Severity of impacts of an introduced species corresponds with regional eco‐evolutionary experience

Abstract

Invasive plant impacts vary widely across introduced ranges. We tested the hypothesis that differences in the eco‐evolutionary experience of native communities with the invader correspond with the impacts of invasive species on native vegetation, with impacts increasing with ecological novelty. We compared plant species richness and composition beneath Pinus contorta to that in adjacent vegetation and other P. contorta stands across a network of sites in its native (Canada and USA) and non‐native (Argentina, Chile, Finland, New Zealand, Scotland, Sweden) ranges. At sites in North America and Europe, within the natural distribution of the genus Pinus, P. contorta was not associated with decreases in diversity. In the Southern Hemisphere, where there are no native Pinaceae, plant communities beneath P. contorta were less diverse than in other regions and compared to uninvaded native vegetation. Effects on native vegetation were particularly pronounced where P. contorta was a more novel life form and exhibited higher growth rates. Our results support the hypothesis that the eco‐evolutionary experience of the native vegetation, and thus the novelty of the invader, determines the magnitude of invader impacts on native communities. Understanding the eco‐evolutionary context of invasions will help to better understand and predict where invasion impacts will be greatest and to prioritize invasive species management.

Towards a framework for understanding the context dependence of impacts of non‐native tree species

“…Pre‐introduction evolutionary history, such as eco‐evolutionary experience, can play a major role in impacts of non‐native species during the acute phase of invasion (Zenni, Dickie, et al, ). For example, greater impacts are seen in regions where there are no native equivalents of the invading non‐native species (Davis, Callaway, et al, ). As such, non‐native P. contorta has greater impacts in the Southern Hemisphere where there are no native Pinus spp.…”

“…compared to its impact in the Northern Hemisphere where other Pinus spp. do occur (Davis, Callaway, et al, ).…”

“…As many non‐native species occur over broad geographic ranges (Seebens et al, ), comparing a species’ impacts across regions or continents would inform predictions of its impacts over these larger scales. For example, non‐native pines have been shown to shift towards faster growth rates, greater reproductive efforts and higher rates of establishment in their introduced compared to native ranges (Davis, Callaway, et al, ). Third, there is a need to determine if our framework can be used in conjunction with other species data to predict future impacts of newly arrived or potential invaders.…”

Climate outweighs native vs. nonnative range‐effects for genetics and common garden performance of a cosmopolitan weed

“…, Davis et al. ). This biogeographic phenomenon can be caused by altered abiotic conditions and biotic interactions in nonnative ranges (Mitchell et al.…”

“…Nonnative species often show higher field performance in their nonnative than in their native ranges (Vil a et al 2011, Shah et al 2014, Ledger et al 2015, Davis et al 2018. This biogeographic phenomenon can be caused by altered abiotic conditions and biotic interactions in nonnative ranges (Mitchell et al 2006), such as release from specific antagonists present in the native range (Keane and Crawley 2002).…”