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Functional diversity, functional composition and functional β diversity drive aboveground biomass across different bioclimatic rangelands. Basic Appl Ecol 2021. [DOI: 10.1016/j.baae.2021.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Badali M, Zilman A. Effects of niche overlap on coexistence, fixation and invasion in a population of two interacting species. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192181. [PMID: 32257357 PMCID: PMC7062080 DOI: 10.1098/rsos.192181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/21/2020] [Indexed: 06/11/2023]
Abstract
Synergistic and antagonistic interactions in multi-species populations-such as resource sharing and competition-result in remarkably diverse behaviours in populations of interacting cells, such as in soil or human microbiomes, or clonal competition in cancer. The degree of inter- and intra-specific interaction can often be quantified through the notion of an ecological 'niche'. Typically, weakly interacting species that occupy largely distinct niches result in stable mixed populations, while strong interactions and competition for the same niche result in rapid extinctions of some species and fixations of others. We investigate the transition of a deterministically stable mixed population to a stochasticity-induced fixation as a function of the niche overlap between the two species. We also investigate the effect of the niche overlap on the population stability with respect to external invasions. Our results have important implications for a number of experimental systems.
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Affiliation(s)
- Matthew Badali
- Department of Physics, University of Toronto, 60 St George St., Toronto, CanadaM5S 1A7
| | - Anton Zilman
- Department of Physics, University of Toronto, 60 St George St., Toronto, CanadaM5S 1A7
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
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Size differences predict niche and relative fitness differences between phytoplankton species but not their coexistence. ISME JOURNAL 2019; 13:1133-1143. [PMID: 30607028 DOI: 10.1038/s41396-018-0330-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 10/14/2018] [Accepted: 11/04/2018] [Indexed: 11/09/2022]
Abstract
Here we aim to incorporate trait-based information into the modern coexistence framework that comprises a balance between stabilizing (niche-based) and equalizing (fitness) mechanisms among interacting species. Taking the modern coexistence framework as our basis, we experimentally tested the effect of size differences among species on coexistence by using fifteen unique pairs of resident vs. invading cyanobacteria, resulting in thirty unique invasibility tests. The cyanobacteria covered two orders of magnitude differences in size. We found that both niche and fitness differences increased with size differences. Niche differences increased faster with size differences than relative fitness differences and whereas coexisting pairs showed larger size differences than non-coexisting pairs, ultimately species coexistence could not be predicted on basis of size differences only. Our findings suggest that size is more than a key trait controlling physiological and population-level aspects of phytoplankton, it is also relevant for community-level phenomena such as niche and fitness differences which influence coexistence and biodiversity.
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Rael RC, D'Andrea R, Barabás G, Ostling A. Emergent niche structuring leads to increased differences from neutrality in species abundance distributions. Ecology 2018; 99:1633-1643. [PMID: 29655259 DOI: 10.1002/ecy.2238] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/27/2018] [Accepted: 03/21/2018] [Indexed: 11/09/2022]
Abstract
Species abundance distributions must reflect the dynamic processes involved in community assembly, but whether and when specific processes lead to distinguishable signals is not well understood. Biodiversity and species abundances may be shaped by a variety of influences, but particular attention has been paid to competition, which can involve neutral dynamics, where competitor abundances are governed only by demographic stochasticity and immigration, and dynamics driven by trait differences that enable stable coexistence through the formation of niches. Key recent studies of the species abundance patterns of communities with niches employ simple models with pre-imposed niche structure. These studies suggest that species abundance distributions are insensitive to the relative contributions of niche and neutral processes, especially when diversity is much higher than the number of niches. Here we analyze results from a stochastic population model with competition driven by trait differences. With this model, niche structure emerges as clumps of species that persist along the trait axis, and leads to more substantial differences from neutral species abundance distributions than have been previously shown. We show that heterogeneity in "between-niche" interaction strength (i.e., in the strength of competition between species in different niches) plays the dominant role in shaping the species abundances along the trait axis, acting as a biotic filter favoring species at the centers of niches. Furthermore, we show that heterogeneity in "within-niche" interactions (i.e., in the competition between species in the same niche) counteracts the influence of heterogeneity in "between-niche" interactions on the SAD to some degree. Our results suggest that competitive interactions that produce niches can also influence the shapes of SADs.
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Affiliation(s)
- Rosalyn C Rael
- Ecology and Evolutionary Biology, University of Michigan, 830 North University, Ann Arbor, Michigan, 48109-1048, USA
| | - Rafael D'Andrea
- Ecology and Evolutionary Biology, University of Michigan, 830 North University, Ann Arbor, Michigan, 48109-1048, USA
| | - György Barabás
- Ecology and Evolutionary Biology, University of Michigan, 830 North University, Ann Arbor, Michigan, 48109-1048, USA
| | - Annette Ostling
- Ecology and Evolutionary Biology, University of Michigan, 830 North University, Ann Arbor, Michigan, 48109-1048, USA
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D'Andrea R, Ostling A. Biodiversity maintenance may be lower under partial niche differentiation than under neutrality. Ecology 2017; 98:3211-3218. [PMID: 28898396 DOI: 10.1002/ecy.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 08/22/2017] [Accepted: 08/29/2017] [Indexed: 11/08/2022]
Abstract
Niche differentiation is normally regarded as a key promoter of species coexistence in competitive systems. One might therefore expect that relative to neutral assemblages, niche-differentiated communities should support more species with longer persistence and lower probability of extinction. Here we compare stochastic niche and neutral dynamics in simulated assemblages, and find that when local dynamics combine with immigration from a regional pool, the effect of niches can be more complex. Trait variation that lessens competition between species will not necessarily give all immigrating species their own niche to occupy. Such partial niche differentiation protects certain species from local extinction, but precipitates exclusion of others. Differences in regional abundances and intrinsic growth rates have similar impacts on persistence times as niche differentiation, and therefore blur the distinction between niche and neutral dynamical patterns-although niche dynamics will influence which species persist longer. Ultimately, unless the number of niches available to species is sufficiently high, niches may actually heighten extinction rates and lower species richness and local persistence times. Our results help make sense of recent observations of community dynamics, and point to the dynamical observations needed to discern the influence of niche differentiation.
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Affiliation(s)
- Rafael D'Andrea
- Department of Ecology and Evolutionary Biology, University of Michigan, 2004 Kraus Natural Sciences, 830 North University Avenue, Ann Arbor, Michigan, 48109, USA
| | - Annette Ostling
- Department of Ecology and Evolutionary Biology, University of Michigan, 2004 Kraus Natural Sciences, 830 North University Avenue, Ann Arbor, Michigan, 48109, USA.,Centre for Macroecology, Evolution and Climate, Building 3, 2nd floor, Universitetsparken 15, 2100, København Ø, Denmark
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Trophic isotopic carbon variation increases with pond's hydroperiod: Evidence from an Austral ephemeral ecosystem. Sci Rep 2017; 7:7572. [PMID: 28790380 PMCID: PMC5548932 DOI: 10.1038/s41598-017-08026-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/05/2017] [Indexed: 11/08/2022] Open
Abstract
Trophic variation in food web structure occurs among and within ecosystems. The magnitude of variation, however, differs from system to system. In ephemeral pond ecosystems, temporal dynamics are relatively more important than in many systems given that hydroperiod is the ultimate factor determining the presence of an aquatic state. Here, using stable isotopes we tested for changes in trophic chain length and shape over time in these dynamic aquatic ecosystems. We found that lower and intermediate trophic level structure increased over time. We discuss these findings within the context of temporal environmental stability. The dynamic nature of these ephemeral systems seems to be conducive to greater levels of intermediate and lower trophic level diversity, with omnivorous traits likely being advantageous.
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Carmel Y, Suprunenko YF, Kunin WE, Kent R, Belmaker J, Bar-Massada A, Cornell SJ. Using exclusion rate to unify niche and neutral perspectives on coexistence. OIKOS 2017. [DOI: 10.1111/oik.04380] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yohay Carmel
- Faculty of Civil and Environmental Engineering, The Technion; Haifa Israel
| | | | | | - Rafi Kent
- Dept of Geography and Environment, Bar-Ilan Univ.; Ramat-Gan Israel
| | - Jonathan Belmaker
- Dept of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv Univ; Tel Aviv Israel
| | - Avi Bar-Massada
- Dept of Biology and Environment, Univ. of Haifa at Oranim; Kiryat Tivon Israel
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Sex and species specific isotopic niche specialisation increases with trophic complexity: evidence from an ephemeral pond ecosystem. Sci Rep 2017; 7:43229. [PMID: 28233858 PMCID: PMC5324113 DOI: 10.1038/srep43229] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/20/2017] [Indexed: 11/17/2022] Open
Abstract
It is generally accepted that organisms that naturally exploit an ecosystem facilitate coexistence, at least partially, through resource partitioning. Resource availability is, however, highly variable in space and time and as such the extent of resource partitioning must be somewhat dependent on availability. Here we test aspects of resource partitioning at the inter- and intra-specific level, in relation to resource availability in an atypical aquatic environment using an isotope approach. Using closely related key organisms from an ephemeral pond, we test for differences in isotopic signatures between two species of copepod and between sexes within each species, in relation to heterogeneity of basal food resources over the course of the ponds hydroperiod. We show that basal food resource heterogeneity increases over time initially, and then decreases towards the end of the hydroperiod, reflective of the expected evolution of trophic complexity for these systems. Resource partitioning also varied between species and sexes, over the hydroperiod with intra- and inter-specific specialisation relating to resource availability. Intra-specific specialisation was particularly evident in the omnivorous copepod species. Our findings imply that trophic specialisation at both the intra- and inter-specific level is partly driven by basal food resource availability.
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Mensah S, Veldtman R, Assogbadjo AE, Glèlè Kakaï R, Seifert T. Tree species diversity promotes aboveground carbon storage through functional diversity and functional dominance. Ecol Evol 2016; 6:7546-7557. [PMID: 28725419 PMCID: PMC5513275 DOI: 10.1002/ece3.2525] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 09/01/2016] [Accepted: 09/04/2016] [Indexed: 11/06/2022] Open
Abstract
The relationship between biodiversity and ecosystem function has increasingly been debated as the cornerstone of the processes behind ecosystem services delivery. Experimental and natural field-based studies have come up with nonconsistent patterns of biodiversity-ecosystem function, supporting either niche complementarity or selection effects hypothesis. Here, we used aboveground carbon (AGC) storage as proxy for ecosystem function in a South African mistbelt forest, and analyzed its relationship with species diversity, through functional diversity and functional dominance. We hypothesized that (1) diversity influences AGC through functional diversity and functional dominance effects; and (2) effects of diversity on AGC would be greater for functional dominance than for functional diversity. Community weight mean (CWM) of functional traits (wood density, specific leaf area, and maximum plant height) were calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multitrait functional diversity indices were computed. The first hypothesis was tested using structural equation modeling. For the second hypothesis, effects of environmental variables such as slope and altitude were tested first, and separate linear mixed-effects models were fitted afterward for functional diversity, functional dominance, and both. Results showed that AGC varied significantly along the slope gradient, with lower values at steeper sites. Species diversity (richness) had positive relationship with AGC, even when slope effects were considered. As predicted, diversity effects on AGC were mediated through functional diversity and functional dominance, suggesting that both the niche complementarity and the selection effects are not exclusively affecting carbon storage. However, the effects were greater for functional diversity than for functional dominance. Furthermore, functional dominance effects were strongly transmitted by CWM of maximum plant height, reflecting the importance of forest vertical stratification for diversity-carbon relationship. We therefore argue for stronger complementary effects that would be induced also by complementary light-use efficiency of tree and species growing in the understory layer.
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Affiliation(s)
- Sylvanus Mensah
- Department of Forest and Wood ScienceStellenbosch UniversityMatielandSouth Africa
- Laboratoire de Biomathématiques et d'Estimations ForestièresUniversité d'Abomey‐CalaviCotonouBénin
| | - Ruan Veldtman
- South African National Biodiversity InstituteKirstenbosch Research CentreClaremontSouth Africa
- Department of Conservation Ecology and EntomologyStellenbosch UniversityMatielandSouth Africa
| | | | - Romain Glèlè Kakaï
- Laboratoire de Biomathématiques et d'Estimations ForestièresUniversité d'Abomey‐CalaviCotonouBénin
| | - Thomas Seifert
- Department of Forest and Wood ScienceStellenbosch UniversityMatielandSouth Africa
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