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Kalyuzhny M, Lake JK, Wright SJ, Ostling AM. Pervasive within-species spatial repulsion among adult tropical trees. Science 2023; 381:563-568. [PMID: 37535716 DOI: 10.1126/science.adg7021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 06/30/2023] [Indexed: 08/05/2023]
Abstract
For species to coexist, performance must decline as the density of conspecific individuals increases. Although evidence for such conspecific negative density dependence (CNDD) exists in forests, the within-species spatial repulsion it should produce has rarely been demonstrated in adults. In this study, we show that in comparison to a null model of stochastic birth, death, and limited dispersal, the adults of dozens of tropical forest tree species show strong spatial repulsion, some to surprising distances of approximately 100 meters. We used simulations to show that such strong repulsion can only occur if CNDD considerably exceeds heterospecific negative density dependence-an even stronger condition required for coexistence-and that large-scale repulsion can indeed result from small-scale CNDD. These results demonstrate substantial niche differences between species that may stabilize species diversity.
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Affiliation(s)
- Michael Kalyuzhny
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jeffrey K Lake
- Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, MI 48109, USA
| | - S Joseph Wright
- Smithsonian Tropical Research Institute, Balboa 0843-03092, Republic of Panama
| | - Annette M Ostling
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
- Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, 78712, USA
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2
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Kinlock NL, Munch SB. Interaction network structure and spatial patterns influence invasiveness and invasibility in a stochastic model of plant communities. OIKOS 2021. [DOI: 10.1111/oik.08453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicole L. Kinlock
- Dept of Ecology and Evolution, Stony Brook Univ. Stony Brook NY USA
- Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration Santa Cruz CA USA
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3
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Wiegand T, Wang X, Anderson-Teixeira KJ, Bourg NA, Cao M, Ci X, Davies SJ, Hao Z, Howe RW, Kress WJ, Lian J, Li J, Lin L, Lin Y, Ma K, McShea W, Mi X, Su SH, Sun IF, Wolf A, Ye W, Huth A. Consequences of spatial patterns for coexistence in species-rich plant communities. Nat Ecol Evol 2021; 5:965-973. [PMID: 33941904 PMCID: PMC8257505 DOI: 10.1038/s41559-021-01440-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 03/01/2021] [Indexed: 02/02/2023]
Abstract
Ecology cannot yet fully explain why so many tree species coexist in natural communities such as tropical forests. A major difficulty is linking individual-level processes to community dynamics. We propose a combination of tree spatial data, spatial statistics and dynamical theory to reveal the relationship between spatial patterns and population-level interaction coefficients and their consequences for multispecies dynamics and coexistence. Here we show that the emerging population-level interaction coefficients have, for a broad range of circumstances, a simpler structure than their individual-level counterparts, which allows for an analytical treatment of equilibrium and stability conditions. Mechanisms such as animal seed dispersal, which result in clustering of recruits that is decoupled from parent locations, lead to a rare-species advantage and coexistence of otherwise neutral competitors. Linking spatial statistics with theories of community dynamics offers new avenues for explaining species coexistence and calls for rethinking community ecology through a spatial lens.
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Affiliation(s)
- Thorsten Wiegand
- Department of Ecological Modelling, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
| | - Xugao Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, .
| | - Kristina J Anderson-Teixeira
- Conservation Ecology Center, Smithsonian Conservation Biology Institute, Front Royal, VA, USA
- Forest Global Earth Observatory (ForestGEO), Smithsonian Tropical Research Institute, Washington, DC, USA
| | - Norman A Bourg
- Conservation Ecology Center, Smithsonian Conservation Biology Institute, Front Royal, VA, USA
| | - Min Cao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
| | - Xiuqin Ci
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences
- Centre for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
| | - Stuart J Davies
- Forest Global Earth Observatory (ForestGEO), Smithsonian Tropical Research Institute, Washington, DC, USA
| | - Zhanqing Hao
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences
- School of Ecology and Environment, Northwestern Polytechnical University
| | - Robert W Howe
- Department of Natural and Applied Sciences, University of Wisconsin-Green Bay, Green Bay, WI, USA
| | - W John Kress
- Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Juyu Lian
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences
| | - Jie Li
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences
- Centre for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
| | - Luxiang Lin
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences
| | - Yiching Lin
- Department of Life Science, Tunghai University
| | - Keping Ma
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences
| | - William McShea
- Conservation Ecology Center, Smithsonian Conservation Biology Institute, Front Royal, VA, USA
| | - Xiangcheng Mi
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences
| | | | - I-Fang Sun
- Center for Interdisciplinary Research on Ecology and Sustainability, National Dong Hwa University
| | - Amy Wolf
- Department of Natural and Applied Sciences, University of Wisconsin-Green Bay, Green Bay, WI, USA
| | - Wanhui Ye
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences
| | - Andreas Huth
- Department of Ecological Modelling, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Institute of Environmental Systems Research, University of Osnabrück, Osnabrück, Germany
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4
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Ursell T. Structured environments foster competitor coexistence by manipulating interspecies interfaces. PLoS Comput Biol 2021; 17:e1007762. [PMID: 33412560 PMCID: PMC7790539 DOI: 10.1371/journal.pcbi.1007762] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 10/19/2020] [Indexed: 01/12/2023] Open
Abstract
Natural environments, like soils or the mammalian gut, frequently contain microbial consortia competing within a niche, wherein many species contain genetically encoded mechanisms of interspecies competition. Recent computational work suggests that physical structures in the environment can stabilize local competition between species that would otherwise be subject to competitive exclusion under isotropic conditions. Here we employ Lotka-Volterra models to show that interfacial competition localizes to physical structures, stabilizing competitive ecological networks of many species, even with significant differences in the strength of competitive interactions between species. Within a limited range of parameter space, we show that for stable communities the length-scale of physical structure inversely correlates with the width of the distribution of competitive fitness, such that physical environments with finer structure can sustain a broader spectrum of interspecific competition. These results highlight the potentially stabilizing effects of physical structure on microbial communities and lay groundwork for engineering structures that stabilize and/or select for diverse communities of ecological, medical, or industrial utility.
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Affiliation(s)
- Tristan Ursell
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
- Materials Science Institute, University of Oregon, Eugene, Oregon, United States of America
- Department of Physics, University of Oregon, Eugene, Oregon, United States of America
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5
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McKenna TP, McDonnell J, Yurkonis KA, Brophy C. Helianthus maximiliani and species fine-scale spatial pattern affect diversity interactions in reconstructed tallgrass prairies. Ecol Evol 2019; 9:12171-12181. [PMID: 31832151 PMCID: PMC6854329 DOI: 10.1002/ece3.5696] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 08/28/2019] [Accepted: 08/30/2019] [Indexed: 11/30/2022] Open
Abstract
Biodiversity and Ecosystem Function analyses aim to explain how individual species and their interactions affect ecosystem function. With this study, we asked in what ways do species interact, are these interactions affected by species planting pattern, and are initial (planted) proportions or previous year (realized) proportions a better reference point for characterizing grassland diversity effects?We addressed these questions with experimental communities compiled from a pool of 16 tallgrass prairie species. We planted all species in monocultures and mixtures that varied in their species richness, evenness, and spatial pattern. We recorded species-specific biomass production over three growing seasons and fitted Diversity-Interactions (DI) models to annual plot biomass yields.In the establishment season, all species interacted equally to form the diversity effect. In years 2 and 3, each species contributed a unique additive coefficient to its interaction with every other species to form the diversity effect. These interactions were affected by Helianthus maximiliani and the species planting pattern. Models based on species planted proportions better-fit annual plot yield than models based on species previous contributions to plot biomass.Outcomes suggest that efforts to plant tallgrass prairies to maximize diversity effects should focus on the specific species present and in what arrangement they are planted. Furthermore, for particularly diverse grasslands, the effort of collecting annual species biomass data may not be necessary when quantifying diversity effects with DI models.
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Affiliation(s)
| | - Jack McDonnell
- Department of Mathematics and StatisticsMaynooth UniversityMaynoothIreland
| | | | - Caroline Brophy
- Department of Mathematics and StatisticsMaynooth UniversityMaynoothIreland
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6
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Evidence of within-species specialization by soil microbes and the implications for plant community diversity. Proc Natl Acad Sci U S A 2019; 116:7371-7376. [PMID: 30842279 DOI: 10.1073/pnas.1810767116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Microbes are thought to maintain diversity in plant communities by specializing on particular species, but it is not known whether microbes that specialize within species (i.e., on genotypes) affect diversity or dynamics in plant communities. Here we show that soil microbes can specialize at the within-population level in a wild plant species, and that such specialization could promote species diversity and seed dispersal in plant communities. In a shadehouse experiment in Panama, we found that seedlings of the native tree species, Virola surinamensis (Myristicaceae), had reduced performance in the soil microbial community of their maternal tree compared with in the soil microbial community of a nonmaternal tree from the same population. Performance differences were unrelated to soil nutrients or to colonization by mycorrhizal fungi, suggesting that highly specialized pathogens were the mechanism reducing seedling performance in maternal soils. We then constructed a simulation model to explore the ecological and evolutionary consequences of genotype-specific pathogens in multispecies plant communities. Model results indicated that genotype-specific pathogens promote plant species coexistence-albeit less strongly than species-specific pathogens-and are most effective at maintaining species richness when genetic diversity is relatively low. Simulations also revealed that genotype-specific pathogens select for increased seed dispersal relative to species-specific pathogens, potentially helping to create seed dispersal landscapes that allow pathogens to more effectively promote diversity. Combined, our results reveal that soil microbes can specialize within wild plant populations, affecting seedling performance near conspecific adults and influencing plant community dynamics on ecological and evolutionary time scales.
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7
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Rajala T, Olhede SC, Murrell DJ. When do we have the power to detect biological interactions in spatial point patterns? THE JOURNAL OF ECOLOGY 2019; 107:711-721. [PMID: 31007275 PMCID: PMC6472561 DOI: 10.1111/1365-2745.13080] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/07/2018] [Accepted: 09/12/2018] [Indexed: 05/27/2023]
Abstract
Uncovering the roles of biotic interactions in assembling and maintaining species-rich communities remains a major challenge in ecology. In plant communities, interactions between individuals of different species are expected to generate positive or negative spatial interspecific associations over short distances. Recent studies using individual-based point pattern datasets have concluded that (a) detectable interspecific interactions are generally rare, but (b) are most common in communities with fewer species; and (c) the most abundant species tend to have the highest frequency of interactions. However, it is unclear how the detection of spatial interactions may change with the abundances of each species, or the scale and intensity of interactions. We ask if statistical power is sufficient to explain all three key results.We use a simple two-species model, assuming no habitat associations, and where the abundances, scale and intensity of interactions are controlled to simulate point pattern data. In combination with an approximation to the variance of the spatial summary statistics that we sample, we investigate the power of current spatial point pattern methods to correctly reject the null model of pairwise species independence.We show the power to detect interactions is positively related to both the abundances of the species tested, and the intensity and scale of interactions, but negatively related to imbalance in abundances. Differences in detection power in combination with the abundance distributions found in natural communities are sufficient to explain all the three key empirical results, even if all pairwise interactions are identical. Critically, many hundreds of individuals of both species may be required to detect even intense interactions, implying current abundance thresholds for including species in the analyses are too low. Sy n thesis. The widespread failure to reject the null model of spatial interspecific independence could be due to low power of the tests rather than any key biological process. Since we do not model habitat associations, our results represent a first step in quantifying sample sizes required to make strong statements about the role of biotic interactions in diverse plant communities. However, power should be factored into analyses and considered when designing empirical studies.
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Affiliation(s)
- Tuomas Rajala
- Department of Statistical ScienceUniversity College LondonLondonUK
| | | | - David John Murrell
- Centre for Biodiversity and Environment ResearchUniversity College LondonLondonUK
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8
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Stump SM, Comita LS. Interspecific variation in conspecific negative density dependence can make species less likely to coexist. Ecol Lett 2018; 21:1541-1551. [PMID: 30129216 DOI: 10.1111/ele.13135] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/05/2018] [Accepted: 07/15/2018] [Indexed: 01/19/2023]
Abstract
Conspecific negative density dependence (CNDD) is thought to promote plant species diversity. Theoretical studies showing the importance of CNDD often assumed that all species are equally susceptible to CNDD; however, recent empirical studies have shown species can differ greatly in their susceptibility to CNDD. Using a theoretical model, we show that interspecific variation in CNDD can dramatically alter its impact on diversity. First, if the most common species are the least regulated by CNDD, then the stabilising benefit of CNDD is reduced. Second, when seed dispersal is limited, seedlings that are susceptible to CNDD are at a competitive disadvantage. When parameterised with estimates of CNDD from a tropical tree community in Panama, our model suggests that the competitive inequalities caused by interspecific variation in CNDD may undermine many species' ability to persist. Thus, our model suggests that variable CNDD may make communities less stable, rather than more stable.
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Affiliation(s)
- Simon Maccracken Stump
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
| | - Liza S Comita
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA.,Smithsonian Tropical Research Institute Balboa, Ancón, Panama
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9
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Seahra S, Yurkonis KA, Newman JA. Seeding tallgrass prairie in monospecific patches promotes native species establishment and cover. Restor Ecol 2018. [DOI: 10.1111/rec.12715] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shannon Seahra
- School of Environmental Sciences; University of Guelph; 50 Stone Road East, Guelph ON N1G 2W1 Canada
| | - Kathryn A. Yurkonis
- Department of Biology; University of North Dakota; 10 Cornell Street, Stop 9019, Grand Forks ND 58202 U.S.A
| | - Jonathan A. Newman
- Department of Integrative Biology; University of Guelph; 50 Stone Road East, Guelph ON N1G 2W1 Canada
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10
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Ross RJH, Yates CA, Baker RE. Variable species densities are induced by volume exclusion interactions upon domain growth. Phys Rev E 2017; 95:032416. [PMID: 28415323 DOI: 10.1103/physreve.95.032416] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Indexed: 11/07/2022]
Abstract
In this work we study the effect of domain growth on spatial correlations in agent populations containing multiple species. This is important as heterogenous cell populations are ubiquitous during the embryonic development of many species. We have previously shown that the long-term behavior of an agent population depends on the way in which domain growth is implemented. We extend this work to show that, depending on the way in which domain growth is implemented, different species dominate in multispecies simulations. Continuum approximations of the lattice-based model that ignore spatial correlations cannot capture this behavior, while those that explicitly account for spatial correlations can. The results presented here show that the precise mechanism of domain growth can determine the long-term behavior of multispecies populations and, in certain circumstances, establish spatially varying species densities.
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Affiliation(s)
- Robert J H Ross
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, United Kingdom
| | - C A Yates
- Centre for Mathematical Biology, Department of Mathematical Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom
| | - R E Baker
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, United Kingdom
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11
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Qin L, Zhang F, Wang W, Song W. Interaction between Allee effects caused by organism-environment feedback and by other ecological mechanisms. PLoS One 2017; 12:e0174141. [PMID: 28333974 PMCID: PMC5363850 DOI: 10.1371/journal.pone.0174141] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 03/03/2017] [Indexed: 12/26/2022] Open
Abstract
Understanding Allee effect has crucial importance for ecological conservation and management because it is strongly related to population extinction. Due to various ecological mechanisms accounting for Allee effect, it is necessary to study the influence of multiple Allee effects on the dynamics and persistence of population. We here focus on organism-environment feedback which can incur strong, weak, and fatal Allee effect (AE-by-OEF), and further examine their interaction with the Allee effects caused by other ecological mechanisms (AE-by-OM). The results show that multiple Allee effects largely increase the extinction risk of population either due to the enlargement of Allee threshold or the change of inherent characteristic of Allee effect, and such an increase will be enhanced dramatically with increasing the strength of individual Allee effects. Our simulations explicitly considering spatial structure also demonstrate that local interaction among habitat patches can greatly mitigate such superimposed Allee effects as well as individual Allee effect. This implies that spatially structurized habitat could play an important role in ecological conservation and management.
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Affiliation(s)
- Lijuan Qin
- College of Resources and Environmental Science, Gansu Agricultural University, Lanzhou, China
- Center for Quantitative Biology, College of Science, Gansu Agricultural University, Lanzhou, China
| | - Feng Zhang
- Center for Quantitative Biology, College of Science, Gansu Agricultural University, Lanzhou, China
- * E-mail: (FZ); (WW)
| | - Wanxiong Wang
- College of Resources and Environmental Science, Gansu Agricultural University, Lanzhou, China
- Center for Quantitative Biology, College of Science, Gansu Agricultural University, Lanzhou, China
- * E-mail: (FZ); (WW)
| | - Weixin Song
- Center for Quantitative Biology, College of Science, Gansu Agricultural University, Lanzhou, China
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12
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Detto M, Muller-Landau HC. Stabilization of species coexistence in spatial models through the aggregation-segregation effect generated by local dispersal and nonspecific local interactions. Theor Popul Biol 2016; 112:97-108. [PMID: 27609405 DOI: 10.1016/j.tpb.2016.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 07/14/2016] [Accepted: 08/24/2016] [Indexed: 11/17/2022]
Abstract
Spatial interactions are widely acknowledged to play a significant role in sustaining diversity in ecological communities. However, theoretical work on this topic has focused on how spatial processes affect coexistence of species that differ in their strategies, with less attention to how spatial processes matter when competitors are equivalent. Furthermore, though it is recognized that models with local dispersal and local competition may sustain higher diversities of equivalent competitors than models in which these are not both localized, there is debate as to whether this reflects merely equalizing effects or whether there is also a stabilizing component. In this study, we explore how dispersal limitation and nonspecific local competition influence the outcome of species coexistence in communities driven by stochastic drift. We demonstrate that space alone acts as a stabilizing factor in a continuous space model with local dispersal and competition, as individuals of rare species on average experience lower total neighborhood densities, causing per capita reproductive rates to decrease systematically with increasing abundance. These effects prolong time to extinction in a closed system and enhance species diversity in an open system with constant immigration. Fundamentally, these stabilizing effects are obtained when dispersal limitation interacts with local competition to generate fluctuations in population growth rates. Thus this effect can be considered a fluctuating mechanism similar to spatial or temporal storage effects, but generated purely endogenously without requiring any exogenous environmental variability or species dissimilarities.
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Affiliation(s)
- Matteo Detto
- Smithsonian Tropical Research Institute, Panama City, Panama.
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13
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Barabás G, J Michalska-Smith M, Allesina S. The Effect of Intra- and Interspecific Competition on Coexistence in Multispecies Communities. Am Nat 2016; 188:E1-E12. [PMID: 27322128 DOI: 10.1086/686901] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
For two competing species, intraspecific competition must exceed interspecific competition for coexistence. To generalize this well-known criterion to multiple competing species, one must take into account both the distribution of interaction strengths and community structure. Here we derive a multispecies generalization of the two-species rule in the context of symmetric Lotka-Volterra competition and obtain explicit stability conditions for random competitive communities. We then explore the influence of community structure on coexistence. Results show that both the most and least stabilized cases have striking global structures, with a nested pattern emerging in both cases. The distribution of intraspecific coefficients leading to the most and least stabilized communities also follows a predictable pattern that can be justified analytically. In addition, we show that the size of the parameter space allowing for feasible communities always increases with the strength of intraspecific effects in a characteristic way that is independent of the interspecific interaction structure. We conclude by discussing possible extensions of our results to nonsymmetric competition.
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14
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Distance-responsive predation is not necessary for the Janzen–Connell hypothesis. Theor Popul Biol 2015; 106:60-70. [DOI: 10.1016/j.tpb.2015.10.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/13/2015] [Accepted: 10/13/2015] [Indexed: 01/07/2023]
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15
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Vaumourin E, Vourc'h G, Gasqui P, Vayssier-Taussat M. The importance of multiparasitism: examining the consequences of co-infections for human and animal health. Parasit Vectors 2015; 8:545. [PMID: 26482351 PMCID: PMC4617890 DOI: 10.1186/s13071-015-1167-9] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 10/14/2015] [Indexed: 11/23/2022] Open
Abstract
Most parasites co-occur with other parasites, although the importance of such multiparasitism has only recently been recognised. Co-infections may result when hosts are independently infected by different parasites at the same time or when interactions among parasite species facilitate co-occurrence. Such interactions can have important repercussions on human or animal health because they can alter host susceptibility, infection duration, transmission risks, and clinical symptoms. These interactions may be synergistic or antagonistic and thus produce diverse effects in infected humans and animals. Interactions among parasites strongly influence parasite dynamics and therefore play a major role in structuring parasite populations (both within and among hosts) as well as host populations. However, several methodological challenges remain when it comes to detecting parasite interactions. The goal of this review is to summarise current knowledge on the causes and consequences of multiparasitism and to discuss the different methods and tools that researchers have developed to study the factors that lead to multiparasitism. It also identifies new research directions to pursue.
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Affiliation(s)
- Elise Vaumourin
- UR346 Animal Epidemiology Research Unit, INRA, Saint Genès Champanelle, France. .,USC BIPAR, INRA-ANSES-ENVA, Maisons-Alfort, France.
| | - Gwenaël Vourc'h
- UR346 Animal Epidemiology Research Unit, INRA, Saint Genès Champanelle, France.
| | - Patrick Gasqui
- UR346 Animal Epidemiology Research Unit, INRA, Saint Genès Champanelle, France.
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16
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Velázquez J, Garrahan JP, Eichhorn MP. Spatial complementarity and the coexistence of species. PLoS One 2014; 9:e114979. [PMID: 25532018 PMCID: PMC4274010 DOI: 10.1371/journal.pone.0114979] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 11/16/2014] [Indexed: 11/19/2022] Open
Abstract
Coexistence of apparently similar species remains an enduring paradox in ecology. Spatial structure has been predicted to enable coexistence even when population-level models predict competitive exclusion if it causes each species to limit its own population more than that of its competitor. Nevertheless, existing hypotheses conflict with regard to whether clustering favours or precludes coexistence. The spatial segregation hypothesis predicts that in clustered populations the frequency of intra-specific interactions will be increased, causing each species to be self-limiting. Alternatively, individuals of the same species might compete over greater distances, known as heteromyopia, breaking down clusters and opening space for a second species to invade. In this study we create an individual-based model in homogeneous two-dimensional space for two putative sessile species differing only in their demographic rates and the range and strength of their competitive interactions. We fully characterise the parameter space within which coexistence occurs beyond population-level predictions, thereby revealing a region of coexistence generated by a previously-unrecognised process which we term the triadic mechanism. Here coexistence occurs due to the ability of a second generation of offspring of the rarer species to escape competition from their ancestors. We diagnose the conditions under which each of three spatial coexistence mechanisms operates and their characteristic spatial signatures. Deriving insights from a novel metric - ecological pressure - we demonstrate that coexistence is not solely determined by features of the numerically-dominant species. This results in a common framework for predicting, given any pair of species and knowledge of the relevant parameters, whether they will coexist, the mechanism by which they will do so, and the resultant spatial pattern of the community. Spatial coexistence arises from complementary combinations of traits in each species rather than solely through self-limitation.
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Affiliation(s)
- Jorge Velázquez
- School of Physics & Astronomy, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
- Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Puebla, 72001, Puebla, Pue., México
| | - Juan P. Garrahan
- School of Physics & Astronomy, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Markus P. Eichhorn
- School of Life Sciences, The University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
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Flügge AJ, Olhede SC, Murrell DJ. A method to detect subcommunities from multivariate spatial associations. Methods Ecol Evol 2014. [DOI: 10.1111/2041-210x.12295] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anton J. Flügge
- Department of Genetics, Evolution and Environment; University College London; Gower Street London WC1E 6BT UK
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology; University College London; London UK
- Centre for Biodiversity and Environment Research; University College London; Gower Street London WC1E 6BT UK
| | - Sofia C. Olhede
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology; University College London; London UK
- Department of Statistical Science; University College London; Gower Street London WC1E 6BT UK
| | - David J. Murrell
- Department of Genetics, Evolution and Environment; University College London; Gower Street London WC1E 6BT UK
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology; University College London; London UK
- Centre for Biodiversity and Environment Research; University College London; Gower Street London WC1E 6BT UK
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Ying Z, Liao J, Wang S, Lu H, Liu Y, Ma L, Li Z. Species coexistence in a lattice-structured habitat: Effects of species dispersal and interactions. J Theor Biol 2014; 359:184-91. [DOI: 10.1016/j.jtbi.2014.05.048] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 05/10/2014] [Accepted: 05/28/2014] [Indexed: 11/24/2022]
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19
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Diversity and spatial clustering of shade trees affect cacao yield and pathogen pressure in Costa Rican agroforests. Basic Appl Ecol 2013. [DOI: 10.1016/j.baae.2013.03.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Maire V, Gross N, Börger L, Proulx R, Wirth C, Pontes LDS, Soussana JF, Louault F. Habitat filtering and niche differentiation jointly explain species relative abundance within grassland communities along fertility and disturbance gradients. THE NEW PHYTOLOGIST 2012; 196:497-509. [PMID: 22931515 DOI: 10.1111/j.1469-8137.2012.04287.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 07/18/2012] [Indexed: 06/01/2023]
Abstract
Deterministic niche-based processes have been proposed to explain species relative abundance within communities but lead to different predictions: habitat filtering (HF) predicts dominant species to exhibit similar traits while niche differentiation (ND) requires that species have dissimilar traits to coexist. Using a multiple trait-based approach, we evaluated the relative roles of HF and ND in determining species abundances in productive grasslands. Four dimensions of the functional niche of 12 co-occurring grass species were identified using 28 plant functional traits. Using this description of the species niche, we investigated patterns of functional similarity and dissimilarity and linked them to abundance in randomly assembled six-species communities subjected to fertilization/disturbance treatments. Our results suggest that HF and ND jointly determined species abundance by acting on contrasting niche dimensions. The effect of HF decreased relative to ND with increasing disturbance and decreasing fertilization. Dominant species exhibited similar traits in communities whereas dissimilarity favored the coexistence of rare species with dominants by decreasing inter-specific competition. This stabilizing effect on diversity was suggested by a negative relationship between species over-yielding and relative abundance. We discuss the importance of considering independent dimensions of functional niche to better understand species abundance and coexistence within communities.
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Affiliation(s)
- Vincent Maire
- INRA UR874 UREP, 234 Avenue du Brézet, F-63100, Clermont-Ferrand, France
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Nicolas Gross
- CEBC-CNRS (UPR 1934), 79360, Beauvoir sur Niort, France
- INRA, USC 1339, CEBC-CNRS, 79360, Beauvoir sur Niort, France
| | - Luca Börger
- CEBC-CNRS (UPR 1934), 79360, Beauvoir sur Niort, France
- INRA, USC 1339, CEBC-CNRS, 79360, Beauvoir sur Niort, France
| | - Raphaël Proulx
- Max-Planck Institute for Biogeochemistry, D-07745, Jena, Germany
- Université du Québec à Trois-Rivières, CP 500, Trois-Rivières, Québec, Canada, G9A 5H7
| | - Christian Wirth
- Max-Planck Institute for Biogeochemistry, D-07745, Jena, Germany
| | | | | | - Frédérique Louault
- INRA UR874 UREP, 234 Avenue du Brézet, F-63100, Clermont-Ferrand, France
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21
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Porensky LM, Vaughn KJ, Young TP. Can initial intraspecific spatial aggregation increase multi-year coexistence by creating temporal priority? ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2012; 22:927-936. [PMID: 22645821 DOI: 10.1890/11-0818.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Both intraspecific spatial aggregation and temporal priority effects have the potential to increase long-term species coexistence. Theory and models suggest that intraspecific aggregation can facilitate coexistence via limited dispersal or asymmetric interaction distances. During community assembly, intraspecific aggregation may also delay interactions between more and less competitive species, thus creating opportunities for priority effects to facilitate longer-term coexistence. Few empirical studies have tested predictions about aggregation and coexistence, especially in the context of community assembly or ecological restoration. We investigated (1) impacts of intraspecific aggregation on the assembly of eight-species communities over three years, (2) the scale dependence of these impacts, and (3) implications for California prairie restoration. We planted eight native species in each of 19, 5 m wide, octagonal plots. Species were either interspersed throughout the plot or aggregated into eight, 2.2-m(2), wedge-shaped, monospecific sectors. Over three years, species diversity declined more quickly in interspersed plots than in aggregated plots. Two species had higher cover or increased more in interspersed than aggregated plots and were identified as "aggressives." Four species had higher cover or increased more in aggregated than interspersed plots and were identified as "subordinates." Within aggregated plots, aggressive species expanded beyond the sector in which they were originally seeded. Cover of aggressive species increased faster and reached higher values in sectors that were adjacent to the originally planted sector, compared to nonadjacent sectors. Cover of aggressive species also increased more and faster near plot centers, compared to plot edges. Areas near plot centers were representative of smaller aggregation patches since species were planted closer to heterospecific neighbors. Two subordinate species maintained higher cover near plot edges than near plot centers. Moreover, two subordinate species maintained higher cover when seeded in sectors farther away from aggressive species. These results suggest that initial intraspecific aggregation can facilitate species coexistence for at least three years, and larger aggregation patches may be more effective than smaller ones in the face of dispersing dominants. The creation of temporal priority effects may represent an underappreciated pathway by which intraspecific aggregation can increase coexistence. Restorationists may be able to maintain more diverse communities by planting in a mosaic of monospecific patches.
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Affiliation(s)
- Lauren M Porensky
- Department of Plant Sciences and Graduate Group in Ecology, University of California, One Shields Avenue, Davis, California 95616, USA.
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22
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Intense or spatially heterogeneous predation can select against prey dispersal. PLoS One 2012; 7:e28924. [PMID: 22247764 PMCID: PMC3256147 DOI: 10.1371/journal.pone.0028924] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 11/17/2011] [Indexed: 11/30/2022] Open
Abstract
Dispersal theory generally predicts kin competition, inbreeding, and temporal variation in habitat quality should select for dispersal, whereas spatial variation in habitat quality should select against dispersal. The effect of predation on the evolution of dispersal is currently not well-known: because predation can be variable in both space and time, it is not clear whether or when predation will promote dispersal within prey. Moreover, the evolution of prey dispersal affects strongly the encounter rate of predator and prey individuals, which greatly determines the ecological dynamics, and in turn changes the selection pressures for prey dispersal, in an eco-evolutionary feedback loop. When taken all together the effect of predation on prey dispersal is rather difficult to predict. We analyze a spatially explicit, individual-based predator-prey model and its mathematical approximation to investigate the evolution of prey dispersal. Competition and predation depend on local, rather than landscape-scale densities, and the spatial pattern of predation corresponds well to that of predators using restricted home ranges (e.g. central-place foragers). Analyses show the balance between the level of competition and predation pressure an individual is expected to experience determines whether prey should disperse or stay close to their parents and siblings, and more predation selects for less prey dispersal. Predators with smaller home ranges also select for less prey dispersal; more prey dispersal is favoured if predators have large home ranges, are very mobile, and/or are evenly distributed across the landscape.
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Chipperfield JD, Holland EP, Dytham C, Thomas CD, Hovestadt T. On the approximation of continuous dispersal kernels in discrete-space models. Methods Ecol Evol 2011. [DOI: 10.1111/j.2041-210x.2011.00117.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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