biology unit 2 test

What are the three main requirements for evolution by natural selection to occur?

1. Genetic variation (heritable differences)

2. Trait causes differences in fitness

3. Time (changes across generations)

what does mutation do?

Create new, genetic creation

what does gene flow do?

Move alleles between populations

what does genetic drift do?

Change allele frequencies by chance

what does natural selection do?

Favours advantages inherited traits

two types of genetic drift

Bottom, neck, effect, and founder effect

on what type of population does genetic drift work better

On smaller populations

mechanism of evolution: mutation

A random change in DNA that creates a new allele

mutation example

Mutation changes an animals fur Colour

genetic drift mechanism

Random changes in a allele frequencies due to change

genetic drift example

A storm randomly kills some beetles

non-random meeting mechanism example

Peacock the attractive feathers attract More mates

natural selection mechanism

Organism with advantages, inherited trait reproduce more successfully

non-random mating mechanism

Individual select may based on particular characteristics

natural mechanism example

Dark mode survive better and dark tree bark

mechanism gene flow example

birds, migrate and reproduce with another population

mechanism of evolution: gene flow

movement of allele from one population to another

How is fitness defined in evolutionary biology?

An organism's ability to survive and reproduce in its specific environment.

an example of evolution

Giraffes with longer necks may have an advantage when reaching food and tall treats of man and longer neck may become more common in the population

how and when does evolution happen?

• Evolution happens in populations, not individual Organisms

• It can lead to new adoptions a new species

• It involves change in allele Frequencies

• It occurs every many generations

what is a mechanism of evolution?

Mechanisms of evolution are processes that caused changes in the genetic make up of a population

what are the mechanisms of evolution?

• Mutation

• gene flow

• genetic drift

• natural selection

what do traits cause in Fitness?

Differences

how are treats pass down?

Randomly

Why do more fit variants drive evolutionary change in a population?

They produce more offspring, successfully passing down their genes for that specific trait to the next generation.

What did Charles Darwin mean by the phrase "survival of the fittest"?

Only the individuals that are well adapted to their environmental conditions manage to survive.

What is a selective pressure? Give three examples.

The evolutionary force that affects the fitness of a trait's variants. Examples:

• Competition for food, mates, or territory

• Evading predation

• Surviving disease or harsh weather

What happens to the gene pool over time during evolution?

The frequency of alleles changes, causing helpful adaptations to become more common.

What is the evolutionary definition of an adaptation?

A heritable trait that contributes to an organism's survival and/or reproduction.

What determines whether evolution occurs rapidly or slowly?

The strength of the selective pressure

In the peppered moth example, why did the black variants have higher fitness after the Industrial Revolution?

They were better camouflaged to avoid predation by birds on soot-darkened trees.

Over many generations, how did the allele frequencies of the peppered moth shift?

The frequency of 'white' alleles decreased, while the frequency of 'black' alleles increased.

How would Darwin break down the evolution of long necks in giraffes into 3 steps?

1. Variation: Ancestral giraffes naturally had different neck lengths due to random genetic differences.

2. Fitness: Longer-necked giraffes reached more food, survived better, and reproduced more.

3. Time: Over generations, long-neck alleles became increasingly common in the gene pool.

Why is the idea of an organism's "desire to change" incorrect in modern evolution?

Populations do not evolve because they want to. Evolution happens strictly due to differential success in survival and reproduction.

Complete the biological rule: "Populations evolve; ____________ do not evolve."

Individuals

What is the only mechanism by which entirely new alleles and new variations can be produced?

Mutation

Are mutations intentional, and how do they typically affect an organism's fitness?

Mutations are completely random, and they usually have a negative or neutral effect on fitness.

Is Pokémon "evolution" closer to Lamarckian or Darwinian evolution? Why?

It is closer to Lamarckian evolution. The individual changes its own traits within its single lifetime due to its own effort/experience, rather than a population changing across generations.

What occurs during Directional Selection?

One extreme phenotype is favored over the others, shifting the population distribution toward that extreme.

What occurs during Stabilizing Selection?

The average phenotype is selected for, while the extremes are selected against.

What occurs during Disruptive Selection?

Both extremes are favored, while the average phenotypes are selected against.

What sets Artificial Selection (Selective Breeding) apart from Natural Selection?

The selective pressure is determined entirely by humans breeding organisms for specific purposes (e.g., companion animals, farm livestock), rather than by the natural environment.

What are the four mechanisms of evolution, and how does each change the gene pool?

• Natural Selection: Non-randomly shifts alleles based on environmental fitness.

• Mutation: Randomly introduces entirely new alleles into the gene pool.

• Gene Flow: Moves existing alleles between different populations via migration.

• Genetic Drift: Randomly changes allele frequencies due to pure chance events.

What is the definition of Gene Flow?

The passage of genetic information from the gene pool of one population to another (migration).

What is the definition of Genetic Drift?

Random changes to the allele frequencies in a population due entirely to chance.

Is there a selective pressure acting on alleles during genetic drift?

No. It is driven entirely by chance events. It doesn't matter if an allele is beneficial, harmful, or neutral.

Does genetic drift cause evolution to occur fastest in a large population or a small population?

In a small population, because random chance events have a much larger percentage impact on a tiny gene pool.

Is the specific outcome of genetic drift predictable?

No, because it is based entirely on random occurrences. You cannot predict which specific alleles will randomly increase or decrease.

What is the Bottleneck Effect?

A sharp, temporary reduction in population size due to a sudden random disaster (e.g., a volcano erupting or overhunting).

What is the Founder Effect?

A type of genetic drift that occurs when a new colony is isolated and formed by a few individuals breaking away from a larger population.

Does the Bottleneck Effect or Founder Effect involve physical isolation from the original parent population?

Only the Founder Effect involves physical isolation.

Why might protecting an endangered species' habitat fail to save it if its population has already dropped to just a few individuals?

The species went through a severe genetic bottleneck. The "damage is already done" because they permanently lost genetic variation, leaving them highly vulnerable to inbreeding and unable to adapt to future diseases.

Give a human example of the Founder Effect mentioned in the worksheet.

The Afrikaner population of Dutch settlers in South Africa, who have a uniquely high frequency of the Huntington's disease allele.

what is evolution?

The change in inherited characteristics of a population over many generations