Explain the observations made by charles darwin when he visited the finches and tortoise at the galápagos islands

He observed somewhat similar species with traits that suited their particular environment

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it