Evolution

Question 1

What is human variation?

Answer 1

The genetic differences between people and populations

Human variation is influenced by environmental adaptations and genetic diversity.

Question 2

Why are humans different from one another?

Answer 2

A specific trait is more advantageous in a particular environment

Example: Paler skin allows for more vitamin D absorption in areas with little sunlight.

Question 3

What is the concept of race?

Answer 3

Socially constructed, defined by society, but has real implications like racism
No such thing as a race gene

There is no race gene.

Question 4

Do different skin colors have specific evolutionary advantages? Yes or No?

Answer 4

Yes:
* Darker skin provides protection from ultraviolet rays
* All mammal populations in warmer climates have more melanin

No:
* Fair-skinned populations exist at the same latitudes as dark-skinned populations
* Skin cancer affects individuals after they have children.

Question 5

What is the gene pool of a population?

Answer 5

All the alleles of all genes of each individual in that population
Provides the population’s genetic variation

Gene pools provide genetic variation for the population.

Question 6

What is microevolution?

Answer 6

Change in percentages or frequencies of alleles within populations
These are small events that lead to evolution within a population

These small events lead to evolution within a population.

Question 7

What are the five processes that can cause microevolution?

Answer 7

• Mutation
• Gene flow (migration)
• Non-random mating
• Genetic drift
• Natural selection - the most significant in the formation of new species

Question 8

What is the source of genetic variation in a population?

Answer 8

Mutations

Mutations provide selective advantages in changing environments.

Question 9

What is gene flow?

Answer 9

A random process where genes are exchanged between different populations

It tends to reduce genetic differences between populations.

Question 10

What is non-random mating?

Answer 10

Mating among individuals based on specific phenotypes or due to inbreeding

Inbreeding often results in health problems in animals.

Question 11

What is genetic drift?

Answer 11

Change in the gene pool of a population due to chance

More impactful in smaller populations.

Question 12

What is the Founder Effect?

Answer 12

Formation of new populations by a few individuals, leading to a reduced gene pool

This can result in reduced genetic diversity.

Question 13

What is the Bottleneck Effect?

Answer 13

Reduction of a population due to catastrophe, leading to a smaller, less diverse gene pool

Surviving populations may have lost alleles present before the decline.

Question 14

What is Hardy-Weinberg Equilibrium?

Answer 14

Condition where allele frequencies in a gene pool remain constant over time

Rarely maintained in nature; requires specific conditions.

Question 15

What are the five conditions for Hardy-Weinberg Equilibrium?

Answer 15

• Random mating
• Large population
• No movement in or out
• No mutations
• No natural selection

Question 16

What is stabilizing selection?

Answer 16

Occurs when individuals near the center of the phenotype range have higher fitness

Improves adaptation to constant environmental aspects.

Question 17

What is directional selection?

Answer 17

Occurs when individuals at one end of the phenotype range have higher fitness

Common during environmental change or migration.

Question 18

What is disruptive selection?

Answer 18

Occurs when individuals at both ends of the phenotype range have higher fitness

Can lead to the rise of two distinct phenotypes.

Question 19

What is speciation?

Answer 19

Formation of new species from existing species

Occurs when populations become reproductively isolated.

Question 20

What are pre-zygotic isolating mechanisms?

Answer 20

Mechanisms that impede mating or prevent fertilization between different species

Examples include behavioral, temporal, and mechanical isolation.

Question 21

What are post-zygotic isolating mechanisms?

Answer 21

Prevent hybrids from developing into viable, fertile individuals

Examples include zygote mortality and hybrid sterility.

Question 22

What are the two types of speciation?

Answer 22

• Allopatric speciation
• Sympatric speciation

Question 23

What is allopatric speciation?

Answer 23

Occurs when populations are separated by a geographical barrier

Leads to genetic divergence.

Question 24

What is sympatric speciation?

Answer 24

Occurs when populations diverge genetically in the same habitat

Often due to chromosomal changes or non-random mating.

Question 25

What is adaptive radiation?

Answer 25

Form of allopatric speciation where several new species evolve from a common ancestor ## Footnote Often occurs when species colonize new areas.

Question 26

What is divergent evolution?

Answer 26

Pattern of evolution where species become increasingly distinct from a common ancestor ## Footnote Driven by different selective pressures.

Question 27

What is convergent evolution?

Answer 27

Pattern of evolution where similar traits arise in different species due to similar environmental conditions ## Footnote Example: Wings of birds and bats.

Question 28

What are the two models of evolutionary change?

Answer 28

* Gradualism * Punctuated equilibrium

Question 29

What does gradualism propose about evolutionary change?

Answer 29

Evolutionary change occurs slowly and steadily over time ## Footnote Supported since Darwin's time.

Question 30

What does punctuated equilibrium propose about evolutionary change?

Answer 30

Evolutionary history consists of long periods of stasis interrupted by periods of divergence ## Footnote Recognizes both rapid and gradual changes in evolution.

Question 31

Norway Rat's resistance to poison (mutation)

Answer 31

It is likely that an allele already existed in the Norway rat population that gave some individuals resistance to the poison warfarin. When warfarin was applied, those individuals survived, reproduced, and passed on the allele. This selective advantage changed the allele frequency of this characteristic.

Question 32

Gene flow (migration)

Answer 32

Populations of a species are often isolated by physical barriers, like mountains or oceans. Gene flow is a random process where genes are exchanged between two different populations if/when these barriers are overcome.

Question 33

Grey wolves (migration)

Answer 33

Grey wolves will often travel great distances to find a neighbouring pack and mate with an individual in that pack. This brings new alleles into the distant pack and may change the allele frequencies and increase genetic diversity.

Question 34

Pollen (migration)

Answer 34

A windstorm may blow pollen from one population of flowers to another.