why do mammal reproduce in highly adverse conditions when fish and such do not?

[tantric]

ever tried to breed aquarium fish? everything has to be *perfect* or no dice. tried keeping mice? doesn't matter if they are starving, overcrowded and filled with disease - they keep on popping them out.

what is the difference?

 

[Keith&Co.]

The difference is how the species evolved, what solutions they came up with for environmental crises and which ones worked.
And it's not all mammals. If a human woman's body fat drops below a certain point, she becomes infertile. If men's caloric intake drops too low, they lose their sex drive.

 

[EricK]

Ever tried to breed giant pandas?

 

[Bronzeage]

ever tried to breed aquarium fish? everything has to be *perfect* or no dice. tried keeping mice? doesn't matter if they are starving, overcrowded and filled with disease - they keep on popping them out.

what is the difference?

I think the operative word with mice is "keeping." It's not possible for you to keep mice and starve them at the same time. I think if you were to carefully control the food supply and keep the caloric value to subsistence level, infant mortality would increase, and reproduction would decline quickly.

Besides the fact that one is under water and the other is not, a fish's environment is greatly different from that of a mouse. The fish may need ideal conditions to spawn, but when spawning, releases hundreds of small fish to the world and has no more investment in them after that. All of a fish's work is done before birth. The survival rate is fairly low, so waiting for ideal environmental conditions are the most a most a mother can do.

 

[Deepak]

If you put the mice in the aquarium they won't fare so well.

 

[Loren Pechtel]

Mammals breed internally in a controlled environment. Fish breed externally in whatever the local environment is.

 

[Malintent]

Aquariums are very hard to keep for those purposes. In the wild, the marine environment does not change much... there is little adaptive capability in marine life. Things being just a little off in an aquarium would represent quite the catastrophic change in earths actual environment. mammals are studied much closer to their natural environment. they adapt to the same climate changes we do, and as easily as we do. so it is not a fair comparison... in reality, marine life reproduces like crazy, and regularly. The difference is in the stability of their captivity.