Figure 2.
Results of the simulations of (a) single individuals and (b) whole populations. Individuals were moving with biased correlated random walk with time-dependent bias in three types of landscapes. The varying parameters were the switching time (h) and path straightness (ρ, reflected in the shade of the symbols). (a) Straight-line distance made and survival probability of individuals moving until they reach a patch. A single point reflects one individual, for which the probability of survival after making n steps was calculated assuming 1% per-step mortality (M), thus survival = (1 − M)n. (b) Mean velocity of populations' expansion (longitudinal shift in spatial units per generation). Each point is a result of one simulation of a population with different parameters. The population was allowed to expand its range over 2000 generations. In calculation of the mean speed, we included only the timesteps until the range reached the border of the landscape. The values of parameter ρ ranged from 0.75 to 0.99 between individuals/populations. The shape of the bias function was a sharp sigmoid (s = 25). ρ = 0.99 (white symbols), ρ = 0.97 (light grey symbols), ρ = 0.90 (dark grey symbols) and ρ = 0.75 (black symbols).