Origin òf Species

What happens to poorly adapted intermediates?

They go extinct

In an ecosystem, birds and insects both pollinate flowers. This is an example of:

Ecological interdependence

If a gardener selects plants with the most colorful flowers to breed, what is he doing?

Performing methodical selection

A dog breeder notices her puppies have slightly different ear shapes. What explains this difference?

Inherited variation

What big idea does Darwin propose in the final chapter?

All life may descend from a common ancestor

Two similar birds are found in the same forest, but scientists argue if they’re different species. Why?

The species/variety line is blurry

When does Darwin say a variety becomes a new species?

When differences accumulate over time

Why might slight variations in pigeons' beak length matter to breeders?

These differences can be selected over generations

A moth’s camouflage helps it avoid predators. What is this trait?

Favorable variation selected by nature

A breeder notices some hens occasionally have no tail feathers. This rare change is an example of:

"Sport" or abrupt mutation

A dog’s long legs come with thin bones. This is due to:

Correlation of growth

How does classification support Darwin’s theory?

It reflects shared ancestry

Whales with tiny leg bones show:

Vestigial traits from ancestors

Rabbits in an overpopulated forest compete for grass. What concept is this?

Struggle for existence

Animals adapting to heat over generations show:

They’re fine-tuned by natural selection

Why do only a few offspring survive to adulthood in most species?

Checks like disease and predators

A bird lays eggs in other nests. This instinct:

Is inherited and selected over time

A specialized plant species dies off when its pollinator disappears. What happened?

It was outcompeted and went extinct

Even partial eyes help survival. This supports:

Evolution of complex organs

Darwin’s theory predicts evolution is:

Gradual and shaped by selection

Fossils appear suddenly in rocks due to:

Gaps in fossil records

What does Darwin say is the source of all species and varieties?

Common ancestry

Two lizards are separated by a river. Over time, their features change. Why?

Geographic isolation

Larger plant groups tend to show more variation. What does this support?

Diversification through evolution

Why don’t we often see fast evolutionary change?

Evolution is gradual

Why is competition fiercest among similar species?

They need the same resources

What limits the survival of a species in a competitive environment?

Limited resources

Embryos of different animals look alike because of:

Common ancestry

Animals adapting to heat over generations show:

Acclimatization

Why can’t extinct species return?

Line of descent is broken

How does natural selection lead to new species?

By favoring useful traits over time

Why are vestigial organs important?

They show ancestral traits

What happens when species interbreed but produce sterile offspring?

It confirms they’re different species

A farmer breeds only the sheep with the thickest wool. What process is this?

Artificial selection

Darwin’s view of instincts is that they:

Are inherited and shaped by selection

A species on a volcanic island resembles mainland species. Why?

They share a common ancestor

Why is natural variation important in wild populations?

It provides raw material for natural selection

Why are transitional fossils hard to find?

Fossilization is rare

Slave-making ants evolved their behavior:

Gradually by survival advantage

Blind fish in caves lack vision due to:

Disuse of eyes over generations