No Evidence for Enemy Release During Range Expansion of an Evergreen Tree in Northern Europe

Skou, Anne-Marie T.; Markussen, Bo; Sigsgaard, Lene; Kollmann, Johannes

doi:10.1603/en11063

Cited by 8 publications

(8 citation statements)

References 53 publications

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“…, Lakeman‐Fraser and Ewers ), although this result is not universal (e.g., Skou et al. ). Combined with the results of Brown and Vellend (), our results have some important implications for understanding potential responses of species distributions to climate warming, as described in the following paragraphs.…”

Section: Discussionsupporting

confidence: 73%

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Increased seedling establishment via enemy release at the upper elevational range limit of sugar maple

Urli

Brown

Perez

et al. 2016

Ecology

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The enemy release hypothesis is frequently invoked to explain invasion by nonnative species, but studies focusing on the influence of enemies on natural plant range expansion due to climate change remain scarce. We combined multiple approaches to study the influence of plant-enemy interactions on the upper elevational range limit of sugar maple (Acer saccharum) in southeastern Québec, Canada, where a previous study had demonstrated intense seed predation just beyond the range limit. Consistent with the hypothesis of release from natural enemies at the range limit, data from both natural patterns of regeneration and from seed and seedling transplant experiments showed higher seedling densities at the range edge than in the core of the species' distribution. A growth chamber experiment manipulating soil origin and temperature indicated that this so-called "happy edge" was not likely caused by temperature (i.e., the possibility that climate warming has made high elevation temperatures optimal for sugar maple) or by abiotic soil factors that vary along the elevational gradient. Finally, an insect-herbivore-exclusion experiment showed that insect herbivory was a major cause of seedling mortality in the core of sugar maple's distribution, whereas seedlings transplanted at or beyond the range edge experienced minimal herbivory (i.e., enemy release). Insect herbivory did not completely explain the high levels of seedling mortality in the core of the species' distribution, suggesting that seedlings at or beyond the range edge may also experience release from pathogens. In sum, while some effects of enemies are magnified beyond range edges (e.g., seed predation), others are dampened at and beyond the range edge (e.g., insect herbivory), such that understanding the net outcome of different biotic interactions within, at and beyond the edge of distribution is critical to predicting species' responses to global change.

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Section: Discussionsupporting

confidence: 73%

“…, Lakeman‐Fraser and Ewers ), while others find no such effect (e.g., Skou et al. ). However, we cannot draw generalizations at present given that so few empirical studies have tested how non‐climatic factors influence the leading edge of natural species ranges (HilleRisLambers et al.…”

Section: Introductionmentioning

confidence: 93%

Increased seedling establishment via enemy release at the upper elevational range limit of sugar maple

Urli

Brown

Perez

et al. 2016

Ecology

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“…In order to conduct a statistically valid analysis with power sufficient enough to detect significant differences in metabolic features associated with environmental and geographic variation and address low sampling numbers, we use the two‐step model proposed by Skou, Markussen, Sigsgaard, and Kollmann (2011) (see also Thiele & Markussen, 2012). The two‐step model includes a log‐normal model and a binary model and is well suited to address metabolomic data where all observations are non‐negative, but a substantial portion of the observations are zero values, as a result of many metabolic features being not present or below the detection limit.…”

Section: Methodsmentioning

confidence: 99%

“…Skou et al. (2011) did not baptize their model, but for future reference we suggest that this model is called the conditional log‐normal model . A log‐normal model often fits well for strictly positive observations, and the conditional log‐normal model is an extension that allows for zero observations that also occur frequently in ecological datasets.…”

Section: Methodsmentioning

confidence: 99%

Untargeted metabolic profiling reveals geography as the strongest predictor of metabolic phenotypes of a cosmopolitan weed

Ahlstrand

Reghev

Markussen

et al. 2018

Ecology and Evolution

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Plants produce a multitude of metabolites that contribute to their fitness and survival and play a role in local adaptation to environmental conditions. The effects of environmental variation are particularly well studied within the genus Plantago; however, previous studies have largely focused on targeting specific metabolites. Studies exploring metabolome‐wide changes are lacking, and the effects of natural environmental variation and herbivory on the metabolomes of plants growing in situ remain unknown. An untargeted metabolomic approach using ultra‐high‐performance liquid chromatography–mass spectrometry, coupled with variation partitioning, general linear mixed modeling, and network analysis was used to detect differences in metabolic phenotypes of Plantago major in fifteen natural populations across Denmark. Geographic region, distance, habitat type, phenological stage, soil parameters, light levels, and leaf area were investigated for their relative contributions to explaining differences in foliar metabolomes. Herbivory effects were further investigated by comparing metabolomes from damaged and undamaged leaves from each plant. Geographic region explained the greatest number of significant metabolic differences. Soil pH had the second largest effect, followed by habitat and leaf area, while phenological stage had no effect. No evidence of the induction of metabolic features was found between leaves damaged by herbivores compared to undamaged leaves on the same plant. Differences in metabolic phenotypes explained by geographic factors are attributed to genotypic variation and/or unmeasured environmental factors that differ at the regional level in Denmark. A small number of specialized features in the metabolome may be involved in facilitating the success of a widespread species such as Plantago major into such wide range of environmental conditions, although overall resilience in the metabolome was found in response to environmental parameters tested. Untargeted metabolomic approaches have great potential to improve our understanding of how specialized plant metabolites respond to environmental change and assist in adaptation to local conditions.

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“…Some tests have confirmed it only partially [25][26][27], have proved negative (e.g., [28][29][30]), or have led to conclusions contradicting it [31][32][33]. A review of the results of ERH tests [34] indicated that for alien plant species the hypothesis was confirmed in about 57% of experimental studies.…”

Section: Introductionmentioning

confidence: 99%

Do local enemies attack alien and native Impatiens alike?

2017

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The enemy release hypothesis (ERH) attributes the invasive behavior of some alien species to decreased pressure from natural enemies, as they have been left behind in the hosts' native range. The majority of research supports this idea, but some studies confirm it only partially or even contradict it. Here, we present the results of ERH tests of three Impatiens species studied in southern Poland in 2010-2011. Two of them are alien and invasive in Europe (Impatiens glandulifera, I. parviflora) and one is native (I. noli-tangere). We compared the three species in terms of the percentage of all leaves showing symptoms of disease and/or damage, and also the number of pests recorded on the monitored plants.In 1071 individual plant controls, we assessed 17 180 leaves, 7552 of which showed symptoms of disease/damage, and we recorded 5721 invertebrates, 5220 of them were pests. Rusts and spots were the predominant symptoms and Aphidoidea were the dominant group of pests. Comparisons of the two alien and one native Impatiens did not confirm the ERH in 90% of the performed tests. Most of the differences between the species were not significant, and most of the significant ones contradicted the ERH. The only results confirming the ERH were found in comparisons between I. parviflora and I. noli-tangere. The tests between two alien species showed that I. parviflora was under higher pest pressure, while I. glandulifera had more disease and damage symptoms, thus, plant-enemy relations differed between the two balsams. In summary, the presented results add evidence that the success of some alien species may depend on factors related to biotic and/or abiotic conditions in ways that are not explained by the enemy release hypothesis.

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No Evidence for Enemy Release During Range Expansion of an Evergreen Tree in Northern Europe

Cited by 8 publications

References 53 publications

Increased seedling establishment via enemy release at the upper elevational range limit of sugar maple

Increased seedling establishment via enemy release at the upper elevational range limit of sugar maple

Untargeted metabolic profiling reveals geography as the strongest predictor of metabolic phenotypes of a cosmopolitan weed

Do local enemies attack alien and native Impatiens alike?

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