Biological Evolution I

Question 1

What is evolution?

Answer 1

Process in which species accumulate changes over time, leading to development of new forms of organisms from pre-existing forms.
* Descent with modification via natural selection.

Question 2

Define evolution as descent with modification.

Answer 2

• All organisms are related through descent and share a common ancestor.
• Descendants accumulate modifications that help them better adapt to their environment.
• Descendants are different from their ancestors.

Question 3

What is microevolution?

Answer 3

Microevolution refers to changes in the allele frequency of a gene pool from one generation to the next.

It may bring about formation of new species if genetic changes result in reproductive isolation from its ancestral population.

Question 4

What is macroevolution?

Answer 4

Marcoevolution involves descent of different species from a common ancestor over many generations.

Question 5

Explain the link between microevolution and macroevolution.

Answer 5

1. Both are driven by natural selection.
2. Microevolution is small scale changes in allele frequencies at population level in a shorter period of time
3. Macroevolution is large scale changes in phenotypes across different populations and species over longer periods of time.

Question 6

What is the link between microevolution and macroevolution?

Answer 6

Macroevolution is the consequence of accumulated microevolution over a longer period of time.

Question 7

Define population.

Answer 7

A summation of all the organisms of the same species, who live in the same geographical area, and have the capability of interbreeding.

Question 8

Why is a population the smallest unit to evolve?

Answer 8

1. Individuals cannot mutate and change their alleles in their lifetime.
2. Changes in allele frequency cannot be obtained in an individual.
3. Individuals have to reproduce, pass down alleles to offspring in many generations –> change in allele frequency

Question 9

Define gene pool.

Answer 9

The collection of all the genes and the various allelic forms of those genes within a particular population.

Question 10

Define allele frequency.

Answer 10

The frequency or proportion of a particular allele in the gene pool of a population.

Question 11

State the conditions for natural selection to occur.

Answer 11

• Variation exists among individuals in a population.
• Differential reproductive success.
• Inheritable variation.
• Presence of selection pressure.

Question 12

Briefly outline the natural selection process.

Answer 12

1. Variation between individuals within a population.
2. Selective pressure.
3. Differential reproductive success.
4. Passing down advantageous alleles.
5. Change in allele frequency.

Question 13

State the drivers of microevolution.

Answer 13

• Natural Selection
• Genetic Drift
• Gene Flow

Question 14

What is genetic drift?

Answer 14

Random changes of allele and genotype frequencies, due to chance alone.
Eg: Bottleneck effect, Founder effect

Does not equal natural selection!

Question 15

What is the Bottleneck Effect?

Answer 15

When natural calamities, diseases or predators destory large numbers of individuals, resulting in large scale temporary reduction in population size.
Alleles can be under-represented, over-represented or completely removed.

Question 16

What is the Founder Effect?

Answer 16

When one or few individuals take over a new habitat or upon being isolated from their original population by chance.
- Alleles could be under-represented, over-represented or completely removed.

Question 17

What is gene flow?

Answer 17

Movement of alleles between populations that result in increased homogeneity and reduces differences between poplulations.
Eg: Via migration, travel