1. A computer-implemented method of rendering a map, the method comprising: determining, by a map feature system that includes one or more computers, a geographical range to be shown on a map; determining, by the map feature system, which geographic features are within the geographical range; identifying, by the map feature system, rank scores of the geographic features determined to be within the geographical range, at least some of the rank scores being derived from a degree of biodiversity of the geographic feature and at least one of (a) a first relationship between a land area occupied by the geographic feature and a total area of land on Earth, or (b) a second relationship between a water area occupied by the geographic feature and a total area of water on Earth; adjusting, by the map feature system, the identified rank score of each of at least one of the geographic features based on rank scores of related geographic features, wherein the adjusted rank score of the at least one of the geographic features depends on a relationship between the at least one of the geographic features and the related geographic features; determining, by the map feature system, which of the geographic features to show on the map based on a scale of the map and the rank scores of the geographic features; and rendering, for presentation in a user interface, the map to show the determined geographic features.