"evolutionary terms" is the chance of survival not having more babies.
^^^^^
CB: In natural selection terms, the only thing that matters
about surviving is surviving long enough to have babies.
http://evolution.berkeley.edu/evosite/evo101/IIIENaturalSelection.shtml
Natural Selection
.
Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles:
There is variation in traits. For example, some beetles are green and some are brown.
1)There is differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. ( The shorter survival matters because it means having fewer baby green beetles - CB)
2)There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis. ( The significance of the longer survival for natural selection is that there are more brown beetle babies - CB)
End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown. ( Brown Power ! - Cbrown)
If you have variation, differential reproduction, and heredity, you will have evolution by natural selection as an outcome. It is as simple as that.