Indirect Effects and Context Dependency in Stream Fish Invasions

Diversity and Distributions, Journal Year: 2025, Volume and Issue: 31(1)

Published: Jan. 1, 2025

ABSTRACT Aim Invasion ecology is replete with a body of well‐supported yet contradictory evidence for numerous invasion hypotheses, likely as result context dependency. Context dependency in studies can arise two ways: (1) apparent , when results differ between solely due to methodical differences, or (2) mechanistic truly ecological processes. One form occurs causally linked factors associated success (hereafter, drivers ) either mask enhance each other's effect on success. Mechanistic occur regional scale processes modify the influence local Together, and give rise conflicting support hypotheses via confounding effects related region‐specific Location 2339 stream segments ecoregions United States. Methods Using fish community data distinct ecoregions, we constructed identical path models estimate direct indirect nonnative richness. We chose one variable index from following categories: propagule pressure, natural abiotic, anthropogenic abiotic biotic factors. Results found through presence effects, which pressure richness were modulated by The differed both regions, providing Main Conclusions Apparent lead hypotheses. Accounting important gaining more general understanding process. Furthermore, because varied regionally, it understand large‐scale that contextualise

Language: Английский

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Spatial Scale and the Underestimation of Stream Fish Community Invadedness

Global Ecology and Biogeography, Journal Year: 2025, Volume and Issue: 34(1)

Published: Jan. 1, 2025

ABSTRACT Scale‐Dependency of Native Status Classifying populations as native or nonnative requires well‐defined range boundaries for species. While many studies define status according to large biogeographic realms, natural dispersal barriers often limit species distributions at regional smaller spatial extents. As such, native/nonnative definitions are inherently scale‐dependent and estimates community invadedness thus depend on the resolution which is defined. For example, can be introduced among regions within ecological provinces (hereafter, simply “provinces”). By explicitly considering scale‐dependency definitions, we more effectively compare results across studies, comprehensively evaluate degree invasion levels, objectively communicate a Location 30,034 stream segments, conterminous United States. Time Period 2000–2023. Major Taxa Studied Freshwater fishes. Quantifying Fish Community Invadedness Across US Streams We illustrate importance by quantifying richness relative abundance in fish communities States, finding that provincially nearly four times prevalent extra‐realm species, represented approximately 10% all individuals average surveys. Implications Unrealistically broad underestimate invadedness. Dismissing regionally have severe consequences, including displacement hybridisation with loss unique through biotic homogenisation. These consequences may undermine efforts maintain protect distinct local biodiversity conserve endemic

Language: Английский

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Distance From the Road, Habitat Type and Environmental Factors Predict Distribution of Invasive and Native Plant Species in the Above‐Ground Vegetation and Soil Seedbanks

Diversity and Distributions, Journal Year: 2025, Volume and Issue: 31(2)

Published: Feb. 1, 2025

ABSTRACT Aim Road networks are common landscape disturbances that can facilitate the spread of invasive plants. This study explored influence distance from road, habitat type and broader environmental factors in shaping distribution patterns both native species above‐ground vegetation soil seed banks. Location Guangxi, China. Methods We collected data on plant composition banks at six distances road edge: 0 m, 2 4 9 14 m 24 three types, including abandoned land, Eucalyptus plantations natural secondary forests. variables each sampling location. examined compositional similarity communities by non‐metric multidimensional scaling (NMDS) identified redundancy analysis (RDA). Results Our results indicated richness decreased with especially Conversely, did not show consistent relative to roads across various habitats. The was similar vegetation, while only 13.33% were observed vegetation. characteristics, human disturbance properties correlated species, strength these correlations varying among types. density plants associated presence alien types Main Conclusions highlights proximity critical determining within nature reserves. Moreover, it underscores importance integrating bank perspectives for effective management strategies control promote communities.

Language: Английский

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Nonnative Species Richness and Dominance Reveal Differing Support for Invasion Theory at a Continental Extent

Global Ecology and Biogeography, Journal Year: 2025, Volume and Issue: 34(5)

Published: April 30, 2025

ABSTRACT Aim Empirical tests of conceptual hypotheses describing species invasions often differ depending on the spatial scale (spatial resolution and extent study area) at which they were conducted. Some this disparity may arise from tradeoffs in data quality necessitating use different indices community invadedness among scales. Local‐scale studies typically fine‐resolution, descriptive measures (‘dominance’, proportion nonnative individuals) limited extents, while macroscale aggregate datasets to cover large extents but coarser less (nonnative richness). We investigated consequences using represent scales, explored implications for hypothesis testing when richness dominance are not related. Location 23,793 stream segments within 17 regional watersheds, conterminous United States. Time Period 2000–2023. Major Taxa Studied Freshwater fishes. Methods Using a large‐extent, fine‐resolution dataset, we evaluated correlation between communities, compared empirical support prominent invasion (biotic resistance, disturbance facilitation) identical Bayesian hierarchical models with represented by each metric. Results Nonnative weakly correlated, allowing us classify communities into four archetypes based relationships two indices. both differed overall watersheds. Main Conclusions describe facets process under‐ or over‐represent considered alone. estimating metrics be an important source scale‐dependent inference ecology. When assembling studies, retaining fine as much possible will allow researchers opportunities more potentially complementary invadedness.

Language: Английский

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Intraspecific and biogeographical variation in foliar fungal communities and pathogen damage of native and invasivePhragmites australis

Global Ecology and Biogeography, Journal Year: 2020, Volume and Issue: 29(7), P. 1199 - 1211

Published: March 26, 2020

Abstract Aim Recent research has highlighted that the relationship between species interactions and latitude can differ native invasive plant taxa, generating biogeographical heterogeneity in community resistance to invasions. In first study with foliar pathogens, we tested whether co‐occurring lineages of common reed ( Phragmites australis ) exhibit non‐parallel latitudinal gradients fungal communities, pathogen susceptibility damage, these patterns influence success invasion. Location North America. Time period 2015–2017. Major taxa studied Perennial grass P. . Methods We surveyed 35 field populations, spanning 17° comprising four phylogeographical lineages, including one endemic America from Europe. For each population, quantified percentage leaf damage cultured fungi diseased leaves, which identified using molecular tools. To assess had a genetic basis, inoculated plants 73 populations putative pathogens complementary garden experiment measured (i.e., area). Results isolated 84 taxa. lineage influenced composition but not diversity. Despite European being least susceptible three experiment, was similar providing no evidence release contributes Genetically based observed were isolate specific obscured by local environmental conditions field, where threefold higher for northern compared southern regardless lineage. Main conclusions Our results highlight host genetically strongly communities susceptibility, do translate field.

Language: Английский

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