Stratification.

Sometimes we want to stratify (break-up, arrange, or classify) features by spatial units or even other features, for example, ecosystems or local administration units.

Take this Giant Anteater. Its range is across three different ecosystems. If we don't stratify, any targets we set for the Anteater's distribution to be included in a conservation area may be located in just one ecosystem. 

This is problematic if our goal is to “represent, or sample, the full variety of biodiversity, ideally at all levels of organization” – a core systematic conservation planning principle. To solve this problem we can use stratification. 

Stratifying breaks up the original feature distribution into three new features, each with their own targets.