As long as no species would exceed its Population, the three species would get 2, 4, and 4 Plant Food. However, if at any time a food could not be taken as a result of Population limits, the numbers would be lower.
To work this out, let's say you have species {A}, {B} and {C}.
- {A} has the traits Long Neck, Foraging, and Cooperative.
- {B} has Foraging and Cooperative.
- {C} has neither.
After each trait triggers, I'll note the amount of cumulative food like this: ({A}:0; {B}:0; {C}:0).
When the Food Cards are revealed,
- {A} is going to take 1 Plant Food from the Food Bank because of Long Neck ({A}:1; {B}:0; {C}:0).
- {B} takes 1 Plant Food from the Food Bank because of {A}'s Cooperation ({A}:1; {B}:1; {C}:0).
- {C} takes 1 Plant Food from the Food Bank because of {B}'s Cooperation ({A}:1; {B}:1; {C}:1).
- {B} takes another 1 Plant Food from the Food Bank because of its Foraging trait ({A}:1; {B}:2; {C}:1).
- {C} takes another 1 Plant Food from the Food Bank because of {B}'s Cooperation ({A}:1; {B}:2; {C}:2).
So far, the only thing {A} has used is the Long Neck trait. Continuing on:
- {A} takes an additional 1 Plant Food from the Food Bank because of Foraging, which is triggered from the Long Neck ({A}:2; {B}:2; {C}:2).
- {B} takes 1 Plant Food from the Food Bank because of {A}'s Cooperation ({A}:2; {B}:3; {C}:2).
- {C} takes 1 Plant Food from the Food Bank because of {B}'s Cooperation ({A}:2; {B}:3; {C}:3).
- {B} takes another 1 Plant Food from the Food Bank because of its Foraging trait ({A}:2; {B}:4; {C}:3).
- {C} takes another 1 Plant Food from the Food Bank because of {B}'s Cooperation ({A}:2; {B}:4; {C}:4).
Final tally: {A} gets 2 Plant Food, {B} gets 4 Plant Food, and {C} gets 4 Plant Food.
This assumes that Population limits are not met. If, for example, {A} met it's limit after just the Long Neck trait, steps 6-10 would be skipped because {A} didn't take a second Plant Food from its Foraging trait.
Rules can be found here.