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Menchions, Emma

University of British Columbia

Climate change is driving species ranges both polewards and upslope in elevation. These shifts may differ in rate or magnitude among species, leading to novel community formations and species interactions. Most research has focused on predicting range shifts and elucidating the evolutionary dynamics of range expansions for species on the move (range-shifting invaders). However, slower-moving (resident) species could also evolve when competing with range-shifting invaders. This could result in the evolution of increased resident biotic resistance, impeding the invader’s growth, as seen in biological invasions. Range-shifting invaders, however, may differ from invasive species in their selective impacts on resident competitors. Therefore, it remains unknown whether biotic resistance can also evolve in residents facing range-shifting invaders driven by climate change. Here we construct populations of eight duckweed genotypes (Lemna minor = resident), from various localities near and beyond the range edge of a potential range-shifting competitor, Spirodela polyrhiza (invader), and invade them with one genotype of S. polyrhiza. Such a scenario could occur in Northern Europe where climate change may propel S. polyrhiza to repeatedly invade L. minor populations inexperienced to competition with S. polyrhiza. Following 14 weeks of lab-simulated invasion, we observed significant rapid evolution and morphological plasticity in L. minor. Selection favoured faster growth rates and genotypes with less geographic proximity to (less co-evolutionary history with) S. polyrhiza. Morphological plasticity was inconsistent across L. minor genotypes, but some genotypes developed longer roots and larger raft sizes in invaded populations. Finally, we observed weak evidence for increased biotic resistance in L. minor when S. polyrhiza was re-introduced to previously invaded (experienced) L. minor populations. Collectively, rapid evolution and plasticity created subtle phenotypic differences in L. minor populations with invaders compared to those without, which may have driven increased biotic resistance to invasion in L. minor. Our results indicate that range-shifting species, even at low densities, may drive evolution, plasticity, and increased biotic resistance in resident competitors that could feed back to influence range expansion by the invader.

Text

2024-07-15

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88641

Botany

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/