1
|
Zwolak R, Clement D, Sih A, Schreiber SJ. Granivore abundance shapes mutualism quality in plant-scatterhoarder interactions. THE NEW PHYTOLOGIST 2024; 241:1840-1850. [PMID: 38044708 DOI: 10.1111/nph.19443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 11/08/2023] [Indexed: 12/05/2023]
Abstract
Conditional mutualisms involve costs and benefits that vary with environmental factors, but mechanisms driving these dynamics remain poorly understood. Scatterhoarder-plant interactions are a prime example of this phenomenon, as scatterhoarders can either increase or reduce plant recruitment depending on the balance between seed dispersal and predation. We explored factors that drive the magnitude of net benefits for plants in this interaction using a mathematical model, with parameter values based on European beech (Fagus sylvatica) and yellow-necked mice (Apodemus flavicollis). We measured benefits as the percentage of germinating seeds, and examined how varying rodent survival (reflecting, e.g. changes in predation pressure), the rate of seed loss to other granivores, the abundance of alternative food resources, and changes in masting patterns affect the quality of mutualism. We found that increasing granivore abundance can degrade the quality of plant-scatterhoarder mutualism due to increased cache pilferage. Scatterhoarders are predicted to respond by increasing immediate consumption of gathered seeds, leading to higher costs and reduced benefits for plants. Thus, biotic changes that are detrimental to rodent populations can be beneficial for tree recruitment due to adaptive behavior of rodents. When scatterhoarder populations decline too drastically (< 5 individuals ha-1 ); however, tree recruitment may also suffer.
Collapse
Affiliation(s)
- Rafał Zwolak
- Department of Systematic Zoology, Institute of Environmental Biology, Adam Mickiewicz University, Umultowska 89, Poznań, 61-614, Poland
| | - Dale Clement
- School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Andrew Sih
- Center of Population Biology, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Sebastian J Schreiber
- Center of Population Biology, University of California, One Shields Avenue, Davis, CA, 95616, USA
| |
Collapse
|
2
|
Kamaru DN, Palmer TM, Riginos C, Ford AT, Belnap J, Chira RM, Githaiga JM, Gituku BC, Hays BR, Kavwele CM, Kibungei AK, Lamb CT, Maiyo NJ, Milligan PD, Mutisya S, Ng'weno CC, Ogutu M, Pietrek AG, Wildt BT, Goheen JR. Disruption of an ant-plant mutualism shapes interactions between lions and their primary prey. Science 2024; 383:433-438. [PMID: 38271503 DOI: 10.1126/science.adg1464] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 12/01/2023] [Indexed: 01/27/2024]
Abstract
Mutualisms often define ecosystems, but they are susceptible to human activities. Combining experiments, animal tracking, and mortality investigations, we show that the invasive big-headed ant (Pheidole megacephala) makes lions (Panthera leo) less effective at killing their primary prey, plains zebra (Equus quagga). Big-headed ants disrupted the mutualism between native ants (Crematogaster spp.) and the dominant whistling-thorn tree (Vachellia drepanolobium), rendering trees vulnerable to elephant (Loxodonta africana) browsing and resulting in landscapes with higher visibility. Although zebra kills were significantly less likely to occur in higher-visibility, invaded areas, lion numbers did not decline since the onset of the invasion, likely because of prey-switching to African buffalo (Syncerus caffer). We show that by controlling biophysical structure across landscapes, a tiny invader reconfigured predator-prey dynamics among iconic species.
Collapse
Affiliation(s)
- Douglas N Kamaru
- Department of Zoology & Physiology and Program in Ecology & Evolution, University of Wyoming, Laramie, WY, USA
- Ol Pejeta Conservancy, Private Bag 10400, Nanyuki, Kenya
| | - Todd M Palmer
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Corinna Riginos
- Department of Zoology & Physiology and Program in Ecology & Evolution, University of Wyoming, Laramie, WY, USA
- The Nature Conservancy, Lander, WY, USA
| | - Adam T Ford
- Department of Biology, University of British Columbia, Kelowna, BC, Canada
| | - Jayne Belnap
- Southwest Biological Science Center, US Geological Survey, Moab, UT, USA
| | - Robert M Chira
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - John M Githaiga
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | | | - Brandon R Hays
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Cyrus M Kavwele
- School of Mathematics & Statistics and School of Biodiversity, University of Glasgow, Glasgow, Scotland
- School of Natural Resources, Karatina University, Nyeri, Kenya
| | | | - Clayton T Lamb
- Department of Biology, University of British Columbia, Kelowna, BC, Canada
| | - Nelly J Maiyo
- Ol Pejeta Conservancy, Private Bag 10400, Nanyuki, Kenya
| | - Patrick D Milligan
- Ol Pejeta Conservancy, Private Bag 10400, Nanyuki, Kenya
- Department of Biology, University of Nevada, Reno, NV, USA
| | - Samuel Mutisya
- Ol Pejeta Conservancy, Private Bag 10400, Nanyuki, Kenya
| | | | - Michael Ogutu
- Ol Pejeta Conservancy, Private Bag 10400, Nanyuki, Kenya
| | - Alejandro G Pietrek
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Salta, Argentina
| | - Brendon T Wildt
- Department of Zoology & Physiology and Program in Ecology & Evolution, University of Wyoming, Laramie, WY, USA
| | - Jacob R Goheen
- Department of Zoology & Physiology and Program in Ecology & Evolution, University of Wyoming, Laramie, WY, USA
| |
Collapse
|