10.8 changing population characteristics

What is natural selection?

The process by which organisms with advantageous inherited characteristics are more likely to survive and reproduce.

What causes genetic variation within a population?

Mutations and the introduction of new alleles through sexual reproduction.

What is a selection pressure?

An environmental factor that affects an organism's chances of survival and reproduction.

What are examples of selection pressures?

Predators, disease, competition, climate and availability of resources.

What happens during natural selection?

Individuals with advantageous characteristics have a greater chance of surviving and reproducing.

How does natural selection change a population over generations?

The proportion of individuals possessing advantageous characteristics increases over generations.

How does natural selection affect allele frequencies?

Alleles associated with advantageous characteristics become more common in the population.

What is evolution?

A change in the inherited characteristics of a population over successive generations.

How does natural selection lead to adaptation?

Advantageous inherited characteristics become more common, making the population better adapted to its environment.

How does pesticide resistance evolve in insects?

Insects with resistance survive pesticide treatment and reproduce, passing resistance alleles to offspring.

Why do pesticides become less effective over time?

Resistant insects survive and reproduce, increasing the proportion of resistant insects.

Why does using the same pesticide repeatedly encourage resistance?

It creates continued selection pressure favouring resistant insects.

How can pesticide resistance be reduced?

Rotate pesticides with different modes of action and use integrated pest management.

How does antibiotic resistance evolve in bacteria?

Resistant bacteria survive antibiotic treatment, reproduce and pass on resistance genes.

Why do antibiotics become less effective over time?

Resistant bacteria survive treatment and increase in frequency within the population.

How can antibiotic resistance genes spread between bacteria?

Through horizontal gene transfer, including the transfer of plasmids.

Why does incomplete antibiotic treatment encourage resistance?

Surviving bacteria may reproduce, increasing the frequency of resistant bacteria.

How can the spread of antibiotic resistance be reduced?

Use antibiotics only when necessary and follow prescribed treatment instructions.

Why is antibiotic resistance an example of natural selection?

Antibiotics select for resistant bacteria, which survive and reproduce.

Why does resistance increase in frequency over generations?

Resistant individuals have greater reproductive success under the selection pressure.

What is the difference between individual adaptation and population evolution?

Individuals do not evolve; inherited characteristics become more common in populations over generations.