Dispersal limitation and seed predation drive rarity of a plant species at its range edge
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Date
2025
Authors
Neigel, Emma R.
Schwinghammer, Timothy D.
McCune, Jenny L.
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
1. Understanding the causes of species rarity is a central goal in ecology. The three
filters thought to predict if a species is present or not in a community are the suit-
ability of abiotic conditions, dispersal limitation and biotic interactions. Theory
emphasizes the importance of the availability of abiotically suitable habitat in de-
termining occurrence frequency, especially for species at their range edge, where
the amount of suitable habitat is predicted to decline. However, the relative influ-
ence of these filters in driving species rarity is mostly unknown.
2. We used species distribution models (SDMs) to estimate habitat suitability based
on broad-scale abiotic predictors for a rare plant species (Stylophorum diphyllum)
at the northern edge of its global distribution. We tested the role of dispersal limi-
tation by planting seeds in unoccupied sites that varied in their predicted habitat
suitability and measured seedling emergence and seedling survival over 2 years.
To manipulate the biotic interactions, we excluded seed predators by caging half
of the seeds. We also measured the microclimate at each microsite, including soil
moisture, temperature and canopy cover.
3. The habitat suitability estimated by the SDMs did not predict seedling emergence or
short-term seedling survival. We found that dispersal limitation coupled with seed pre-
dation was a significant predictor of seedling emergence, while microclimate, specifi-
cally microsite temperature, was a significant predictor of short-term seedling survival.
4. Synthesis. Contrary to the assumption that species occur at a low frequency near
their range edges due to a lack of suitable habitat, we found that dispersal limita-
tion coupled with biotic interactions can drive rarity. If this is the case for many
rare species at risk of extinction at their range edges, effective conservation
strategies must incorporate assisted dispersal (i.e. translocations) into appropri-
ate microsites and the management of biotic interactions to establish new popu-
lations and ensure long-term persistence.
Description
Open access article. Creative Commons Attribution-NonCommercial 4.0 International license (CC BY-NC 4.0) applies
Keywords
Community assembly , Community theory , Conservation , Habitat suitability , Rare plant , SDM , Seed addition , Species at risk , Species distribution model
Citation
Neigel, E. R., Schwinghammer, T. D., & McCune, J. L. (2025). Dispersal limitation and seed predation drive rarity of a plant species at its range edge. Journal of Ecology, 113(8), 2148-2159. https://doi.org/10.1111/1365-2745.70083