4 factors in population?

Question

What are the 4 factors that produce changes in population size?

Answer 1

THE 4?   I hate to be constrained by other peoples definitions. I will offer the following (some are related) :  food supply.  climate; both average and extremes.  Water supply.  relationships with neighboring tribes or states: warfare or trade.  medical facilities,  WATER TREATMENT PLANTS, religion, technological level, sustainability of agriculture,  diversity of plants and animals raised for food.  Education level.  Endemic diseases. Willingness to change vs adherence to tradition. I could probably come up with more but people keep asking me things.  Of course, being a reference librarian thats my job, but I don't have to like it.

Answer 2

This might belong in the Biology section.

I can think of changes in food supply, changes in size of habitat, appearance of an invasive species, changes in environment (rainfall, temperature, etc.), lack of genetic variability (inbreeding), and genetic drift. I am sure there are more, but Biology was a looooong time ago.

Answer 3

reproduction rate

death rate / mortality rate

Ecological niche room (this has to do with the availability of resources and room to live)

Competition (for said resources)

Others include evolution...this will allow the organism to change over time and better adapt to a changing environment