Generalist &amp;lt;i&amp;gt;versus&amp;lt;/i&amp;gt; Specialist Herbivores on the Invasive &amp;lt;i&amp;gt;Senecio inaequidens&amp;lt;/i&amp;gt; and a Native Related Species: What Makes the Difference?

Jacquemart, Anne‐Laure; Vanparys, Valérie; Meerts, Pierre Jacques

doi:10.4236/ajps.2013.42a050

Cited by 7 publications

(8 citation statements)

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“…The presence of alien species may, however, have positive effects on the competitive ability of native species by reducing the pressure of generalist herbivores on native species. Recent studies (Jacquemart et al, 2013 ) and meta-analyses (Parker and Hay, 2005 ; Parker et al, 2006 ) indicate that some generalists have a preference for alien plant hosts over native plants, while some alien plants may negatively impact on the survival of generalist herbivores (Tallamy et al, 2010 ), and may thus benefit native species, altering the competitive balance between alien and native species. How apparent competition may affect or interact with resource competition in determining the establishment of alien species remains unclear and requires additional investigations.…”

Section: Disentangling Resource Competition From Other Mechanismsmentioning

confidence: 99%

Resource competition in plant invasions: emerging patterns and research needs

2014

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Invasions by alien plants provide a unique opportunity to examine competitive interactions among plants. While resource competition has long been regarded as a major mechanism responsible for successful invasions, given a well-known capacity for many invaders to become dominant and reduce plant diversity in the invaded communities, few studies have measured resource competition directly or have assessed its importance relative to that of other mechanisms, at different stages of an invasion process. Here, we review evidence comparing the competitive ability of invasive species vs. that of co-occurring native plants, along a range of environmental gradients, showing that many invasive species have a superior competitive ability over native species, although invasive congeners are not necessarily competitively superior over native congeners, nor are alien dominants are better competitors than native dominants. We discuss how the outcomes of competition depend on a number of factors, such as the heterogeneous distribution of resources, the stage of the invasion process, as well as phenotypic plasticity and evolutionary adaptation, which may result in increased or decreased competitive ability in both invasive and native species. Competitive advantages of invasive species over natives are often transient and only important at the early stages of an invasion process. It remains unclear how important resource competition is relative to other mechanisms (competition avoidance via phenological differences, niche differentiation in space associated with phylogenetic distance, recruitment and dispersal limitation, indirect competition, and allelopathy). Finally, we identify the conceptual and methodological issues characterizing competition studies in plant invasions, and we discuss future research needs, including examination of resource competition dynamics and the impact of global environmental change on competitive interactions between invasive and native species.

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Section: Disentangling Resource Competition From Other Mechanismsmentioning

confidence: 99%

Resource competition in plant invasions: emerging patterns and research needs

2014

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“…Thus, genetic/phenotypic divergence between native and non-native populations of D. stramonium cannot be ruled out. For instance, it is likely that other toxins that may be absent in populations that lack coevolved herbivores [ 14 ] explain the differential host recognition and, hence, herbivore load on plants [ 33 ]. This suggests that compounds like HIVPs and VOCs should be compared between native and non-native plants.…”

Section: Discussionmentioning

confidence: 99%

A Trip Back Home: Resistance to Herbivores of Native and Non-Native Plant Populations of Datura stramonium

Núñez-Farfán,

Velázquez-Márquez,

Torres-García

et al. 2024

Plants

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When colonizing new ranges, plant populations may benefit from the absence of the checks imposed by the enemies, herbivores, and pathogens that regulated their numbers in their original range. Therefore, rates of plant damage or infestation by natural enemies are expected to be lower in the new range. Exposing both non-native and native plant populations in the native range, where native herbivores are present, can be used to test whether resistance mechanisms have diverged between populations. Datura stramonium is native to the Americas but widely distributed in Spain, where populations show lower herbivore damage than populations in the native range. We established experiments in two localities in the native range (Mexico), exposing two native and two non-native D. stramonium populations to natural herbivores. Plant performance differed between the localities, as did the abundance of the main specialist herbivore, Lema daturaphila. In Teotihuacán, where L. daturaphila is common, native plants had significantly more adult beetles and herbivore damage than non-native plants. The degree of infestation by the specialist seed predator Trichobaris soror differed among populations and between sites, but the native Ticumán population always had the lowest level of infestation. The Ticumán population also had the highest concentration of the alkaloid scopolamine. Scopolamine was negatively related to the number of eggs deposited by L. daturaphila in Teotihuacán. There was among-family variation in herbivore damage (resistance), alkaloid content (scopolamine), and infestation by L. daturaphila and T. soror, indicating genetic variation and potential for further evolution. Although native and non-native D. stramonium populations have not yet diverged in plant resistance/constitutive defense, the differences between ranges (and the two experimental sites) in the type and abundance of herbivores suggest that further research is needed on the role of resource availability and adaptive plasticity, specialized metabolites (induced, constitutive), and the relationship between genealogical origin and plant defense in both ranges.

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“…A study from Belgium showed that S. inaquidens was more prone to generalist herbivores in its introduced range compared to the related J. vulgaris, which was more susceptible to herbivory by specialist feeders (Jacquemart et al 2013). Introduced plants are suggested to be able to exhibit adaptations for increased generalist defence compared to their native conspecifics as shown for J. vulgaris populations in their introduced range (i.e.…”

mentioning

confidence: 99%

“…and has therefore been continued to be used as a model species for other Senecio spp. for insect herbivore research (Jacquemart et al 2013). Within farming, J. vulgaris is known to be toxic to livestock and can cause hepatic failure and death.…”

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Direct and indirect interactions of native and introduced species in coastal habitats

Krejcek¹

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<p>Current research has emphasized the need to identify and quantify the effects of positive and negative interactions (both direct and indirect) between species, taking into account the influence of abiotic conditions and spatial scales. In this research it is particularly challenging to adequately assess and predict the impact of introduced species on native communities. This study examined interactions of introduced and native species on coastal sand dunes in New Zealand. Substantial areas of this habitat have become dominated by the highly competitive exotic sand-binder marram grass (Ammophila arenaria) and other exotic weeds, replacing native species, including the native eco-engineering spinifex (Spinifex sericeus). First, I examined direct interactions (competition and facilitation) between marram and spinifex along an abiotic stress gradient where experimental plots were subject to different restoration management techniques. In my large-scale dune experiment I planted 2475 spinifex seedlings in three different treatments (bare sand, live marram, dead marram) including an unplanted control, and monitored the plots for one year along exposed marram grass-dominated dune fields near Whanganui, West Coast, North Island/New Zealand. The stress gradient hypothesis predicts facilitation will be greatest where stress is most severe. I hypothesized facilitation of spinifex plantings and other self-colonizing plants in dead sprayed marram compared to live marram and a change of interaction between spinifex and marram grass along an abiotic stress gradient. Spinifex survival was not significantly different across treatments, but the interaction between treatment and location from the sea as well as pre-existing marram cover were significant predictors of plant growth in a linear mixed effect model. Exotic weeds such as Senecio elegans, Conyza canadensis, dandelions and legumes were facilitated by sprayed marram grass relative to abundances in live marram grass, while grasses other than marram grass and spinifex performed best in bare sand, in the absence of competitors. For S. elegans, abundances were higher closer to the sea. Spinifex growth was greatest in plots closest to the sea. Comparing spinifex growth in live marram grass and dead marram showed similar patterns at the fore, mid and back dune, but sprayed maram showed better facilitation of spinifex. For restoration plantings it is only recommended to plant into dead marram if the site is not weed prone as weeds were facilitated in the same way as spinifex and in some instances appeared to hinder spinifex growth. Crucial for a successful conversion from marram to spinifex is that the initial marram cover is not too high prior to spraying- lower densities allow for better spinifex growth. Second, I examined indirect competition with a survey of natural populations and a common garden experiment at a shingle beach. I was interested in determining the influence of plant density at different spatial scales as well as plant morphology on insect abundances. I studied indirect interactions by choosing native and introduced Senecio spp. as host plants for insect colonization and incorporated fine scale plant density (50cm radius circle, area = 0.8 m²) and coarse scale plant density (6m quadrat annulus, area = 32 m²) as predictors for insect colonization in addition to plant morphology. I surveyed Senecio spp. over a period of three growth seasons and conducted an experiment where I manipulated densities of pairs of species of either introduced Senecio elegans, S. skirrhodon and native S. lautus. My survey of natural populations and the manipulative field experiment show a negative impact of high conspecific and heterospecific plant density on the colonization of the seed head predator fly Sphenella fascigera. Along with plant density, plant size was a significant predictor of insect abundances. Higher densities of introduced S. elegans indirectly facilitated S. lautus at fine spatial scales by reducing the incidence of S. fascigera. This supports the resource dilution hypothesis which predicts higher insect herbivore numbers on isolated resource patches. Thus, my results provide empirical evidence for apparent facilitation of a native plant by an introduced plant via a shared herbivore. For future assessments of the impacts of invasive species it will be important to consider the net-outcome of direct and indirect competitive and facilitative interactions. In particular, for restoration purposes in stressful environments removal of invasive species may have to occur in a carefully controlled manner taking into account the abiotic conditions and spatial scales at which interactions occur.</p>

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Generalist <i>versus</i> Specialist Herbivores on the Invasive <i>Senecio inaequidens</i> and a Native Related Species: What Makes the Difference?

Cited by 7 publications

References 77 publications

Resource competition in plant invasions: emerging patterns and research needs

Resource competition in plant invasions: emerging patterns and research needs

A Trip Back Home: Resistance to Herbivores of Native and Non-Native Plant Populations of Datura stramonium

Direct and indirect interactions of native and introduced species in coastal habitats

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