Sunday, January 16, 2011

Before I forget_3 _ DArwin's Principle of Evolution through Natural Selection

Hypothesis 1
Organisms produce more offsprings than that is needed. But not all survive until reproductive age. Most of them dies. And only some survives

Hypothesis 2
The number of individuals in each species remains approximately  constant over time

When the above two hypothesis are operational
Not all individuals survive
There is a struggle for existence.

Thus differential survival

Hypothesis 3
Individuals of a species are not all alike
They vary in form and behavior
Some characteristics of individuals are heritable

Hypothesis 4
Some varieties of heritable characteristics (which are called traits ) are more adaptive than others.


When the Hypothesis 3 and 4 are operational
Some kinds of individuals are more successful than the others. They have a greater chance of reproducing

Thus Differential Reproduction

These individuals with adaptive traits produce a greater proportion of the individuals in the new generation.
Those traits increase in frequency from generation to generation.

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