HELP WITH A B A What is the result of directional selectio

HELP WITH A ,B ??

A ) What is the result of directional selection? Stabilizing selection? Disruptive selection?

b) Why can’t natural selection fashion perfect organisms?

Solution

A. RESULTS OF SELECTION

DIRECTIONAL SELECTION :- New phenotypes are produced.

STABILIZING SELECTION :- Genetic variance is decreased within the population

DISRUPTIVE SELECTION :- Intermediate varaints are results these are neither dominant nor recessive.

FEATURES OF DIRECTIONAL SELECTION :-

FEATURES OF STABILIZING SELECTION:-

Under stabilising selection extreme varieties from both ends of the frequency distribution are eliminated. The frequency distribution looks exactly as it did in the generation before. A real life example is that of birth weight og human babies.

FEATURES OF DISRUPTIVE SELECTION:-

Under disruptive selection both extremes are favored at the expenses of intermediate varieties. This is uncommon but theoretical interest because it suggest mechanism for species formation without geographic isolation.

B. Natural selection is not perfect organism because :-

Genetic drift, random change in the allele frequencies causing sample error across generations in a finite population. Due to this polymorphism no organism is perfect.