(N/A) Experiments on microorganisms show that pre-existing advantageous mutations,when selected,result in new phenotypes. Over a few generations,this leads to speciation.
Natural selection is a process in which heritable variations enable survival,lead to higher reproductive success,and result in the production of a large number of offspring. Logical analysis suggests that variations caused by mutation,gene flow,genetic drift,or recombination during gametogenesis result in changes in the frequency of genes and alleles in future generations.
Through natural selection,organisms increase their reproductive success and become established as a new population. Natural selection leads to three types of evolutionary changes:
$1$. Stabilizing selection: Where many individuals acquire the mean character value.
$2$. Directional change: Where many individuals acquire values other than the mean character value.
$3$. Disruptive evolution: Where more individuals acquire peripheral character values at both ends of the distribution curve.