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Thapa SK, de Jong JF, Hof AR, Subedi N, Liefting Y, Prins HHT. Integration of the landscape of fear concept in grassland management: An experimental study on subtropical monsoon grasslands in Bardia National Park, Nepal. Ecol Evol 2024; 14:e70098. [PMID: 39100204 PMCID: PMC11294578 DOI: 10.1002/ece3.70098] [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: 04/28/2024] [Revised: 06/30/2024] [Accepted: 07/17/2024] [Indexed: 08/06/2024] Open
Abstract
The 'landscape of fear' concept offers valuable insights into wildlife behaviour, yet its practical integration into habitat management for conservation remains underexplored. In this study, conducted in the subtropical monsoon grasslands of Bardia National Park, Nepal, we aimed to bridge this gap through a multi-year, landscape-scale experimental investigation in Bardia National Park, Nepal. The park has the highest density of tigers (with an estimated density of ~7 individuals per 100 km2) in Nepal, allowing us to understand the effect of habitat management on predation risk and resource availability especially for three cervid species: chital (Axis axis), swamp deer (Rucervus duvaucelii) and hog deer (Axis porcinus). We used plots with varying mowing frequency (0-4 times per year), size (ranging from small: 49 m2 to large: 3600 m2) and artificial fertilisation type (none, phosphorus, nitrogen) to assess the trade-offs between probable predation risk and resources for these cervid species, which constitute primary prey for tigers in Nepal. Our results showed distinct responses of these deer to perceived predation risk within grassland habitats. Notably, these deer exhibited heightened use of larger plots, indicative of a perceived sense of safety, as evidenced by the higher occurrence of pellet groups in the larger plots (mean = 0.1 pellet groups m-2 in 3600 m2 plots vs. 0.07 in 400 m2 and 0.05 in 49 m2 plots). Furthermore, the level of use by the deer was significantly higher in larger plots that received mowing and fertilisation treatments compared to smaller plots subjected to similar treatments. Of particular interest is the observation that chital and swamp deer exhibited greater utilisation of the centre (core) areas within the larger plots (mean = 0.21 pellet groups m-2 at the centre vs. 0.13 at the edge) despite the edge (periphery) also provided attractive resources to these deer. In contrast, hog deer did not display any discernible reaction to the experimental treatments, suggesting potential species-specific variations in response to perceived predation risk arising from management interventions. Our findings emphasise the importance of a sense of security as a primary determinant of habitat selection for medium-sized deer within managed grassland environments. These insights carry practical implications for park managers, providing a nuanced understanding of integrating the 'landscape of fear' into habitat management strategies. This study emphasises that the 'landscape of fear' concept can and should be integrated into habitat management to maintain delicate predator-prey dynamics within ecosystems.
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Affiliation(s)
- Shyam Kumar Thapa
- National Trust for Nature ConservationLalitpurNepal
- Zoological Society of London, Nepal OfficeKathmanduNepal
| | - Joost F. de Jong
- Wildlife Ecology and Conservation GroupWageningen University and ResearchWageningenThe Netherlands
| | - Anouschka R. Hof
- Wildlife Ecology and Conservation GroupWageningen University and ResearchWageningenThe Netherlands
| | | | - Yorick Liefting
- Wildlife Ecology and Conservation GroupWageningen University and ResearchWageningenThe Netherlands
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2
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Karp AT, Koerner SE, Hempson GP, Abraham JO, Anderson TM, Bond WJ, Burkepile DE, Fillion EN, Goheen JR, Guyton JA, Kartzinel TR, Kimuyu DM, Mohanbabu N, Palmer TM, Porensky LM, Pringle RM, Ritchie ME, Smith MD, Thompson DI, Young TP, Staver AC. Grazing herbivores reduce herbaceous biomass and fire activity across African savannas. Ecol Lett 2024; 27:e14450. [PMID: 38857323 DOI: 10.1111/ele.14450] [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: 08/28/2023] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 06/12/2024]
Abstract
Fire and herbivory interact to alter ecosystems and carbon cycling. In savannas, herbivores can reduce fire activity by removing grass biomass, but the size of these effects and what regulates them remain uncertain. To examine grazing effects on fuels and fire regimes across African savannas, we combined data from herbivore exclosure experiments with remotely sensed data on fire activity and herbivore density. We show that, broadly across African savannas, grazing herbivores substantially reduce both herbaceous biomass and fire activity. The size of these effects was strongly associated with grazing herbivore densities, and surprisingly, was mostly consistent across different environments. A one-zebra increase in herbivore biomass density (~100 kg/km2 of metabolic biomass) resulted in a ~53 kg/ha reduction in standing herbaceous biomass and a ~0.43 percentage point reduction in burned area. Our results indicate that fire models can be improved by incorporating grazing effects on grass biomass.
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Affiliation(s)
- Allison Tyler Karp
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, Rhode Island, USA
| | - Sally E Koerner
- Department of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, USA
| | - Gareth P Hempson
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Joel O Abraham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - William J Bond
- Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Deron E Burkepile
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, USA
- South African Environmental Observation Network, Ndlovu Node, Scientific Services, Kruger National Park, Phalaborwa, South Africa
| | - Elizabeth N Fillion
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
| | - Jacob R Goheen
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
- Mpala Research Centre, Nanyuki, Kenya
| | - Jennifer A Guyton
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Tyler R Kartzinel
- Institute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USA
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - Duncan M Kimuyu
- Mpala Research Centre, Nanyuki, Kenya
- Department of Natural Resources, Karatina University, Karatina, Kenya
| | - Neha Mohanbabu
- Department of Biology, Syracuse University, Syracuse, New York, USA
- University of Minnesota, Twin Cities, Minnesota, USA
| | - Todd M Palmer
- Biological Sciences, University of Cape Town, Cape Town, South Africa
- Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Lauren M Porensky
- Rangeland Resources and Systems Research Unit, USDA Agricultural Research Service, Fort Collins, Colorado, USA
| | - Robert M Pringle
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Mark E Ritchie
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
| | - Melinda D Smith
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Dave I Thompson
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
- South African Environmental Observation Network, Ndlovu Node, Scientific Services, Kruger National Park, Phalaborwa, South Africa
| | - Truman P Young
- Mpala Research Centre, Nanyuki, Kenya
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - A Carla Staver
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
- Yale Institute for Biospheric Studies, Yale University, New Haven, Connecticut, USA
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3
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Rhodes AC, Plowes RM, Bowman EA, Gaitho A, Ng'Iru I, Martins DJ, Gilbert LE. Systematic reduction of natural enemies and competition across variable precipitation approximates buffelgrass invasiveness ( Cenchrus ciliaris) in its native range. Ecol Evol 2024; 14:e11350. [PMID: 38737568 PMCID: PMC11087885 DOI: 10.1002/ece3.11350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/28/2024] [Accepted: 04/12/2024] [Indexed: 05/14/2024] Open
Abstract
Invasive grasses cause devastating losses to biodiversity and ecosystem function directly and indirectly by altering ecosystem processes. Escape from natural enemies, plant-plant competition, and variable resource availability provide frameworks for understanding invasion. However, we lack a clear understanding of how natural stressors interact in their native range to regulate invasiveness. In this study, we reduced diverse guilds of natural enemies and plant competitors of the highly invasive buffelgrass across a precipitation gradient throughout major climatic shifts in Laikipia, Kenya. To do this, we used a long-term ungulate exclosure experiment design across a precipitation gradient with nested treatments that (1) reduced plant competition through clipping, (2) reduced insects through systemic insecticide, and (3) reduced fungal associates through fungicide application. Additionally, we measured the interaction of ungulates on two stem-boring insect species feeding on buffelgrass. Finally, we measured a multiyear smut fungus outbreak. Our findings suggest that buffelgrass exhibits invasive qualities when released from a diverse group of natural stressors in its native range. We show natural enemies interact with precipitation to alter buffelgrass productivity patterns. In addition, interspecific plant competition decreased the basal area of buffelgrass, suggesting that biotic resistance mediates buffelgrass dominance in the home range. Surprisingly, systemic insecticides and fungicides did not impact buffelgrass production or reproduction, perhaps because other guilds filled the niche space in these highly diverse systems. For example, in the absence of ungulates, we showed an increase in host-specific stem-galling insects, where these insects compensated for reduced ungulate use. Finally, we documented a smut outbreak in 2020 and 2021, corresponding to highly variable precipitation patterns caused by a shifting Indian Ocean Dipole. In conclusion, we observed how reducing natural enemies and competitors and certain interactions increased properties related to buffelgrass invasiveness.
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Affiliation(s)
- Aaron C. Rhodes
- Brackenridge Field LaboratoryThe University of Texas at AustinAustinTexasUSA
| | - Robert M. Plowes
- Brackenridge Field LaboratoryThe University of Texas at AustinAustinTexasUSA
| | - Elizabeth A. Bowman
- Brackenridge Field LaboratoryThe University of Texas at AustinAustinTexasUSA
- Hiro Technologies, IncAustinTexasUSA
| | - Aimee Gaitho
- Mpala Research Centre NanyukiNanyukiKenya
- Turkana Basin InstituteNairobiKenya
| | - Ivy Ng'Iru
- UK Centre for Ecology & HydrologyCardiff UniversityWallingfordUK
| | | | - Lawrence E. Gilbert
- Brackenridge Field LaboratoryThe University of Texas at AustinAustinTexasUSA
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4
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Creel S, Reyes de Merkle J, Goodheart B, Mweetwa T, Mwape H, Simpamba T, Becker MS. An integrated population model reveals source-sink dynamics for competitively subordinate African wild dogs linked to anthropogenic prey depletion. J Anim Ecol 2024; 93:417-427. [PMID: 38311822 DOI: 10.1111/1365-2656.14052] [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: 06/08/2023] [Accepted: 01/04/2024] [Indexed: 02/06/2024]
Abstract
Many African large carnivore populations are declining due to decline of the herbivore populations on which they depend. The densities of apex carnivores like the lion and spotted hyena correlate strongly with prey density, but competitively subordinate carnivores like the African wild dog benefit from competitive release when the density of apex carnivores is low, so the expected effect of a simultaneous decrease in resources and dominant competitors is not obvious. Wild dogs in Zambia's South Luangwa Valley Ecosystem occupy four ecologically similar areas with well-described differences in the densities of prey and dominant competitors due to spatial variation in illegal offtake. We used long-term monitoring data to fit a Bayesian integrated population model (IPM) of the demography and dynamics of wild dogs in these four regions. The IPM used Leslie projection to link a Cormack-Jolly-Seber model of area-specific survival (allowing for individual heterogeneity in detection), a zero-inflated Poisson model of area-specific fecundity and a state-space model of population size that used estimates from a closed mark-capture model as the counts from which (latent) population size was estimated. The IPM showed that both survival and reproduction were lowest in the region with the lowest density of preferred prey (puku, Kobus vardonii and impala, Aepyceros melampus), despite little use of this area by lions. Survival and reproduction were highest in the region with the highest prey density and intermediate in the two regions with intermediate prey density. The population growth rate (λ ) was positive for the population as a whole, strongly positive in the region with the highest prey density and strongly negative in the region with the lowest prey density. It has long been thought that the benefits of competitive release protect African wild dogs from the costs of low prey density. Our results show that the costs of prey depletion overwhelm the benefits of competitive release and cause local population decline where anthropogenic prey depletion is strong. Because competition is important in many guilds and humans are affecting resources of many types, it is likely that similarly fundamental shifts in population limitation are arising in many systems.
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Affiliation(s)
- Scott Creel
- Department of Ecology, Montana State University, Bozeman, Montana, USA
- Zambian Carnivore Programme, Mfuwe, Eastern Province, Zambia
| | - Johnathan Reyes de Merkle
- Department of Ecology, Montana State University, Bozeman, Montana, USA
- Zambian Carnivore Programme, Mfuwe, Eastern Province, Zambia
| | - Ben Goodheart
- Department of Ecology, Montana State University, Bozeman, Montana, USA
- Zambian Carnivore Programme, Mfuwe, Eastern Province, Zambia
| | | | - Henry Mwape
- Zambian Carnivore Programme, Mfuwe, Eastern Province, Zambia
| | - Twakundine Simpamba
- Department of National Parks and Wildlife, South Luangwa Area Management Unit, Mfuwe, Eastern Province, Zambia
| | - Matthew S Becker
- Department of Ecology, Montana State University, Bozeman, Montana, USA
- Zambian Carnivore Programme, Mfuwe, Eastern Province, Zambia
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5
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Tan HZ, Jansen JJFJ, Allport GA, Garg KM, Chattopadhyay B, Irestedt M, Pang SEH, Chilton G, Gwee CY, Rheindt FE. Megafaunal extinctions, not climate change, may explain Holocene genetic diversity declines in Numenius shorebirds. eLife 2023; 12:e85422. [PMID: 37549057 PMCID: PMC10406428 DOI: 10.7554/elife.85422] [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: 12/07/2022] [Accepted: 06/27/2023] [Indexed: 08/09/2023] Open
Abstract
Understanding the relative contributions of historical and anthropogenic factors to declines in genetic diversity is important for informing conservation action. Using genome-wide DNA of fresh and historic specimens, including that of two species widely thought to be extinct, we investigated fluctuations in genetic diversity and present the first complete phylogenomic tree for all nine species of the threatened shorebird genus Numenius, known as whimbrels and curlews. Most species faced sharp declines in effective population size, a proxy for genetic diversity, soon after the Last Glacial Maximum (around 20,000 years ago). These declines occurred prior to the Anthropocene and in spite of an increase in the breeding area predicted by environmental niche modeling, suggesting that they were not caused by climatic or recent anthropogenic factors. Crucially, these genetic diversity declines coincide with mass extinctions of mammalian megafauna in the Northern Hemisphere. Among other factors, the demise of ecosystem-engineering megafauna which maintained open habitats may have been detrimental for grassland and tundra-breeding Numenius shorebirds. Our work suggests that the impact of historical factors such as megafaunal extinction may have had wider repercussions on present-day population dynamics of open habitat biota than previously appreciated.
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Affiliation(s)
- Hui Zhen Tan
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
| | | | | | - Kritika M Garg
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
| | - Balaji Chattopadhyay
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
| | - Martin Irestedt
- Department of Bioinformatics and Genetics, Swedish Museum of Natural HistoryStockholmSweden
| | - Sean EH Pang
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
| | - Glen Chilton
- Department of Biology, St. Mary's UniversityCalgaryCanada
| | - Chyi Yin Gwee
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
| | - Frank E Rheindt
- Department of Biological Sciences, National University of SingaporeSingaporeSingapore
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6
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Pringle RM, Abraham JO, Anderson TM, Coverdale TC, Davies AB, Dutton CL, Gaylard A, Goheen JR, Holdo RM, Hutchinson MC, Kimuyu DM, Long RA, Subalusky AL, Veldhuis MP. Impacts of large herbivores on terrestrial ecosystems. Curr Biol 2023; 33:R584-R610. [PMID: 37279691 DOI: 10.1016/j.cub.2023.04.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Large herbivores play unique ecological roles and are disproportionately imperiled by human activity. As many wild populations dwindle towards extinction, and as interest grows in restoring lost biodiversity, research on large herbivores and their ecological impacts has intensified. Yet, results are often conflicting or contingent on local conditions, and new findings have challenged conventional wisdom, making it hard to discern general principles. Here, we review what is known about the ecosystem impacts of large herbivores globally, identify key uncertainties, and suggest priorities to guide research. Many findings are generalizable across ecosystems: large herbivores consistently exert top-down control of plant demography, species composition, and biomass, thereby suppressing fires and the abundance of smaller animals. Other general patterns do not have clearly defined impacts: large herbivores respond to predation risk but the strength of trophic cascades is variable; large herbivores move vast quantities of seeds and nutrients but with poorly understood effects on vegetation and biogeochemistry. Questions of the greatest relevance for conservation and management are among the least certain, including effects on carbon storage and other ecosystem functions and the ability to predict outcomes of extinctions and reintroductions. A unifying theme is the role of body size in regulating ecological impact. Small herbivores cannot fully substitute for large ones, and large-herbivore species are not functionally redundant - losing any, especially the largest, will alter net impact, helping to explain why livestock are poor surrogates for wild species. We advocate leveraging a broad spectrum of techniques to mechanistically explain how large-herbivore traits and environmental context interactively govern the ecological impacts of these animals.
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Affiliation(s)
- Robert M Pringle
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Joel O Abraham
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston Salem, NC 27109, USA
| | - Tyler C Coverdale
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Andrew B Davies
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | | | | | - Jacob R Goheen
- Department of Zoology & Physiology, University of Wyoming, Laramie, WY 82072, USA
| | - Ricardo M Holdo
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Matthew C Hutchinson
- Department of Life & Environmental Sciences, University of California Merced, Merced, CA 95343, USA
| | - Duncan M Kimuyu
- Department of Natural Resources, Karatina University, Karatina, Kenya
| | - Ryan A Long
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Amanda L Subalusky
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Michiel P Veldhuis
- Institute of Environmental Sciences, Leiden University, 2333 CC Leiden, The Netherlands
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7
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Brown BRP, Goheen JR, Newsome SD, Pringle RM, Palmer TM, Khasoha LM, Kartzinel TR. Host phylogeny and functional traits differentiate gut microbiomes in a diverse natural community of small mammals. Mol Ecol 2023; 32:2320-2334. [PMID: 36740909 DOI: 10.1111/mec.16874] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 12/27/2022] [Accepted: 02/02/2023] [Indexed: 02/07/2023]
Abstract
Differences in the bacterial communities inhabiting mammalian gut microbiomes tend to reflect the phylogenetic relatedness of their hosts, a pattern dubbed phylosymbiosis. Although most research on this pattern has compared the gut microbiomes of host species across biomes, understanding the evolutionary and ecological processes that generate phylosymbiosis requires comparisons across phylogenetic scales and under similar ecological conditions. We analysed the gut microbiomes of 14 sympatric small mammal species in a semi-arid African savanna, hypothesizing that there would be a strong phylosymbiotic pattern associated with differences in their body sizes and diets. Consistent with phylosymbiosis, microbiome dissimilarity increased with phylogenetic distance among hosts, ranging from congeneric sets of mice and hares that did not differ significantly in microbiome composition to species from different taxonomic orders that had almost no gut bacteria in common. While phylosymbiosis was detected among just the 11 species of rodents, it was substantially weaker at this scale than in comparisons involving all 14 species together. In contrast, microbiome diversity and composition were generally more strongly correlated with body size, dietary breadth, and dietary overlap in comparisons restricted to rodents than in those including all lineages. The starkest divides in microbiome composition thus reflected the broad evolutionary divergence of hosts, regardless of body size or diet, while subtler microbiome differences reflected variation in ecologically important traits of closely related hosts. Strong phylosymbiotic patterns arose deep in the phylogeny, and ecological filters that promote functional differentiation of cooccurring host species may disrupt or obscure this pattern near the tips.
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Affiliation(s)
- Bianca R P Brown
- Department of Ecology, Evolutionary & Organismal Biology, Brown University, Providence, Rhode Island, USA.,Institute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USA.,Mpala Research Centre, Nanyuki, Kenya
| | - Jacob R Goheen
- Mpala Research Centre, Nanyuki, Kenya.,Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, USA
| | - Robert M Pringle
- Mpala Research Centre, Nanyuki, Kenya.,Department of Ecology & Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Todd M Palmer
- Mpala Research Centre, Nanyuki, Kenya.,Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Leo M Khasoha
- Mpala Research Centre, Nanyuki, Kenya.,Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
| | - Tyler R Kartzinel
- Department of Ecology, Evolutionary & Organismal Biology, Brown University, Providence, Rhode Island, USA.,Institute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USA.,Mpala Research Centre, Nanyuki, Kenya
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8
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Coetsee C, Botha J, Case MF, Manganyi A, Siebert F. The hard lives of trees in African savanna—Even without elephants. AUSTRAL ECOL 2023. [DOI: 10.1111/aec.13283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Corli Coetsee
- Scientific Services South African National Parks, Savanna Node, Kruger National Park Skukuza South Africa
- School of Natural Resource Management Nelson Mandela University George South Africa
| | - Judith Botha
- Scientific Services South African National Parks, Savanna Node, Kruger National Park Skukuza South Africa
| | - Madelon F. Case
- University of Oregon Eugene Oregon USA
- U.S. Geological Survey Forest and Rangeland Ecosystem Science Center Corvallis Oregon USA
| | - Adolf Manganyi
- Scientific Services South African National Parks, Savanna Node, Kruger National Park Skukuza South Africa
| | - Frances Siebert
- Unit for Environmental Sciences and Management North‐West University Potchefstroom South Africa
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9
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Ford AT, Dorsey B, Lee TS, Clevenger AP. A before-after-control-impact study of wildlife fencing along a highway in the Canadian Rocky Mountains. FRONTIERS IN CONSERVATION SCIENCE 2022. [DOI: 10.3389/fcosc.2022.935420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Wildlife exclusion fencing has become a standard component of highway mitigation systems designed to reduce collisions with large mammals. Past work on the effectiveness of exclusion fencing has relied heavily on control–impact (i.e., space-for-time substitutions) and before–after study designs. These designs limit inference and may confound the effectiveness of mitigation with co-occurring process that also changes the rate of collisions. We used a replicated (n = 2 sites monitored for over 1000 km years combined) before-after-control-impact study design to assess fencing effectiveness along the Trans-Canada Highway in the Rocky Mountains of Canada. We found that collisions declined for common ungulates species (elk, mule deer, and white-tailed deer) by up to 96% but not for large carnivores. The weak response of carnivores is likely due to the combination of fence intrusions and low sample sizes. We calculated realized fencing effectiveness by applying the same change in collision rates observed at control (unfenced) sites as the expected change for adjacent fenced sections. Compared with the apparent fencing effectiveness (i.e., the difference in WVCs rates before and after fencing was installed), the realized estimates of fencing effectiveness declined by 6% at one site and increased by 10% at another site. When factoring in the cost of ungulate collisions to society, fencing provided a net economic gain within 1 year of construction. Over a 10-year period, fencing would provide a net economic gain of > $500,000 per km in reduced collisions. Our study highlights the benefits of long-term monitoring of road mitigation projects and provides evidence of fencing effectiveness for reducing wildlife–vehicle collisions involving large mammals.
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10
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Buisson E, Archibald S, Fidelis A, Suding KN. Ancient grasslands guide ambitious goals in grassland restoration. Science 2022; 377:594-598. [PMID: 35926035 DOI: 10.1126/science.abo4605] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Grasslands, which constitute almost 40% of the terrestrial biosphere, provide habitat for a great diversity of animals and plants and contribute to the livelihoods of more than 1 billion people worldwide. Whereas the destruction and degradation of grasslands can occur rapidly, recent work indicates that complete recovery of biodiversity and essential functions occurs slowly or not at all. Grassland restoration-interventions to speed or guide this recovery-has received less attention than restoration of forested ecosystems, often due to the prevailing assumption that grasslands are recently formed habitats that can reassemble quickly. Viewing grassland restoration as long-term assembly toward old-growth endpoints, with appreciation of feedbacks and threshold shifts, will be crucial for recognizing when and how restoration can guide recovery of this globally important ecosystem.
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Affiliation(s)
- Elise Buisson
- Institut Méditerranéen de Biodiversité et d'Ecologie, Avignon Université, CNRS, IRD, Aix Marseille Université, 84911 Avignon, France
| | - Sally Archibald
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Alessandra Fidelis
- Instituto de Biociências, Lab of Vegetation Ecology, Universidade Estadual Paulista (UNESP), Rio Claro 13506-900, Brazil
| | - Katharine N Suding
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA.,Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA
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11
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Wigley BJ, Coetsee C, Mawoyo KA, Fritz H. No evidence for the simultaneous induction of structural and chemical defences in spiny southern African savanna trees. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Benjamin J. Wigley
- Plant Ecology University of Bayreuth Universitätsstr. 30 Bayreuth 95440 Germany
- School of Natural Resource Management Nelson Mandela University George South Africa
- Scientific Services, Kruger National Park Skukuza South Africa
| | - Corli Coetsee
- School of Natural Resource Management Nelson Mandela University George South Africa
- Scientific Services, Kruger National Park Skukuza South Africa
| | - Kuzivakwashe A. Mawoyo
- Scientific Services, Kyle Recreational Park Masvingo Zimbabwe
- LTSER France RI, Zone Atelier “Hwange” (Hwange LTSER) Hwange National Park Dete Zimbabwe
| | - Hervé Fritz
- LTSER France RI, Zone Atelier “Hwange” (Hwange LTSER) Hwange National Park Dete Zimbabwe
- REHABS International Research Laboratory CNRS‐Université de Lyon1‐Nelson Mandela University George South Africa
- Sustainability Research Unit Nelson Mandela University George South Africa
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12
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Rastogi S, Chanchani P, Sankaran M, Warrier R. Grasslands half‐full: investigating drivers of spatial heterogeneity in ungulate occurrence in Indian Terai. J Zool (1987) 2021. [DOI: 10.1111/jzo.12939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- S. Rastogi
- Post‐Graduate Program in Wildlife Biology and Conservation National Centre for Biological Sciences Bangalore Karnataka India
| | - P. Chanchani
- World Wide Fund for Nature (WWF) New Delhi India
| | - M. Sankaran
- Ecology and Evolution National Centre for Biological Sciences Bangalore Karnataka India
- School of Biology University of Leeds Leeds UK
| | - R. Warrier
- School of Global Environmental Sustainability Colorado State University Fort Collins Colorado USA
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13
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Monk JD, Schmitz OJ. Landscapes shaped from the top down: predicting cascading predator effects on spatial biogeochemistry. OIKOS 2021. [DOI: 10.1111/oik.08554] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julia D. Monk
- School of the Environment, Yale Univ. New Haven CT USA
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14
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Large herbivores suppress liana infestation in an African savanna. Proc Natl Acad Sci U S A 2021; 118:2101676118. [PMID: 34580170 DOI: 10.1073/pnas.2101676118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2021] [Indexed: 11/18/2022] Open
Abstract
African savannas are the last stronghold of diverse large-mammal communities, and a major focus of savanna ecology is to understand how these animals affect the relative abundance of trees and grasses. However, savannas support diverse plant life-forms, and human-induced changes in large-herbivore assemblages-declining wildlife populations and their displacement by livestock-may cause unexpected shifts in plant community composition. We investigated how herbivory affects the prevalence of lianas (woody vines) and their impact on trees in an East African savanna. Although scarce (<2% of tree canopy area) and defended by toxic latex, the dominant liana, Cynanchum viminale (Apocynaceae), was eaten by 15 wild large-herbivore species and was consumed in bulk by native browsers during experimental cafeteria trials. In contrast, domesticated ungulates rarely ate lianas. When we experimentally excluded all large herbivores for periods of 8 to 17 y (simulating extirpation), liana abundance increased dramatically, with up to 75% of trees infested. Piecewise exclusion of different-sized herbivores revealed functional complementarity among size classes in suppressing lianas. Liana infestation reduced tree growth and reproduction, but herbivores quickly cleared lianas from trees after the removal of 18-y-old exclosure fences (simulating rewilding). A simple model of liana contagion showed that, without herbivores, the long-term equilibrium could be either endemic (liana-tree coexistence) or an all-liana alternative stable state. We conclude that ongoing declines of wild large-herbivore populations will disrupt the structure and functioning of many African savannas in ways that have received little attention and that may not be mitigated by replacing wildlife with livestock.
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15
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Wells HBM, Crego RD, Opedal ØH, Khasoha LM, Alston JM, Reed CG, Weiner S, Kurukura S, Hassan AA, Namoni M, Ekadeli J, Kimuyu DM, Young TP, Kartzinel TR, Palmer TM, Pringle RM, Goheen JR. Experimental evidence that effects of megaherbivores on mesoherbivore space use are influenced by species' traits. J Anim Ecol 2021; 90:2510-2522. [PMID: 34192343 DOI: 10.1111/1365-2656.13565] [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: 03/16/2021] [Accepted: 06/23/2021] [Indexed: 11/27/2022]
Abstract
The extinction of 80% of megaherbivore (>1,000 kg) species towards the end of the Pleistocene altered vegetation structure, fire dynamics and nutrient cycling world-wide. Ecologists have proposed (re)introducing megaherbivores or their ecological analogues to restore lost ecosystem functions and reinforce extant but declining megaherbivore populations. However, the effects of megaherbivores on smaller herbivores are poorly understood. We used long-term exclusion experiments and multispecies hierarchical models fitted to dung counts to test (a) the effect of megaherbivores (elephant and giraffe) on the occurrence (dung presence) and use intensity (dung pile density) of mesoherbivores (2-1,000 kg), and (b) the extent to which the responses of each mesoherbivore species was predictable based on their traits (diet and shoulder height) and phylogenetic relatedness. Megaherbivores increased the predicted occurrence and use intensity of zebras but reduced the occurrence and use intensity of several other mesoherbivore species. The negative effect of megaherbivores on mesoherbivore occurrence was stronger for shorter species, regardless of diet or relatedness. Megaherbivores substantially reduced the expected total use intensity (i.e. cumulative dung density of all species) of mesoherbivores, but only minimally reduced the expected species richness (i.e. cumulative predicted occurrence probabilities of all species) of mesoherbivores (by <1 species). Simulated extirpation of megaherbivores altered use intensity by mesoherbivores, which should be considered during (re)introductions of megaherbivores or their ecological proxies. Species' traits (in this case shoulder height) may be more reliable predictors of mesoherbivores' responses to megaherbivores than phylogenetic relatedness, and may be useful for predicting responses of data-limited species.
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Affiliation(s)
- Harry B M Wells
- Lolldaiga Hills Research Programme, Nanyuki, Kenya.,Sustainability Research Institute, School of Earth and Environment, University of Leeds, Leeds, UK.,Space for Giants, Nanyuki, Kenya
| | - Ramiro D Crego
- National Zoo and Smithsonian Conservation Biology Institute, Conservation Ecology Center, Front Royal, VA, USA
| | | | - Leo M Khasoha
- Mpala Research Centre, Nanyuki, Kenya.,Program in Ecology, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Jesse M Alston
- Program in Ecology, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA.,Center for Advanced Systems Understanding (CASUS), Görlitz, Germany
| | - Courtney G Reed
- Mpala Research Centre, Nanyuki, Kenya.,Institute at Brown for Environment and Society, Brown University, Providence, RI, USA.,Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA
| | - Sarah Weiner
- Mpala Research Centre, Nanyuki, Kenya.,Program in Ecology, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | | | | | | | | | - Duncan M Kimuyu
- Mpala Research Centre, Nanyuki, Kenya.,Department of Natural Resources, Karatina University, Karatina, Kenya
| | - Truman P Young
- Mpala Research Centre, Nanyuki, Kenya.,Department of Plant Sciences and Ecology Graduate Group, University of California, Davis, CA, USA
| | - Tyler R Kartzinel
- Mpala Research Centre, Nanyuki, Kenya.,Institute at Brown for Environment and Society, Brown University, Providence, RI, USA.,Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA
| | - Todd M Palmer
- Mpala Research Centre, Nanyuki, Kenya.,Department of Biology, University of Florida, Gainesville, FL, USA
| | - Robert M Pringle
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Jacob R Goheen
- Mpala Research Centre, Nanyuki, Kenya.,Program in Ecology, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
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16
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Contrasting dynamical responses of sympatric caribou and muskoxen to winter weather and earlier spring green-up in the Arctic. FOOD WEBS 2021. [DOI: 10.1016/j.fooweb.2021.e00196] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Large herbivores transform plant-pollinator networks in an African savanna. Curr Biol 2021; 31:2964-2971.e5. [PMID: 34004144 DOI: 10.1016/j.cub.2021.04.051] [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: 01/11/2021] [Revised: 03/08/2021] [Accepted: 04/20/2021] [Indexed: 11/23/2022]
Abstract
Pollination by animals is a key ecosystem service1,2 and interactions between plants and their pollinators are a model system for studying ecological networks,3,4 yet plant-pollinator networks are typically studied in isolation from the broader ecosystems in which they are embedded. The plants visited by pollinators also interact with other consumer guilds that eat stems, leaves, fruits, or seeds. One such guild, large mammalian herbivores, are well-known ecosystem engineers5-7 and may have substantial impacts on plant-pollinator networks. Although moderate herbivory can sometimes promote plant diversity,8 potentially benefiting pollinators, large herbivores might alternatively reduce resource availability for pollinators by consuming flowers,9 reducing plant density,10 and promoting somatic regrowth over reproduction.11 The direction and magnitude of such effects may hinge on abiotic context-in particular, rainfall, which modulates the effects of ungulates on vegetation.12 Using a long-term, large-scale experiment replicated across a rainfall gradient in central Kenya, we show that a diverse assemblage of native large herbivores, ranging from 5-kg antelopes to 4,000-kg African elephants, limited resource availability for pollinators by reducing flower abundance and diversity; this in turn resulted in fewer pollinator visits and lower pollinator diversity. Exclusion of large herbivores increased floral-resource abundance and pollinator-assemblage diversity, rendering plant-pollinator networks larger, more functionally redundant, and less vulnerable to pollinator extinction. Our results show that species extrinsic to plant-pollinator interactions can indirectly and strongly alter network structure. Forecasting the effects of environmental change on pollination services and interaction webs more broadly will require accounting for the effects of extrinsic keystone species.
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18
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Rojas CA, Ramírez-Barahona S, Holekamp KE, Theis KR. Host phylogeny and host ecology structure the mammalian gut microbiota at different taxonomic scales. Anim Microbiome 2021; 3:33. [PMID: 33892813 PMCID: PMC8063394 DOI: 10.1186/s42523-021-00094-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/04/2021] [Indexed: 12/13/2022] Open
Abstract
The gut microbiota is critical for host function. Among mammals, host phylogenetic relatedness and diet are strong drivers of gut microbiota structure, but one factor may be more influential than the other. Here, we used 16S rRNA gene sequencing to determine the relative contributions of host phylogeny and host diet in structuring the gut microbiotas of 11 herbivore species from 5 families living sympatrically in southwest Kenya. Herbivore species were classified as grazers, browsers, or mixed-feeders and dietary data (% C4 grasses in diet) were compiled from previously published sources. We found that herbivore gut microbiotas were highly species-specific, and that host taxonomy accounted for more variation in the gut microbiota (30%) than did host dietary guild (10%) or sample month (8%). Overall, similarity in the gut microbiota increased with host phylogenetic relatedness (r = 0.74) across the 11 species of herbivores, but among 7 closely related Bovid species, dietary %C4 grass values more strongly predicted gut microbiota structure (r = 0.64). Additionally, within bovids, host dietary guild explained more of the variation in the gut microbiota (17%) than did host species (12%). Lastly, while we found that the gut microbiotas of herbivores residing in southwest Kenya converge with those of distinct populations of conspecifics from central Kenya, fine-scale differences in the abundances of bacterial amplicon sequence variants (ASVs) between individuals from the two regions were also observed. Overall, our findings suggest that host phylogeny and taxonomy strongly structure the gut microbiota across broad host taxonomic scales, but these gut microbiotas can be further modified by host ecology (i.e., diet, geography), especially among closely related host species.
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Affiliation(s)
- Connie A. Rojas
- Department of Integrative Biology, Michigan State University, East Lansing, MI USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI USA
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI USA
| | - Santiago Ramírez-Barahona
- Departament of Botany, Institute of Biology, Universidad Nacional Autónoma de México, Mexico City, MX Mexico
| | - Kay E. Holekamp
- Department of Integrative Biology, Michigan State University, East Lansing, MI USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI USA
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI USA
| | - Kevin R. Theis
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI USA
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI USA
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19
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Tchouassi DP, Torto B, Sang R, Riginos C, Ezenwa VO. Large herbivore loss has complex effects on mosquito ecology and vector-borne disease risk. Transbound Emerg Dis 2020; 68:2503-2513. [PMID: 33170555 DOI: 10.1111/tbed.13918] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/25/2020] [Accepted: 11/06/2020] [Indexed: 12/15/2022]
Abstract
Loss of biodiversity can affect transmission of infectious diseases in at least two ways: by altering host and vector abundance or by influencing host and vector behaviour. We used a large herbivore exclusion experiment to investigate the effects of wildlife loss on the abundance and feeding behaviour of mosquito vectors and to explore consequences for vector-borne disease transmission. Large herbivore loss affected both mosquito abundance and blood-feeding behaviour. For Aedes mcintoshi, the dominant mosquito species in our study and a primary vector of Rift Valley fever virus (RVFV), abundance decreased with large herbivore loss, while blood feeding on humans increased. Despite an elevated human biting rate in the absence of large herbivores, we estimated that the potential for RVFV transmission to humans doubles in the presence of large herbivores. These results demonstrate that multiple effects of biodiversity loss on vectors can lead to counterintuitive outcomes for human disease risk.
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Affiliation(s)
- David P Tchouassi
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Baldwyn Torto
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Rosemary Sang
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | | | - Vanessa O Ezenwa
- Odum School of Ecology and Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
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20
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Long-term grazing removal increased invasion and reduced native plant abundance and diversity in a sagebrush grassland. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01267] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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21
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Schmitz OJ, Leroux SJ. Food Webs and Ecosystems: Linking Species Interactions to the Carbon Cycle. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-104730] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
All species within ecosystems contribute to regulating carbon cycling because of their functional integration into food webs. Yet carbon modeling and accounting still assumes that only plants, microbes, and invertebrate decomposer species are relevant to the carbon cycle. Our multifaceted review develops a case for considering a wider range of species, especially herbivorous and carnivorous wild animals. Animal control over carbon cycling is shaped by the animals’ stoichiometric needs and functional traits in relation to the stoichiometry and functional traits of their resources. Quantitative synthesis reveals that failing to consider these mechanisms can lead to serious inaccuracies in the carbon budget. Newer carbon-cycle models that consider food-web structure based on organismal functional traits and stoichiometry can offer mechanistically informed predictions about the magnitudes of animal effects that will help guide new empirical research aimed at developing a coherent understanding of the interactions and importance of all species within food webs.
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Affiliation(s)
- Oswald J. Schmitz
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
| | - Shawn J. Leroux
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3X9, Canada
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22
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Predators and rainfall control spatial biogeochemistry in a landscape of fear. Proc Natl Acad Sci U S A 2020; 117:24016-24018. [PMID: 32887798 DOI: 10.1073/pnas.2016449117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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23
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Kiffner C, Kioko J, Baylis J, Beckwith C, Brunner C, Burns C, Chavez‐Molina V, Cotton S, Glazik L, Loftis E, Moran M, O'Neill C, Theisinger O, Kissui B. Long-term persistence of wildlife populations in a pastoral area. Ecol Evol 2020; 10:10000-10016. [PMID: 33005359 PMCID: PMC7520174 DOI: 10.1002/ece3.6658] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 01/10/2023] Open
Abstract
Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case-study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long-term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework. By comparing density estimates of the road transect-based long-term monitoring to estimates derived from systematically distributed transects, we found that the bias associated with nonrandom placement of transects was nonsignificant. Overall, cattle and sheep and goat reached the greatest densities and several wildlife species occurred at densities similar (zebra, wildebeest, waterbuck, Kirk's dik-dik) or possibly even greater (giraffe, eland, lesser kudu, Grant's gazelle, Thomson's gazelle) than in adjacent national parks in the same ecosystem. Generalized linear mixed models suggested that most wildlife species (8 out of 14) reached greatest densities during the dry season, that wildlife population densities either remained constant or increased over the 17-year period, and that herbivorous livestock species remained constant, while domestic dog population decreased over time. Cross-species correlations did not provide evidence for interference competition between grazing or mixed livestock species and wildlife species but indicate possible negative relationships between domestic dog and warthog populations. Overall, wildlife and livestock populations in Manyara Ranch appear to coexist over the 17-year span. Most likely, this is facilitated by existing connectivity to adjacent protected areas, effective anti-poaching efforts, spatio-temporal grazing restrictions, favorable environmental conditions of the ranch, and spatial heterogeneity of surface water and habitats. This long-term case study illustrates the potential of rangelands to simultaneously support wildlife conservation and human livelihood goals if livestock grazing is restricted in space, time, and numbers.
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Affiliation(s)
- Christian Kiffner
- Center for Wildlife Management StudiesThe School For Field StudiesKaratuTanzania
| | - John Kioko
- Center for Wildlife Management StudiesThe School For Field StudiesKaratuTanzania
| | - Jack Baylis
- Department of Environmental Studies and SciencesSanta Clara UniversitySanta ClaraCAUSA
| | | | - Craig Brunner
- Psychology DepartmentWhitman CollegeWalla WallaWAUSA
| | - Christine Burns
- Department of Environmental ScienceDickinson CollegeCarlislePAUSA
| | | | - Sara Cotton
- Neuroscience and Behavior DepartmentVassar CollegePoughkeepsieNYUSA
| | - Laura Glazik
- Department of Animal ScienceUniversity of Illinois, Urbana‐ChampaignChampaignILUSA
| | - Ellen Loftis
- Rubenstein School of Environment and Natural ResourcesUniversity of VermontBurlingtonVTUSA
| | - Megan Moran
- Biology DepartmentCollege of the Holy CrossWorcesterMAUSA
| | - Caitlin O'Neill
- Department of BiologySt. Mary's College of MarylandSt. Mary's CityMDUSA
| | - Ole Theisinger
- Center for Wildlife Management StudiesThe School For Field StudiesKaratuTanzania
| | - Bernard Kissui
- Center for Wildlife Management StudiesThe School For Field StudiesKaratuTanzania
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24
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Leroux SJ, Wiersma YF, Vander Wal E. Herbivore Impacts on Carbon Cycling in Boreal Forests. Trends Ecol Evol 2020; 35:1001-1010. [PMID: 32800352 DOI: 10.1016/j.tree.2020.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/08/2020] [Accepted: 07/16/2020] [Indexed: 12/01/2022]
Abstract
Large herbivores can have substantial effects on carbon (C) cycling, yet these animals are often overlooked in C budgets. Zoogeochemical effects may be particularly important in boreal forests, where diverse human activities are facilitating the expansion of large herbivore populations. Here, we argue that considering trophic dynamics is necessary to understand spatiotemporal variability in boreal forest C budgets. We propose a research agenda to scale local studies to landscape extents to measure the zoogeochemical impacts of large herbivores on boreal forest C cycling. Distributed networks of exclosure experiments, empirical studies across gradients in large herbivore abundance, multiscale models using herbivore distribution data, and remote sensing paired with empirical data will provide comprehensive accounting of C source-sink dynamics in boreal forests.
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Affiliation(s)
- Shawn J Leroux
- Department of Biology, Memorial University of Newfoundland, St John's, NL A1B 3X9, Canada.
| | - Yolanda F Wiersma
- Department of Biology, Memorial University of Newfoundland, St John's, NL A1B 3X9, Canada
| | - Eric Vander Wal
- Department of Biology, Memorial University of Newfoundland, St John's, NL A1B 3X9, Canada
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25
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Kartzinel TR, Pringle RM. Multiple dimensions of dietary diversity in large mammalian herbivores. J Anim Ecol 2020; 89:1482-1496. [PMID: 32163591 DOI: 10.1111/1365-2656.13206] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 01/31/2020] [Indexed: 12/01/2022]
Abstract
Theory predicts that trophic specialization (i.e. low dietary diversity) should make consumer populations sensitive to environmental disturbances. Yet diagnosing specialization is complicated both by the difficulty of precisely quantifying diet composition and by definitional ambiguity: what makes a diet 'diverse'? We sought to characterize the relationship between taxonomic dietary diversity (TDD) and phylogenetic dietary diversity (PDD) in a species-rich community of large mammalian herbivores in a semi-arid East African savanna. We hypothesized that TDD and PDD would be positively correlated within and among species, because taxonomically diverse diets are likely to include plants from many lineages. By using DNA metabarcoding to analyse 1,281 faecal samples collected across multiple seasons, we compiled high-resolution diet profiles for 25 sympatric large-herbivore species. For each of these populations, we calculated TDD and PDD with reference to a DNA reference library for local plants. Contrary to our hypothesis, measures of TDD and PDD were either uncorrelated or negatively correlated with each other. Thus, these metrics reflect distinct dimensions of dietary specialization both within and among species. In general, grazers and ruminants exhibited greater TDD, but lower PDD, than did browsers and non-ruminants. We found significant seasonal variation in TDD and/or PDD for all but four species (Grevy's zebra, buffalo, elephant, Grant's gazelle); however, the relationship between TDD and PDD was consistent across seasons for all but one of the 12 best-sampled species (plains zebra). Our results show that taxonomic generalists can be phylogenetic specialists, and vice versa. These two dimensions of dietary diversity suggest contrasting implications for efforts to predict how consumers will respond to climate change and other environmental perturbations. For example, populations with low TDD may be sensitive to phylogenetically 'random' losses of food species, whereas populations with low PDD may be comparatively more sensitive to environmental changes that disadvantage entire plant lineages-and populations with low dietary diversity in both taxonomic and phylogenetic dimensions may be most vulnerable of all.
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Affiliation(s)
- Tyler R Kartzinel
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA
| | - Robert M Pringle
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
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26
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Guyton JA, Pansu J, Hutchinson MC, Kartzinel TR, Potter AB, Coverdale TC, Daskin JH, da Conceição AG, Peel MJS, Stalmans ME, Pringle RM. Trophic rewilding revives biotic resistance to shrub invasion. Nat Ecol Evol 2020; 4:712-724. [PMID: 31932702 DOI: 10.1038/s41559-019-1068-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 11/20/2019] [Indexed: 11/09/2022]
Abstract
Trophic rewilding seeks to rehabilitate degraded ecosystems by repopulating them with large animals, thereby re-establishing strong top-down interactions. Yet there are very few tests of whether such initiatives can restore ecosystem structure and functions, and on what timescales. Here we show that war-induced collapse of large-mammal populations in Mozambique's Gorongosa National Park exacerbated woody encroachment by the invasive shrub Mimosa pigra-considered one of the world's 100 worst invasive species-and that one decade of concerted trophic rewilding restored this invasion to pre-war baseline levels. Mimosa occurrence increased between 1972 and 2015, a period encompassing the near extirpation of large herbivores during the Mozambican Civil War. From 2015 to 2019, mimosa abundance declined as ungulate biomass recovered. DNA metabarcoding revealed that ruminant herbivores fed heavily on mimosa, and experimental exclosures confirmed the causal role of mammalian herbivory in containing shrub encroachment. Our results provide mechanistic evidence that trophic rewilding has rapidly revived a key ecosystem function (biotic resistance to a notorious woody invader), underscoring the potential for restoring ecological health in degraded protected areas.
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Affiliation(s)
- Jennifer A Guyton
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Johan Pansu
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Station Biologique de Roscoff, UMR 7144 CNRS-Sorbonne Université, Roscoff, France.,CSIRO Ocean & Atmosphere, Lucas Heights, New South Wales, Australia
| | - Matthew C Hutchinson
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Tyler R Kartzinel
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Department of Ecology & Evolutionary Biology, Brown University, Providence, RI, USA
| | - Arjun B Potter
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Tyler C Coverdale
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Department of Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Joshua H Daskin
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
| | | | - Mike J S Peel
- ARC-Animal Production Institute, Rangeland Ecology Group, Nelspruit, South Africa
| | - Marc E Stalmans
- Department of Scientific Services, Parque Nacional da Gorongosa, Sofala, Mozambique
| | - Robert M Pringle
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ, USA. .,Department of Scientific Services, Parque Nacional da Gorongosa, Sofala, Mozambique.
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27
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Coverdale TC. Defence emergence during early ontogeny reveals important differences between spines, thorns and prickles. ANNALS OF BOTANY 2020; 124:iii-iv. [PMID: 31904092 PMCID: PMC6943688 DOI: 10.1093/aob/mcz189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- Tyler C Coverdale
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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28
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O'Connor RC, Taylor JH, Nippert JB. Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland. Ecology 2019; 101:e02935. [PMID: 31746458 DOI: 10.1002/ecy.2935] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 09/20/2019] [Accepted: 10/18/2019] [Indexed: 11/12/2022]
Abstract
North American grasslands have experienced increased relative abundance of shrubs and trees over the last 150 yr. Alterations in herbivore composition, abundance, and grazing pressure along with changes in fire frequency are drivers that can regulate the transition from grassland to shrubland or woodland (a process known as woody encroachment). Historically, North American grasslands had a suite of large herbivores that grazed and/or browsed (i.e., bison, elk, pronghorn, deer), as well as frequent and intense fires. In the tallgrass prairie, many large native ungulates were extirpated by the 1860s, corresponding with increased homesteading (which led to decreased fire frequencies and intensities). Changes in the frequency and intensity of these two drivers (browsing and fire) have coincided with woody encroachment in tallgrass prairie. Within tallgrass prairie, woody encroachment can be categorized in to two groups: non-resprouting species that can be killed with fire and resprouting species that cannot be killed with fire. Resprouting species require additional active management strategies to decrease abundance and eventually be removed from the ecosystem. In this study, we investigated plant cover, ramet density, and physiological effects of continuous simulated browsing and prescribed fire on Cornus drummondii C.A. Mey, a resprouting clonal native shrub species. Browsing reduced C. drummondii canopy cover and increased grass cover. We also observed decreased ramet density, which allowed for more infilling of grasses. Photosynthetic rates between browsed and unbrowsed control shrubs did not increase in 2015 or 2016. In 2017, photosynthetic rates for browsed shrubs were higher in the unburned site than the unbrowsed control shrubs at the end of the growing season. Additionally, after the prescribed fire, browsed shrubs had ~90% decreased cover, ~50% reduced ramet density, and grass cover increased by ~80%. In the roots of browsed shrubs after the prescribed fire, nonstructural carbohydrates (NSC) experienced a twofold reduction in glucose and a threefold reduction in both sucrose and starch. The combined effects of browsing and fire show strong potential as a successful management tool to decrease the abundance of clonal-resprouting woody plants in mesic grasslands and illustrate the potential significance of browsers as a key driver in this ecosystem.
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Affiliation(s)
- Rory C O'Connor
- Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA.,O'Connor Rangeland Science, 970 South Lusk Street, Boise, Idaho, 83706, USA
| | - Jeffrey H Taylor
- Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA
| | - Jesse B Nippert
- Division of Biology, Kansas State University, Manhattan, Kansas, 66506, USA
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Abstract
Diet and gut microbiome composition are important for health and nutrition in mammals, but how they covary in response to environmental change remains poorly understood—both because diet composition is rarely quantified precisely, and because studies of diet−microbiome linkages in captive animals may not accurately reflect the dynamics of natural communities. By analyzing diet−microbiome linkages in an assemblage of large mammalian herbivores in Kenya, we found that seasonal changes in diet and microbiome composition were strongly correlated within some populations, whereas other populations exhibited little temporal turnover in either diet or microbiome. Identifying mechanisms that generate species-specific variation in the sensitivity of the diet−microbiome nexus to environmental changes could help to explain differential population performance and food-web structure within ecological communities. A major challenge in biology is to understand how phylogeny, diet, and environment shape the mammalian gut microbiome. Yet most studies of nonhuman microbiomes have relied on relatively coarse dietary categorizations and have focused either on individual wild populations or on captive animals that are sheltered from environmental pressures, which may obscure the effects of dietary and environmental variation on microbiome composition in diverse natural communities. We analyzed plant and bacterial DNA in fecal samples from an assemblage of 33 sympatric large-herbivore species (27 native, 6 domesticated) in a semiarid East African savanna, which enabled high-resolution assessment of seasonal variation in both diet and microbiome composition. Phylogenetic relatedness strongly predicted microbiome composition (r = 0.91) and was weakly but significantly correlated with diet composition (r = 0.20). Dietary diversity did not significantly predict microbiome diversity across species or within any species except kudu; however, diet composition was significantly correlated with microbiome composition both across and within most species. We found a spectrum of seasonal sensitivity at the diet−microbiome nexus: Seasonal changes in diet composition explained 25% of seasonal variation in microbiome composition across species. Species’ positions on (and deviations from) this spectrum were not obviously driven by phylogeny, body size, digestive strategy, or diet composition; however, domesticated species tended to exhibit greater diet−microbiome turnover than wildlife. Our results reveal marked differences in the influence of environment on the degree of diet−microbiome covariation in free-ranging African megafauna, and this variation is not well explained by canonical predictors of nutritional ecology.
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30
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Forbes ES, Cushman JH, Burkepile DE, Young TP, Klope M, Young HS. Synthesizing the effects of large, wild herbivore exclusion on ecosystem function. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13376] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elizabeth S. Forbes
- Department of Ecology, Evolution, and Marine Biology University of California, Santa Barbara Santa Barbara California
| | - J. Hall Cushman
- Department of Natural Resources and Environmental Science University of Nevada – Reno Reno Nevada
| | - Deron E. Burkepile
- Department of Ecology, Evolution, and Marine Biology University of California, Santa Barbara Santa Barbara California
| | - Truman P. Young
- Department of Plant Sciences University of California, Davis Davis California
| | - Maggie Klope
- Department of Ecology, Evolution, and Marine Biology University of California, Santa Barbara Santa Barbara California
| | - Hillary S. Young
- Department of Ecology, Evolution, and Marine Biology University of California, Santa Barbara Santa Barbara California
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31
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Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages. JOURNAL OF TROPICAL ECOLOGY 2019. [DOI: 10.1017/s0266467419000142] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.
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32
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Gill BA, Musili PM, Kurukura S, Hassan AA, Goheen JR, Kress WJ, Kuzmina M, Pringle RM, Kartzinel TR. Plant DNA‐barcode library and community phylogeny for a semi‐arid East African savanna. Mol Ecol Resour 2019; 19:838-846. [DOI: 10.1111/1755-0998.13001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 11/26/2022]
Affiliation(s)
- Brian A. Gill
- Institute for Environment and Society Brown University Providence Rhode Island
| | - Paul M. Musili
- East African Herbarium National Museums of Kenya Nairobi Kenya
| | | | | | - Jacob R. Goheen
- Departments of Zoology and Physiology University of Wyoming Laramie Wyoming
| | - W. John Kress
- National Museum of Natural History Smithsonian Institution Washington District of Columbia
| | - Maria Kuzmina
- Center for Biodiversity Genomics University of Guelph Guelph Ontario Canada
| | - Robert M. Pringle
- Department of Ecology and Evolutionary Biology Princeton University Princeton New Jersey
| | - Tyler R. Kartzinel
- Institute for Environment and Society Brown University Providence Rhode Island
- Department of Ecology and Evolutionary Biology Brown University Providence Rhode Island
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33
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Schmitz OJ, Wilmers CC, Leroux SJ, Doughty CE, Atwood TB, Galetti M, Davies AB, Goetz SJ. Animals and the zoogeochemistry of the carbon cycle. Science 2018; 362:362/6419/eaar3213. [DOI: 10.1126/science.aar3213] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Predicting and managing the global carbon cycle requires scientific understanding of ecosystem processes that control carbon uptake and storage. It is generally assumed that carbon cycling is sufficiently characterized in terms of uptake and exchange between ecosystem plant and soil pools and the atmosphere. We show that animals also play an important role by mediating carbon exchange between ecosystems and the atmosphere, at times turning ecosystem carbon sources into sinks, or vice versa. Animals also move across landscapes, creating a dynamism that shapes landscape-scale variation in carbon exchange and storage. Predicting and measuring carbon cycling under such dynamism is an important scientific challenge. We explain how to link analyses of spatial ecosystem functioning, animal movement, and remote sensing of animal habitats with carbon dynamics across landscapes.
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34
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Coverdale TC, Goheen JR, Palmer TM, Pringle RM. Good neighbors make good defenses: associational refuges reduce defense investment in African savanna plants. Ecology 2018; 99:1724-1736. [DOI: 10.1002/ecy.2397] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/11/2018] [Accepted: 05/21/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Tyler C. Coverdale
- Department of Ecology and Evolutionary Biology Princeton University Princeton New Jersey 08544 USA
| | - Jacob R. Goheen
- Department of Zoology & Physiology University of Wyoming Laramie Wyoming 82071 USA
| | - Todd M. Palmer
- Department of Biology University of Florida Gainesville Florida 32611 USA
| | - Robert M. Pringle
- Department of Ecology and Evolutionary Biology Princeton University Princeton New Jersey 08544 USA
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