Question

tial Question 3 1/2 pts Sometimes random events impact gene frequencies in a population, causing evolution to occur. Two frequent causes of these fluctuations are Founder effect and bottleneck effect Answer 1: founder effect Answer 2: bottleneck effect rect Question 4 0/1 pts Some scientists would add a fifth evolutionary force, which is Force nonrandom mating differentiation Climate

Answer 1

3.

Bottleneck effect:

• The bottleneck effect results due to extreme condition of genetic drift.
• Bottleneck effect may be observed in relation to natural disasters like earthquakes, floods, fire, famine, or other catastrophic effect.
• This results in severe reduction in population size.

Founder effect:

• Results, when a small number of individuals from a population of a geographical region, establishes a new population in a different geographical region.
• Smaller the population, there is higher chance of genetic fixation of small-adaptive allele, due to random chance.

4. Answer: Non-random mating

The sources of evolution include:

1. Natural selection-

Types of natural selection include: All forms of natural selection lead to increase in fitness and adaptation.

a) Directional selection- Reduce genetic variation. Example: The bigger sized animal (like mice) are difficult for predation, which are beneficial for the species survival.

b) Stabilizing selection- Reduce genetic variation. Example: coat color of mice may be black, white or grey. Grey color proves to be more beneficial for camouflage in both day and night. Thus, after generations, grey mice will be more in number.

c) Disruptive selection- Increased genetic variation. Example: flap like skin growth between fingers of mice, which help them to glide away from their predators.

d) Sexual selection- refers to reproduction of the fittest, in case of adaptive evolution. Like intersexual conflict or sexual antagonism.

2. mutation-

• Mutations lead to variations in the DNA sequence, which results in new allele and thus genetic variation.
• However, most genomic alterations do not change the protein sequences. Most of the mutations are detected and repaired before expression into proteins.
• Evolutionary mutations are mainly Non-Synonymous substitution, which results in change in amino acid sequences.

3. Gene flow-

• leads to increased similarity between the remaining populations of the same species because it results gene pools closely resembling one another.
• When a population or individuals from population migrate and interbreed with individuals of another geographic region, gene flow results. Immigration or emigration

4. Genetic drift-

• Due to random selection of allele, variation, heterozygocity and thus, polymorphism will decrease.
• This leads to random selection of an allele, which is established in the population and increases its frequency, until the normal numbers are regained.
• Allele frequency changes, from the initial frequency.
• The reduced population size causes more effect by genetic drift.

5. Non-random mating:

• Mating process is based on selection of specific traits only.
• Hence, it is not a random process, like inbreeding or assertive mating.
• Thus, the factor which may not be responsible for the reduced allele frequency is the white eyed fly not being able to find the abundant food source in the island.
• ·