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Abstract AimAlternative hypotheses of Darwin's Naturalization Conundrum (DNC) predict that the non‐native species that successfully establish within a community are those either more closely or more distantly related to the resident native species. Despite the increasing number of studies using phylogenetic data to testDNCand evaluate community assembly, it remains unknown whether phylogenetic relationships alone can be used to predict invasion susceptibility across communities differing environmentally and in disturbance history. In this study, we evaluate whether phylogenetic structure of diverse native communities predicts the occurrence of non‐native species and offers insight into community assembly. LocationEastern United States of America. MethodsWe examine multiple communities across a north–south transect of the eastern United States to test whether non‐native species richness and abundance are associated with phylogenetic diversity measures of the native community. We also test whether non‐native species are consistently closely or distantly related to native species using two approaches differing in phylogenetic scale and whether this differs with ecologically successful species. ResultsOur analyses did not unambiguously resolveDNC. Non‐native species richness and abundance decreased with increasing native species phylogenetic diversity. Within some communities, non‐native species were significantly more closely related to native species than expected by chance, and tended to be more often closely related to a native species than that native species was to other native relatives. When considering species abundance, only one community showed that ecologically successful non‐native species were closely related to resident species. Main conclusionsPhylogenetic relationships can reveal important details about community assembly in diverse ecological settings. However, given the multifaceted nature of community assembly, phylogenetic metrics alone have limited utility as a general predictive tool for community invasion. Our study highlights a need to incorporate additional types of data to better understand why some communities are more susceptible to non‐native species establishment.
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This content will become publicly available on November 1, 2026
Evidence for environmental filtering and limiting similarity depends on spatial scale and dissimilarity metrics
Abstract Darwin's theory of natural selection provides two seemingly contradictory hypotheses for explaining the success of biological invasions: (1) the pre‐adaptation hypothesis posits that introduced species that are closely related to native species will be more likely to succeed due to shared advantageous characteristics; (2) the limiting similarity hypothesis posits that invaders that are more similar to resident species will be less likely to succeed due to competitive exclusion. Previous studies assessing this conundrum show mixed results, possibly stemming from inconsistent study spatial scales and failure to integrate both functional and phylogenetic information. Here, we address these limitations using a 33‐year grassland successional survey at Cedar Creek Ecosystem Science Reserve (USA). We incorporate functional dissimilarities, phylogenetic distances, environmental covariates, and species origin data for 303 vascular plant taxa (256 native, 47 introduced), collected from 2700 plots. In contrast with other studies, we test both hypotheses at two fine spatial scales—neighborhood (0.5 m2) and site (~40 m2)—to better capture competition and environmental filtering, respectively. Findings related to Darwin's naturalization conundrum depended on spatial scale and dissimilarity metric. Our results agreed with the pre‐adaptation hypothesis at site scale (40 m2)—a much finer resolution than typically used to test the pre‐adaptation hypothesis—highlighting the role of environmental filtering. At the neighborhood scale (0.5 m2), support for the limiting similarity hypothesis emerged when using functional dissimilarity, while phylogenetic distance aligned with the pre‐adaptation hypothesis, demonstrating that different dissimilarity metrics can yield contrasting conclusions. In addition, native and introduced species showed different abundance patterns in relation to functional ranked dissimilarities, with introduced species reaching higher cover when they were taller than co‐occurring species, had higher leaf dry matter content (LDMC) and lower seed mass. Introduced species also reached high cover with higher soil N concentrations and a shorter time after colonization, relative to native species. Our results suggest that inconsistent findings related to Darwin's naturalization conundrum may arise from an overreliance on single dissimilarity metrics and the use of spatial scales failing to capture underlying ecological processes. This highlights the need for more nuanced methodologies when testing the pre‐adaptation and limiting similarity hypotheses.
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- PAR ID:
- 10659509
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Ecology
- Volume:
- 106
- Issue:
- 11
- ISSN:
- 0012-9658
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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