Wind can carry spores, pollen, seeds, and small invertebrates to considerable altitudes.

Birds can carry seeds in their digestive tracts or attached to their feathers and feet.

Insects and other small organisms can be carried by upward air currents.

These dispersal mechanisms are inefficient — most propagules that attempt to cross the cliff barrier do not make it to the summit, and most that do make it do not establish viable populations.

But over millions of years, rare successful colonization events accumulate, and each successful colonist becomes the ancestor of a potentially distinctive tepui population.

The result is a biogeographic pattern that researchers can analyze using molecular genetic tools: comparing the DNA of tepui species to that of their closest lowland relatives reveals how long ago the populations diverged, providing a clock for the timing of colonization and subsequent isolation.