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. 2015 Apr 22;6:6844. doi: 10.1038/ncomms7844

Figure 1. Experimental evolution of dispersal and movement strategies across six replicated range expansions.

Figure 1

(a) Change in movement velocity of individuals in the range core and at the range margin (mean±s.e.; six replicates) over the experimental time period. Dark lines are LMM fits (time: N=156, df=150.72, t=5.75, P<0.001; range position: N=156, df=150.73, t=−1.41, P=0.16; time-range position interaction: N=156, df=150.73, t=−12.0, P<0.001). (b) Dispersal rates (proportion individuals dispersed) significantly increased in the populations at the range margin between day 0 and 24 (median and quartiles; GLMM: N=12, z=2.69, P=0.007), showing that increased velocity translates into higher dispersal rates. (c) The observed differences in movement velocity at the end of the evolution experiment (30% increase at the range margin and 60% decrease in the range core, mean±s.e.; total height of the bars, that is, dark and light coloured areas) remained significant after two days (∼10 doubling time periods) of common garden (8% increase and 12% decrease, only darker shaded area of the bars; LMM, time: N=24, df=6.32, t=1.14, P=0.3; range position: N=24, df=14.94, t=2.11, P=0.052; time-range position interaction: N=24, df=14.94, t=−4.25, P<0.001). Stars indicate significance levels (*: <0.05, **: <0.01, ***: <0.001).