Advancing Toward a General Theory of Invasive Species Impacts: How Do Ecological Effects Vary Across Time and Space?

Flory, S. Luke; Lockwood, Julie L.

doi:10.1002/bes2.1707

Cited by 5 publications

(3 citation statements)

References 21 publications

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“…Species introduction is a major threat to biodiversity and ecosystem functioning (Clavero & Garcia-Berthou, 2005;Flory & Lockwood, 2020). Most ecological impacts depend on both the functional similarities between introduced and resident species and the trophic positions of introduced species in the recipient food-webs (Mollot et al, 2017;Thomsen et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Changes in vertical and horizontal diversities mediated by the size structure of introduced fish collectively shape food‐web stability

Vagnon,

Pomeranz,

Loheac

et al. 2023

Ecology Letters

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Species introductions can alter local food‐web structure by changing the vertical or horizontal diversity within communities, largely driven by their body size distributions. Increasing vertical and horizontal diversities is predicted to have opposing effects on stability. However, their interactive effects remain largely overlooked. We investigated the independent and collective effects of vertical and horizontal diversities on food‐web stability in alpine lakes stocked with variable body size distributions of introduced fish species. Introduced predators destabilize food‐webs by increasing vertical diversity through food chain lengthening. Alternatively, increasing horizontal diversity results in more stable food‐web topologies. A non‐linear interaction between vertical and horizontal diversities suggests that increasing vertical diversity is most destabilizing when horizontal diversity is low. Our findings suggest that the size structure of introduced predators drives their impacts on stability by modifying the structure of food‐webs, and highlights the interactive effects of vertical and horizontal diversities on stability.

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Section: Introductionmentioning

confidence: 99%

Changes in vertical and horizontal diversities mediated by the size structure of introduced fish collectively shape food‐web stability

Vagnon,

Pomeranz,

Loheac

et al. 2023

Ecology Letters

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“…Competition from non‐native, invasive species is an increasing threat to the biodiversity of native species in a globalized world. Invasive species are often considered one of the most important threats to ecological function and a top driver of species extinctions (Dueñas et al, 2021 ; Flory & Lockwood, 2020 ). The presence of invasive species can alter animal communities, trigger trophic cascades, displace native species, and even lead to hybridizations with similar or related species (Doody et al, 2017 ; Huxel, 1999 ).…”

Section: Introductionmentioning

confidence: 99%

Timescale analyses of fluctuations in coexisting populations of a native and invasive tree squirrel

Desharnais

Muchlinski

Ortiz

et al. 2022

Ecology and Evolution

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Competition from invasive species is an increasing threat to biodiversity. In Southern California, the western gray squirrel ( Sciurus griseus , WGS) is facing competition from the fox squirrel ( Sciurus niger , FS), an invasive congener. We used spectral methods to analyze 140 consecutive monthly censuses of WGS and FS within a 11.3 ha section of the California Botanic Garden. Variation in the numbers for both species and their synchrony was distributed across long timescales (>15 months). After filtering out annual changes, concurrent mean monthly temperatures from nearby Ontario Airport yielded a spectrum with a large semi‐annual peak and significant spectral power at long timescales (>28 months). The cospectrum between WGS numbers and temperature revealed a significant negative correlation at long timescales (>35 months). Cospectra also revealed significant negative correlations with temperature at a six‐month timescale for both WGS and FS. Simulations from a model of two competing species indicate that the risk of extinction for the weaker competitor increases quickly as environmental noise shifts from short to long timescales. We analyzed the timescales of fluctuations in detrended mean annual temperatures for the time period 1915–2014 from 1218 locations across the continental USA. In the last two decades, significant shifts from short to long timescales have occurred, from <3 years to 4–6 years. Our results indicate that (i) population fluctuations in co‐occurring native and invasive tree squirrels are synchronous, occur over long timescales, and may be driven by fluctuations in environmental conditions; (ii) long timescale population fluctuations increase the risk of extinction in competing species, especially for the inferior competitor; and (iii) the timescales of interannual environmental fluctuations may be increasing from recent historical values. These results have broad implications for the impact of climate change on the maintenance of biodiversity.

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“…One facet of this confusion stems from differing notions and the understanding of what constitutes an invasive species “impact,” the scales at which it is important to assess this impact (Barney et al, 2013; Crystal‐Ornelas & Lockwood, 2020; Flory & Lockwood, 2020; Parker et al, 1999; Pearson et al, 2016; Ricciardi et al, 2013; Thiele et al, 2010), and furthermore how these impacts are managed (García‐Díaz et al, 2020; Thiele et al, 2010). Impact, whether it be ecological, on native diversity and ecosystem functioning, or social, on economic and agricultural systems, is a central component of the definitions and guidelines for invasive species prioritization (Blackburn et al, 2011; Cassey et al, 2018; Catford et al, 2009; Clark et al, 2010; Hawkins et al, 2015; Kumschick et al, 2012; Lockwood et al, 2013; Obama, 2016; Pearson et al, 2016; Robertson et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Quantifying and linking mechanism scenarios to invasive species impact

Cadotte

2022

Ecological Applications

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Plant species invasion represents one of the major drivers of biodiversity change globally, yet there is confusion about the nature of nonindigenous species (NIS) impact. This confusion stems from differing notions of what constitutes invasive species impact and the scales at which it should be assessed. At local scales, the mechanisms of the impact on local competitors can be classified into four scenarios: (1) minimal impact from NIS inhabiting unique niches; (2) neutral impact spread across the community and proportional to NIS abundance; (3) targeted impact on a small number of competitors with overlapping niches; and (4) pervasive impact that is disproportionate to NIS abundance and caused by modifications that filter out other species. I developed a statistical test to distinguish these four mechanism scenarios based on plant community rank‐abundance curves and then created a scale‐independent standardized impact score. Using an example long‐term dataset with high native plant diversity and an abundance gradient of the invasive vine, Vincetoxicum rossicum, I show that the impact resulted in either targeted or pervasive extirpations. Regardless of whether the NIS impact is neutral, targeted, or pervasive, the net outcome will be the homogenization of ecosystems and reduced biodiversity at larger scales, perhaps reducing ecosystem resilience. The framework and statistical evaluation of impact presented in this paper provide researchers and managers with an objective approach to quantifying NIS impact and prioritizing species for further management actions.

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Advancing Toward a General Theory of Invasive Species Impacts: How Do Ecological Effects Vary Across Time and Space?

Cited by 5 publications

References 21 publications

Changes in vertical and horizontal diversities mediated by the size structure of introduced fish collectively shape food‐web stability

Changes in vertical and horizontal diversities mediated by the size structure of introduced fish collectively shape food‐web stability

Timescale analyses of fluctuations in coexisting populations of a native and invasive tree squirrel

Quantifying and linking mechanism scenarios to invasive species impact

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