Natural Selection and Microevolution

Question 1

How does natural selection occur?

Answer 1

The pressures of environmental selection (selection pressures) confer a selective advantage on a specific phenotype to enhance its chance of survival (viability) and reproduction (fecundity).

Question 2

Is the selection of allele frequency in a gene pool positive or negative?

Answer 2

Tt can be either positive or negative. (Benefit or disadvantage the population)

Question 3

Describe the differences between stabilising, directional and disruptive phenotypic selection.

Answer 3

-Stabilising, selection pressure favour the medium trait
-Directional, selection pressures favour one of the extreme traits
-Disruptive, selection pressures favour both extreme traits

Question 4

Explain microevolutionary change.

Answer 4

Microevolutionary change can occur through several processes:
-Mutations can cause small changes in phenotypes
-Natural selection from selection pressures can affect allele frequency, eliminating an allele
-Genetic drift means alleles may be separated and change
-Gene flow means alleles move between two populations which can change the allele frequency of a population causing changes