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Lynch SC, Savage AM. The changing dynamics of ant-tree cholla mutualisms along a desert urbanization gradient. PLoS One 2023; 18:e0280130. [PMID: 37000864 PMCID: PMC10065256 DOI: 10.1371/journal.pone.0280130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 12/21/2022] [Indexed: 04/03/2023] Open
Abstract
Urbanization, among the most widespread and multifaceted anthropogenic change drivers, exerts strong influences on a diversity of ecological communities worldwide. We have begun to understand how urbanization affects species diversity, yet we still have limited knowledge about the ways that species interactions are altered by urbanization. We have an especially poor understanding of how urbanization influences stress-buffering mutualisms, despite the high levels of multivariate stress that urban organisms must overcome and the importance of these interactions to the fitness of many organisms. In this study, we investigated the effects of urbanization on a mutualism between tree cholla cacti (Cylindropuntia imbricata) and visiting ants. We first examined how plant size, ant species composition, and ant activity varied on C. imbricata across an urbanization gradient (urban, suburban, wild) in and around Albuquerque, NM. Ant species composition and activity varied significantly across the urbanization gradient, with ant communities from wildlands having the highest activity and the most dissimilar species composition compared to both suburban and urban sites. In contrast, plant size remained constant regardless of site type. We then experimentally assessed how nectar levels influenced ant aggressive encounters with proxy prey (Drosophila melanogaster larvae) on C. imbricata across urban and wild sites. Ants were more likely to discover, attack, and remove proxy prey in wild sites compared to urban sites; they also performed these behaviors more quickly in wild sites. Nectar supplementation had weaker effects on ant aggression than urbanization, but consistently increased the speed at which aggressive behaviors occurred. Future studies that examine nectar quality and herbivorous arthropod abundance may help explain why this strong difference in ant composition and aggression was not associated with lower plant fitness proxies (i.e. size traits). Nevertheless, this study provides unique insight into the growing body of work demonstrating that mutualisms vary significantly across urbanization gradients.
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Affiliation(s)
- Shannon C. Lynch
- Rutgers University Camden, Camden, NJ, United States of America
- * E-mail:
| | - Amy M. Savage
- Rutgers University Camden, Camden, NJ, United States of America
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Mooney E, Mitchell A, Den Uyl J, Mullins M, DiBiase C, Heschel MS. Host plant phenology shapes aphid abundance and interactions with ants. OIKOS 2022. [DOI: 10.1111/oik.09109] [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)
- Emily Mooney
- Univ. of Colorado Colorado Springs Colorado SpringsParis CO USA
| | | | - James Den Uyl
- Univ. of Colorado Colorado Springs Colorado SpringsParis CO USA
- Rocky Mountain Biological Laboratory Crested Butte CO USA
| | - Maria Mullins
- Univ. of Colorado Colorado Springs Colorado SpringsParis CO USA
- Rocky Mountain Biological Laboratory Crested Butte CO USA
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Affiliation(s)
- Sandra Siegfried
- Institut für Epidemiologie, Biostatistik und Prävention Universität Zürich Zürich Switzerland
| | - Torsten Hothorn
- Institut für Epidemiologie, Biostatistik und Prävention Universität Zürich Zürich Switzerland
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Rocha EA, Fellowes MDE. Urbanisation alters ecological interactions: Ant mutualists increase and specialist insect predators decrease on an urban gradient. Sci Rep 2020; 10:6406. [PMID: 32286349 PMCID: PMC7156700 DOI: 10.1038/s41598-020-62422-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/12/2020] [Indexed: 11/09/2022] Open
Abstract
The modification of habitats in urban areas is thought to alter patterns of species interactions, by filtering specialist species and those at higher trophic levels. However, empirical studies addressing these hypotheses remain limited in scope and number. This work investigates (1) how main urban land uses affect predator-prey and mutualistic interactions, and (2) how specialist and generalist predators respond to size and availability of urban green spaces. In a large town in the UK, experimental colonies of ant-attended Black bean aphid Aphis fabae and non-ant-attended Pea aphid Acyrthosiphon pisum were monitored over two years. Ants were more frequently found in highly urbanised sites; however mutualistic ants were also more often encountered when the habitat was more plant diverse. Aphids were not affected by urban land uses, but A. fabae numbers were positively related to the presence of mutualists, and so indirectly affected by urbanisation. Predators were the only group negatively affected by increased urbanisation, and specialist species were positively related to increased proportion of urban green areas within the habitats. While this work supports the hypothesis that specialist predators are negatively affected by urbanisation, we also show that a fundamental ecological interaction, mutualism, is affected by urbanisation.
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Affiliation(s)
- Elise A Rocha
- People and Wildlife Research Group, School of Biological Sciences, University of Reading, Whiteknights, Reading, Berkshire, RG6 6AS, UK.
| | - Mark D E Fellowes
- People and Wildlife Research Group, School of Biological Sciences, University of Reading, Whiteknights, Reading, Berkshire, RG6 6AS, UK.
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5
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Kulikowski AJ. Ant–scale mutualism increases scale infestation, decreases folivory, and disrupts biological control in restored tropical forests. Biotropica 2020. [DOI: 10.1111/btp.12786] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Andy J. Kulikowski
- Department of Environmental Studies University of California Santa Cruz Santa Cruz CA USA
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Chomicki G, Weber M, Antonelli A, Bascompte J, Kiers ET. The Impact of Mutualisms on Species Richness. Trends Ecol Evol 2019; 34:698-711. [DOI: 10.1016/j.tree.2019.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/11/2019] [Accepted: 03/18/2019] [Indexed: 11/28/2022]
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Nelson AS, Symanski CT, Hecking MJ, Mooney KA. Elevational cline in herbivore abundance driven by a monotonic increase in trophic-level sensitivity to aridity. J Anim Ecol 2019; 88:1406-1416. [PMID: 31135959 DOI: 10.1111/1365-2656.13034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/01/2019] [Indexed: 11/30/2022]
Abstract
The abiotic environment drives species abundances and distributions both directly and indirectly through effects on multi-trophic species interactions. However, few studies have documented the individual and combined consequences of these direct and indirect effects. We studied an ant-tended aphid along an elevational gradient, where lower elevations were more arid. Hypotheses of stronger species interactions at lower elevations and a greater sensitivity of higher trophic levels to climate led us to predict increased top-down control of aphids by natural enemies (third trophic level) but even stronger protection from mutualist ants (fourth trophic level) with increasing aridity. As a result, we predicted that mutualism strength and aphid abundance would increase with aridity. We documented patterns of aphid abundance and tested for both the direct and multi-trophic indirect effects of aridity on aphid performance. To do so, we used both observational and manipulative methods across two years in replicate high- and low-elevation valleys, where summer temperatures decreased by 3.7°C and precipitation increased by 27 mm/mo from low to high elevations. Aphid colonies were 75% larger in the most (vs. least) arid sites, and this was best explained by changes in interactions with predators and ants. Aphids were unaffected by the direct effects of the abiotic environment or its indirect effects via host plant quality. In contrast, natural enemy effects increased with aridity; under ant exclusion, natural enemies had no effect on aphids in the least arid sites but depressed colony growth by 252% in the most arid sites. Ant activity also increased with aridity, with ants discovering more aphid colonies and experimental baits and allocating more foragers per aphid, although there was no effect of aridity on ant abundance or community composition. Correspondingly, the mutualist services provided by ants increased with aridity; ants provided no benefits to aphids in the least arid sites but doubled colony growth in the most arid sites. In summary, an elevational cline in herbivore abundance was driven by a monotonic increase in trophic-level sensitivity to aridity. These findings illustrate that predicting species responses to climate change will require a multi-trophic perspective.
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Affiliation(s)
- Annika S Nelson
- Department of Ecology and Evolutionary Biology, University of California at Irvine, Riverside, California.,Rocky Mountain Biological Laboratory, Crested Butte, Colorado
| | - Cole T Symanski
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado.,Department of Entomology, University of California at Riverside, Riverside, California
| | - Matthew J Hecking
- Rocky Mountain Biological Laboratory, Crested Butte, Colorado.,School of Natural Sciences, Hampshire College, Amherst, Massachusetts
| | - Kailen A Mooney
- Department of Ecology and Evolutionary Biology, University of California at Irvine, Riverside, California.,Rocky Mountain Biological Laboratory, Crested Butte, Colorado
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Nelson AS, Carvajal Acosta N, Mooney KA. Plant chemical mediation of ant behavior. CURRENT OPINION IN INSECT SCIENCE 2019; 32:98-103. [PMID: 31113639 DOI: 10.1016/j.cois.2018.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 10/23/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Ants are ecologically dominant members of terrestrial communities. Ant foraging is often strongly associated with plants and depends upon associative learning of chemicals in the environment. As a result, plant chemicals can affect ant behaviors and, in so doing, have strong multi-trophic indirect effects. Plant chemicals mediate ant behaviors in the contexts of floral visitation, seed dispersal and predation, leaf cutting, interactions with ant-mutualist host plants, interactions with mutualist and prey insects in plant canopies, and plant predation of ants by carnivorous plants. Here, we review what is known about these differing contexts in which plant chemicals influence ant behavior, the mechanisms by which ants are affected by plant chemicals, and future directions within these topics.
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Affiliation(s)
- Annika S Nelson
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States; Rocky Mountain Biological Laboratory, PO Box 319, Crested Butte, CO 81224, United States
| | - Nalleli Carvajal Acosta
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States
| | - Kailen A Mooney
- Department of Ecology and Evolutionary Biology, University of California at Irvine, 321 Steinhaus Hall, Irvine, CA 92697, United States; Rocky Mountain Biological Laboratory, PO Box 319, Crested Butte, CO 81224, United States.
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Nelson AS, Pratt RT, Pratt JD, Smith RA, Symanski CT, Prenot C, Mooney KA. Progressive sensitivity of trophic levels to warming underlies an elevational gradient in ant–aphid mutualism strength. OIKOS 2018. [DOI: 10.1111/oik.05650] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Annika S. Nelson
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Dept of Ecology and Evolutionary Biology, Univ. of California at Irvine, 321 Steinhaus Hall Irvine CA 92697 USA
| | - Riley T. Pratt
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- California State Parks San Clemente CA USA
| | - Jessica D. Pratt
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Dept of Ecology and Evolutionary Biology, Univ. of California at Irvine, 321 Steinhaus Hall Irvine CA 92697 USA
| | - Richard Alexander Smith
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Dept of Computational Medicine and Bioinformatics, Univ. of Michigan Ann Arbor MI USA
| | - Cole T. Symanski
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Dept of Entomology, Univ. of California at Riverside Riverside CA USA
| | - Cathrine Prenot
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Estacado High School Lubbock TX USA
| | - Kailen A. Mooney
- Rocky Mountain Biological Laboratory, PO Box 319 Crested Butte CO 81224 USA
- Dept of Ecology and Evolutionary Biology, Univ. of California at Irvine, 321 Steinhaus Hall Irvine CA 92697 USA
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Humphrey PT, Gloss AD, Frazier J, Nelson-Dittrich AC, Faries S, Whiteman NK. Heritable plant phenotypes track light and herbivory levels at fine spatial scales. Oecologia 2018; 187:427-445. [PMID: 29603095 PMCID: PMC5999565 DOI: 10.1007/s00442-018-4116-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 03/11/2018] [Indexed: 02/03/2023]
Abstract
Organismal phenotypes often co-vary with environmental variables across broad geographic ranges. Less is known about the extent to which phenotypes match local conditions when multiple biotic and abiotic stressors vary at fine spatial scales. Bittercress (Brassicaceae: Cardamine cordifolia), a perennial forb, grows across a microgeographic mosaic of two contrasting herbivory regimes: high herbivory in meadows (sun habitats) and low herbivory in deeply shaded forest understories (shade habitats). We tested for local phenotypic differentiation in plant size, leaf morphology, and anti-herbivore defense (realized resistance and defensive chemicals, i.e., glucosinolates) across this habitat mosaic through reciprocal transplant-common garden experiments with clonally propagated rhizomes. We found habitat-specific divergence in morphological and defensive phenotypes that manifested as contrasting responses to growth in shade common gardens: weak petiole elongation and attenuated defenses in populations from shade habitats, and strong petiole elongation and elevated defenses in populations from sun habitats. These divergent phenotypes are generally consistent with reciprocal local adaptation: plants from shade habitats that naturally experience low herbivory show reduced investment in defense and an attenuated shade avoidance response, owing to its ineffectiveness within forest understories. By contrast, plants from sun habitats with high herbivory show shade-induced elongation, but no evidence of attenuated defenses canonically associated with elongation in shade-intolerant plant species. Finally, we observed differences in flowering phenology between habitat types that could potentially contribute to inter-habitat divergence by reducing gene flow. This study illuminates how clonally heritable plant phenotypes track a fine-grained mosaic of herbivore pressure and light availability in a native plant.
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Affiliation(s)
- P T Humphrey
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Rocky Mountain Biological Laboratory, Gothic, CO, 81224, USA
| | - A D Gloss
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Rocky Mountain Biological Laboratory, Gothic, CO, 81224, USA
| | - J Frazier
- Rocky Mountain Biological Laboratory, Gothic, CO, 81224, USA
| | - A C Nelson-Dittrich
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - S Faries
- Rocky Mountain Biological Laboratory, Gothic, CO, 81224, USA
| | - N K Whiteman
- Rocky Mountain Biological Laboratory, Gothic, CO, 81224, USA.
- Department of Integrative Biology, University of California, Berkeley, CA, 91645, USA.
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11
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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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12
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Robinson A, Inouye DW, Ogilvie JE, Mooney EH. Multitrophic interactions mediate the effects of climate change on herbivore abundance. Oecologia 2017; 185:181-190. [DOI: 10.1007/s00442-017-3934-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/13/2017] [Indexed: 01/07/2023]
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Karban R, Grof-Tisza P, Holyoak M. Wet years have more caterpillars: interacting roles of plant litter and predation by ants. Ecology 2017; 98:2370-2378. [PMID: 28590554 DOI: 10.1002/ecy.1917] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 05/18/2017] [Accepted: 05/24/2017] [Indexed: 11/12/2022]
Abstract
Climate is widely recognized as an important factor that affects temporal and spatial patterns of occurrence and abundance of herbivorous insects, although the ecological mechanisms responsible are poorly understood. We found that precipitation and standing water were positively correlated with locations and years of high abundance of caterpillars of the ranchman's tiger moth, Platyprepia virginalis. We analyzed 30 years of survey data and found that the number of large rainfall events was a better predictor of caterpillar abundance than total annual accumulation. We considered three ecological mechanisms that could drive this relationship and conducted observations and manipulative experiments to evaluate these mechanisms. (1) Rainfall facilitates more plant growth, although we found no evidence that increased food quality or quantity was causing the positive association between precipitation and caterpillar abundance. (2) Large rainfall events cause predatory ground-nesting ants to be less abundant and we found that the number of ants that recruited to local sites was negatively associated with survival and abundance of caterpillars. (3) We found that litter from wet sites provided a refuge from ant predation; litter from wet sites was not beneficial to caterpillars in the absence of ants. Both abiotic factors (precipitation) and biotic factors (predatory ants) affected the temporal and spatial abundance of caterpillars directly and interactively. Climate models predict that rainfall will become more variable, suggesting that populations of this caterpillar may also become more variable in the future.
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Affiliation(s)
- Richard Karban
- Department of Entomology and Nematology, University of California, Davis, California, 95616, USA
| | - Patrick Grof-Tisza
- Department of Entomology and Nematology, University of California, Davis, California, 95616, USA
| | - Marcel Holyoak
- Department of Environmental Science and Policy, University of California, Davis, California, 95616, USA
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Defensive Symbionts Mediate Host–Parasite Interactions at Multiple Scales. Trends Parasitol 2017; 33:53-64. [DOI: 10.1016/j.pt.2016.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 01/22/2023]
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