Variation and Natural Selection

What is variation?

Differences between individuals of the same species

What is phenotypic variation?

Differences in observable characteristics between individuals of the same species

What causes genetic variation?

Differences in genes inherited from parents

What are the two main types of variation?

Continuous variation and discontinuous variation

What is continuous variation?

Variation with a full range of values showing many small differences between individuals

Give examples of continuous variation

Height, mass, finger length

How is continuous variation measured?

Using a scale with a range of values

What type of graph represents continuous variation?

A smooth bell-shaped curve

What is discontinuous variation?

Variation with distinct categories and no intermediate values

Give examples of discontinuous variation

Blood group, sex, tongue rolling ability

How is discontinuous variation displayed on graphs?

As separate categories with a step-like appearance

What causes phenotypic variation?

Genetic factors, environmental factors, or a combination of both

What is genetic variation?

Variation caused entirely by differences in genes

What is environmental variation?

Variation caused entirely by environmental conditions

Give examples of environmental variation

Skin colour from sun exposure, language spoken

What is adaptive feature?

A characteristic that helps an organism survive and reproduce in its environment

What are structural adaptations?

Physical features of an organism that aid survival

Give examples of structural adaptations

Thick fur, long necks, camouflage colouring

What are behavioural adaptations?

Actions or ways an organism behaves to survive

Give examples of behavioural adaptations

Migration, nocturnal activity

What are physiological adaptations?

Internal processes that help survival

Give examples of physiological adaptations

Poison production, water retention

What is camouflage?

An adaptation that allows organisms to blend into their environment

What is mimicry?

When one organism resembles another to gain protection

What is natural selection?

The process by which organisms better adapted to their environment survive and reproduce

Who proposed the theory of natural selection?

Charles Darwin

What are the steps of natural selection?

Variation, overproduction, struggle for survival, survival of the fittest, reproduction, inheritance

Why do organisms produce more offspring than needed?

To increase chances of survival despite competition

What is meant by “survival of the fittest”?

Individuals best adapted to the environment are more likely to survive and reproduce

What happens to advantageous characteristics over time?

They become more common in the population

What happens to disadvantageous characteristics?

They become less common or disappear

What is a selection pressure?

An environmental factor that affects survival

Give examples of selection pressures

Predators, disease, climate, competition

How does natural selection lead to evolution?

By gradually changing allele frequencies over generations

What is evolution?

A change in the characteristics of a population over time

What is artificial selection?

The process by which humans breed organisms for desired traits

Give examples of artificial selection

Dog breeding, crop improvement

How does artificial selection differ from natural selection?

Humans choose traits rather than the environment

What are disadvantages of artificial selection?

Reduced genetic variation and increased risk of disease

Why is genetic variation important?

It allows populations to adapt to changing environments

What is mutation?

A random change in DNA that creates new alleles

How do mutations affect variation?

They introduce new genetic differences in populations

What is sexual reproduction’s role in variation?

It combines genetic material from two parents to increase diversity

What is a species?

A group of organisms that can interbreed to produce fertile offspring

How does environment influence natural selection?

It determines which traits are advantageous

What is antibiotic resistance?

When bacteria evolve to survive antibiotics due to natural selection

How does antibiotic resistance develop?

Resistant bacteria survive treatment and reproduce

Why is overuse of antibiotics dangerous?

It increases the rate of resistance development

What is selective breeding?

Another term for artificial selection

What is a gene pool?

The total number of alleles in a population

What happens to allele frequency during natural selection?

Beneficial alleles increase in frequency

What is extinction?

When all members of a species die out

How can lack of variation lead to extinction?

Populations cannot adapt to environmental changes

What is competition?

Struggle between organisms for limited resources

What resources do organisms compete for?

Food, water, space, mates

What is adaptation?

A characteristic that improves survival and reproduction

How long does natural selection take?

Many generations over long periods of time

What type of organisms are more likely to survive environmental change?

Those with advantageous adaptations