interstices are small spaces that intervene between things - in space or time - like the spaces between rocks in the bottom of a stream. And it is in the intersticies where interesting things are found
Back in the early 1990s when wolf recovery strategies were being developed, projections were made on how fast the population would increase from a wolf reintroduction option. This option was compared to a natural recovery option where wolves would recolonize central Idaho and the greater Yellowstone area.
What actually happened was much different, where population growth greatly exceeded the projections, as the blue and purple lines indicate.