The phrase "population diversity" means that a group of people contains individuals with different characteristics, cultures, or backgrounds. Full definition
How to make people to accept increasing population diversity? (pathstomath.com)
The scientists say that their paper, which is the first to quantify the stabilizing effects of population diversity, is a «game changer» because it suggests better ways of managing species everywhere. (scientificamerican.com)
Scientists at the University of Washington in Seattle's (U.W.) School of Aquatic and Fishery Sciences think they know why Bristol Bay is so productive year after year: Several hundred discrete populations of sockeye salmon inhabit the network of rivers and lakes that empty into the bay, and this tremendous population diversity buffers the entire fishery against the vicissitudes of the environment. (scientificamerican.com)