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Where is the extended phenotype in the wild? The community composition of arthropods on mature oak trees does not depend on the oak genotype. PLoS One 2015; 10:e0115733. [PMID: 25635387 PMCID: PMC4321774 DOI: 10.1371/journal.pone.0115733] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 12/01/2014] [Indexed: 12/03/2022] Open
Abstract
Through a series of common garden experiments, it has been shown that heritable
phenotypic differences between individual trees can affect arthropod communities.
However, field studies under heterogeneous environmental conditions remain rare. In
the present study, we investigated the genetic constitution of 121 mature oak host
trees at different trophic levels from 10 sites across Bavaria, southern Germany and
their associated insect communities. A total of 23,576 individuals representing 395
species of beetles and true bugs were evaluated. In particular, we determined whether
the composition of arthropod communities is related to the oak genotype and whether
the strength of the relationships decreases from lower to higher trophic levels, such
as for phytophagous, xylophagous, zoophagous, and mycetophagous species. The genetic
differentiation of oaks was assessed using eight microsatellite markers. We found no
significant influence of the oak genotype on neither the full beetle and true bug
community nor on any of the analyzed trophic guilds. In contrast, the community
composition of the insects was highly related to the space and climate, such that the
community similarity decreased with increases in spatial distance and climatic
differences. The relationship with space and climate was much stronger in beetles
than in true bugs, particularly in mycetophagous species. Our results suggest that
spatial processes override the genetic effects of the host plant in structuring
arthropod communities on oak trees. Because we used neutral markers, we cannot
exclude the possibility that trait-specific markers may reveal a genetic imprint of
the foundation tree species on the composition of the arthropod community. However,
based on the strength of the spatial patterns in our data set, we assume that genetic
differences among oaks are less important in the structuring of arthropod
communities. Future whole-genome studies are required to draw a final conclusion.
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Wojtowicz T, Compson ZG, Lamit LJ, Whitham TG, Gehring CA. Plant genetic identity of foundation tree species and their hybrids affects a litter-dwelling generalist predator. Oecologia 2014; 176:799-810. [PMID: 25205028 DOI: 10.1007/s00442-014-2998-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 06/09/2014] [Indexed: 12/01/2022]
Abstract
The effects of plant genetics on predators, especially those not living on the plant itself, are rarely studied and poorly understood. Therefore, we investigated the effect of plant hybridization and genotype on litter-dwelling spiders. Using an 18-year-old cottonwood common garden, we recorded agelenid sheet-web density associated with the litter layers of replicated genotypes of three tree cross types: Populus fremontii, Populus angustifolia, and their F1 hybrids. We surveyed 118 trees for agelenid litter webs at two distances from the trees (0-100 and 100-200 cm from trunk) and measured litter depth as a potential mechanism of web density patterns. Five major results emerged: web density within a 1-m radius of P. angustifolia was approximately three times higher than within a 1-m radius of P. fremontii, with F1 hybrids having intermediate densities; web density responded to P. angustifolia and F1 hybrid genotypes as indicated by a significant genotype × distance interaction, with some genotypes exhibiting a strong decline in web density with distance, while others did not; P. angustifolia litter layers were deeper than those of P. fremontii at both distance classes, and litter depth among P. angustifolia genotypes differed up to 300%; cross type and genotype influenced web density via their effects on litter depth, and these effects were influenced by distance; web density was more sensitive to the effects of tree cross type than genotype. By influencing generalist predators, plant hybridization and genotype may indirectly impact trophic interactions such as intraguild predation, possibly affecting trophic cascades and ecosystem processes.
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Affiliation(s)
- Todd Wojtowicz
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, 86011-5640, USA,
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Wimp GM, Wooley S, Bangert RK, Young WP, Martinsen GD, Keim P, Rehill B, Lindroth RL, Whitham TG. Plant genetics predicts intra-annual variation in phytochemistry and arthropod community structure. Mol Ecol 2007; 16:5057-69. [PMID: 17927708 DOI: 10.1111/j.1365-294x.2007.03544.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
With the emerging field of community genetics, it is important to quantify the key mechanisms that link genetics and community structure. We studied cottonwoods in common gardens and in natural stands and examined the potential for plant chemistry to be a primary mechanism linking plant genetics and arthropod communities. If plant chemistry drives the relationship between plant genetics and arthropod community structure, then several predictions followed. We would find (i) the strongest correlation between plant genetic composition and chemical composition; (ii) an intermediate correlation between plant chemical composition and arthropod community composition; and (iii) the weakest relationship between plant genetic composition and arthropod community composition. Our results supported our first prediction: plant genetics and chemistry had the strongest correlation in the common garden and the wild. Our results largely supported our second prediction, but varied across space, seasonally, and according to arthropod feeding group. Plant chemistry played a larger role in structuring common garden arthropod communities relative to wild communities, free-living arthropods relative to leaf and stem modifiers, and early-season relative to late-season arthropods. Our results did not support our last prediction, as host plant genetics was at least as tightly linked to arthropod community structure as plant chemistry, if not more so. Our results demonstrate the consistency of the relationship between plant genetics and biodiversity. Additionally, plant chemistry can be an important mechanism by which plant genetics affects arthropod community composition, but other genetic-based factors are likely involved that remain to be measured.
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Affiliation(s)
- G M Wimp
- Department of Biology, Georgetown University, Washington, DC 20057, USA.
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O'Reilly-Wapstra JM, Potts BM, McArthur C, Davies NW, Tilyard P. Inheritance Of Resistance To Mammalian Herbivores and Of Plant Defensive Chemistry In A Eucalyptus Species. J Chem Ecol 2005; 31:519-37. [PMID: 15898499 DOI: 10.1007/s10886-005-2030-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their F1 hybrids. We assessed browsing damage of three-year-old trees in a common environment field trial on four hybrid types of known progeny. The progency were artificial intra-race crosses and reciprocal inter-race F1 hybrids of two geographically distinct populations (races) of E. globulus; north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race F1 hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the F1 hybrids varied among groups of individual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race F1 hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing.
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Affiliation(s)
- Julianne M O'Reilly-Wapstra
- School of Zoology, CRC for Sustainable Production Forestry, University of Tasmania, Hobart, Tasmania, Australia.
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O'Reilly-Wapstra JM, Potts BM, McArthur C, Davies NW, Tilyard P. Inheritance Of Resistance to Mammalian Herbivores and of Plant Defensive Chemistry in an Eucalyptus Species. J Chem Ecol 2005; 31:357-75. [PMID: 15856789 DOI: 10.1007/s10886-005-1346-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their Fl hybrids. We assessed browsing damage of 3-year-old trees in a common environment field trial on four hybrid types of known progeny. The progeny were artificial intra-race crosses and reciprocal inter-race F1 hybrids of two geographically distinct populations (races) of E. globulus north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race Fl hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the Fl hybrids varied among major groups of individual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race Fl hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing.
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Affiliation(s)
- Julianne M O'Reilly-Wapstra
- School of Zoology, CRCfor Sustainable Production Forestry, University of Tasmania Private Bag 5, Hobart, Tasmania, Australia, 7001.
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Wimp GM, Martinsen GD, Floate KD, Bangert RK, Whitham TG. PLANT GENETIC DETERMINANTS OF ARTHROPOD COMMUNITY STRUCTURE AND DIVERSITY. Evolution 2005. [DOI: 10.1111/j.0014-3820.2005.tb00894.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wimp GM, Martinsen GD, Floate KD, Bangert RK, Whitham TG. PLANT GENETIC DETERMINANTS OF ARTHROPOD COMMUNITY STRUCTURE AND DIVERSITY. Evolution 2005. [DOI: 10.1554/04-018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fritz RS, Hochwender CG, Brunsfeld SJ, Roche BM. Genetic architecture of susceptibility to herbivores in hybrid willows. J Evol Biol 2003; 16:1115-26. [PMID: 14640403 DOI: 10.1046/j.1420-9101.2003.00617.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We performed a common garden experiment using parental, F1, F2, and backcross willow hybrids to test the hypothesis that hybrid willows experience breakdown of resistance to herbivores. After exposing plants to herbivores in the field, we measured the densities/damage caused by 13 insect herbivores and one herbivorous mite. Using joint-scaling tests, we determined the contribution of additive, dominance, and epistasis to variation in susceptibility to herbivores (measured either as density or damage level) among the six genetic classes. We found the genetic architecture of susceptibility/resistance in the parental species to be complex, involving additive, dominance, and epistasis for each herbivore species. Although genic interactions altered plant susceptibility for each of the 14 herbivores, three distinct patterns of response of herbivores to hybrids were expressed. One pattern, observed in four herbivore species, supported the hypothesis of breakdown of resistance genes in recombinant hybrids. A second pattern, shown by six other herbivore species, supported the hypothesis of hybrid breakdown of host recognition genes. In other words, epistatic interactions for host recognition traits (probably oviposition/feeding stimulants or attractants) appeared to be important in determining herbivore abundance for those six species. The final patterns supported a structure of dominance, either for host recognition traits (in the case of three herbivore species) or for host resistance traits (for one herbivore species). The combination of differing responses of herbivore species, including members of the same genus and tribe, and the ubiquitous importance of epistasis suggests that many genes affect herbivore resistance in this hybrid willow system.
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Affiliation(s)
- R S Fritz
- Department of Biology, Vassar College, Poughkeepsie, NY 12604, USA.
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Fritz RS, Moulia C, Newcombe G. Resistance of Hybrid Plants and Animals to Herbivores, Pathogens, and Parasites. ACTA ACUST UNITED AC 1999. [DOI: 10.1146/annurev.ecolsys.30.1.565] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
▪ Abstract Interspecific hybridization can disrupt normal resistance of plant and animal species to their parasites. Resistance to parasites is affected by hybridization in the following ways: no difference between hybrids and parentals, additivity, hybrid susceptibility, and dominance to susceptibility. Similar patterns were seen across host taxa. Responses of different parasite species vary widely to the same hybrid host, which indicates diverse genetic effects of interspecific hybridization on resistance. Differences between field and common garden or laboratory studies suggest that environmental factors in hybrid zones influence the patterns seen in the field. Based on recent studies of hybrid-parasite interactions, three avenues of future research will provide a more complete understanding of the roles of hybrids and the roles of parasites in host evolution. First, the relationship between inheritance of putative resistance mechanisms of hosts and responses of parasites needs study using analyses of recombinant progenies. Second, the interaction among environmental variation in hybrid zones, resistance mechanisms, responses of parasites, and the impact of parasites on host fitness needs experimental analysis using reciprocal transplant experiments in hybrid zones. Finally, the role of hybrids in the community structure and interactions of parasites needs study.
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Affiliation(s)
- Robert S. Fritz
- Department of Biology, Vassar College, Poughkeepsie, New York 12604-0133
| | - Catherine Moulia
- Laboratoire Genome, Populations, Interactions; UPR 9060 CNRS, CC105, UM II Place Eugene Bataillon, Montpellier Cedex O5, France
| | - George Newcombe
- Puyallup Research & Extension Center, Washington State University, Puyallup, Washington 98371-4998 USA
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Whitham TG, Martinsen GD, Keim P, Floate KD, Dungey HS, Potts BM. PLANT HYBRID ZONES AFFECT BIODIVERSITY: TOOLS FOR A GENETIC-BASED UNDERSTANDING OF COMMUNITY STRUCTURE. Ecology 1999. [DOI: 10.1890/0012-9658(1999)080[0416:phzabt]2.0.co;2] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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