Chapter 20.4 - Natural Selection Flashcards
Does the change in allele frequency over time impact the survival and reproductive capabilities of individuals?
Yes.
What is modern synthesis?
It is a combination of Darwin theory of natural selection and Mendelian genetics to form the current theory of evolution.
What are the three claims that natural selection depends on?
- There is variation among individuals within a species
- The variation is heritable
- There is competition for resources
Which plant is the most fit?
A. Plant who produces the most offspring by 5% in comparison to the other plant.
B. Plant who survives the longest.
C. Plant who reproduces with 7 other plants.
D. Plant who has the most vibrant colour.
A. plant who produces the most offspring by 5% in comparison to the other plant. This is because fitness is related to who has more surviving offspring.
What is positive selection?
Natural selection that favors advantageous mutations
What is negative selection?
Natural selection that decreases the frequency of a deleterious mutation
Does negative selection act on all deleterious mutations?
No. It only acts on homozygous mutations that are expressed.
Why will negative selection never get rid of a deleterious mutation?
It does not act on the heterozygous mutations, as the deleterious mutation will not be expressed.
What is balancing selection?
Keeping allele frequency between 0-1
What is a heterozygote advantage?
When a heterozygous fitness is higher than homozygous, so they are kept at an intermediate level.
Stabilizing selection
Maintains the avg of the trait. In other words favors the middle.
Directional selection
Change in trait overtime
Disruptive selection
Favors extremes against intermediate forms
Selective pressure
The set of environmental conditions that give an advantage for some organisms to survive and reproduce over others.
Sexual selection
Promotes traits that inc reproductive opportunities
