Propagule size and dispersal costs mediate establishment success of an invasive species

Lange, Rolanda; Marshall, Dustin J.

doi:10.1890/15-1573

Cited by 16 publications

(9 citation statements)

References 53 publications

(125 reference statements)

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“…, Burgess and Marshall , Britton and Gozlan , Estrada et al. , Lange and Marshall ). Whether this pattern is general remains to be seen, but increased demographic stochasticity in small populations should yield a positive association between abundance and the likelihood of population persistence over time and thus a similar relationship between propagule pressure and both metrics (although see Memmott et al.…”

Section: Discussionmentioning

confidence: 97%

Propagule pressure and genetic diversity enhance colonization by a ruderal species: a multi‐generation field experiment

Hovick

Whitney

2019

Ecological Monographs

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Colonization is a critical filter, setting the stage for short‐term and long‐term population success. Increased propagule pressure (e.g., more founding individuals) usually enhances colonization; however, this pattern may be driven by purely numeric effects, population genetic diversity effects, or both. To determine the independent and interactive effects of propagule pressure and genetic diversity, we conducted a seed addition experiment in the field using the ruderal annual Arabidopsis thaliana. Propagule pressure treatments spanned five levels, from 32 to 960 seeds per 0.25‐m2 plot. Founder populations were composed of one, four, or eight genotypes and exposed to ambient or reduced levels of interspecific competition. Genotype monocultures were included to quantify additive vs. non‐additive effects. Populations were followed for three generations, with abundance, population persistence and genotype retention (the proportion of introduced genotypes persisting over time) as the major response variables. Increased propagule pressure enhanced abundance immediately following introduction, particularly where nutrient availability was high and competition reduced. Greater propagule pressure also increased the likelihood of population persistence and genotype retention through three generations. However, most populations experienced rapid abundance declines over time, yielding no relationship between propagule pressure and third‐generation abundance across persisting populations. Under reduced competition, increased genetic diversity led to a marginal increase in persistence through the third generation that was more pronounced, and statistically significant, in low nutrient conditions. Genetic diversity did not affect persistence through the first generation, thus indicating that genetic diversity effects strengthened over time. Nevertheless, genotypic mixture populations fell short of expectations based on performance in monocultures (negative non‐additive effects). Increased genetic diversity was also associated with abundance declines, largely due to one particularly high‐performing genotype in the lowest diversity treatments (i.e., genotypic identity effects). Overall, our results indicate that increases in both propagule pressure and genetic diversity can enhance colonization success but are highly context dependent. They also highlight novel ways in which both factors can impact the retention of introduced genetic diversity over time. Our findings pinpoint the determinants of a fundamental population process and have key implications for applications where enhanced or suppressed colonization is desired, including ecological restoration and invasive species management.

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Section: Discussionmentioning

confidence: 97%

Propagule pressure and genetic diversity enhance colonization by a ruderal species: a multi‐generation field experiment

Hovick

Whitney

2019

Ecological Monographs

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“…Although further experimental work is needed to identify the underpinning mechanisms, our study provides novel evidence that facilitation among different types of propagules may allow an invader to overcome the biotic resistance of native habitats. The large variability of propagule quality documented in nature (Lange & Marshall, ; Smulders et al, ; Verling et al, ) indicates that single quality propagule inocula are unlikely. Hence, assessing how propagules differing in quality perform in different habitats might be not sufficient to draw a comprehensive picture of invasion risk, as their establishment and spread can be modulated by both negative and positive interactions among them.…”

Section: Discussionmentioning

confidence: 99%

Propagule composition regulates the success of an invasive seaweed across a heterogeneous seascape

et al. 2019

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1. Propagule pressure is acknowledged as a key determinant of invasion success.Nonetheless, the role of morphological or physiological attributes of propagules (i.e. their quality) in regulating invader establishment has been little explored. In particular, no study has investigated how the presence of propagules differing in quality within an inoculum influences establishment across heterogeneous landscapes.2. We experimentally tested the hypothesis that the quality (+Fronds+Rhizoids; +Fronds−Rhizoids; −Fronds+Rhizoids) and the diversity (1, 2 and 3 fragment types) of vegetative fragments of the seaweed Caulerpa taxifolia determine their establishment success across seascapes consisting of bare sediments and patches of the seagrass Zostera muelleri exposed to different disturbance intensities (control, seagrass canopy clipping and total removal).3. After 6 weeks, seaweed biomass, stolon and frond length, frond and rhizoid number were generally greater in unvegetated habitats (bare sediments and total seagrass removal) than full or reduced seagrass canopies. The type and the diversity of types of fragments inoculated had significant effects on the final biomass and morphological features of C. taxifolia only in vegetated habitats. In control plots, inocula of fragments retaining both fronds and rhizoids achieved higher biomass, developed longer stolons and more fronds. In canopy clipping plots, mixed inocula of +Fronds+Rhizoids and −Fronds+Rhizoids fragments had the greatest biomass and stolon length. Synthesis.Assessing how propagules differing in quality perform in different habitats might be not sufficient to draw a comprehensive picture of invasion risk, as their establishment can be modulated by both negative and positive interactions among them. Propagule composition should be, therefore, considered as a further dimension of propagule pressure. Our results also suggest that the relevance of specific propagule traits for invader establishment decreases from intact to degraded habitats. Considering propagule size in terms of amount of competent propagules, rather than an absolute measure, would refine our ability of predicting invasion risk across habitats differing in biotic or abiotic conditions.

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“…Propagule pressure is a dominant driver of establishment success in small populations of introduced non‐native species (Lockwood et al ., 2005; Cassey et al ., 2018a; Duncan et al ., 2019). Propagule pressure refers to the number of individuals in the arriving population, the frequency of arrival, the physical distance between individuals, as well as their quality and genetic diversity (Hufbauer et al ., 2013; Lange & Marshall, 2016). The arrival of a large founding population is more likely to lead to establishment than arrival of small founding populations (Lockwood et al ., 2005; Drake & Lodge, 2006).…”

Section: Introductionmentioning

confidence: 99%

Probing the role of propagule pressure, stochasticity, and Allee effects on invasion success using experimental introductions of a biological control agent

Williams

Brockerhoff

Liebhold

et al. 2020

Ecological Entomology

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1. Although most populations of non-native species arriving in new environments fail to establish, mechanisms behind failed biological invasions are still poorly understood. 2. Propagule pressure has been found to be a dominant driver of establishment success, underpinned by processes such as stochasticity and Allee effects. While studies have revealed the presence of a component Allee effect in field populations, empirical support for demographic Allee effects has been limited. 3. We used the leaf-feeding beetle Neolema ogloblini, a biological control agent against the plant Tradescantiafluminensis, as a proxy invasive species to experimentally study the process of establishment. We investigated how the initial size of the population released affects the probability of establishment and population growth in the first season after introduction at isolated sites in New Zealand. 4. The probability of establishment was found to increase with numbers of individuals released. A significant quadratic relationship was found between population size released and per capita population growth rate; that is per capita population growth rate initially increased as population size released increased but decreased at higher population levels. 5. These results support the presence of a demographic Allee effect. However, as the influence of stochasticity (environmental and demographic) could not be completely separated from that of a demographic Allee effect, we conclude that extinction probability in the experimental populations of N. ogloblini was influenced by both a demographic Allee effect and stochasticity. 6. Our study demonstrates and supports the concept that experimental biocontrol agent releases can be used for testing hypotheses regarding invasion biology.

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Propagule size and dispersal costs mediate establishment success of an invasive species

Cited by 16 publications

References 53 publications

Propagule pressure and genetic diversity enhance colonization by a ruderal species: a multi‐generation field experiment

Propagule pressure and genetic diversity enhance colonization by a ruderal species: a multi‐generation field experiment

Propagule composition regulates the success of an invasive seaweed across a heterogeneous seascape

Probing the role of propagule pressure, stochasticity, and Allee effects on invasion success using experimental introductions of a biological control agent

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