses using camera traps across contrasting bioregions (desert, forest and alpine), habitats (open and closed canopy) and seasons (warm and cool). We predicted that wedge‐tailed eagles would discover carcasses quicker in open habitats, and that intrinsic carrion value (ICV), or the desirability of carrion, would be related to dietary stress as a function of productivity and season (i.e. we expected to see increased carcass use by eagles in the less productive desert bioregion and in cooler seasons). Across all bioregions, we found that wedge‐tailed eagles discovered carcasses in open habitats 2.7 times faster than in closed habitats and 5.3 times faster in cool seasons compared with warm seasons. Scavenging was less likely to occur in open environments, was more frequent in cool seasons and in the desert bioregion. ICV largely governed social interactions; there were more aggressive encounters between wedge‐tailed eagles during cool seasons and in the desert bioregion. Our results highlight how bioregional, habitat, and seasonal variation can drive scavenging rates and social interactions between conspecific apex scavengers. Further studies considering both carrion use and corresponding behavioural interactions will enhance our understanding of how carrion contributes to shaping interactions between and within species groups as well as scavenger communities more broadly.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215624","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}
Ecological interactions between species can affect the performance of individuals, influence ecological and evolutionary dynamics of populations, and ultimately shape community structure. Therefore, documenting and studying interactions is necessary for a better comprehension of ecological patterns. Yet, sampling interactions in the field is challenging. Even with extensive sampling efforts we can hardly obtain a comprehensive picture of which species interact with each other. Such missing interactions can produce substantial gaps that affect how we perceive and interpret the network formed by species interactions and the roles of individual species within those networks. In this study we propose two methods that combine data on species interactions with information on species traits and phylogenies to estimate potentially missing interactions. We use one of the largest datasets on plant‐frugivore interactions, depicting thousands of interactions between birds and plants in the Atlantic Forest hotspot, to test those methods. Then, we analyze how adding newly estimated interactions change the network's overall structure and the topological importance of each species within the seed‐dispersal network. We show that estimated missing interactions more than tripled the number of interactions in the network and impact the general topological properties of the network increasing nestedness and reducing modularity. Both methods generated networks with a similar structure and were effective in estimating new interactions, accurately predicting known interactions without overestimating interactions in place of true absences. More importantly, added interactions changed our perception on the topological role of species, with several undersampled species earning novel interactions and becoming more central to network structure. This shows that estimating missing interactions can be helpful to get a more complete idea of how a network may look like, besides helping to inform which interactions should be the focus of further sampling efforts.
{"title":"Estimated missing interactions change the structure and alter species roles in one of the world's largest seed‐dispersal networks","authors":"André Nunes Martinez, Mathias Mistretta Pires","doi":"10.1111/oik.10521","DOIUrl":"https://doi.org/10.1111/oik.10521","url":null,"abstract":"Ecological interactions between species can affect the performance of individuals, influence ecological and evolutionary dynamics of populations, and ultimately shape community structure. Therefore, documenting and studying interactions is necessary for a better comprehension of ecological patterns. Yet, sampling interactions in the field is challenging. Even with extensive sampling efforts we can hardly obtain a comprehensive picture of which species interact with each other. Such missing interactions can produce substantial gaps that affect how we perceive and interpret the network formed by species interactions and the roles of individual species within those networks. In this study we propose two methods that combine data on species interactions with information on species traits and phylogenies to estimate potentially missing interactions. We use one of the largest datasets on plant‐frugivore interactions, depicting thousands of interactions between birds and plants in the Atlantic Forest hotspot, to test those methods. Then, we analyze how adding newly estimated interactions change the network's overall structure and the topological importance of each species within the seed‐dispersal network. We show that estimated missing interactions more than tripled the number of interactions in the network and impact the general topological properties of the network increasing nestedness and reducing modularity. Both methods generated networks with a similar structure and were effective in estimating new interactions, accurately predicting known interactions without overestimating interactions in place of true absences. More importantly, added interactions changed our perception on the topological role of species, with several undersampled species earning novel interactions and becoming more central to network structure. This shows that estimating missing interactions can be helpful to get a more complete idea of how a network may look like, besides helping to inform which interactions should be the focus of further sampling efforts.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142215623","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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