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Although many species shift their phenology with climate change, species vary significantly in the direction and magnitude of these responses (i.e., phenological sensitivity). Studies increasingly detect early phenology or high phenological sensitivity to climate in non-native species, which may favor non-native species over natives in warming climates. Yet relatively few studies explicitly compare phenological responses to climate between native vs. non-native species or between non-native populations in the native vs. introduced range, limiting our ability to quantify the role of phenology in invasion success. Here, we review the empirical evidence for and against differences in phenology and phenological sensitivity to climate in both native vs. non-native species and native and introduced populations of non-native species. Contrary to common assumptions, native and non-native plant species did not consistently differ in mean phenology or phenological sensitivity. However, non-native plant species were often either just as or more sensitive, but rarely less sensitive, to climate as natives. Introduced populations of non-native plant species often show earlier reproduction than native populations of the same species, but there was mixed evidence for differences in phenological sensitivity between introduced and native plant populations. We found very few studies comparing native vs. invasive animal phenology. Future work should characterize phenological sensitivity to climate in native vs. non-native plant and animal species, in native vs. introduced populations of non-native species, and across different stages of invasion, and should carefully consider how differences in phenology might promote invasion success or disadvantage native species under climate change.
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This content will become publicly available on May 26, 2027
Climate mediates phenological and phylogenetic differentiation in plant invasions
Darwin’s Naturalization Conundrum holds that both functional similarity and distinctiveness can facilitate biological invasions: invaders similar to natives may succeed through preadaptation to local abiotic conditions, whereas functionally distinct invaders may succeed by reducing competition. Yet the contexts in which either mechanism dominates are unclear. Prior research has primarily attributed variability in native–invasive differentiation to shifts in the balance between biotic and climatic barriers to invasion from local to regional scales. However, similarity and distinctiveness are frequent at both local and regional levels, indicating key drivers of native–invasive differentiation remain overlooked. Crucially, theory and evidence show that as climatic stress increases, competition weakens. This implies that harsh climates should favor invaders functionally similar to natives, whereas mesic climates should favor distinctiveness. However, this hypothesis has not been tested across climate regimes and functional traits. We addressed this gap by combining models of species distributions and flowering phenology for 2,810 species across the United States, estimating phylogenetic distance and phenological differentiation between natives and invasives relative to differentiation among co-occurring natives. In warm, humid regions, invasives flowered earlier, less synchronously, and were more distantly related to natives. In cold or dry regions, they flowered at similar or later times, more synchronously, and were more closely related than natives themselves. Across all climates, invasives consistently exhibited longer flowering durations, with little evidence of greater phenological plasticity. These findings reveal that Darwin’s Conundrum reflects a predictable continuum shaped by environmental context, highlighting climate as a key axis of invasion success.
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- PAR ID:
- 10688021
- Publisher / Repository:
- National Academy of Sciences
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences
- Volume:
- 123
- Issue:
- 21
- ISSN:
- 0027-8424
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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