Soil calcium and plant disease in serpentine ecosystems: a test of the pathogen refuge hypothesis

Springer, Yuri P.; Hardcastle, Bree A.; Gilbert, Gregory S.

doi:10.1007/s00442-006-0566-1

Cited by 22 publications

(40 citation statements)

References 59 publications

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“…While many studies have probed the interactions among the vertices of the disease triangle (e.g., [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]), investigations of the larger ecological context in which host-pathogen-environment interactions occur, including the interactions among multiple microbial species infecting the same host, multiple species in a host community, and the impact of multiple abiotic parameters have generally been observational or limited in spatial scope [17], [18], [19], [20], [21].…”

Section: Introductionmentioning

confidence: 99%

Richness and Composition of Niche-Assembled Viral Pathogen Communities

et al. 2013

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The pathogen and parasite community that inhabits every free-living organism can control host vital rates including lifespan and reproductive output. To date, however, there have been few experiments examining pathogen community assembly replicated at large-enough spatial scales to inform our understanding of pathogen dynamics in natural systems. Pathogen community assembly may be driven by neutral stochastic colonization and extinction events or by niche differentiation that constrains pathogen distributions to particular environmental conditions, hosts, or vectors.Here, we present results from a regionally-replicated experiment investigating the community of barley and cereal yellow dwarf viruses (B/CYDV's) in over 5000 experimentally planted individuals of six grass species along a 700 km latitudinal gradient along the Pacific coast of North America (USA) in response to experimentally manipulated nitrogen and phosphorus supplies. The composition of the virus community varied predictably among hosts and across nutrient-addition treatments, indicating niche differentiation among virus species. There were some concordant responses among the viral species. For example, the prevalence of most viral species increased consistently with perennial grass cover, leading to a 60% increase in the richness of the viral community within individual hosts (i.e., coinfection) in perennial-dominated plots. Furthermore, infection rates of the six host species in the field were highly correlated with vector preferences assessed in laboratory trials. Our results reveal the importance of niche differentiation in structuring virus assemblages. Virus species distributions reflected a combination of local host community composition, host species-specific vector preferences, and virus responses to host nutrition. In addition, our results suggest that heterogeneity among host species in their capacity to attract vectors or support pathogens between growing seasons can lead to positive covariation among virus species.

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Section: Introductionmentioning

confidence: 99%

Richness and Composition of Niche-Assembled Viral Pathogen Communities

et al. 2013

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“…From a historical perspective, specialization has been placed in a phylogenetic context with the goal of inferring diversification rates associated with soil endemism either within or across groups (4)(5)(6). On the other hand, studies with a contemporary ecological perspective have, with experimental manipulations in either field or controlled conditions, tested hypotheses that address the drivers of edaphic specialization by focusing on plant performance in different microhabitats (7); along environmental gradients (8); when plants are grown on different substrates or with different elemental supplements (9-11); or in the presence of neighbors (12,13), pathogens (14), or herbivores (15,16).…”

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confidence: 99%

Occupation of bare habitats, an evolutionary precursor to soil specialization in plants

Cacho

Strauss

2014

Proc. Natl. Acad. Sci. U.S.A.

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Plant soil specialists contribute greatly to global diversity; however, the ecoevolutionary forces responsible for generating this diversity are poorly understood. We integrate molecular phylogenies with descriptive and experimental ecological data, creating a powerful framework with which to elucidate forces driving soil specialization. Hypotheses explaining edaphic specialization have historically focused on costs of adaptation to elements (e.g., nickel, calcium/magnesium) and accompanying tradeoffs in competitive ability in benign soils. We combine in situ microhabitat data for 37 streptanthoid species (Brassicaceae), soil analyses, and competition experiments with their phylogeny to reconstruct selective forces generating serpentine soil endemism, which has four to five independent origins in this group. Coupling ancestral state reconstruction with phylogenetic independent contrasts, we examine the magnitude and timing of changes in soil and habitat attributes relative to inferred shifts to serpentine. We find large changes in soil chemistry at nodes associated with soil shifts, suggesting that elemental changes occurred concomitantly with soil transitions. In contrast, the amount of bare ground surrounding plants in the field (“bareness”), which is greater in serpentine environments, is conserved across soil-type shifts. Thus, occupation of bare environments preceded shifts to serpentine, and may serve as an evolutionary precursor to harsh elemental soils and environments. In greenhouse experiments, taxa from barer environments are poorer competitors, a tradeoff that may contribute to soil endemism. The hypothesis of occupation of bare habitats as a precursor of soil specialization can be tested in other systems with a similar integrative ecophylogenetic approach, thereby providing deeper insights into this rich source of biodiversity.

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“…First, our study was conducted at a single site but serpentine soils vary in their characteristics, including the Ca/Mg ratio (e.g., Springer et al 2007), in ways that might affect the magnitude of the agents' net impact on the plant. Second, any form of management, including biocontrol, that reduces seed production has the potential to reduce the density of this invasive, annual thistle when and where recruitment is seed limited (Louda 1983;Crawley 1989;Sheppard et al 2002, Parker 2001.…”

Section: Implications For Biocontrolmentioning

confidence: 99%

“…concentration in serpentine soils and found that Hesperolinon californicum plants in the higher Ca ?? soils had lower rates of infection by the rust pathogen Melampsora lini (Springer et al 2007). They also found that experimentally increasing soil Ca ??…”

Section: Introductionmentioning

confidence: 98%

Soil type mediates indirect interactions between Centaurea solstitialis and its biocontrol agents

Swope

Stein

2012

Biol Invasions

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Many invasive plants are attacked by more than one biocontrol agent. Attack by multiple enemies may give rise to indirect interactions, the nature of which may be influenced by the abiotic environment. We conducted a field experiment to determine (1) whether indirect interactions arose between Centaurea solstitialis, a foliar pathogen and three insect seed predators and (2) how the outcome was influenced by soil type (serpentine and non-serpentine). Because serpentine soils support high numbers of endemic species they are a priority for conservation. They also have very low calcium concentrations and Ca ?? regulates plants' ability to defend against pathogen infection. C. solstitialis growing on serpentine soil may therefore be more vulnerable to the pathogen and this may in turn affect the plant's subsequent interactions with seed predators. We found that pathogen infection had a direct, negative impact on plant performance but its impact was not greater on serpentine plants. When attacked by the seed predators, inflorescences produced more viable seed when they were on plants infected with the pathogen than when they were on uninfected plants and the data suggest that this reflects reductions in larval seedfeeding. On the non-serpentine soil, the pathogen's direct, negative impact was entirely canceled out by its indirect, positive effect via reduced seed predation. On the serpentine soil, plants attacked by the pathogen and the insect seed predators produced half as many seeds than plants attacked only by the seed predators. Our results demonstrate that biocontrol agent interactions may be modified by the plant and by the abiotic environment in a way that fundamentally alters their net impact on the weed.

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Soil calcium and plant disease in serpentine ecosystems: a test of the pathogen refuge hypothesis

Cited by 22 publications

References 59 publications

Richness and Composition of Niche-Assembled Viral Pathogen Communities

Richness and Composition of Niche-Assembled Viral Pathogen Communities

Occupation of bare habitats, an evolutionary precursor to soil specialization in plants

Soil type mediates indirect interactions between Centaurea solstitialis and its biocontrol agents

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