How does biodiversity sustain a population in an area?

If there was a sudden, significant event in the area (such as a volcanic eruption) then a population with higher biodiversity is more likely to contain at least 1 species which will be adapted enough to survive in the changed environment than an area with lower species diversity.

The  pan-african movement  was an "emotional, cultural, psychological and ideological  movement  that began among the  african  dispora in the western hemisphere, for a closer  purpose, so that  african  people could feel secure, attain political, economic as well as psychological power visa vis other races or world regions" .