Latitudinal Variation in Palatability of Salt-Marsh Plants: Which Traits Are Responsible?

Siska, Erin L.; Pennings, Steven C.; Buck, Tracy L.; Hanisak, M. Dennis

doi:10.2307/3072086

Cited by 24 publications

(50 citation statements)

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“…Recently, we demonstrated that L. irrorata prefers to establish fungal farms on S. alterniflora rather than on other available marsh plants, largely because S. alterniflora produces weaker chemical defenses against snails and fungi than do other marsh plant species ). However, S. alterniflora does possess chemical de fenses: its extracts significantly inhibited fungal growth and L. irrorata grazing in laboratory assays relative to negative controls , complementing other studies demonstrating that S. alterniflora produces chemical defenses against L. irrorata (Long et al 2011) and other invertebrates (Siska et al 2002).…”

Section: Introductionsupporting

confidence: 71%

“…in Georgia) are constitutively defended, populations with moderate grazing pressure induce chemical defenses upon exposure to herbivore cues, and populations exposed to low herbivore densities do not invest in chemical defenses at all. Increased investment in chemical defenses because of a greater threat of herbivory may also explain why plants from southern marshes are generally less palatable to a range of herbivores than their northern counterparts (Pennings et al 2001, Siska et al 2002, Salgado & Pennings 2005, Long et al 2011.…”

Section: Discussionmentioning

confidence: 99%

“…Since fungal farming by snails can lead to massive losses in plant biomass, salt marsh grasses including Spartina alterniflora should be under selective pressure to limit damage or infection due to Littoraria irrorata and their cultivated fungi. Marine and terrestrial autotrophs frequently employ structural and chemical defenses to deter herbivores (Hay & Steinberg 1992) and microbes (Pearce 1996, Lane & Kuba nek 2008, as do salt marsh plants bordering these ecosystems (Siska et al 2002, Hendricks et al 2011. Recently, we demonstrated that L. irrorata prefers to establish fungal farms on S. alterniflora rather than on other available marsh plants, largely because S. alterniflora produces weaker chemical defenses against snails and fungi than do other marsh plant species ).…”

Section: Introductionmentioning

confidence: 91%

“…However, chemical defenses were neither constitutively produced nor induced in S. alterniflora in New England marshes that contained lower ambient herbivore densities (Long et al 2011), suggesting that S. alterniflora allocates resources toward defense only when herbivore grazing is substantial. Tissues and extracts from southern salt marsh plant populations also tended to be less palatable to herbivores than those from northern marshes (Pennings et al 2001, Siska et al 2002, and these differences in palatability persisted for multiple plant generations even when grown in common gardens (Salgado & Pennings 2005).…”

Section: Introductionmentioning

confidence: 99%

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Multiple chemical defenses produced by Spartina alterniflora deter farming snails and their fungal crop

Sieg¹,

Willey²,

Wolfe³

et al. 2013

Mar. Ecol. Prog. Ser.

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Plants are exposed to a variety of ecological threats from herbivores, pathogens, and parasites. In cases in which chemical defenses play a role in plant resistance, plants may produce a single molecule that inhibits a diverse array of enemies, or they may invest in a suite of deterrent compounds that each protect against specific threats. The snail Littoraria irrorata exerts substantial top-down control over smooth cordgrass Spartina alterniflora by culturing and grazing fungi on plant tissues. To combat fungal farming, S. alterniflora produces chemical defenses that inhibit fungal growth and reduce L. irrorata grazing. Guided by ecological assays, we isolated a fatty acid (α-dimorphecolic acid) from S. alterniflora that inhibited growth of Mycosphaerella sp., a marsh fungus commonly farmed by L. irrorata. Mycosphaerella sp. was more susceptible to the inhibitory effects of α-dimorphecolic acid than another farmed fungus, Phaeosphaeria spartinicola. Several phenolic compounds isolated from S. alterniflora deterred grazing by L. irrorata, of which one, the flavonoid glycoside orientin, was fully characterized. These defenses are not potent enough to completely deter fungi and snails but may slow down the negative effects caused by fungal farming. In a heavily grazed marsh, chemical defenses were constitutively expressed in S. alterniflora even after a month-long experiment in which exposure to fungi and herbivores was manipulated. Thus, S. alterniflora relies on multiple types of secondary metabolites instead of a single class of molecule to combat associated herbivores and fungi. Although α-dimorphecolic acid was not expressed in sufficient concentration on plant surfaces to prevent fungal establishment, this chemical defense may reduce fungal growth in plant tissues and increase the resistance of S. alterniflora to fungal farming. KEY WORDS: Littoraria irrorata · Antiherbivore · Antifungal · Chemical defense · Induction · Herbivore · Pathogen Resale or republication not permitted without written consent of the publisher

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Section: Introductionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multiple chemical defenses produced by Spartina alterniflora deter farming snails and their fungal crop

Sieg¹,

Willey²,

Wolfe³

et al. 2013

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…Collected leaves were processed (sheaths and stems were removed), and fresh‐ and dry‐weight measured to determine water content, then ground using a ball‐mill and analysed for leaf N and C concentration using an elemental analyzer. Leaf toughness was measured using a modified penetrometer, which can record the force needed to penetrate a leaf with a thin rod (Siska et al ). Cellulose was measured using the anthrone colorimetry method (Abidi et al ), where dry ground samples were first mixed with 60% sulphuric acid for 30 min, filtered and diluted.…”

Section: Methodsmentioning

confidence: 99%

Herbivore phenology can predict response to changes in plant quality by livestock grazing

Zhu

Veen

Wang

et al. 2020

Oikos

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Livestock grazing can have a strong impact on herbivore abundance, distribution and community. However, not all species of herbivores respond the same way to livestock grazing, and we still have a poor understanding of the underlying mechanisms driving these differential responses. Here, we investigate the effect of light intensity cattle grazing on the abundance of two grasshoppers (Euchorthippus cheui and E. unicolor) that co‐occur in the same grasslands and feed on the same food plant (the dominant grass Leymus chinensis). The two grasshopper species differ in phenology so that their peak abundances are separated into early‐ and late‐growing seasons. We used an exclosure experiment to monitor grasshopper abundance and food quality in the field under grazed and ungrazed conditions, and performed feeding trials to examine grasshopper preference for grazed or ungrazed food plants in the laboratory. We found that the nitrogen content of L. chinensis leaves continuously declined in the ungrazed areas, but was significantly enhanced by cattle grazing over the growing season. Cattle grazing facilitated the early‐season grasshopper E. cheui, whereas it suppressed the late‐season grasshopper E. unicolor. Moreover, feeding trials showed that E. cheui preferred L. chinensis from grazed plots, while E. unicolor preferred the leaves from ungrazed plots. We conclude that livestock grazing has opposite effects on the two grasshopper species, and that these effects may be driven by grazing‐induced changes in plant nutrient content and the unique nutritional niches of the grasshoppers. These results suggest that insects that belong to the same guild can have opposite nutrient requirements, related to their distinct phenologies, and that this can ultimately affect their response to cattle grazing. Our results show that phenology may link insect physiological needs to local resource availabilities, and should be given more attention in future work on interactions between large herbivores and insects.

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Variable effects on growth and defense traits for plant ecotypic differentiation and phenotypic plasticity along elevation gradients

Bakhtiari

Formenti

Caggìa

et al. 2019

Ecology and Evolution

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Along ecological gradients, phenotypic differentiation can arise through natural selection on trait diversity and magnitude, and environment‐driven plastic changes. The magnitude of ecotypic differentiation versus phenotypic plasticity can vary depending on the traits under study. Using reciprocal transplant‐common gardens along steep elevation gradients, we evaluated patterns of ecotypic differentiation and phenotypic plasticity of several growth and defense‐related traits for two coexisting but unrelated plant species, Cardamine pratensis and Plantago major . For both species, we observed ecotypic differentiation accompanied by plasticity in growth‐related traits. Plants grew faster and produced more biomass when placed at low elevation. In contrast, we observed fixed ecotypic differentiation for defense and resistance traits. Generally, low‐elevation ecotypes produced higher chemical defenses regardless of the growing elevation. Yet, some plasticity was observed for specific compounds, such as indole glucosinolates. The results of this study may suggest that ecotypic differentiation in defense traits is maintained by costs of chemical defense production, while plasticity in growth traits is regulated by temperature‐driven growth response maximization.

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Latitudinal Variation in Palatability of Salt-Marsh Plants: Which Traits Are Responsible?

Cited by 24 publications

References 0 publications

Multiple chemical defenses produced by Spartina alterniflora deter farming snails and their fungal crop

Multiple chemical defenses produced by Spartina alterniflora deter farming snails and their fungal crop

Herbivore phenology can predict response to changes in plant quality by livestock grazing

Variable effects on growth and defense traits for plant ecotypic differentiation and phenotypic plasticity along elevation gradients

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