Обсуждение:Butterfly model

Pe’er et al. (2005) quantified corridor width by dividing the number of patches visited by all individuals during 1000 time steps by the distance between the start patch and the hill’s summit. In our version of the model, different butterflies can start and end in different places, so we slightly modify this measure. We will quantify the width of the “corridors” used by all butterflies as (a) the number of patches that are visited by any butterflies divided by (b) the mean distance between starting and ending locations, over all butterflies. This corridor width measure should be low (approaching 1.0) when all butterflies start at the same place and follow the same, straight path uphill, but should increase as the individual butterflies follow different, increasingly crooked, paths.

The measure of corridor width for a group of uphill-migrating butterflies (here, 500 butterflies that started at location 68,65 with q = 0.4). Corridor width is (a) the number of patches used by any butterflies (the white patches here), divided by (b) the average straight-line distance (in units of patch lengths) between butterflies’ starting patch and ending hilltop. Here, most butterflies went up the two lower hills, but some went up the upper hills. The number of white patches is 4266 and the mean distance between starting point (the black dot) and ending points for all butterflies is 62.0 patches; hence, corridor width is 68.8 patches.