Invasion triple trouble: Environmental fluctuations, fluctuation-adapted invaders and fluctuation-mal-adapted communities all govern invasion success

24 25 It has been suggested that climate change will lead to increased environmental 26 fluctuations, which will undoubtedly have evolutionary consequences for all biota. For 27 instance, fluctuations can directly increase the risk of invasions of alien species into 28 new areas, as these species have repeatedly been proposed to benefit from disturbances. 29 At the same time increased environmental fluctuations may also select for better 30 invaders. However, selection by fluctuations may also influence the resistance of 31 communities to invasions, which has rarely been tested. We tested eco-evolutionary 32 dynamics of invasion with bacterial clones, evolved either in constant or fluctuating 33 temperatures, and conducted experimental invasions in both conditions. We found clear 34 evidence that ecological fluctuations, as well as adaptation to fluctuations by both the 35 invader and community, all affected invasions, but played different roles at different 36 stages of invasion. Ecological fluctuations clearly promoted invasions, especially into 37 fluctuation mal-adapted communities. The evolutionary background of the invader 38 clearly played a smaller role, and only at the later stages of invasion in the fluctuating 39 environments. Our results indicate that climate change associated disturbances can 40 directly increase the risk of invasions by altering ecological conditions during invasions, 41 as well as via the evolution of both the invader and communities. Our experiment 42 provides novel information on the complex consequences of climate change on 43 invasions in general, and also charts risk factors associated with the spread of 44 environmentally growing opportunistic pathogens. 45 46 . CC-BY-ND 4.0 International license not peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/186254 doi: bioRxiv preprint first posted online Sep. 8, 2017;