DU Zoology geeks: Do animal populations react differently right before extinction?

[Taverner]

Like when their numbers start dwindling, and they are not as common in the Animal Kingdom as they once were - do the animal populations act differently, or do they behave as they did for thousands of years...

Or does this differ from species to species?

[exboyfil]

1. I don't think individual animals understand that they are

on the verge of extinction. I would think that solitary animals will notice that no mate is available for procreation and that would be a problem for them. They would probably welcome the lack of competition for food.

Group animals that depend on each other would notice that their group is declining and making it for vulnerable for all (for example penguins trying to shettle their rooks, zebras trying to confuse predators, etc). They would adopt different survival mechanisms depending upon there intelligence and prior genetic wiring I would think.

As far as knowing their entire species is dying - I don't think they would have a clue.

[Taverner]

2. Thats what I was talking about

It seems in Natural Selection, behavior-based characteristics get changed faster (say less than 5 generations) than others just based on the ramifications.

[izquierdista]

3. Lots of species differences

If they can adapt, then yes, that would be acting differently, so that is kind of circular reasoning.

This reference on the Lotka-Volterra equation may help to explain: http://en.wikipedia.org/wiki/Lotka-Volterra_equation

Looking at the population curves, at any local minimum, there is the possibility of falling below the level needed to restore the population and then the species could go extinct. Such an overshoot would not be something that could be corrected by the members of the population acting differently.

On the other end, there are changes in behavior that can occur when populations go to maxima. Grasshoppers in large enough numbers turn into locusts which exhibit different behavior and exhaust their environment so that it can only support them as grasshoppers.

[TZ]

4. Well ecologically speaking yes...

More reproductive inducing behavior will occur. Its the same thing when a population grows to be too large for its environment. Behaviors that limit population control happen (including homosexual behavior!)
Sometimes this leads to genetically reduced populations as sibling and parental mating will occur if there aren't many individuals left. The cheetah is a population that has very little genetic diversity, possibly because of this.
Also weaker animals that might not survive in otherwise thriving populations will have the chance to reproduce which unfortunately leads to populations more subject to disease and other infirmaties.
There are minimal limits that populations of animals can't survive without intervention...