1
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Stauffer GE, Olson ER, Belant JL, Stenglein JL, Price Tack JL, van Deelen TR, MacFarland DM, Roberts NM. Uncertainty and precaution in hunting wolves twice in a year: Reanalysis of Treves and Louchouarn. PLoS One 2024; 19:e0301487. [PMID: 38865308 PMCID: PMC11168653 DOI: 10.1371/journal.pone.0301487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/15/2024] [Indexed: 06/14/2024] Open
Abstract
Management of wolves is controversial in many jurisdictions where wolves live, which underscores the importance of rigor, transparency, and reproducibility when evaluating outcomes of management actions. Treves and Louchouarn 2022 (hereafter TL) predicted outcomes for various fall 2021 hunting scenarios following Wisconsin's judicially mandated hunting and trapping season in spring 2021, and concluded that even a zero harvest scenario could result in the wolf population declining below the population goal of 350 wolves specified in the 1999 Wisconsin wolf management plan. TL further concluded that with a fall harvest of > 16 wolves there was a "better than average possibility" that the wolf population size would decline below that 350-wolf threshold. We show that these conclusions are incorrect and that they resulted from mathematical errors and selected parameterizations that were consistently biased in the direction that maximized mortality and minimized reproduction (i.e., positively biased adult mortality, negatively biased pup survival, further halving pup survival to November, negatively biased number of breeding packs, and counting harvested wolves twice among the dead). These errors systematically exaggerated declines in predicted population size and resulted in erroneous conclusions that were not based on the best available or unbiased science. Corrected mathematical calculations and more rigorous parameterization resulted in predicted outcomes for the zero harvest scenario that more closely coincided with the empirical population estimates in 2022 following a judicially prevented fall hunt in 2021. Only in scenarios with simulated harvest of 300 or more wolves did probability of crossing the 350-wolf population threshold exceed zero. TL suggested that proponents of some policy positions bear a greater burden of proof than proponents of other positions to show that "their estimates are accurate, precise, and reproducible". In their analysis, TL failed to meet this standard that they demanded of others.
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Affiliation(s)
- Glenn E. Stauffer
- Office of Applied Sciences, Wisconsin Department of Natural Resources, Rhinelander, WI, United States of America
| | - Erik R. Olson
- Department of Forest and Wildlife Ecology, Northland College, Ashland, WI, United States of America
| | - Jerrold L. Belant
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, United States of America
| | - Jennifer L. Stenglein
- Office of Applied Sciences, Wisconsin Department of Natural Resources, Rhinelander, WI, United States of America
| | - Jennifer L. Price Tack
- Office of Applied Sciences, Wisconsin Department of Natural Resources, Rhinelander, WI, United States of America
| | - Timothy R. van Deelen
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, WI, United States of America
| | - David M. MacFarland
- Office of Applied Sciences, Wisconsin Department of Natural Resources, Rhinelander, WI, United States of America
| | - Nathan M. Roberts
- Department of Conservation and Wildlife Management, College of the Ozarks, Point Lookout, MO, United States of America
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2
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Gebreyohannes DT, Houlahan JE. Weak evidence of density dependent population regulation when using the ability of two simple density dependent models to predict population size. Sci Rep 2024; 14:5051. [PMID: 38424456 PMCID: PMC10904816 DOI: 10.1038/s41598-024-55533-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 02/24/2024] [Indexed: 03/02/2024] Open
Abstract
The relative importance of density dependence regulation in natural population fluctuations has long been debated. The concept of density dependence implies that current abundance is determined by historical abundance. We have developed four models-two density dependent and two density independent-to predict population size one year beyond the training set and used predictive performance on more than 16,000 populations from 14 datasets to compare the understanding captured by those models. For 4 of 14 datasets the density dependent models make better predictions (i.e., density dependent regulated) than either of the density independent models. However, neither of the density dependent models is statistically significantly superior to density independent models for any of the 14 datasets. We conclude that the evidence for widespread density dependent population regulation in the forms represented by these two simple density-dependent models is weak. However, the density dependent models used here-the Logistic and Gompertz models-are simple representations of how population density might regulate natural populations and only examine density-dependent effects on population size. A comprehensive assessment of the relative importance of density-dependent population regulation will require testing the predictive ability of a wider range of density-dependent models including models examining effects on population characteristics other than population size.
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Affiliation(s)
| | - Jeff E Houlahan
- Department of Biological Sciences, University of New Brunswick, Saint John, E2L 4L5, Canada
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3
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Martin EC, Hansen BB, Lee AM, Herfindal I. Generation time and seasonal migration explain variation in spatial population synchrony across European bird species. J Anim Ecol 2023; 92:1904-1918. [PMID: 37448134 DOI: 10.1111/1365-2656.13983] [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: 01/04/2023] [Accepted: 06/19/2023] [Indexed: 07/15/2023]
Abstract
Spatial population synchrony is common among populations of the same species and is an important predictor of extinction risk. Despite the potential consequences for metapopulation persistence, we still largely lack understanding of what makes one species more likely to be synchronized than another given the same environmental conditions. Generally, environmental conditions in a shared environment or a species' sensitivity to the environment can explain the extent of synchrony. Populations that are closer together experience more similar fluctuations in their environments than those populations that are further apart and are therefore more synchronized. The relative importance of environmental and demographic stochasticity for population dynamics is strongly linked to species' life-history traits, such as pace of life, which may impact population synchrony. For populations that migrate, there may be multiple environmental conditions at different locations driving synchrony. However, the importance of life history and migration tactics in determining patterns of spatial population synchrony have rarely been explored empirically. We therefore hypothesize that increasing generation time, a proxy for pace of life, would decrease spatial population synchrony and that migrants would be less synchronized than resident species. We used population abundance data on breeding birds from four countries to investigate patterns of spatial population synchrony in growth rate and abundance. We calculated the mean spatial population synchrony between log-transformed population growth rates or log-transformed abundances for each species and country separately. We investigated differences in synchrony across generation times in resident (n = 67), short-distance migrant (n = 86) and long-distance migrant (n = 39) bird species. Species with shorter generation times were more synchronized than species with longer generation times. Short-distance migrants were more synchronized than long-distance migrants and resident birds. Our results provide novel empirical links between spatial population synchrony and species traits known to be of key importance for population dynamics, generation time and migration tactics. We show how these different mechanisms can be combined to understand species-specific causes of spatial population synchrony. Understanding these specific drivers of spatial population synchrony is important in the face of increasingly severe threats to biodiversity and could be key for successful future conservation outcomes.
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Affiliation(s)
- Ellen C Martin
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Brage Bremset Hansen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Terrestrial Ecology, Norwegian Institute for Nature Research, Trondheim, Norway
| | - Aline Magdalena Lee
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
- The Gjaerevoll Centre for Biodiversity Foresight Analyses, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ivar Herfindal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
- The Gjaerevoll Centre for Biodiversity Foresight Analyses, Norwegian University of Science and Technology, Trondheim, Norway
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4
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Sinclair JS, Briland R, Fraker ME, Hood JM, Frank KT, Faust MD, Knight C, Ludsin SA. Anthropogenic change decouples a freshwater predator's density feedback. Sci Rep 2023; 13:7613. [PMID: 37165038 PMCID: PMC10172374 DOI: 10.1038/s41598-023-34408-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/28/2023] [Indexed: 05/12/2023] Open
Abstract
Intraspecific interactions within predator populations can affect predator-prey dynamics and community structure, highlighting the need to better understand how these interactions respond to anthropogenic change. To this end, we used a half-century (1969-2018) of abundance and size-at-age data from Lake Erie's walleye (Sander vitreus) population to determine how anthropogenic alterations have influenced intraspecific interactions. Before the 1980s, the length-at-age of younger walleye (ages 1 and 2) negatively correlated with older (age 3 +) walleye abundance, signaling a 'density feedback' in which intraspecific competition limited growth. However, after the early 1980s this signal of intraspecific competition disappeared. This decoupling of the density feedback was related to multiple anthropogenic changes, including a larger walleye population resulting from better fisheries management, planned nutrient reductions to improve water quality and transparency, warmer water temperatures, and the proliferation of a non-native fish with novel traits (white perch, Morone americana). We argue that these changes may have reduced competitive interactions by reducing the spatial overlap between older and younger walleye and by introducing novel prey. Our findings illustrate the potential for anthropogenic change to diminish density dependent intraspecific interactions within top predator populations, which has important ramifications for predicting predator dynamics and managing natural resources.
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Affiliation(s)
- J S Sinclair
- Department of River Ecology and Conservation, Senckenberg Research Institute and Natural History Museum, Clamecystraße 12, 63571, Gelnhausen, Hesse, Germany.
- Aquatic Ecology Laboratory, The Ohio State University, 1314 Kinnear Rd, Columbus, OH, 43221, USA.
| | - R Briland
- Aquatic Ecology Laboratory, The Ohio State University, 1314 Kinnear Rd, Columbus, OH, 43221, USA
- Ohio Environmental Protection Agency, 50 W. Town St. Suite 700, Columbus, OH, 43215, USA
| | - M E Fraker
- Cooperative Institute for Great Lakes Research and Michigan Sea Grant, School for Environment and Sustainability, University of Michigan, 4840 S. State, Ann Arbor, MI, 48108, USA
| | - J M Hood
- Aquatic Ecology Laboratory, The Ohio State University, 1314 Kinnear Rd, Columbus, OH, 43221, USA
- Translational Data Analytics Institute, The Ohio State University, 1760 Neil Ave, Columbus, OH, 43210, USA
| | - K T Frank
- Ocean and Ecosystem Sciences Division, Bedford Institute of Oceanography, Dartmouth, NS, B2Y 4A2, Canada
- Department of Biology, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - M D Faust
- Ohio Department of Natural Resources, Division of Wildlife, Sandusky Fisheries Research Station, 305 East Shoreline Drive, Sandusky, OH, 44870, USA
| | - C Knight
- Ohio Department of Natural Resources, Division of Wildlife, Fairport Fisheries Research Unit, 1190 High Street, Fairport Harbor, OH, 44077, USA
| | - S A Ludsin
- Aquatic Ecology Laboratory, The Ohio State University, 1314 Kinnear Rd, Columbus, OH, 43221, USA
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5
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Bradshaw CJA, Herrando‐Pérez S. Logistic-growth models measuring density feedback are sensitive to population declines, but not fluctuating carrying capacity. Ecol Evol 2023; 13:e10010. [PMID: 37122772 PMCID: PMC10131297 DOI: 10.1002/ece3.10010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/27/2023] [Accepted: 03/31/2023] [Indexed: 05/02/2023] Open
Abstract
Analysis of long-term trends in abundance of animal populations provides insights into population dynamics. Population growth rates are the emergent interplay of inter alia fertility, survival, and dispersal. However, the density feedbacks operating on some vital rates ("component feedback") can be decoupled from density feedbacks on population growth rates estimated using abundance time series ("ensemble feedback"). Many of the mechanisms responsible for this decoupling are poorly understood, thereby questioning the validity of using logistic-growth models versus vital rates to infer long-term population trends. To examine which conditions lead to decoupling, we simulated age-structured populations of long-lived vertebrates experiencing component density feedbacks on survival. We then quantified how imposed stochasticity in survival rates, density-independent mortality (catastrophes, harvest-like removal of individuals) and variation in carrying capacity modified the ensemble feedback in abundance time series simulated from age-structured populations. The statistical detection of ensemble density feedback from census data was largely unaffected by density-independent processes. Long-term population decline caused from density-independent mortality was the main mechanism decoupling the strength of component versus ensemble density feedbacks. Our study supports the use of simple logistic-growth models to capture long-term population trends, mediated by changes in population abundance, when survival rates are stochastic, carrying capacity fluctuates, and populations experience moderate catastrophic mortality over time.
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Affiliation(s)
- Corey J. A. Bradshaw
- Global Ecology, College of Science and EngineeringFlinders UniversityAdelaideSouth AustraliaAustralia
- Australian Research Council Centre of Excellence for Australian Biodiversity and HeritageWollongongNew South WalesAustralia
| | - Salvador Herrando‐Pérez
- Department of Biogeography and Global ChangeMuseo Nacional de Ciencias Naturales, Spanish National Research Council (CSIC)MadridSpain
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6
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Beltran RS, Hernandez KM, Condit R, Robinson PW, Crocker DE, Goetsch C, Kilpatrick AM, Costa DP. Physiological tipping points in the relationship between foraging success and lifetime fitness of a long-lived mammal. Ecol Lett 2023; 26:706-716. [PMID: 36888564 DOI: 10.1111/ele.14193] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 03/09/2023]
Abstract
Although anthropogenic change is often gradual, the impacts on animal populations may be precipitous if physiological processes create tipping points between energy gain, reproduction or survival. We use 25 years of behavioural, diet and demographic data from elephant seals to characterise their relationships with lifetime fitness. Survival and reproduction increased with mass gain during long foraging trips preceding the pupping seasons, and there was a threshold where individuals that gained an additional 4.8% of their body mass (26 kg, from 206 to 232 kg) increased lifetime reproductive success three-fold (from 1.8 to 4.9 pups). This was due to a two-fold increase in pupping probability (30% to 76%) and a 7% increase in reproductive lifespan (6.0 to 6.4 years). The sharp threshold between mass gain and reproduction may explain reproductive failure observed in many species and demonstrates how small, gradual reductions in prey from anthropogenic disturbance could have profound implications for animal populations.
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Affiliation(s)
- Roxanne S Beltran
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Keith M Hernandez
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA.,Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, USA
| | - Richard Condit
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Patrick W Robinson
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California, USA
| | - Chandra Goetsch
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - A Marm Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, USA.,Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, USA
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7
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Conquet E, Ozgul A, Blumstein DT, Armitage KB, Oli MK, Martin JGA, Clutton-Brock TH, Paniw M. Demographic consequences of changes in environmental periodicity. Ecology 2023; 104:e3894. [PMID: 36208282 DOI: 10.1002/ecy.3894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 07/27/2022] [Accepted: 08/04/2022] [Indexed: 01/24/2023]
Abstract
The fate of natural populations is mediated by complex interactions among vital rates, which can vary within and among years. Although the effects of random, among-year variation in vital rates have been studied extensively, relatively little is known about how periodic, nonrandom variation in vital rates affects populations. This knowledge gap is potentially alarming as global environmental change is projected to alter common periodic variations, such as seasonality. We investigated the effects of changes in vital-rate periodicity on populations of three species representing different forms of adaptation to periodic environments: the yellow-bellied marmot (Marmota flaviventer), adapted to strong seasonality in snowfall; the meerkat (Suricata suricatta), adapted to inter-annual stochasticity as well as seasonal patterns in rainfall; and the dewy pine (Drosophyllum lusitanicum), adapted to fire regimes and periodic post-fire habitat succession. To assess how changes in periodicity affect population growth, we parameterized periodic matrix population models and projected population dynamics under different scenarios of perturbations in the strength of vital-rate periodicity. We assessed the effects of such perturbations on various metrics describing population dynamics, including the stochastic growth rate, log λS . Overall, perturbing the strength of periodicity had strong effects on population dynamics in all three study species. For the marmots, log λS decreased with increased seasonal differences in adult survival. For the meerkats, density dependence buffered the effects of perturbations of periodicity on log λS . Finally, dewy pines were negatively affected by changes in natural post-fire succession under stochastic or periodic fire regimes with fires occurring every 30 years, but were buffered by density dependence from such changes under presumed more frequent fires or large-scale disturbances. We show that changes in the strength of vital-rate periodicity can have diverse but strong effects on population dynamics across different life histories. Populations buffered from inter-annual vital-rate variation can be affected substantially by changes in environmentally driven vital-rate periodic patterns; however, the effects of such changes can be masked in analyses focusing on inter-annual variation. As most ecosystems are affected by periodic variations in the environment such as seasonality, assessing their contributions to population viability for future global-change research is crucial.
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Affiliation(s)
- Eva Conquet
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Daniel T Blumstein
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California, USA.,The Rocky Mountain Biological Laboratory, Crested Butte, Colorado, USA
| | - Kenneth B Armitage
- Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, Kansas, USA
| | - Madan K Oli
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida, USA
| | - Julien G A Martin
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.,School of Biological Sciences, University of Aberdeen, Aberdeen, UK
| | - Tim H Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Trust, Kuruman River Reserve, Northern Cape, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Maria Paniw
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.,Department of Conservation and Global Change, Doñana Biological Station (EBD-CSIC), Seville, Spain
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8
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Skoglund S, Whitlock R, Petersson E, Palm S, Leonardsson K. From spawner habitat selection to stock-recruitment: Implications for assessment. Ecol Evol 2022; 12:e9679. [PMID: 36590336 PMCID: PMC9797469 DOI: 10.1002/ece3.9679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 11/30/2022] [Accepted: 12/09/2022] [Indexed: 12/29/2022] Open
Abstract
The relationship between the spawning stock size and subsequent number of recruits is a central concept in fisheries ecology. The influence of habitat selection of spawning individuals on the stock-recruitment relationship is poorly known. Here we explore how each of four different spawner behaviors might influence the stock-recruitment relationship and estimates of its parameters in the two most commonly used stock-recruitment functions (Beverton-Holt and Ricker). Using simulated stock-recruitment data generated by four different spawner behaviors applied to multiple discrete habitats, we show that when spawners were distributed proportionally to local carrying capacities, there was small or no bias in estimated recruitment and stock-recruitment parameters. For an ideal free distribution of spawners, larger bias in the estimates of recruitment and stock-recruitment parameters was obtained, whereas a random and a stepwise spawner behavior introduced the largest bias. Using stock-recruitment data corresponding to a "realistic" range of population densities and adding measurement error (20%-60%) to the simulated stock-recruitment data generated larger variation in the estimation bias than what was introduced by the spawner behavior. Thus, for exploited stocks at low population density and where spawning stock size and recruitment cannot be observed perfectly, partial observation of the possible spawner abundance range and measurement error might be of higher concern for management.
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Affiliation(s)
- Stefan Skoglund
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Rebecca Whitlock
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Erik Petersson
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Stefan Palm
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Kjell Leonardsson
- Department of Wildlife, Fish and Environmental StudiesSwedish University of Agricultural SciencesUmeåSweden
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9
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Uzal A, Martinez-Artero J, Ordiz A, Zarzo-Arias A, Penteriani V. Habitat characteristics around dens in female brown bears with cubs are density dependent. MAMMAL RES 2022. [DOI: 10.1007/s13364-022-00640-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Abstract
The mechanisms determining habitat use in animal populations have important implications for population dynamics, conservation, and management. Here, we investigated how an increase in annual numbers of brown bear females with cubs of the year (FCOY) in a growing, yet threatened population, could explain differences in the habitat characteristics around reproductive dens. Habitat characteristics around FCOY dens were compared between a low bear density period (1995–2005) and a period when the population was increasing (2006–2016). We also compared the distance to the nearest breeding area and to all other breeding areas observed during the same year. The results suggested that during the second period, breeding areas were closer to rivers, fruit trees, and anthropogenic sources of disturbance (trails, highways) than in 1995–2005. There were also shorter distances to the closest neighboring breeding area, while the mean distance among FCOY breeding areas increased as the population grew and expanded at the landscape level. These changes may reflect that the best den locations were increasingly occupied (i.e., ideal-despotic distribution), and may be further explained by the avoidance of conspecifics by FCOY in a critical time of the year, when newborn cubs are most vulnerable. We suggest that both density-dependent factors and human-related features of the landscape are crucial to understanding long-term dynamics in the habitat use of a threatened species.
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10
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Xu W, Li X, Li Y, Sun Y, Zhang L, Huang Y, Yang Z. Rising temperature more strongly promotes low-abundance Paramecium to remove Microcystis and degrade microcystins. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 291:118143. [PMID: 34517177 DOI: 10.1016/j.envpol.2021.118143] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 06/13/2023]
Abstract
Driven by global warming and eutrophication, Microcystis blooms have posed a severe threat to freshwater ecosystems, especially their derived pollutants cause serious harm to aquatic organisms, thus it is urgent to develop an effective strategy to eliminate nuisance Microcystis. Some protozoa can efficiently graze on toxic Microcystis aeruginosa and degrade cyanotoxins, and play a vital role in regulating harmful cyanobacteria. In the process of protozoa feeding on harmful algae, both temperature and protozoa population density are critical factors that affect the consequences of harmful M. aeruginosa population dynamics. In this study, we first found that Paramecium multimicronucleatum has strong ability to feed on M. aeruginosa, and then studied the interactive effects between temperature and initial density of P. multimicronucleatum on controlling M. aeruginosa. Results showed that increasing temperature accelerated the elimination of M. aeruginosa by P. multimicronucleatum, e.g. the time for M. aeruginosa elimination at 32 °C was shortened to 3.5-4 days. The higher temperatures (26, 29, and 32 °C) were more conducive to improve the efficiency of controlling M. aeruginosa by P. multimicronucleatum with low initial density (10 inds mL-1). Furthermore, P. multimicronucleatum can rapidly degrade microcystins, and the degradation ratio approximately 100% at 32 °C after 6 days. This is the first study to discover that P. multimicronucleatum can high efficiently graze on M. aeruginosa and has a much higher grazing rate (3.5-5.5 × 104Microcystis Paramecium-1 d-1) than other protozoa. These findings contribute to the establishment of a new feasible method for the biological control of M. aeruginosa, and provide a theoretical guidance for the practical application of P. multimicronucleatum in the removal of M. aeruginosa.
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Affiliation(s)
- Wenjie Xu
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Xianxian Li
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Yapeng Li
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Yunfei Sun
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Lu Zhang
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Yuan Huang
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China
| | - Zhou Yang
- Jiangsu Province Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, China.
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11
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Sørbye SH, Nicolau PG, Rue H. Finite-sample properties of estimators for first and second order autoregressive processes. STATISTICAL INFERENCE FOR STOCHASTIC PROCESSES 2021. [DOI: 10.1007/s11203-021-09262-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractThe class of autoregressive (AR) processes is extensively used to model temporal dependence in observed time series. Such models are easily available and routinely fitted using freely available statistical software like . A potential problem is that commonly applied estimators for the coefficients of AR processes are severely biased when the time series are short. This paper studies the finite-sample properties of well-known estimators for the coefficients of stationary AR(1) and AR(2) processes and provides bias-corrected versions of these estimators which are quick and easy to apply. The new estimators are constructed by modeling the relationship between the true and originally estimated AR coefficients using weighted orthogonal polynomial regression, taking the sampling distribution of the original estimators into account. The finite-sample distributions of the new bias-corrected estimators are approximated using transformations of skew-normal densities, combined with a Gaussian copula approximation in the AR(2) case. The properties of the new estimators are demonstrated by simulations and in the analysis of a real ecological data set. The estimators are easily available in our accompanying -package for AR(1) and AR(2) processes of length 10–50, both giving bias-corrected coefficient estimates and corresponding confidence intervals.
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12
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McCabe RA, Therrien JF, Wiebe K, Gauthier G, Brinker D, Weidensaul S, Reid D, Doyle FI, Jacobsen KO, Aarvak T, Øien IJ, Solheim R, Fitzgerald G, Smith N, Bates K, Fuller M, Miller E, Elliott KH. Density-dependent winter survival of immatures in an irruptive raptor with pulsed breeding. Oecologia 2021; 198:295-306. [PMID: 34657176 DOI: 10.1007/s00442-021-05057-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 09/28/2021] [Indexed: 11/30/2022]
Abstract
Highly mobile predators can show strong numerical responses to pulsed resources, sometimes resulting in irruptions where large numbers of young invade landscapes at a continental scale. High production of young in irruption years may have a strong influence on the population dynamics unless immature survival is reduced compared to non-irruption years. This could occur if subordinate individuals (mainly immatures) are forced into suboptimal habitats due to density-dependent effects in irruption years. To test whether irruptive individuals had lower survival than non-irruptive ones, we combined necropsy results (N = 365) with telemetry (N = 185) from more than 20 years to record timing and causes of mortality in snowy owls (Bubo scandiacus), which irrupt into eastern North America during winter following high breeding output caused by lemming peaks in the Arctic. Mortality was more than four times higher in irruption years than non-irruption years, but only for immatures, and occurred disproportionately in early winter for immatures, but not adults. Mortality was also higher in eastern North America, where owl abundance fluctuates considerably between years, compared to core winter regions of the Arctic and Prairies where populations are more stable. Most mortality was not due to starvation, but rather associated with human activity, especially vehicle collisions. We conclude that immature snowy owls that irrupt into eastern North America are limited by density-dependent factors, such as increased competition forcing individuals to occupy risky human-altered habitats. For highly mobile, irruptive animals, resource pulses may have a limited impact on population dynamics due to low subsequent survival of breeding output during the nonbreeding season.
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Affiliation(s)
- Rebecca A McCabe
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore, Ste-Anne-de-Bellevue, QC, Canada.
| | - Jean-François Therrien
- Acopian Center for Conservation Learning, Hawk Mountain Sanctuary Association, Orwigsburg, PA, USA
| | - Karen Wiebe
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Gilles Gauthier
- Department of Biology and Centre d'études Nordiques, Université Laval, Québec, QC, Canada
| | - David Brinker
- Maryland Department of Natural Resources, Annapolis, MD, USA
| | | | - Donald Reid
- Wildlife Conservation Society Canada, Whitehorse, YT, Canada
| | - Frank I Doyle
- Department of Biology, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Karl-Otto Jacobsen
- Department of Arctic Ecology, Norwegian Institute for Nature Research, Tromsø, Norway
| | - Tomas Aarvak
- Norwegian Ornithological Society/BirdLife Norway, Trondheim, Norway
| | | | - Roar Solheim
- Natural History Museum, University of Agder, Kristiansand S, Norway
| | - Guy Fitzgerald
- Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | | | - Kirk Bates
- Boise State University, Raptor Research Center, Boise, ID, USA
| | - Mark Fuller
- Boise State University, Raptor Research Center, Boise, ID, USA
| | - Erica Miller
- Wildlife Futures Program, Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, USA
| | - Kyle H Elliott
- Department of Natural Resource Sciences, McGill University, 21111 Lakeshore, Ste-Anne-de-Bellevue, QC, Canada
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13
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A nonlinear model for stage-structured population dynamics with nonlocal density-dependent regulation: An application to the fall armyworm moth. Math Biosci 2021; 335:108573. [PMID: 33662404 DOI: 10.1016/j.mbs.2021.108573] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 02/23/2021] [Accepted: 02/23/2021] [Indexed: 11/21/2022]
Abstract
The assessment and the management of the risks linked to insect pests can be supported by the use of physiologically-based demographic models. These models are useful in population ecology to simulate the dynamics of stage-structured populations, by means of functions (e.g., development, mortality and fecundity rate functions) realistically representing the nonlinear individuals physiological responses to environmental forcing variables. Since density-dependent responses are important regulating factors in population dynamics, we propose a nonlinear physiologically-based Kolmogorov model describing the dynamics of a stage-structured population in which a time-dependent mortality rate is coupled with a nonlocal density-dependent term. We prove existence and uniqueness of the solution for this resulting highly nonlinear partial differential equation. Then, the equation is discretized by finite volumes in space and semi-implicit backward Euler scheme in time. The model is applied for simulating the population dynamics of the fall armyworm moth (Spodoptera frugiperda), a highly invasive pest threatening agriculture worldwide.
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14
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Bellier E, Sæther BE, Engen S. Sustainable strategies for harvesting predators and prey in a fluctuating environment. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2020.109350] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Johnson‐Bice SM, Ferguson JM, Erb JD, Gable TD, Windels SK. Ecological forecasts reveal limitations of common model selection methods: predicting changes in beaver colony densities. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02198. [PMID: 32583507 PMCID: PMC7816246 DOI: 10.1002/eap.2198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 03/13/2020] [Accepted: 03/30/2020] [Indexed: 05/20/2023]
Abstract
Over the past two decades, there have been numerous calls to make ecology a more predictive science through direct empirical assessments of ecological models and predictions. While the widespread use of model selection using information criteria has pushed ecology toward placing a higher emphasis on prediction, few attempts have been made to validate the ability of information criteria to correctly identify the most parsimonious model with the greatest predictive accuracy. Here, we used an ecological forecasting framework to test the ability of information criteria to accurately predict the relative contribution of density dependence and density-independent factors (forage availability, harvest, weather, wolf [Canis lupus] density) on inter-annual fluctuations in beaver (Castor canadensis) colony densities. We modeled changes in colony densities using a discrete-time Gompertz model, and assessed the performance of four models using information criteria values: density-independent models with (1) and without (2) environmental covariates; and density-dependent models with (3) and without (4) environmental covariates. We then evaluated the forecasting accuracy of each model by withholding the final one-third of observations from each population and compared observed vs. predicted densities. Information criteria and our forecasting accuracy metrics both provided strong evidence of compensatory density dependence in the annual dynamics of beaver colony densities. However, despite strong within-sample performance by the most complex model (density-dependent with covariates) as determined using information criteria, hindcasts of colony densities revealed that the much simpler density-dependent model without covariates performed nearly as well predicting out-of-sample colony densities. The hindcast results indicated that the complex model over-fit our data, suggesting that parameters identified by information criteria as important predictor variables are only marginally valuable for predicting landscape-scale beaver colony dynamics. Our study demonstrates the importance of evaluating ecological models and predictions with long-term data and revealed how a known limitation of information criteria (over-fitting of complex models) can affect our interpretation of ecological dynamics. While incorporating knowledge of the factors that influence animal population dynamics can improve population forecasts, we suggest that comparing forecast performance metrics can likewise improve our knowledge of the factors driving population dynamics.
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Affiliation(s)
- Sean M. Johnson‐Bice
- Department of Biological SciencesUniversity of Manitoba50 Sifton RoadWinnipegManitobaR3T 2N2Canada
- Natural Resources Research InstituteUniversity of Minnesota Duluth5013 Miller Trunk HighwayDuluthMinnesota55812USA
| | - Jake M. Ferguson
- Department of BiologyUniversity of Hawai`i at Mānoa2538 McCarthy MallHonoluluHawaii96822USA
| | - John D. Erb
- Forest Wildlife Populations and Research GroupMinnesota Department of Natural Resources1201 E. highway 2Grand RapidsMinnesota55744USA
| | - Thomas D. Gable
- Department of Fisheries, Wildlife and Conservation BiologyUniversity of Minnesota Twin Cities2003 Upper Buford CircleSt. PaulMinnesota55108USA
| | - Steve K. Windels
- Natural Resources Research InstituteUniversity of Minnesota Duluth5013 Miller Trunk HighwayDuluthMinnesota55812USA
- Department of Fisheries, Wildlife and Conservation BiologyUniversity of Minnesota Twin Cities2003 Upper Buford CircleSt. PaulMinnesota55108USA
- Voyageurs National Park360 Highway 11 E.International FallsMinnesota56649USA
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16
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Clark TJ, Horne JS, Hebblewhite M, Luis AD. Stochastic predation exposes prey to predator pits and local extinction. OIKOS 2020. [DOI: 10.1111/oik.07381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- T. J. Clark
- Wildlife Biology Program, Dept of Ecosystem and Conservation Sciences, W. A. Franke College of Forestry and Conservation, Univ. of Montana Missoula MT USA
| | | | - Mark Hebblewhite
- Wildlife Biology Program, Dept of Ecosystem and Conservation Sciences, W. A. Franke College of Forestry and Conservation, Univ. of Montana Missoula MT USA
| | - Angela D. Luis
- Wildlife Biology Program, Dept of Ecosystem and Conservation Sciences, W. A. Franke College of Forestry and Conservation, Univ. of Montana Missoula MT USA
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17
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Jaatinen K, Westerbom M, Norkko A, Mustonen O, Koons DN. Detrimental impacts of climate change may be exacerbated by density-dependent population regulation in blue mussels. J Anim Ecol 2020; 90:562-573. [PMID: 33073861 DOI: 10.1111/1365-2656.13377] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/07/2020] [Indexed: 11/30/2022]
Abstract
The climate on our planet is changing and the range distributions of organisms are shifting in response. In aquatic environments, species might not be able to redistribute poleward or into deeper water when temperatures rise because of barriers, reduced light availability, altered water chemistry or any combination of these. How species respond to climate change may depend on physiological adaptability, but also on the population dynamics of the species. Density dependence is a ubiquitous force that governs population dynamics and regulates population growth, yet its connections to the impacts of climate change remain little known, especially in marine studies. Reductions in density below an environmental carrying capacity may cause compensatory increases in demographic parameters and population growth rate, hence masking the impacts of climate change on populations. On the other hand, climate-driven deterioration of conditions may reduce environmental carrying capacities, making compensation less likely and populations more susceptible to the effects of stochastic processes. Here we investigate the effects of climate change on Baltic blue mussels using a 17-year dataset on population density. Using a Bayesian modelling framework, we investigate the impacts of climate change, assess the magnitude and effects of density dependence, and project the likelihood of population decline by the year 2030. Our findings show negative impacts of warmer and less saline waters, both outcomes of climate change. We also show that density dependence increases the likelihood of population decline by subjecting the population to the detrimental effects of stochastic processes (i.e. low densities where random bad years can cause local extinction, negating the possibility for random good years to offset bad years). We highlight the importance of understanding, and accounting for both density dependence and climate variation when predicting the impact of climate change on keystone species, such as the Baltic blue mussel.
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Affiliation(s)
- Kim Jaatinen
- Nature and Game Management Trust Finland, Degerby, Finland
| | | | - Alf Norkko
- Tvärminne Zoological Station, Hanko, Finland
| | | | - David N Koons
- Department of Fish, Wildlife, and Conservation Biology, and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, USA
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18
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Li Y, Sun M, Ren Y, Chen Y. Impact of pre-closure fishing effort on marine protected area performance in social-ecological dimensions: Implications for developing marine conservation plans. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 729:138936. [PMID: 32361451 DOI: 10.1016/j.scitotenv.2020.138936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/21/2020] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
Marine protected areas (MPAs) have been increasingly used as a primary tool for fisheries management and conservation. Over the past few decades, the implementation of MPAs has achieved mixed results with regard to conservation goals, which has driven the scientific community to contemplate what factors may determine the effectiveness of an MPA. Most previous analyses have tended to focus on the design criteria of MPAs as well as post-closure management capabilities, but pre-closure conditions are seldom considered. Here, we investigate the effects of varying pre-closure fishing effort scenarios on MPA performance by applying a developed evaluation framework and age-structured dynamic model for the small yellow croaker (Larimichthys polyactis) in Haizhou Bay, China. We specifically focus on the overall fishing pressure imposed on the fish population and the spatial heterogeneity of fishing effort. We used ecological and social indicators to evaluate the effects of MPAs. Our results demonstrate that MPAs with lower pre-closure fishing pressure are more effective than those with higher pre-closure fishing pressure in recovering the fish population. Highly aggregated fishing efforts inside the MPAs prior to their implementations could also make MPAs less effective. By comparing our findings to other studies, we noticed that evaluation metrics and time frames could make a difference in determining the effects of a given MPA, which indicates the importance of monitoring programs. From a social perspective, placing MPAs in heavily exploited areas without additional harvest regulations may result in a tragedy of the commons situation that leads to a significant loss in catches. This study highlights the ecological and social risks of establishing MPAs under different pre-closure fishing scenarios and provides insights for the development of marine conservation plans.
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Affiliation(s)
- Yunzhou Li
- College of Fisheries, Ocean University of China, Qingdao 266003, China; School of Marine Sciences, University of Maine, Orono, ME 04469, USA; Field Observation and Research Station of Haizhou Bay Fishery Ecosystem, Ministry of Education, Qingdao 266003, China
| | - Ming Sun
- College of Fisheries, Ocean University of China, Qingdao 266003, China; School of Marine Sciences, University of Maine, Orono, ME 04469, USA; Field Observation and Research Station of Haizhou Bay Fishery Ecosystem, Ministry of Education, Qingdao 266003, China
| | - Yiping Ren
- College of Fisheries, Ocean University of China, Qingdao 266003, China; Field Observation and Research Station of Haizhou Bay Fishery Ecosystem, Ministry of Education, Qingdao 266003, China; Laboratory for Marine Fisheries Science and Food Production Processes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China.
| | - Yong Chen
- School of Marine Sciences, University of Maine, Orono, ME 04469, USA
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19
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Fadai NT, Simpson MJ. Population Dynamics with Threshold Effects Give Rise to a Diverse Family of Allee Effects. Bull Math Biol 2020; 82:74. [PMID: 32533355 PMCID: PMC7292819 DOI: 10.1007/s11538-020-00756-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 05/27/2020] [Indexed: 12/22/2022]
Abstract
The Allee effect describes populations that deviate from logistic growth models and arises in applications including ecology and cell biology. A common justification for incorporating Allee effects into population models is that the population in question has altered growth mechanisms at some critical density, often referred to as a threshold effect. Despite the ubiquitous nature of threshold effects arising in various biological applications, the explicit link between local threshold effects and global Allee effects has not been considered. In this work, we examine a continuum population model that incorporates threshold effects in the local growth mechanisms. We show that this model gives rise to a diverse family of Allee effects, and we provide a comprehensive analysis of which choices of local growth mechanisms give rise to specific Allee effects. Calibrating this model to a recent set of experimental data describing the growth of a population of cancer cells provides an interpretation of the threshold population density and growth mechanisms associated with the population.
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Affiliation(s)
- Nabil T Fadai
- School of Mathematical Sciences, University of Nottingham, Nottingham, NG7 2RD, UK.
| | - Matthew J Simpson
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, QLD, 4001, Australia
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20
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Bos D, Loon EE, Klop E, Ydenberg R. A Large‐Scale Experiment to Evaluate Control of Invasive Muskrats. WILDLIFE SOC B 2020. [DOI: 10.1002/wsb.1099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daan Bos
- Altenburg and Wymenga Ecological Consultants Suderwei 2, 9269 TZ Feanwâlden The Netherlands
| | - E. Emiel Loon
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam P.O. Box 94240 NL‐1090 GE Amsterdam The Netherlands
| | - Erik Klop
- Altenburg and Wymenga Ecological Consultants Suderwei 2, 9269 TZ Feanwâlden The Netherlands
| | - Ron Ydenberg
- Centre for Wildlife Ecology, Simon Fraser University Burnaby B.C. Canada V5A 1S6
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21
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22
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Hurley MA, Hebblewhite M, Gaillard J. Competition for safe real estate, not food, drives density-dependent juvenile survival in a large herbivore. Ecol Evol 2020; 10:5464-5475. [PMID: 32607167 PMCID: PMC7319175 DOI: 10.1002/ece3.6289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 02/28/2020] [Accepted: 03/21/2020] [Indexed: 12/04/2022] Open
Abstract
Density-dependent competition for food reduces vital rates, with juvenile survival often the first to decline. A clear prediction of food-based, density-dependent competition for large herbivores is decreasing juvenile survival with increasing density. However, competition for enemy-free space could also be a significant mechanism for density dependence in territorial species. How juvenile survival is predicted to change across density depends critically on the nature of predator-prey dynamics and spatial overlap among predator and prey, especially in multiple-predator systems. Here, we used a management experiment that reduced densities of a generalist predator, coyotes, and specialist predator, mountain lions, over a 5-year period to test for spatial density dependence mediated by predation on juvenile mule deer in Idaho, USA. We tested the spatial density-dependence hypothesis by tracking the fate of 251 juvenile mule deer, estimating cause-specific mortality, and testing responses to changes in deer density and predator abundance. Overall juvenile mortality did not increase with deer density, but generalist coyote-caused mortality did, but not when coyote density was reduced experimentally. Mountain lion-caused mortality did not change with deer density in the reference area in contradiction of the food-based competition hypothesis, but declined in the treatment area, opposite to the pattern of coyotes. These observations clearly reject the food-based density-dependence hypothesis for juvenile mule deer. Instead, our results provide support for the spatial density-dependence hypothesis that competition for enemy-free space increases predation by generalist predators on juvenile large herbivores.
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Affiliation(s)
| | - Mark Hebblewhite
- Wildlife Biology ProgramDepartment of Ecosystem Sciences and ConservationW.A. Franke College of Forestry and ConservationUniversity of MontanaMissoulaMTUSA
| | - Jean‐Michel Gaillard
- Laboratoire Biométrie & Biologie ÉvolutiveCNRSUMR‐CNRS 5558University Claude Bernard ‐ Lyon IVilleurbanne CedexFrance
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23
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Vasilieva NA, Tchabovsky AV. Early predictors of female lifetime reproductive success in a solitary hibernator: evidence for "silver spoon" effect. Oecologia 2020; 193:77-87. [PMID: 32318852 DOI: 10.1007/s00442-020-04649-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 04/08/2020] [Indexed: 02/05/2023]
Abstract
Fitness consequences of early-life conditions remain unclear and poorly studied in mammals. Based on long-term observations of yellow ground squirrels (Spermophilus fulvus), we identified early determinants of female fitness by analyzing the effects of early-life individual and environmental characteristics (weaning weight, weight gain rate, date of natal emergence, natal litter size, location of the natal burrow, local density of juveniles, population density and precipitation in the post-weaning period) on lifetime reproductive success (LRS). We found high variation and right-skewed distribution in all five LRS components (survival to adulthood, adult lifespan, and lifetime numbers of weaned litters, weanlings, and yearling offspring). Numbers of litters, weanlings, and adult offspring were correlated with each other and increased with lifespan, confirming that longevity is a better predictor of LRS than fecundity. Survival to adulthood was the most sensitive fitness component to early conditions and was higher in females (a) with greater weaning weight, (b) born further from human settlement and (c) born at lower population density. Population density at birth was the best early predictor of all LRS components and negatively influenced adult lifespan and numbers of weanlings and yearling offspring. Early growth rate positively affected the probability of reproducing after the first hibernation and the number of offspring weaned. Such syndrome of high-quality (heavy and fast-growing) young born in a favourable environment ("a silver spoon effect") with downstream damping fitness consequences has been observed so far in only a few mammalian species.
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Affiliation(s)
- Nina A Vasilieva
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33, Leninskii pr., Moscow, 119071, Russia.
| | - Andrey V Tchabovsky
- A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33, Leninskii pr., Moscow, 119071, Russia
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24
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Gifford SJ, Gese EM, Parmenter RR. FOOD HABITS OF COYOTES (CANIS LATRANS) IN THE VALLES CALDERA NATIONAL PRESERVE, NEW MEXICO. SOUTHWEST NAT 2020. [DOI: 10.1894/0038-4909-64-2-122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Suzanne J. Gifford
- Department of Wildland Resources, Utah State University, Logan, UT 84322 (SJG)
| | - Eric M. Gese
- United States Department of Agriculture, Wildlife Services, National Wildlife Research Center, Department of Wildland Resources, Utah State University, Logan, UT 84322 (EMG)
| | - Robert R. Parmenter
- Valles Caldera National Preserve, P.O. Box 359, Jemez Springs, NM 87025 (RRP)
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25
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Fay R, Michler S, Laesser J, Jeanmonod J, Schaub M. Can temporal covariation and autocorrelation in demographic rates affect population dynamics in a raptor species? Ecol Evol 2020; 10:1959-1970. [PMID: 32128129 PMCID: PMC7042680 DOI: 10.1002/ece3.6027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 11/07/2019] [Accepted: 01/06/2020] [Indexed: 11/15/2022] Open
Abstract
Theoretical studies suggest that temporal covariation among and temporal autocorrelation within demographic rates are important features of population dynamics. Yet, empirical studies have rarely focused on temporal covariation and autocorrelation limiting our understanding of these patterns in natural populations. This lack of knowledge restrains our ability to fully understand population dynamics and to make reliable population forecasts. In order to fill this gap, we used a long-term monitoring (15 years) of a kestrel Falco tinnunculus population to investigate covariation and autocorrelation in survival and reproduction at the population level and their impact on population dynamics. Using Bayesian joint analyses, we found support for positive covariation between survival and reproduction, but weak autocorrelation through time. This positive covariation was stronger in juveniles compared with adults. As expected for a specialized predator, we found that the reproductive performance was strongly related to an index of vole abundance explaining 86% of the temporal variation. This very strong relationship suggests that the temporally variable prey abundance may drive the positive covariation between survival and reproduction in this kestrel population. Simulations suggested that the observed effect size of covariation could be strong enough to affect population dynamics. More generally, positive covariation and autocorrelation have a destabilizing effect increasing substantially the temporal variability of population size.
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Affiliation(s)
- Rémi Fay
- Swiss Ornithological InstituteSempachSwitzerland
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26
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Vaugeois M, Venturelli PA, Hummel SL, Accolla C, Forbes VE. Population context matters: Predicting the effects of metabolic stress mediated by food availability and predation with an agent- and energy budget-based model. Ecol Modell 2020. [DOI: 10.1016/j.ecolmodel.2019.108903] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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Nowicki R, Heithaus M, Thomson J, Burkholder D, Gastrich K, Wirsing A. Indirect legacy effects of an extreme climatic event on a marine megafaunal community. ECOL MONOGR 2019. [DOI: 10.1002/ecm.1365] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Robert Nowicki
- International Center for Coral Reef Research and Restoration Mote Marine Laboratory 24244 Overseas Highway Summerland Key Florida 33042 USA
- Department of Biological Sciences and Marine Education and Research Initiative Florida International University Miami Florida 33199 USA
| | - Michael Heithaus
- Department of Biological Sciences and Marine Education and Research Initiative Florida International University Miami Florida 33199 USA
| | - Jordan Thomson
- School of Life and Environmental Sciences Deakin University Warrnambool Campus Warrnambool Victoria 3280 Australia
| | - Derek Burkholder
- Guy Harvey Research Institute Nova Southeastern University Ft Lauderdale Florida 33314 USA
| | - Kirk Gastrich
- Department of Biological Sciences and Marine Education and Research Initiative Florida International University Miami Florida 33199 USA
| | - Aaron Wirsing
- School of Environmental and Forest Sciences University of Washington Box 352100 Seattle Washington 98195 USA
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28
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Dibner RR, DeMarche ML, Louthan AM, Doak DF. Multiple mechanisms confer stability to isolated populations of a rare endemic plant. ECOL MONOGR 2019. [DOI: 10.1002/ecm.1360] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Reilly R. Dibner
- Program in Ecology and Haub School of Environment and Natural Resources University of Wyoming Bim Kendall House, 804 E. Fremont Street Laramie Wyoming 82070 USA
| | - Megan L. DeMarche
- Environmental Studies Program University of Colorado Boulder Colorado 80309 USA
| | | | - Daniel F. Doak
- Environmental Studies Program University of Colorado Boulder Colorado 80309 USA
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29
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Bårdsen BJ, Hanssen SA, Bustnes JO. Multiple stressors: modeling the effect of pollution, climate, and predation on viability of a sub-arctic marine bird. Ecosphere 2018. [DOI: 10.1002/ecs2.2342] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Bård-Jørgen Bårdsen
- Arctic Ecology Department; Fram Centre; Norwegian Institute for Nature Research (NINA); N-9296 Tromsø Norway
| | - Sveinn Are Hanssen
- Arctic Ecology Department; Fram Centre; Norwegian Institute for Nature Research (NINA); N-9296 Tromsø Norway
| | - Jan Ove Bustnes
- Arctic Ecology Department; Fram Centre; Norwegian Institute for Nature Research (NINA); N-9296 Tromsø Norway
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30
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Specht HM, Arnold TW. Banding age ratios reveal prairie waterfowl fecundity is affected by climate, density dependence and predator–prey dynamics. J Appl Ecol 2018. [DOI: 10.1111/1365-2664.13186] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Hannah M. Specht
- Department of Fisheries, Wildlife and Conservation BiologyUniversity of Minnesota St. Paul Minnesota
| | - Todd W. Arnold
- Department of Fisheries, Wildlife and Conservation BiologyUniversity of Minnesota St. Paul Minnesota
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31
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Does urbanization explain differences in interactions between an insect herbivore and its natural enemies and mutualists? Urban Ecosyst 2018. [DOI: 10.1007/s11252-017-0727-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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32
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Skonhoft A, Johannesen AB, Olaussen JO. On the tragedy of the commons: When predation and livestock loss may improve the economic lot of herders. AMBIO 2017; 46:644-654. [PMID: 28361495 PMCID: PMC5595741 DOI: 10.1007/s13280-017-0910-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/26/2016] [Accepted: 02/21/2017] [Indexed: 06/07/2023]
Abstract
This paper studies the practice of semi-domestic reindeer (Rangifer t. tarandus) herding in Finnmark county in northern Norway. In this area, the Saami reindeer herders compete for space and grazing areas and keep large herds, while at the same time, the reindeer population is heavily exposed to carnivore predation by the lynx (Lynx lynx), the wolverine (Gulo gulo), and the golden eagle (Aquila chrysaetos). It is demonstrated that predation actually may improve the economic lot of livestock holders in this unmanaged local common setting. There are ecological as well as economic reasons as to why this happens. The ecological reason is that predation compensates for natural mortality; that is, increased predation reduces natural mortality, indicating that the net loss due to predation actually may be quite small. When predation reduces livestock density, the feeding conditions of the animals will improve, resulting in increased livestock weight and higher per animal slaughter value. At the same time, a smaller stock reduces the operating costs of the herders.
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Ditchkoff SS, Holtfreter RW, Williams BL. Effectiveness of a bounty program for reducing wild pig densities. WILDLIFE SOC B 2017. [DOI: 10.1002/wsb.787] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - Brian L. Williams
- School of Forestry and Wildlife SciencesAuburn UniversityAuburnAL36849USA
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34
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Pöysä H, Rintala J, Johnson DH, Kauppinen J, Lammi E, Nudds TD, Väänänen VM. Environmental variability and population dynamics: do European and North American ducks play by the same rules? Ecol Evol 2017; 6:7004-7014. [PMID: 28725377 PMCID: PMC5513220 DOI: 10.1002/ece3.2413] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 08/01/2016] [Accepted: 08/04/2016] [Indexed: 11/06/2022] Open
Abstract
Density dependence, population regulation, and variability in population size are fundamental population processes, the manifestation and interrelationships of which are affected by environmental variability. However, there are surprisingly few empirical studies that distinguish the effect of environmental variability from the effects of population processes. We took advantage of a unique system, in which populations of the same duck species or close ecological counterparts live in highly variable (north American prairies) and in stable (north European lakes) environments, to distinguish the relative contributions of environmental variability (measured as between-year fluctuations in wetland numbers) and intraspecific interactions (density dependence) in driving population dynamics. We tested whether populations living in stable environments (in northern Europe) were more strongly governed by density dependence than populations living in variable environments (in North America). We also addressed whether relative population dynamical responses to environmental variability versus density corresponded to differences in life history strategies between dabbling (relatively "fast species" and governed by environmental variability) and diving (relatively "slow species" and governed by density) ducks. As expected, the variance component of population fluctuations caused by changes in breeding environments was greater in North America than in Europe. Contrary to expectations, however, populations in more stable environments were not less variable nor clearly more strongly density dependent than populations in highly variable environments. Also, contrary to expectations, populations of diving ducks were neither more stable nor stronger density dependent than populations of dabbling ducks, and the effect of environmental variability on population dynamics was greater in diving than in dabbling ducks. In general, irrespective of continent and species life history, environmental variability contributed more to variation in species abundances than did density. Our findings underscore the need for more studies on populations of the same species in different environments to verify the generality of current explanations about population dynamics and its association with species life history.
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Affiliation(s)
- Hannu Pöysä
- Natural Resources Institute Finland Joensuu Finland
| | - Jukka Rintala
- Natural Resources Institute Finland Helsinki Finland
| | - Douglas H Johnson
- USGS Northern Prairie Wildlife Research Center St. Paul MN USA.,Fisheries, Wildlife, and Conservation Biology University of Minnesota St. Paul MN USA
| | | | - Esa Lammi
- Environmental Planning ENVIRO Espoo Finland
| | - Thomas D Nudds
- Department of Integrative Biology University of Guelph Guelph ON Canada
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35
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Smith HM, Dickman CR, Banks PB. Exotic black rats increase invertebrate Ordinal richness in urban habitat remnants. Biol Invasions 2017. [DOI: 10.1007/s10530-016-1340-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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36
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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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Flowerdew JR, Amano T, Sutherland WJ. Strong "bottom-up" influences on small mammal populations: State-space model analyses from long-term studies. Ecol Evol 2017; 7:1699-1711. [PMID: 28331581 PMCID: PMC5355190 DOI: 10.1002/ece3.2725] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/25/2016] [Accepted: 12/18/2016] [Indexed: 11/07/2022] Open
Abstract
“Bottom‐up” influences, that is, masting, plus population density and climate, commonly influence woodland rodent demography. However, “top‐down” influences (predation) also intervene. Here, we assess the impacts of masting, climate, and density on rodent populations placed in the context of what is known about “top‐down” influences. To explain between‐year variations in bank vole Myodes glareolus and wood mouse Apodemus sylvaticus population demography, we applied a state‐space model to 33 years of catch‐mark‐release live‐trapping, winter temperature, and precise mast‐collection data. Experimental mast additions aided interpretation. Rodent numbers in European ash Fraxinus excelsior woodland were estimated (May/June, November/December). December–March mean minimum daily temperature represented winter severity. Total marked adult mice/voles (and juveniles in May/June) provided density indices validated against a model‐generated population estimate; this allowed estimation of the structure of a time‐series model and the demographic impacts of the climatic/biological variables. During two winters of insignificant fruit‐fall, 6.79 g/m2 sterilized ash seed (as fruit) was distributed over an equivalent woodland similarly live‐trapped. September–March fruit‐fall strongly increased bank vole spring reproductive rate and winter and summer population growth rates; colder winters weakly reduced winter population growth. September–March fruit‐fall and warmer winters marginally increased wood mouse spring reproductive rate and September–December fruit‐fall weakly elevated summer population growth. Density dependence significantly reduced both species' population growth. Fruit‐fall impacts on demography still appeared after a year. Experimental ash fruit addition confirmed its positive influence on bank vole winter population growth with probable moderation by colder temperatures. The models show the strong impact of masting as a “bottom‐up” influence on rodent demography, emphasizing independent masting and weather influences; delayed effects of masting; and the importance of density dependence and its interaction with masting. We conclude that these rodents show strong “bottom‐up” and density‐dependent influences on demography moderated by winter temperature. “Top‐down” influences appear weak and need further investigation.
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Affiliation(s)
| | - Tatsuya Amano
- Department of Zoology University of Cambridge Cambridge UK
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38
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Hinton JW, White GC, Rabon DR, Chamberlain MJ. Survival and population size estimates of the red wolf. J Wildl Manage 2016. [DOI: 10.1002/jwmg.21206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Joseph W. Hinton
- Warnell School of Forestry and Natural Resources; University of Georgia; 180 E. Green Street Athens GA 30605 USA
| | - Gary C. White
- Department of Fish, Wildlife, and Conservation Biology; Colorado State University; Fort Collins CO 80523 USA
| | - David R. Rabon
- Endangered Wolf Center; P.O. Box 760 Eureka MO 63025 USA
| | - Michael J. Chamberlain
- Warnell School of Forestry and Natural Resources; University of Georgia; 180 E. Green Street Athens GA 30605 USA
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39
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Monterroso P, Garrote G, Serronha A, Santos E, Delibes-Mateos M, Abrantes J, Perez de Ayala R, Silvestre F, Carvalho J, Vasco I, Lopes AM, Maio E, Magalhães MJ, Mills LS, Esteves PJ, Simón MÁ, Alves PC. Disease-mediated bottom-up regulation: An emergent virus affects a keystone prey, and alters the dynamics of trophic webs. Sci Rep 2016; 6:36072. [PMID: 27796353 PMCID: PMC5086860 DOI: 10.1038/srep36072] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 10/10/2016] [Indexed: 11/19/2022] Open
Abstract
Emergent diseases may alter the structure and functioning of ecosystems by creating new biotic interactions and modifying existing ones, producing cascading processes along trophic webs. Recently, a new variant of the rabbit haemorrhagic disease virus (RHDV2 or RHDVb) arguably caused widespread declines in a keystone prey in Mediterranean ecosystems - the European rabbit (Oryctolagus cuniculus). We quantitatively assess the impact of RHDV2 on natural rabbit populations and in two endangered apex predator populations: the Iberian lynx (Lynx pardinus) and the Spanish Imperial eagle (Aquila adalberti). We found 60–70% declines in rabbit populations, followed by decreases of 65.7% in Iberian lynx and 45.5% in Spanish Imperial eagle fecundities. A revision of the web of trophic interactions among rabbits and their dependent predators suggests that RHDV2 acts as a keystone species, and may steer Mediterranean ecosystems to management-dependent alternative states, dominated by simplified mesopredator communities. This model system stresses the importance of diseases as functional players in the dynamics of trophic webs.
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Affiliation(s)
- Pedro Monterroso
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - Germán Garrote
- Agencia de Medio Ambiente y Agua de Andalucía, C/Johan G. Gutenberg. 1, 41092, Seville, Spain
| | - Ana Serronha
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - Emídio Santos
- Instituto da Conservação da Natureza e das Florestas, Av. da República, 161050-191, Lisbon, Portugal
| | - Miguel Delibes-Mateos
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal.,IESA-CSIC, Instituto de Estudios Sociales Avanzados, Plz Campo Santo de los Mártires. 7, 14004 Córdoba, Spain
| | - Joana Abrantes
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | | | - Fernando Silvestre
- Fundación CBD-Habitat, C/ Gustavo Fernández Balbuena 2, Entreplanta, Oficina A, 28002, Madrid, Spain
| | - João Carvalho
- ANPC, Associação Nacional Proprietários Rurais, Gestão Cinegética e Biodiversidade, R. Mestre Lima de Freitas, 1-5°, 1549-012, Lisbon, Portugal
| | - Inês Vasco
- Instituto da Conservação da Natureza e das Florestas, Av. da República, 161050-191, Lisbon, Portugal
| | - Ana M Lopes
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal.,Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, R. Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Elisa Maio
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - Maria J Magalhães
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal
| | - L Scott Mills
- Wildlife Biology Program, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
| | - Pedro J Esteves
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal.,Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, R. Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Miguel Ángel Simón
- Consejería de Medio Ambiente de la Junta de Andalucía, C/ Doctor Eduardo García-Triviño López 15, 23071 Jaén, Spain
| | - Paulo C Alves
- CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, 4485-661, Vairão, Portugal.,Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, R. Campo Alegre s/n, 4169-007, Porto, Portugal.,Wildlife Biology Program, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
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40
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Werner JR, Gillis EA, Boonstra R, Krebs CJ. You can hide but you can't run: apparent competition, predator responses and the decline of Arctic ground squirrels in boreal forests of the southwest Yukon. PeerJ 2016; 4:e2303. [PMID: 27635312 PMCID: PMC5012268 DOI: 10.7717/peerj.2303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/07/2016] [Indexed: 11/20/2022] Open
Abstract
Throughout much of North America's boreal forest, the cyclical fluctuations of snowshoe hare populations (Lepus americanus) may cause other herbivores to become entrained in similar cycles. Alternating apparent competition via prey switching followed by positive indirect effects are the mechanisms behind this interaction. Our purpose is to document a change in the role of indirect interactions between sympatric populations of hares and arctic ground squirrels (Urocitellus parryii plesius), and to emphasize the influence of predation for controlling ground squirrel numbers. We used mark-recapture to estimate the population densities of both species over a 25-year period that covered two snowshoe hare cycles. We analysed the strength of association between snowshoe hare and ground squirrel numbers, and the changes to the seasonal and annual population growth rates of ground squirrels over time. A hyperbolic curve best describes the per capita rate of increase of ground squirrels relative to their population size, with a single stable equilibrium and a lower critical threshold below which populations drift to extinction. The crossing of this unstable boundary resulted in the subsequent uncoupling of ground squirrel and hare populations following the decline phase of their cycles in 1998. The implications are that this sustained Type II predator response led to the local extinction of ground squirrels. When few individuals are left in a colony, arctic ground squirrels may also have exhibited an Allee effect caused by the disruption of social signalling of approaching predators.
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Affiliation(s)
- Jeffery R Werner
- Biodiversity Research Centre, Department of Zoology, University of British Columbia , Vancouver , British Columbia , Canada
| | - Elizabeth A Gillis
- Department of Resource Management and Protection, Vancouver Island University , Nanaimo , British Columbia , Canada
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto, Scarborough , Toronto , Ontario , Canada
| | - Charles J Krebs
- Department of Zoology, University of British Columbia , Vancouver , British Columbia , Canada
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41
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Hik DS, McColl CJ, Boonstra R. Why are Arctic ground squirrels more stressed in the boreal forest than in alpine meadows? ECOSCIENCE 2016. [DOI: 10.1080/11956860.2001.11682654] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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42
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Loss SR, Will T, Marra PP. Direct Mortality of Birds from Anthropogenic Causes. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2015. [DOI: 10.1146/annurev-ecolsys-112414-054133] [Citation(s) in RCA: 192] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Scott R. Loss
- Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, Oklahoma 74078;
| | - Tom Will
- Division of Migratory Birds, Midwest Regional Office, US Fish and Wildlife Service, Bloomington, Minnesota 55437-1458;
| | - Peter P. Marra
- Migratory Bird Center, National Zoological Park, Smithsonian Conservation Biology Institute, Washington, DC 20013;
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43
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Myrvold KM, Kennedy BP. Density dependence and its impact on individual growth rates in an age-structured stream salmonid population. Ecosphere 2015. [DOI: 10.1890/es15-00390.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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44
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Woodland caribou calf mortality in Newfoundland: insights into the role of climate, predation and population density over three decades of study. POPUL ECOL 2015. [DOI: 10.1007/s10144-015-0525-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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45
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Tablado Z, Jenni L. Determinants of uncertainty in wildlife responses to human disturbance. Biol Rev Camb Philos Soc 2015; 92:216-233. [DOI: 10.1111/brv.12224] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/07/2015] [Accepted: 09/09/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Zulima Tablado
- Swiss Ornithological Institute, Seerose 1; CH-6204 Sempach Switzerland
| | - Lukas Jenni
- Swiss Ornithological Institute, Seerose 1; CH-6204 Sempach Switzerland
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46
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Myrvold KM, Kennedy BP. Local habitat conditions explain the variation in the strength of self-thinning in a stream salmonid. Ecol Evol 2015; 5:3231-42. [PMID: 26380659 PMCID: PMC4569021 DOI: 10.1002/ece3.1591] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 05/31/2015] [Accepted: 06/11/2015] [Indexed: 11/25/2022] Open
Abstract
Self-thinning patterns are frequently used to describe density dependence in populations on timescales shorter than the organism's life span and have been used to infer carrying capacity of the environment. Among mobile animals, this concept has been used to document density dependence in stream salmonids, which compete over access to food and space. The carrying capacity, growth conditions, and initial cohort sizes often vary between streams and stream sections, which would influence the onset and strength of the density dependence. Despite much effort in describing habitat relationships in stream fishes, few studies have explicitly tested how the physical environment affects the slope of the thinning curves. Here, we investigate the prevalence and strength of self-thinning in juvenile stages of a steelhead (Oncorhynchus mykiss) population in Idaho, USA. Further, we investigate the roles of local physical habitat and metabolic constraints in explaining the variation in thinning curves among study sites in the watershed. Only yearling steelhead exhibited an overall significant thinning trend, but the slope of the mass–density relationship (−0.53) was shallower than predicted by theory and reported from empirical studies. There was no detectable relationship in subyearling steelhead. Certain abiotic factors explained a relatively large portion of the variation in the strength of the self-thinning among the study reaches. For subyearling steelhead, the slopes were negatively associated with the average water depth and flow velocity in the study sites, whereas slopes in yearlings were steeper in sites that incurred a higher metabolic cost. Our results show that the prevalence and strength of density dependence in natural fish populations can vary across heterogeneous watersheds and can be more pronounced during certain stages of a species' life history, and that environmental factors can mediate the extent to which density dependence is manifested in predictable ways.
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Affiliation(s)
- Knut Marius Myrvold
- Department of Fish and Wildlife Sciences, University of Idaho Moscow, Idaho, 83844-1136, Unites States
| | - Brian P Kennedy
- Department of Fish and Wildlife Sciences, University of Idaho Moscow, Idaho, 83844-1136, Unites States ; Departments of Biological Sciences and Geological Sciences, University of Idaho Moscow, Idaho, 83844-1136, Unites States
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47
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Melero Y, Robinson E, Lambin X. Density- and age-dependent reproduction partially compensates culling efforts of invasive non-native American mink. Biol Invasions 2015. [DOI: 10.1007/s10530-015-0902-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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48
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Marescot L, Forrester TD, Casady DS, Wittmer HU. Using multistate capture–mark–recapture models to quantify effects of predation on age-specific survival and population growth in black-tailed deer. POPUL ECOL 2014. [DOI: 10.1007/s10144-014-0456-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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49
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Quinn TP, Cunningham CJ, Randall J, Hilborn R. Can intense predation by bears exert a depensatory effect on recruitment in a Pacific salmon population? Oecologia 2014; 176:445-56. [DOI: 10.1007/s00442-014-3043-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 08/11/2014] [Indexed: 11/24/2022]
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50
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Ricca MA, Van Vuren DH, Weckerly FW, Williams JC, Miles AK. Irruptive dynamics of introduced caribou on Adak Island, Alaska: an evaluation of Riney-Caughley model predictions. Ecosphere 2014. [DOI: 10.1890/es13-00338.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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