Chapter 14 - Microevolution

Question 1

Population

Answer 1

A group of individuals of the same species that live in the same area and interbreed

Question 2

Gene pool

Answer 2

All of the alleles in all of the individuals making up a population

Question 3

Microevolution

Answer 3

The smallest scale on which evolutionary change can be measured

Ex. When the relative frequency of a alleles in a population change over time

Question 4

Where do new alleles originate from?

Answer 4

Mutations

Question 5

Mutation

Answer 5

Change in the nucleotide sequence of DNA.

It is the ultimate source of genetic variation for evolution to act upon if mutation occurs on a cell that produces gametes to pass to offspring.

Question 6

What organisms are you more likely to see mutations in and why?

Answer 6

Prokaryotes because they multiply so rapidly and because they are haploid.

Question 7

What is the average mutation rate in plants and animals?

Answer 7

1 in every 100,000 genes per generation.

Question 8

What does the Hardy Weinberg equilibrium mean?

Answer 8

Means a population in NOT evolving because:
- the population is very large
- there’s no gene flow between populations
- there is no mutation
- there is random mating
- there is no natural selection

Question 9

Genetic drift

Answer 9

Results when chance events cause allele frequencies to fluctuate unpredictably from one generation to the next.

Has a greater impact on smaller populations.

Question 10

What are the 2 types of genetic drift?

Answer 10

1. The bottleneck effect
2. The founder effect

Question 11

The bottleneck effect

Answer 11

When a catastrophe occurs and kills large numbers of individuals of the population.
This reduces the gene pool, and can rapidly change allele frequencies within the population.

Question 12

The founder effect

Answer 12

The reduction of genetic variability that occurs when a small group of individuals becomes separated from a larger population.

Ex. A rare genetic trait chance is 1/100,000, if 10 individuals get stranded on an island and one person has the rare trait the chance is now 1/10 if they breed within the new population.

Question 13

Gene flow

Answer 13

The transfer of genetic material from one population to another.

Occurs when a population either gains or loses alleles when individuals migrate.

Question 14

Relative fitness

Answer 14

The contribution that individual makes to the gene pool of the next generation relative to the contributions of other individuals.

More “fit” individuals produce greater number of viable fertile offspring and pass on the most genes to the next generation.

Question 15

What are the 3 ways that natural selection can alter populations?

Answer 15

1. Stabilizing selection
2. Directional selection
3. Disruptive selection

Question 16

Stabilizing selection

Answer 16

Favours the intermediate phenotypes.
Tends to reduce variation of a population.

Ex. extremely light and extremely dark mice are eliminated, medium coloured mice continue on.

Question 17

Directional selection

Answer 17

Favours of the phenotypic extremes.

Ex. The darker coloured mice are selected and the population become gradually darker over time, with fewer light mice being produced.

Question 18

Disruptive selection

Answer 18

Favours the extremes over the immediate phenotypes.

Ex. The light and dark coloured mice continue on all the medium coloured ones are eliminated.

Question 19

Sexual selection

Answer 19

When individuals with certain traits are more likely to obtain mates than other individuals.

2 types:
1. Intersexual - individuals of one sex (usually females) choose their mate.
2. Intrasexual - when individuals (usually males) compete for a mate

Question 20

Sexual dimorphism

Answer 20

When there is a noticeable different between male and female species .

Ex. Male birds having bright feathers for attraction, females don’t.

Question 21

What things cause microevolution?

Answer 21

1. Natural selection
2. Genetic drift
3. Gene flow

Question 22

What things cause macroevolution?

Answer 22

1. Continental drift
2. Mass extinctions
3. Adaptive radiations