Since all ruby-throated hummingbirds migrate at around the same time each year, many populations that were possibly isolated during the winter intermingle during the summer breeding season. This annual migratory behavior results in a transfer of genetic information from one population to another, which is known as .

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.

A- a reduction in biodiversity