So the text is a support, because of the comma. In addition, the first sentence suggests an increased dependence for vegetables due to population increase.
Use block of four. Since its a support the latter half should convey the same idea too. If an increased population causes vegetables to be preferred over meat. Then a reduced population would cause the opposite, which is preferring meat over vegetable.
Second blank would be synonymous with decrease in population, first would be dependence. Recourse means to choose a better alternative, limiting is akin with reduced.
Note: Both independent phrases (after and before the semicolon) convey the same meaning. Reduced population and meat might seem like contrast, but it’s actually conveying the same idea but in a negative sense. Like for eg: I prefer coke over water on a sunny day and I prefer water over coke on a non-sunny day.
Hope this helps