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Fung T, Pande J, Shnerb NM, O'Dwyer JP, Chisholm RA. Processes governing species richness in communities exposed to temporal environmental stochasticity: A review and synthesis of modelling approaches. Math Biosci 2024; 369:109131. [PMID: 38113973 DOI: 10.1016/j.mbs.2023.109131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/10/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
Research into the processes governing species richness has often assumed that the environment is fixed, whereas realistic environments are often characterised by random fluctuations over time. This temporal environmental stochasticity (TES) changes the demographic rates of species populations, with cascading effects on community dynamics and species richness. Theoretical and applied studies have used process-based mathematical models to determine how TES affects species richness, but under a variety of frameworks. Here, we critically review such studies to synthesise their findings and draw general conclusions. We first provide a broad mathematical framework encompassing the different ways in which TES has been modelled. We then review studies that have analysed models with TES under the assumption of negligible interspecific interactions, such that a community is conceptualised as the sum of independent species populations. These analyses have highlighted how TES can reduce species richness by increasing the frequency at which a species becomes rare and therefore prone to extinction. Next, we review studies that have relaxed the assumption of negligible interspecific interactions. To simplify the corresponding models and make them analytically tractable, such studies have used mean-field theory to derive fixed parameters representing the typical strength of interspecific interactions under TES. The resulting analyses have highlighted community-level effects that determine how TES affects species richness, for species that compete for a common limiting resource. With short temporal correlations of environmental conditions, a non-linear averaging effect of interspecific competition strength over time gives an increase in species richness. In contrast, with long temporal correlations of environmental conditions, strong selection favouring the fittest species between changes in environmental conditions results in a decrease in species richness. We compare such results with those from invasion analysis, which examines invasion growth rates (IGRs) instead of species richness directly. Qualitative differences sometimes arise because the IGR is the expected growth rate of a species when it is rare, which does not capture the variation around this mean or the probability of the species becoming rare. Our review elucidates key processes that have been found to mediate the negative and positive effects of TES on species richness, and by doing so highlights key areas for future research.
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Affiliation(s)
- Tak Fung
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558, Singapore.
| | - Jayant Pande
- Department of Physical and Natural Sciences, FLAME University, Pune, Maharashtra 412115, India
| | - Nadav M Shnerb
- Department of Physics, Bar-Ilan University, Ramat Gan 52900, Israel
| | - James P O'Dwyer
- Department of Plant Biology, School of Integrative Biology, University of Illinois, 505, South Goodwin Avenue, Urbana, IL 61801, United States
| | - Ryan A Chisholm
- Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, Singapore 117558, Singapore
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Fung T, O'Dwyer JP, Chisholm RA. Effects of temporal environmental stochasticity on species richness: a mechanistic unification spanning weak to strong temporal correlations. OIKOS 2021. [DOI: 10.1111/oik.08667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Tak Fung
- National Univ. of Singapore, Dept of Biological Sciences Singapore Singapore
| | - James P. O'Dwyer
- Dept of Plant Biology, School of Integrative Biology, Univ. of Illinois Urbana IL USA
| | - Ryan A. Chisholm
- National Univ. of Singapore, Dept of Biological Sciences Singapore Singapore
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3
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Holyoak M, Caspi T, Redosh LW. Integrating Disturbance, Seasonality, Multi-Year Temporal Dynamics, and Dormancy Into the Dynamics and Conservation of Metacommunities. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.571130] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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4
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Kaur T, Dutta PS. Persistence and stability of interacting species in response to climate warming: the role of trophic structure. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00456-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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5
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Shoemaker LG, Sullivan LL, Donohue I, Cabral JS, Williams RJ, Mayfield MM, Chase JM, Chu C, Harpole WS, Huth A, HilleRisLambers J, James ARM, Kraft NJB, May F, Muthukrishnan R, Satterlee S, Taubert F, Wang X, Wiegand T, Yang Q, Abbott KC. Integrating the underlying structure of stochasticity into community ecology. Ecology 2020; 101:e02922. [PMID: 31652337 PMCID: PMC7027466 DOI: 10.1002/ecy.2922] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 08/26/2019] [Accepted: 09/10/2019] [Indexed: 01/13/2023]
Abstract
Stochasticity is a core component of ecology, as it underlies key processes that structure and create variability in nature. Despite its fundamental importance in ecological systems, the concept is often treated as synonymous with unpredictability in community ecology, and studies tend to focus on single forms of stochasticity rather than taking a more holistic view. This has led to multiple narratives for how stochasticity mediates community dynamics. Here, we present a framework that describes how different forms of stochasticity (notably demographic and environmental stochasticity) combine to provide underlying and predictable structure in diverse communities. This framework builds on the deep ecological understanding of stochastic processes acting at individual and population levels and in modules of a few interacting species. We support our framework with a mathematical model that we use to synthesize key literature, demonstrating that stochasticity is more than simple uncertainty. Rather, stochasticity has profound and predictable effects on community dynamics that are critical for understanding how diversity is maintained. We propose next steps that ecologists might use to explore the role of stochasticity for structuring communities in theoretical and empirical systems, and thereby enhance our understanding of community dynamics.
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Affiliation(s)
- Lauren G. Shoemaker
- Department of BotanyUniversity of Wyoming1000 E. University Ave.LaramieWyoming82017USA
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota1987 Upper Buford CircleSaint PaulMinnesota55108USA
- Department of Ecology and Evolutionary BiologyUniversity of Colorado1900 Pleasant StreetBoulderColorado80309USA
| | - Lauren L. Sullivan
- Department of Ecology, Evolution, and BehaviorUniversity of Minnesota1987 Upper Buford CircleSaint PaulMinnesota55108USA
- Division of Biological SciencesUniversity of Missouri105 Tucker HallColumbiaMissouri65211USA
| | - Ian Donohue
- Department of Zoology, School of Natural SciencesTrinity CollegeCollege Green Dublin 2Ireland
| | - Juliano S. Cabral
- Synthesis Centre of the German Centre for Integrative Biodiversity Research (sDiv) Halle-Jena-LeipzigDeutscher Platz 5eLeipzig04103Germany
- Ecosystem Modeling, Center of Computation and Theoretical BiologyUniversity of WürzburgEmil-Fischer-Strasse 3297074WürzburgGermany
| | - Ryan J. Williams
- Division of Biological SciencesUniversity of Missouri105 Tucker HallColumbiaMissouri65211USA
| | - Margaret M. Mayfield
- The University of QueenslandSchool of Biological SciencesGoddard BuildingBrisbaneQueensland4072Australia
| | - Jonathan M. Chase
- German Centre for Integrative Biodiversity Research (iDiv)Deutscher Platz 5eLeipzig04103Germany
- Institute for Computer ScienceMartin Luther University Halle-WittenbergHalle06099Germany
| | - Chengjin Chu
- Department of Ecology, State Key Laboratory of Biocontrol and School of Life SciencesSun Yat-sen University510275GuangzhouGuangdongChina
| | - W. Stanley Harpole
- German Centre for Integrative Biodiversity Research (iDiv)Deutscher Platz 5eLeipzig04103Germany
- Helmholtz Center for Environmental Research–UFZPermoserstrasse 1504318LeipzigGermany
- Institute of BiologyMartin Luther University Halle-WittenbergAm Kirchtor 106108Halle (Saale)Germany
| | - Andreas Huth
- German Centre for Integrative Biodiversity Research (iDiv)Deutscher Platz 5eLeipzig04103Germany
- Helmholtz Center for Environmental Research–UFZPermoserstrasse 1504318LeipzigGermany
- Institute of Environmental Research SystemsUniversity of OsnabrückP.O. Box 44 69,49069OsnabrückGermany
| | | | - Aubrie R. M. James
- Department of Ecology and Evolutionary BiologyCornell UniversityE145 Corson HallIthacaNew York14853USA
| | - Nathan J. B. Kraft
- Department of Ecology and Evolutionary BiologyUniversity of California, Los Angeles621 Charles E. Young Drive East, P.O. Box 957246Los AngelesCA90095USA
| | - Felix May
- German Centre for Integrative Biodiversity Research (iDiv)Deutscher Platz 5eLeipzig04103Germany
- Institute for Computer ScienceMartin Luther University Halle-WittenbergHalle06099Germany
- Center for MethodologyLeuphana University LüneburgUniversitätsallee 1D‐21335LüneburgGermany
| | - Ranjan Muthukrishnan
- Environmental Resilience InstituteIndiana University717 E 8th StBloomingtonIndiana 47408USA
- Department of Fisheries, Wildlife, and Conservation BiologyUniversity of Minnesota2003 Upper Buford CircleSt. PaulMinnesota55108USA
| | - Sean Satterlee
- Department of Ecology, Evolution, and Organismal BiologyIowa State University251 Bessey HallAmesIowa50011USA
| | - Franziska Taubert
- Helmholtz Center for Environmental Research–UFZPermoserstrasse 1504318LeipzigGermany
| | - Xugao Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China
| | - Thorsten Wiegand
- German Centre for Integrative Biodiversity Research (iDiv)Deutscher Platz 5eLeipzig04103Germany
- Helmholtz Center for Environmental Research–UFZPermoserstrasse 1504318LeipzigGermany
| | - Qiang Yang
- Department of Zoology, School of Natural SciencesTrinity CollegeCollege Green Dublin 2Ireland
- Department of BiologyUniversity of KonstanzUniversitätsstraße 1078464KonstanzGermany
| | - Karen C. Abbott
- Department of BiologyCase Western Reserve University10900 Euclid AvenueClevelandOH44106USA
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6
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Identifying risk factors for persistent versus casual establishment to prioritize rapid response to non-indigenous aquarium fish. Biol Invasions 2020. [DOI: 10.1007/s10530-019-02191-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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7
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Exploring resilience with agent-based models: State of the art, knowledge gaps and recommendations for coping with multidimensionality. ECOLOGICAL COMPLEXITY 2019. [DOI: 10.1016/j.ecocom.2018.06.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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May R, Masden EA, Bennet F, Perron M. Considerations for upscaling individual effects of wind energy development towards population-level impacts on wildlife. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2019; 230:84-93. [PMID: 30273787 DOI: 10.1016/j.jenvman.2018.09.062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 09/10/2018] [Accepted: 09/20/2018] [Indexed: 06/08/2023]
Abstract
The expansion of wind energy poses challenges to policy- and decision-makers to address conflicts with wildlife. Conflicts are associated with impacts of existing and planned projects on wildlife, and associated difficulties of prediction where impacts are subject to considerable uncertainty. Many post-construction studies have demonstrated adverse effects on individuals of various bird and bat species. These effects may come in the form of collision-induced mortality or behavioral or physiological changes reducing the fitness of individuals exposed to wind energy facilities. Upscaling these individual effects to population impacts provides information on the true value of interest from a conservation point of view. This paper identifies methodological issues associated when moving from individual effects to population impacts in the context of wind energy. Distinct methodological approaches to predict population impacts are described using published case studies. The various choices of study design and metrics available to detect significant changes at the population level are further assessed based on these. Ways to derive impact thresholds relevant for decision-making are discussed in detail. Robust monitoring schemes and sophisticated modelling techniques may inevitably be unable to describe the whole complexity of wind and wildlife interactions and the natural variability of animal populations. Still, they will provide an improved understanding of the response of wildlife to wind energy and better-informed policies to support risk-based decision-making. Policies that support the use of adaptive management will promote assessments at the population level. Providing information to adequately balance the development of wind energy with the persistence of wildlife populations.
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Affiliation(s)
- R May
- Norwegian Institute for Nature Research (NINA), P.O. Box 5685 Sluppen, N-7485 Trondheim, Norway.
| | - E A Masden
- Environmental Research Institute, North Highland College-UHI, University of the Highlands and Islands, Ormlie Road, Thurso, Caithness KW14 7EE, UK
| | - F Bennet
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB, UK
| | - M Perron
- Nateco AG, Sissacherstrasse 20, CH-4460 Gelterkinden, Switzerland
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9
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Abbott RE, Doak DF, Peterson ML. Portfolio effects, climate change, and the persistence of small populations: analyses on the rare plant Saussurea weberi. Ecology 2017; 98:1071-1081. [PMID: 28112402 DOI: 10.1002/ecy.1738] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 11/21/2016] [Accepted: 01/06/2017] [Indexed: 11/08/2022]
Abstract
The mechanisms that stabilize small populations in the face of environmental variation are crucial to their long-term persistence. Building from diversity-stability concepts in community ecology, within-population diversity is gaining attention as an important component of population stability. Genetic and microhabitat variation within populations can generate diverse responses to common environmental fluctuations, dampening temporal variability across the population as a whole through portfolio effects. Yet, the potential for portfolio effects to operate at small scales within populations or to change with systematic environmental shifts, such as climate change, remain largely unexplored. We tracked the abundance of a rare alpine perennial plant, Saussurea weberi, in 49 1-m2 plots within a single population over 20 yr. We estimated among-plot correlations in log annual growth rate to test for population-level synchrony and quantify portfolio effects across the 20-yr study period and also in 5-yr subsets based on June temperature quartiles. Asynchrony among plots, due to different plot-level responses to June temperature, reduced overall fluctuations in abundance and the probability of decline in population models, even when accounting for the effects of density dependence on dynamics. However, plots became more synchronous and portfolio effects decreased during the warmest years of the study, suggesting that future climate warming may erode stabilizing mechanisms in populations of this rare plant.
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Affiliation(s)
- Ronald E Abbott
- Independent Researcher, P.O. Box 1431, Greeley, Colorado, 80632, USA
| | - Daniel F Doak
- Environmental Studies Program, University of Colorado Boulder, 4001 Discovery Drive, Boulder, Colorado, 80309, USA
| | - Megan L Peterson
- Environmental Studies Program, University of Colorado Boulder, 4001 Discovery Drive, Boulder, Colorado, 80309, USA
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10
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Nadeau CP, Urban MC, Bridle JR. Coarse climate change projections for species living in a fine-scaled world. GLOBAL CHANGE BIOLOGY 2017; 23:12-24. [PMID: 27550861 DOI: 10.1111/gcb.13475] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 07/29/2016] [Accepted: 08/05/2016] [Indexed: 06/06/2023]
Abstract
Accurately predicting biological impacts of climate change is necessary to guide policy. However, the resolution of climate data could be affecting the accuracy of climate change impact assessments. Here, we review the spatial and temporal resolution of climate data used in impact assessments and demonstrate that these resolutions are often too coarse relative to biologically relevant scales. We then develop a framework that partitions climate into three important components: trend, variance, and autocorrelation. We apply this framework to map different global climate regimes and identify where coarse climate data is most and least likely to reduce the accuracy of impact assessments. We show that impact assessments for many large mammals and birds use climate data with a spatial resolution similar to the biologically relevant area encompassing population dynamics. Conversely, impact assessments for many small mammals, herpetofauna, and plants use climate data with a spatial resolution that is orders of magnitude larger than the area encompassing population dynamics. Most impact assessments also use climate data with a coarse temporal resolution. We suggest that climate data with a coarse spatial resolution is likely to reduce the accuracy of impact assessments the most in climates with high spatial trend and variance (e.g., much of western North and South America) and the least in climates with low spatial trend and variance (e.g., the Great Plains of the USA). Climate data with a coarse temporal resolution is likely to reduce the accuracy of impact assessments the most in the northern half of the northern hemisphere where temporal climatic variance is high. Our framework provides one way to identify where improving the resolution of climate data will have the largest impact on the accuracy of biological predictions under climate change.
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Affiliation(s)
- Christopher P Nadeau
- Ecology and Evolutionary Biology Department, University of Connecticut, 75 North Eagleville Road, Storrs, CT, 06269, USA
| | - Mark C Urban
- Ecology and Evolutionary Biology Department, University of Connecticut, 75 North Eagleville Road, Storrs, CT, 06269, USA
- Institute of Biological Risk, University of Connecticut, 75 North Eagleville Road, Storrs, CT, 06269, USA
| | - Jon R Bridle
- School of Biological Sciences, University of Bristol, Bristol, BS8 1UD, UK
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11
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Cuddington K, Hastings A. Autocorrelated environmental variation and the establishment of invasive species. OIKOS 2016. [DOI: 10.1111/oik.02859] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kim Cuddington
- Dept of Biology Univ. of Waterloo Waterloo ON N2L 3G1 Canada
| | - Alan Hastings
- Dept of Environmental Science and Policy Univ. of California – Davis Davis CA 95616 USA
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12
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Vercken E, Fauvergue X, Ris N, Crochard D, Mailleret L. Temporal autocorrelation in host density increases establishment success of parasitoids in an experimental system. Ecol Evol 2015; 5:2684-93. [PMID: 26257880 PMCID: PMC4523363 DOI: 10.1002/ece3.1505] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/18/2015] [Accepted: 04/02/2015] [Indexed: 11/23/2022] Open
Abstract
Environmental variation is classically expected to affect negatively population growth and to increase extinction risk, and it has been identified as a major determinant of establishment failures in the field. Yet, recent theoretical investigations have shown that the structure of environmental variation and more precisely the presence of positive temporal autocorrelation might alter this prediction. This is particularly likely to affect the establishment dynamics of biological control agents in the field, as host–parasitoid interactions are expected to induce temporal autocorrelation in host abundance. In the case where parasitoid populations display overcompensatory dynamics, the presence of such positive temporal autocorrelation should increase their establishment success in a variable environment. We tested this prediction in laboratory microcosms by introducing parasitoids to hosts whose abundances were manipulated to simulate uncorrelated or positively autocorrelated variations in carrying capacity. We found that environmental variability decreased population size and increased parasitoid population variance, which is classically expected to extinction risk. However, although exposed to significant environmental variation, we found that parasitoid populations experiencing positive temporal autocorrelation in host abundance were more likely to persist than populations exposed to uncorrelated variation. These results confirm that environmental variation is a key determinant of extinction dynamics that can have counterintuitive effects depending on its autocorrelation structure.
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Affiliation(s)
- Elodie Vercken
- INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France
| | - Xavier Fauvergue
- INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France
| | - Nicolas Ris
- INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France
| | - Didier Crochard
- INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France
| | - Ludovic Mailleret
- INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; INRIA, Biocore 06902, Sophia Antipolis, France
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De Roissart A, Wang S, Bonte D. Spatial and spatiotemporal variation in metapopulation structure affects population dynamics in a passively dispersing arthropod. J Anim Ecol 2015; 84:1565-74. [PMID: 25988264 DOI: 10.1111/1365-2656.12400] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 05/06/2015] [Indexed: 12/27/2022]
Abstract
The spatial and temporal variation in the availability of suitable habitat within metapopulations determines colonization-extinction events, regulates local population sizes and eventually affects local population and metapopulation stability. Insights into the impact of such a spatiotemporal variation on the local population and metapopulation dynamics are principally derived from classical metapopulation theory and have not been experimentally validated. By manipulating spatial structure in artificial metapopulations of the spider mite Tetranychus urticae, we test to which degree spatial (mainland-island metapopulations) and spatiotemporal variation (classical metapopulations) in habitat availability affects the dynamics of the metapopulations relative to systems where habitat is constantly available in time and space (patchy metapopulations). Our experiment demonstrates that (i) spatial variation in habitat availability decreases variance in metapopulation size and decreases density-dependent dispersal at the metapopulation level, while (ii) spatiotemporal variation in habitat availability increases patch extinction rates, decreases local population and metapopulation sizes and decreases density dependence in population growth rates. We found dispersal to be negatively density dependent and overall low in the spatial variable mainland-island metapopulation. This demographic variation subsequently impacts local and regional population dynamics and determines patterns of metapopulation stability. Both local and metapopulation-level variabilities are minimized in mainland-island metapopulations relative to classical and patchy ones.
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Affiliation(s)
- Annelies De Roissart
- Terrestrial Ecology Unit, Department Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000, Ghent, Belgium
| | - Shaopeng Wang
- Centre for Biodiversity Theory and Modelling, Station d'Ecologie Expérimentale du CNRS, 09200, Moulis, France
| | - Dries Bonte
- Terrestrial Ecology Unit, Department Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000, Ghent, Belgium
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Rueda-Cediel P, Anderson KE, Regan TJ, Franklin J, Regan HM. Combined Influences of Model Choice, Data Quality, and Data Quantity When Estimating Population Trends. PLoS One 2015; 10:e0132255. [PMID: 26177511 PMCID: PMC4503393 DOI: 10.1371/journal.pone.0132255] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 06/11/2015] [Indexed: 11/18/2022] Open
Abstract
Estimating and projecting population trends using population viability analysis (PVA) are central to identifying species at risk of extinction and for informing conservation management strategies. Models for PVA generally fall within two categories, scalar (count-based) or matrix (demographic). Model structure, process error, measurement error, and time series length all have known impacts in population risk assessments, but their combined impact has not been thoroughly investigated. We tested the ability of scalar and matrix PVA models to predict percent decline over a ten-year interval, selected to coincide with the IUCN Red List criterion A.3, using data simulated for a hypothetical, short-lived organism with a simple life-history and for a threatened snail, Tasmaphena lamproides. PVA performance was assessed across different time series lengths, population growth rates, and levels of process and measurement error. We found that the magnitude of effects of measurement error, process error, and time series length, and interactions between these, depended on context. We found that high process and measurement error reduced the reliability of both models in predicted percent decline. Both sources of error contributed strongly to biased predictions, with process error tending to contribute to the spread of predictions more than measurement error. Increasing time series length improved precision and reduced bias of predicted population trends, but gains substantially diminished for time series lengths greater than 10-15 years. The simple parameterization scheme we employed contributed strongly to bias in matrix model predictions when both process and measurement error were high, causing scalar models to exhibit similar or greater precision and lower bias than matrix models. Our study provides evidence that, for short-lived species with structured but simple life histories, short time series and simple models can be sufficient for reasonably reliable conservation decision-making, and may be preferable for population projections when unbiased estimates of vital rates cannot be obtained.
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Affiliation(s)
- Pamela Rueda-Cediel
- Department of Biology, University of California Riverside, Riverside, CA, United States of America
| | - Kurt E. Anderson
- Department of Biology, University of California Riverside, Riverside, CA, United States of America
- * E-mail:
| | - Tracey J. Regan
- Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria, Australia
- The School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Janet Franklin
- School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ 85287, United States of America
| | - Helen M. Regan
- Department of Biology, University of California Riverside, Riverside, CA, United States of America
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Regan TJ, Taylor BL, Thompson GG, Cochrane JF, Ralls K, Runge MC, Merrick R. Testing decision rules for categorizing species' extinction risk to help develop quantitative listing criteria for the U.S. Endangered Species Act. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2013; 27:821-831. [PMID: 23646933 DOI: 10.1111/cobi.12055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 11/27/2012] [Indexed: 06/02/2023]
Abstract
Lack of guidance for interpreting the definitions of endangered and threatened in the U.S. Endangered Species Act (ESA) has resulted in case-by-case decision making leaving the process vulnerable to being considered arbitrary or capricious. Adopting quantitative decision rules would remedy this but requires the agency to specify the relative urgency concerning extinction events over time, cutoff risk values corresponding to different levels of protection, and the importance given to different types of listing errors. We tested the performance of 3 sets of decision rules that use alternative functions for weighting the relative urgency of future extinction events: a threshold rule set, which uses a decision rule of x% probability of extinction over y years; a concave rule set, where the relative importance of future extinction events declines exponentially over time; and a shoulder rule set that uses a sigmoid shape function, where relative importance declines slowly at first and then more rapidly. We obtained decision cutoffs by interviewing several biologists and then emulated the listing process with simulations that covered a range of extinction risks typical of ESA listing decisions. We evaluated performance of the decision rules under different data quantities and qualities on the basis of the relative importance of misclassification errors. Although there was little difference between the performance of alternative decision rules for correct listings, the distribution of misclassifications differed depending on the function used. Misclassifications for the threshold and concave listing criteria resulted in more overprotection errors, particularly as uncertainty increased, whereas errors for the shoulder listing criteria were more symmetrical. We developed and tested the framework for quantitative decision rules for listing species under the U.S. ESA. If policy values can be agreed on, use of this framework would improve the implementation of the ESA by increasing transparency and consistency.
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Affiliation(s)
- Tracey J Regan
- The School of Botany, The University of Melbourne, Parkville, Victoria 3010, Australia.
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Pertoldi C, Faurby S. Consequences of environmental fluctuations on Taylor's power law and implications for the dynamics and persistence of populations. Acta Biotheor 2013. [PMID: 23184387 DOI: 10.1007/s10441-012-9167-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Conservation Biologists have found that demographic stochasticity causes the mean time to extinction to increase exponentially with population size. This has proved helpful in analyses determining extinction times and characterizing the pathway to extinction. The aim of this investigation is to explore the possible interactions between environmental/demographic noises and the scaling effect of the mean population size with its variance, which is expected to follow Taylor's power law relationship. We showed that the combined effects of environmental/demographic noises and the scaling of population size variability interact with the population dynamics and affect the mean time to extinction.
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Affiliation(s)
- C Pertoldi
- Department of Biosciences, Aarhus University, Aarhus, Denmark.
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Mallard F, Le Bourlot V, Tully T. An automated image analysis system to measure and count organisms in laboratory microcosms. PLoS One 2013; 8:e64387. [PMID: 23734199 PMCID: PMC3667193 DOI: 10.1371/journal.pone.0064387] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/12/2013] [Indexed: 11/18/2022] Open
Abstract
1. Because of recent technological improvements in the way computer and digital camera perform, the potential use of imaging for contributing to the study of communities, populations or individuals in laboratory microcosms has risen enormously. However its limited use is due to difficulties in the automation of image analysis. 2. We present an accurate and flexible method of image analysis for detecting, counting and measuring moving particles on a fixed but heterogeneous substrate. This method has been specifically designed to follow individuals, or entire populations, in experimental laboratory microcosms. It can be used in other applications. 3. The method consists in comparing multiple pictures of the same experimental microcosm in order to generate an image of the fixed background. This background is then used to extract, measure and count the moving organisms, leaving out the fixed background and the motionless or dead individuals. 4. We provide different examples (springtails, ants, nematodes, daphnia) to show that this non intrusive method is efficient at detecting organisms under a wide variety of conditions even on faintly contrasted and heterogeneous substrates. 5. The repeatability and reliability of this method has been assessed using experimental populations of the Collembola Folsomia candida. 6. We present an ImageJ plugin to automate the analysis of digital pictures of laboratory microcosms. The plugin automates the successive steps of the analysis and recursively analyses multiple sets of images, rapidly producing measurements from a large number of replicated microcosms.
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Affiliation(s)
- François Mallard
- CNRS/UPMC/ENS, Écologie et Évolution, UMR 7625, École Normale Supérieure, Paris, France
| | - Vincent Le Bourlot
- CNRS/UPMC/ENS, Écologie et Évolution, UMR 7625, École Normale Supérieure, Paris, France
- CERES - ERTI, École Normale Supérieure, Paris, France
| | - Thomas Tully
- CNRS/UPMC/ENS, Écologie et Évolution, UMR 7625, École Normale Supérieure, Paris, France
- ESPE de Paris, Université Paris 4 - Sorbonne, Paris, France
- * E-mail:
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Robinson JD, Wares JP, Drake JM. Extinction hazards in experimental Daphnia magna populations: effects of genotype diversity and environmental variation. Ecol Evol 2012; 3:233-43. [PMID: 23467276 PMCID: PMC3586633 DOI: 10.1002/ece3.449] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 10/10/2012] [Accepted: 11/20/2012] [Indexed: 11/23/2022] Open
Abstract
Extinction is ubiquitous in natural systems and the ultimate fate of all biological populations. However, the factors that contribute to population extinction are still poorly understood, particularly genetic diversity and composition. A laboratory experiment was conducted to examine the influences of environmental variation and genotype diversity on persistence in experimental Daphnia magna populations. Populations were initiated in two blocks with one, two, three, or six randomly selected and equally represented genotypes, fed and checked for extinction daily, and censused twice weekly over a period of 170 days. Our results show no evidence for an effect of the number of genotypes in a population on extinction hazard. Environmental variation had a strong effect on hazards in both experimental blocks, but the direction of the effect differed between blocks. In the first block, variable environments hastened extinction, while in the second block, hazards were reduced under variable food input. This occurred despite greater fluctuations in population size in variable environments in the second block of our experiment. Our results conflict with previous studies, where environmental variation consistently increased extinction risk. They are also at odds with previous studies in other systems that documented significant effects of genetic diversity on population persistence. We speculate that the lack of sexual reproduction, or the phenotypic similarity among our experimental lines, might underlie the lack of a significant effect of genotype diversity in our study.
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Affiliation(s)
- John D Robinson
- Biology Department, City College of New York New York, NY, USA ; Department of Genetics, University of Georgia Athens, Georgia
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20
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Grazer VM, Martin OY. Investigating climate change and reproduction: experimental tools from evolutionary biology. BIOLOGY 2012; 1:411-38. [PMID: 24832232 PMCID: PMC4009780 DOI: 10.3390/biology1020411] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 08/30/2012] [Accepted: 09/04/2012] [Indexed: 11/16/2022]
Abstract
It is now generally acknowledged that climate change has wide-ranging biological consequences, potentially leading to impacts on biodiversity. Environmental factors can have diverse and often strong effects on reproduction, with obvious ramifications for population fitness. Nevertheless, reproductive traits are often neglected in conservation considerations. Focusing on animals, recent progress in sexual selection and sexual conflict research suggests that reproductive costs may pose an underestimated hurdle during rapid climate change, potentially lowering adaptive potential and increasing extinction risk of certain populations. Nevertheless, regime shifts may have both negative and positive effects on reproduction, so it is important to acquire detailed experimental data. We hence present an overview of the literature reporting short-term reproductive consequences of exposure to different environmental factors. From the enormous diversity of findings, we conclude that climate change research could benefit greatly from more coordinated efforts incorporating evolutionary approaches in order to obtain cross-comparable data on how individual and population reproductive fitness respond in the long term. Therefore, we propose ideas and methods concerning future efforts dealing with reproductive consequences of climate change, in particular by highlighting the advantages of multi-generational experimental evolution experiments.
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Affiliation(s)
- Vera M Grazer
- ETH Zurich, Experimental Ecology, Institute for Integrative Biology, Universitätsstrasse 16, CH-8092 Zurich, Switzerland.
| | - Oliver Y Martin
- ETH Zurich, Experimental Ecology, Institute for Integrative Biology, Universitätsstrasse 16, CH-8092 Zurich, Switzerland
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21
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Bartholomeus RP, Witte JPM, van Bodegom PM, van Dam JC, Aerts R. Climate change threatens endangered plant species by stronger and interacting water-related stresses. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jg001693] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Drake JM, Shapiro J, Griffen BD. Experimental demonstration of a two-phase population extinction hazard. J R Soc Interface 2011; 8:1472-9. [PMID: 21429907 DOI: 10.1098/rsif.2011.0024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Population extinction is a fundamental biological process with applications to ecology, epidemiology, immunology, conservation biology and genetics. Although a monotonic relationship between initial population size and mean extinction time is predicted by virtually all theoretical models, attempts at empirical demonstration have been equivocal. We suggest that this anomaly is best explained with reference to the transient properties of ensembles of populations. Specifically, we submit that under experimental conditions, many populations escape their initially vulnerable state to reach quasi-stationarity, where effects of initial conditions are erased. Thus, extinction of populations initialized far from quasi-stationarity may be exposed to a two-phase extinction hazard. An empirical prediction of this theory is that the fit Cox proportional hazards regression model for the observed survival time distribution of a group of populations will be shown to violate the proportional hazards assumption early in the experiment, but not at later times. We report results of two experiments with the cladoceran zooplankton Daphnia magna designed to exhibit this phenomenon. In one experiment, habitat size was also varied. Statistical analysis showed that in one of these experiments a transformation occurred so that very early in the experiment there existed a transient phase during which the extinction hazard was primarily owing to the initial population size, and that this was gradually replaced by a more stable quasi-stationary phase. In the second experiment, only habitat size unambiguously displayed an effect. Analysis of data pooled from both experiments suggests that the overall extinction time distribution in this system results from the mixture of extinctions during the initial rapid phase, during which the effects of initial population size can be considerable, and a longer quasi-stationary phase, during which only habitat size has an effect. These are the first results, to our knowledge, of a two-phase population extinction process.
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Affiliation(s)
- John M Drake
- Odum School of Ecology, University of Georgia, Athens, GA 30602-2202, USA.
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Abstract
PURPOSE Cancer Stem Cells (CSC) are hypothesised to influence tumour growth through their self-replication, cell loss, and differentiation into growth-limited cell types. A model for the random gain and loss of metastatic CSC is developed to investigate how the balance between these processes might affect metastatic efficiency, tumour involution and treatment response. MATERIALS AND METHODS A stochastic birth-death model for metastasis was constructed for the replication and loss of CSC. The model was extended to account for single and sequential cancer treatments, with CSC repopulation. RESULTS If CSC losses exceed gains, the metastasis would become extinct. The resultant extinction probability was greatest during a period of stochastic susceptibility; treatment could extend, or reestablish, this period. CONCLUSION Random CSC losses, with 'seed and soil' selection, provided a mechanistic explanation for the involution of metastases, as well as for metastatic inefficiency. With such background losses, and the growth limitations of differentiated cells, a metastasis could take years to reach macroscopic size. The susceptibility period could be protracted, providing for a window for therapeutic opportunity. Metastases with a high background CSC loss would be more responsive to treatment than stabler metastases. Modulation of this loss could enhance the efficacy of conventional cancer treatment.
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Affiliation(s)
- Wayne S Kendal
- Division of Radiation Oncology, The Ottawa Hospital Cancer Centre, The University of Ottawa, and The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
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Matter SF, Roland J. Effects of experimental population extinction for the spatial population dynamics of the butterfly Parnassius smintheus. OIKOS 2010. [DOI: 10.1111/j.1600-0706.2010.18666.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Schreiber SJ. Interactive effects of temporal correlations, spatial heterogeneity and dispersal on population persistence. Proc Biol Sci 2010; 277:1907-14. [PMID: 20164099 DOI: 10.1098/rspb.2009.2006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It is an ecological truism that population persistence depends on a population's growth rate when rare. To understand the interplay between temporal correlations, spatial heterogeneity and dispersal on persistence, an analytic approximation for this growth rate is derived for partially mixing populations. Partial mixing has two effects on population growth. In the absence of temporal correlations in relative fitness, greater movement to patches with, on average, higher relative fitness increases population growth rates. In the absence of spatial heterogeneity in the average relative fitnesses, lower dispersal rates enhance population growth when temporal autocorrelations of relative fitness within a patch exceed temporal cross-correlations in relative fitness between patches. This approximation implies that metapopulations whose expected fitness in every patch is less than 1 can persist if there are positive temporal autocorrelations in relative fitness, sufficiently weak spatial correlations and the population disperses at intermediate rates. It also implies that movement into lower quality habitats increases the population growth rate whenever the net temporal variation in per capita growth rates is sufficiently larger than the difference in the means of these per capita growth rates. Moreover, temporal autocorrelations, whether they be negative or positive, can enhance population growth for optimal dispersal strategies.
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Affiliation(s)
- Sebastian J Schreiber
- Department of Evolution and Ecology, Center for Population Biology, University of California, Davis, CA 95616, USA.
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27
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Ezard TH, Coulson T. How sensitive are elasticities of long-run stochastic growth to how environmental variability is modelled? Ecol Modell 2010. [DOI: 10.1016/j.ecolmodel.2009.09.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Griffen BD, Drake JM. Effects of habitat quality and size on extinction in experimental populations. Proc Biol Sci 2008; 275:2251-6. [PMID: 18544509 DOI: 10.1098/rspb.2008.0518] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Stochastic population theory makes clear predictions about the effects of reproductive potential and carrying capacity on characteristic time-scales of extinction. At the same time, the effects of habitat size and quality on reproduction and regulation have been hotly debated. To trace the causal relationships among these factors, we looked at the effects of habitat size and quality on extinction time in experimental populations of Daphnia magna. Replicate model systems representative of a broad-spectrum consumer foraging on a continuously supplied resource were established under crossed treatments of habitat size (two levels) and habitat quality (three levels) and monitored until eventual extinction of all populations. Using statistically derived estimates of key parameters, we related experimental treatments to persistence time through their effect on carrying capacity and the population growth rate. We found that carrying capacity and the intrinsic rate of increase were each influenced similarly by habitat size and quality, and that carrying capacity and the intrinsic rate of increase were in turn both correlated with time to population extinction. We expected habitat quality to have a greater influence on extinction. However, owing to an unexpected effect of habitat size on reproductive potential, habitat size and quality were similarly important for population persistence. These results support the idea that improving the population growth rate or carrying capacity will reduce extinction risk and demonstrate that both are possible by improving habitat quality or increasing habitat size.
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Affiliation(s)
- Blaine D Griffen
- Odum School of Ecology, University of Georgia, Athens, GA 30602-2202, USA.
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31
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Abstract
Predicting population extinctions is a key element of quantitative conservation biology and population ecology. Although stochastic population theories have long been used to obtain theoretical distributions of population extinction times, model-based predictions have rarely been tested. Here I report results from a quantitative analysis of extinction time in 281 experimental populations of water fleas (Daphnia magna) in variable environments. To my knowledge, this is the first quantitative estimate of the shape of the distribution of population extinction times based on extinction data for any species. The finding that the distribution of population extinction times was extraordinarily peaked is consistent with theoretical predictions for density-independent populations, but inconsistent with predictions for density-dependent populations. The tail of the extinction time distribution was not exponential. These results imply that our current theories of extinction are inadequate. Future work should focus on how demographic stochasticity scales with population size and effects of nonrandom variable environments on population growth and decline.
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Affiliation(s)
- John M Drake
- National Center for Ecological Analysis and Synthesis, 735 State Street, Ste. 300, Santa Barbara, California 93101, USA.
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33
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Lewison R. Population responses to natural and human-mediated disturbances: assessing the vulnerability of the common hippopotamus (Hippopotamus amphibius). Afr J Ecol 2007. [DOI: 10.1111/j.1365-2028.2006.00747.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bull JC, Pickup NJ, Pickett B, Hassell MP, Bonsall MB. Metapopulation extinction risk is increased by environmental stochasticity and assemblage complexity. Proc Biol Sci 2007; 274:87-96. [PMID: 17018431 PMCID: PMC1679879 DOI: 10.1098/rspb.2006.3691] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Extinction risk is a key area of investigation for contemporary ecologists and conservation biologists. Practical conservation efforts for vulnerable species can be considerably enhanced by thoroughly understanding the ecological processes that interact to determine species persistence or extinction. Theory has highlighted the importance of both extrinsic environmental factors and intrinsic demographic processes. In laboratory microcosms, single-species single-habitat patch experimental designs have been widely used to validate the theoretical prediction that environmental heterogeneity can increase extinction risk. Here, we develop on this theme by testing the effects of fluctuating resource levels in experimental multispecies metapopulations. We compare a three-species host-parasitoid assemblage that exhibits apparent competition to the individual pairwise, host-parasitoid interactions. Existing theory is broadly supported for two-species assemblages: environmental stochasticity reduces trophic interaction persistence time, while metapopulation structure increases persistence time. However, with increasing assemblage complexity, the effects of trophic interactions mask environmental impacts and persistence time is further reduced, regardless of resource renewal regime. We relate our findings to recent theory, highlighting the importance of taking into account both intrinsic and extrinsic factors, over a range of spatial scales, in order to understand resource-consumer dynamics.
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Affiliation(s)
- James C Bull
- Division of Biology, Imperial College LondonSilwood Park Campus, Ascot, Berkshire SL5 7PY, UK
- Institute of Zoology, Zoological Society of LondonRegent's Park, London NW1 4RY, UK
| | - Nicola J Pickup
- Division of Biology, Imperial College LondonSilwood Park Campus, Ascot, Berkshire SL5 7PY, UK
- Department of Zoology, University of OxfordSouth Parks Road, Oxford OX1 3PS, UK
| | - Brian Pickett
- Division of Biology, Imperial College LondonSilwood Park Campus, Ascot, Berkshire SL5 7PY, UK
| | - Michael P Hassell
- Division of Biology, Imperial College LondonSilwood Park Campus, Ascot, Berkshire SL5 7PY, UK
| | - Michael B Bonsall
- Division of Biology, Imperial College LondonSilwood Park Campus, Ascot, Berkshire SL5 7PY, UK
- Department of Zoology, University of OxfordSouth Parks Road, Oxford OX1 3PS, UK
- Author for correspondence ()
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Drake JM, Baggenstos P, Lodge DM. Propagule pressure and persistence in experimental populations. Biol Lett 2007; 1:480-3. [PMID: 17148238 PMCID: PMC1626370 DOI: 10.1098/rsbl.2005.0375] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Average inoculum size and number of introductions are known to have positive effects on population persistence. However, whether these factors affect persistence independently or interact is unknown. We conducted a two-factor experiment in which 112 populations of parthenogenetic Daphnia magna were maintained for 41 days to study effects of inoculum size and introduction frequency on: (i) population growth, (ii) population persistence and (iii) time-to-extinction. We found that the interaction of inoculum size and introduction frequency-the immigration rate-affected all three dependent variables, while population growth was additionally affected by introduction frequency. We conclude that for this system the most important aspect of propagule pressure is immigration rate, with relatively minor additional effects of introduction frequency and negligible effects of inoculum size.
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Affiliation(s)
- John M Drake
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
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Melbourne BA, Cornell HV, Davies KF, Dugaw CJ, Elmendorf S, Freestone AL, Hall RJ, Harrison S, Hastings A, Holland M, Holyoak M, Lambrinos J, Moore K, Yokomizo H. Invasion in a heterogeneous world: resistance, coexistence or hostile takeover? Ecol Lett 2007; 10:77-94. [PMID: 17204119 DOI: 10.1111/j.1461-0248.2006.00987.x] [Citation(s) in RCA: 308] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We review and synthesize recent developments in the study of the invasion of communities in heterogeneous environments, considering both the invasibility of the community and impacts to the community. We consider both empirical and theoretical studies. For each of three major kinds of environmental heterogeneity (temporal, spatial and invader-driven), we find evidence that heterogeneity is critical to the invasibility of the community, the rate of spread, and the impacts on the community following invasion. We propose an environmental heterogeneity hypothesis of invasions, whereby heterogeneity both increases invasion success and reduces the impact to native species in the community, because it promotes invasion and coexistence mechanisms that are not possible in homogeneous environments. This hypothesis could help to explain recent findings that diversity is often increased as a result of biological invasions. It could also explain the scale dependence of the diversity-invasibility relationship. Despite the undoubted importance of heterogeneity to the invasion of communities, it has been studied remarkably little and new research is needed that simultaneously considers invasion, environmental heterogeneity and community characteristics. As a young field, there is an unrivalled opportunity for theoreticians and experimenters to work together to build a tractable theory informed by data.
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Affiliation(s)
- Brett A Melbourne
- Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA.
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Rankin DJ. Resolving the tragedy of the commons: the feedback between intraspecific conflict and population density. J Evol Biol 2007; 20:173-80. [PMID: 17210010 DOI: 10.1111/j.1420-9101.2006.01211.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Competition and conflict among individuals can favour exploitative strategies that undermine the common good. Theory suggests that this can lead to a tragedy of the commons and ultimately population extinction, a phenomenon known as evolutionary suicide. Here, I present a model of the evolutionary tragedy of the commons that explicitly considers the population dynamics where individuals invest in individually costly competitive traits. In the simplest form, this supports the notion that selection for high levels of conflict can cause evolutionary suicide. However, as competition comes with survival and fecundity costs, a feedback between the investment in competition and population density can act to reduce the level of conflict and prevent the population from going extinct. This suggests that the interaction between population ecology and the evolution of competition and conflict among individuals may be an important mechanism in resolving the level of competition and conflict among individuals.
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Affiliation(s)
- D J Rankin
- Laboratory of Ecological and Evolutionary Dynamics, Department of Biological and Environmental Science, University of Helsinki, Finland.
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Reuman DC, Desharnais RA, Costantino RF, Ahmad OS, Cohen JE. Power spectra reveal the influence of stochasticity on nonlinear population dynamics. Proc Natl Acad Sci U S A 2006; 103:18860-5. [PMID: 17116860 PMCID: PMC1693752 DOI: 10.1073/pnas.0608571103] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Indexed: 11/18/2022] Open
Abstract
Stochasticity alters the nonlinear dynamics of inherently cycling populations. The power spectrum can describe and explain the impacts of stochasticity. We fitted models to short observed time series of flour beetle populations in the frequency domain, then used a well fitting stochastic mechanistic model to generate detailed predictions of population spectra. Some predicted spectral peaks represent periodic phenomena induced or modified by stochasticity and were experimentally confirmed. For one experimental treatment, linearization theory explained that these peaks represent overcompensatory decay of deviations from deterministic oscillation. In another treatment, stochasticity caused frequent directional phase shifting around a cyclic attractor. This directional phase shifting was not explained by linearization theory and modified the periodicity of the system. If field systems exhibit directional phase shifting, then changing the intensity of demographic or environmental noise while holding constant the structure of the noise can change the main frequency of population fluctuations.
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Affiliation(s)
- Daniel C. Reuman
- *Laboratory of Populations, The Rockefeller University, Box 20, 1230 York Avenue, New York, NY 10021
| | - Robert A. Desharnais
- Department of Biological Sciences, California State University, Los Angeles, CA 90032
| | - Robert F. Costantino
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721
| | - Omar S. Ahmad
- Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10021; and
| | - Joel E. Cohen
- *Laboratory of Populations, The Rockefeller University, Box 20, 1230 York Avenue, New York, NY 10021
- Laboratory of Sensory Neuroscience, The Rockefeller University, 1230 York Avenue, New York, NY 10021; and
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Lodge DM, Williams S, MacIsaac HJ, Hayes KR, Leung B, Reichard S, Mack RN, Moyle PB, Smith M, Andow DA, Carlton JT, McMichael A. Biological invasions: recommendations for U.S. policy and management. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2006; 16:2035-54. [PMID: 17205888 DOI: 10.1890/1051-0761(2006)016[2035:birfup]2.0.co;2] [Citation(s) in RCA: 364] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The Ecological Society of America has evaluated current U.S. national policies and practices on biological invasions in light of current scientific knowledge. Invasions by harmful nonnative species are increasing in number and area affected; the damages to ecosystems, economic activity, and human welfare are accumulating. Without improved strategies based on recent scientific advances and increased investments to counter invasions, harm from invasive species is likely to accelerate. Federal leadership, with the cooperation of state and local governments, is required to increase the effectiveness of prevention of invasions, detect and respond quickly to new potentially harmful invasions, control and slow the spread of existing invasions, and provide a national center to ensure that these efforts are coordinated and cost effective. Specifically, the Ecological Society of America recommends that the federal government take the following six actions: (1) Use new information and practices to better manage commercial and other pathways to reduce the transport and release of potentially harmful species; (2) Adopt more quantitative procedures for risk analysis and apply them to every species proposed for importation into the country; (3) Use new cost-effective diagnostic technologies to increase active surveillance and sharing of information about invasive species so that responses to new invasions can be more rapid and effective; (4) Create new legal authority and provide emergency funding to support rapid responses to emerging invasions; (5) Provide funding and incentives for cost-effective programs to slow the spread of existing invasive species in order to protect still uninvaded ecosystems, social and industrial infrastructure, and human welfare; and (6) Establish a National Center for Invasive Species Management (under the existing National Invasive Species Council) to coordinate and lead improvements in federal, state, and international policies on invasive species. Recent scientific and technical advances provide a sound basis for more cost-effective national responses to invasive species. Greater investments in improved technology and management practices would be more than repaid by reduced damages from current and future invasive species. The Ecological Society of America is committed to assist all levels of government and provide scientific advice to improve all aspects of invasive-species management.
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Affiliation(s)
- David M Lodge
- Department of Biological Sciences, P.O. Box 369, University of Notre Dame, Indiana 46556, USA.
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Chen X, Barrows CW, Li BL. IS THE COACHELLA VALLEY FRINGE-TOED LIZARD (UMA INORNATA) ON THE EDGE OF EXTINCTION AT THOUSAND PALMS PRESERVE IN CALIFORNIA? SOUTHWEST NAT 2006. [DOI: 10.1894/0038-4909(2006)51[28:itcvfl]2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Whitmire SL, Tobin PC. Persistence of invading gypsy moth populations in the United States. Oecologia 2005; 147:230-7. [PMID: 16341893 DOI: 10.1007/s00442-005-0271-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Accepted: 09/08/2005] [Indexed: 11/24/2022]
Abstract
Exotic invasive species are a mounting threat to native biodiversity, and their effects are gaining more public attention as each new species is detected. Equally important are the dynamics of exotic invasives that are previously well established. While the literature reports many examples of the ability of a newly arrived exotic invader to persist prior to detection and population growth, we focused on the persistence dynamics of an established invader, the European gypsy moth (Lymantria dispar) in the United States. The spread of gypsy moth is largely thought to be the result of the growth and coalescence of isolated colonies in a transition zone ahead of the generally infested area. One important question is thus the ability of these isolated colonies to persist when subject to Allee effects and inimical stochastic events. We analyzed the US gypsy moth survey data and identified isolated colonies of gypsy moth using the local indicator of spatial autocorrelation. We then determined region-specific probabilities of colony persistence given the population abundance in the previous year and its relationship to a suite of ecological factors. We observed that colonies in Wisconsin, US, were significantly more likely to persist in the following year than in other geographic regions of the transition zone, and in all regions, the abundance of preferred host tree species and land use category did not appear to influence persistence. We propose that differences in region-specific rates of persistence may be attributed to Allee effects that are differentially expressed in space, and that the inclusion of geographically varying Allee effects into colony-invasion models may provide an improved paradigm for addressing the establishment and spread of gypsy moth and other invasive exotic species.
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Affiliation(s)
- Stefanie L Whitmire
- Department of Biology, West Virginia University, P. O. Box 6057, Morgantown, WV 26506, USA.
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Drake JM. Density-dependent demographic variation determines extinction rate of experimental populations. PLoS Biol 2005; 3:e222. [PMID: 15934788 PMCID: PMC1150291 DOI: 10.1371/journal.pbio.0030222] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Accepted: 04/21/2005] [Indexed: 11/26/2022] Open
Abstract
Understanding population extinctions is a chief goal of ecological theory. While stochastic theories of population growth are commonly used to forecast extinction, models used for prediction have not been adequately tested with experimental data. In a previously published experiment, variation in available food was experimentally manipulated in 281 laboratory populations of Daphnia magna to test hypothesized effects of environmental variation on population persistence. Here, half of those data were used to select and fit a stochastic model of population growth to predict extinctions of populations in the other half. When density-dependent demographic stochasticity was detected and incorporated in simple stochastic models, rates of population extinction were accurately predicted or only slightly biased. However, when density-dependent demographic stochasticity was not accounted for, as is usual when forecasting extinction of threatened and endangered species, predicted extinction rates were severely biased. Thus, an experimental demonstration shows that reliable estimates of extinction risk may be obtained for populations in variable environments if high-quality data are available for model selection and if density-dependent demographic stochasticity is accounted for. These results suggest that further consideration of density-dependent demographic stochasticity is required if predicted extinction rates are to be relied upon for conservation planning.
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Affiliation(s)
- John M Drake
- Department of Biological Sciences, University of Notre Dame, Indiana, USA.
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Sæther BE, Engen S, Møller AP, Visser ME, Matthysen E, Fiedler W, Lambrechts MM, Becker PH, Brommer JE, Dickinson J, du Feu C, Gehlbach FR, Merilä J, Rendell W, Robertson RJ, Thomson D, Török J. TIME TO EXTINCTION OF BIRD POPULATIONS. Ecology 2005. [DOI: 10.1890/04-0878] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Abstract
Understanding the factors that affect most severely the extinction risk of populations is crucial for maintaining biodiversity. An important general pattern derived from stochastic population theory is that time to extinction should decrease with increasing environmental stochasticity. Drake and Lodge recently provided one of the first pieces of experimental support for this simple prediction by artificially manipulating the dynamics of populations of Daphnia. A future challenge will be to include both demographic stochasticity and environmental stochasticity in such studies.
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Affiliation(s)
- Bernt-Erik Saether
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
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