LECTURE 05: EVOLUTION OF POPULATIONS

Question 1

Evolution of population

Answer 1

the study of how the genetic makeup of populations changes over time, primarily through mechanisms like natural selection, genetic drift, mutation, and gene flow.

Question 2

Population

Answer 2

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.

Question 3

Gene pool

Answer 3

The complete set of different alleles (variations of a gene present in a population). It represents the genetic diversity of that population.

Question 4

non-evolving population

Answer 4

A non-evolving population is a theoretical concept where the genetic makeup (allele frequencies) of the population does not change over time. in other words, the population is in a state of genetic equilibrium, meaning that evolution is not occurring.

Question 5

the hard-weinberg equilibrium

Answer 5

This concept states that allele and genotype frequencies in a population will remain constant from one generation the next if certain conditions are met.

1. no mutations
2. random mating
3. no natural selection
4. large population size
5. no gene flow

Question 5

Natural selection

Answer 5

The process by which organisms with advantageous traits survive, reproduce, and pass on their traits to the next generation, leading to changes in the population over time.

Question 5

Struggle for existence

Answer 5

The competition among individuals of a species for limited resources like food, shelter, and mates

Question 6

genetic variability

Answer 6

The diversity in gene frequencies within a population, which is crucial for natural selection to act up.

Question 7

Mutations

Answer 7

changes in the DNA sequence of a gene, which can introduce new genetic variations into a population

Question 8

Intensity of selection

Answer 8

The strength with which natural selection acts on certain traits or genes in a population

Question 9

Stabilizing selection

Answer 9

A type of natural selection that favours the average individuals in a population and reduces variation.

Question 10

Directional selection

Answer 10

A type of natural selection that favours individuals at one extreme end of the trait spectrum.

Question 11

Disruptive selection

Answer 11

A form of natural selection in which individuals with extreme traits on both ends of the spectrum are favoured over those with average traits

Question 12

Sexual selection

Answer 12

A mode of natural selection where individuals with certain traits are more likely to attract mates and reproduce.

Question 13

Genetic drift

Answer 13

A mechanism of evolution that refers to random changes in the frequency of alleles in a population, especially in small populations.

Question 14

Sampling error

Answer 14

Random fluctuations in allele frequencies due to change events, often seen in small populations

Question 15

Bottleneck effect

Answer 15

A sharp reduction in the size of population due to environmental events, leading to a loss of genetic variation.

Question 16

Genetic drift and natural selection

Answer 16

while genetic drift is a random process, natural selection is non-random. Both can shape the makeup of a population

Question 17

Gene flow

Answer 17

the transfer of genetic variation from one population to another. It occurs when individuals migrate between populations, bringing new alleles into the gene pool.

Question 18

Mutation

Answer 18

genes. They are the original source of all genetic diversity within and between populations. When a mutation occurs, it can create a new version of a gene, known as an allele. This new allele can alter traits, potentially leading to differences in an organism’s appearance, behaviour, or physiology.

Question 19

How can mutations happen randomly and can they have different effects on an organism?

Answer 19

• Some mutations might benefit an individual, making it better suited to survive and reproduce in its environment.
• Others can be harmful, reducing an individual’s chance of survival or reproductive success.
• Some mutations might be neutral, having no noticeable impact on the organism’s fitness.

Question 20

Adaptive

Answer 20

These are genetic changes that increase an individual’s chances of survival and reproduction in a specific environment.

For example, a mutation that gives certain insects resistance to pesticides is adaptive because it improves their survival rates. Natural selection tends to favor these adaptive traits, leading to their spread through the population over time.

Question 21

Maladaptive variation

Answer 21

• These are genetic changes that reduce an individual’s fitness or ability to survive and reproduce in its environment
• For instance, a mutation causing a bird to have a less effective beak shape for its food source would be maladaptive. Individuals with such traits are less likely to survive and reproduce, so these variations are often removed from the population by natural selection.

Question 22

Neutral variation

Answer 22

• These genetic changes have no effect on an individual’s fitness. They do not improve or hinder survival and reproduction.
• An example might be a mutation that changes the colour of an organism’s fur to a shade that neither benefits nor harms it in its environment. Neutral variations can persist in a population because they are not targeted by natural selection.

Question 23

Nonrandom mating

Answer 23

A process in which individuals select mates based on certain traits, leading to changes in allele frequencies. Nonrandom mating can result in inbreeding or assortative mating, affecting genetic diversity.