Test what you know about Darwin's big idea of natural selection, from pigeons and ants to fossils and far-off islands.
Which bird did Darwin conclude was the ancestor of all domestic pigeon breeds?
The rock-pigeon (Columba livia)
The wood pigeon
The turtle dove
The passenger pigeon
Right! Darwin argued that every domestic breed descended from the rock-pigeon, Columba livia.
The answer is the rock-pigeon. Darwin pointed out that its colouring and markings keep reappearing in crossed breeds, which shows a shared ancestor.
Darwin crossed white fantails with black barbs. What did one grandchild look like?
Pure white like its fantail grandparent
Blue with a white rump and two black wing-bars
Pure black like its barb grandparent
Bright red with a crest
Correct! The grandchild looked like a wild rock-pigeon, a case of reversion to an ancestral character.
It was blue with a white rump and double wing-bar, just like a wild rock-pigeon. Darwin used this reversion as evidence of common descent.
Whose doctrine did Darwin apply to the whole animal and vegetable kingdoms in his chapter on the Struggle for Existence?
Lamarck
Lyell
Malthus
Linnaeus
Yes! Malthus's idea that populations grow faster than their food supply was the basis of Darwin's struggle for existence.
It was Malthus. Far more individuals are born than can survive, so any slight helpful variation gives a better chance of being naturally selected.
Scratch the card to reveal a fact about Darwin's pigeons
Darwin bred pigeons himself, and the Roman writer Pliny noted people paying huge prices for pigeons with known pedigrees.
According to Darwin, why do species with few eggs, like the Fulmar petrel, sometimes outnumber species laying many?
Small clutches are always hatched faster
Egg number only indirectly affects average numbers; protection and survival matter more
Birds with one egg never face predators
Large clutches cause starvation in all cases
Correct! A large number of eggs just makes up for early destruction, so it determines numbers only indirectly.
Egg number only indirectly affects population size. If young are well protected, few eggs can keep numbers high, as with the Fulmar petrel.
What did Darwin say natural selection will tend to cause among the less improved forms of life?
Rapid spread to new continents
Extinction
Immediate hybridisation
Identical appearance
Right! Improved descendants tend to supplant and exterminate their parents and the intermediate forms.
The answer is extinction. Competition is fiercest between closely related forms, so improved forms replace the older, less improved ones.
Tap the card to flip it and reveal a fact
The Mughal emperor Akbar kept about 20,000 pigeons at court around 1600 and improved them by crossing breeds.
Did you know?
Darwin described a woodpecker on the plains of La Plata that showed what unusual habit?
It never climbs a tree
It only eats fruit
It builds nests underground
It hunts at night
Correct! There are no trees on those plains, yet the bird is clearly a woodpecker in every other way.
It never climbs a tree. Darwin used it to show that habits can change and structure can be modified by natural selection.
Why did Darwin find the neuter (sterile worker) insects such a serious difficulty for his theory?
They are too small to study
They live only in Africa
They never eat
Sterile workers differ from their parents and cannot pass on acquired habits
Yes! He solved it by showing selection acts on the fertile parents, which have the family that produces useful workers.
Sterile workers differ greatly from their parents and leave no descendants. Darwin explained that natural selection acts on the fertile parents of the colony.
Darwin argued that the fossil record shows so few transitional forms mainly because:
The geological record is very imperfect
Transitional forms never existed
Fossils dissolve in sea water
Scientists destroyed them
Correct! Fossilisation needs special conditions, and long blank intervals separate formations.
He blamed the imperfection of the geological record. Sediment accumulates only during certain periods, so many links were never preserved.
Drag the slider to reveal a fact about Darwin
How old is the earliest record of pigeons?
The earliest known record of pigeons is from ancient Egypt, around 3000 B.C., so they have been domesticated for thousands of years.
What surprised Darwin about pigeon seeds fed to him by experiments, when a pigeon's crop had floated in salt water for 30 days?
The seeds had turned to salt
The seeds had rotted
Nearly all the seeds still germinated
The seeds sprouted inside the bird
Right! This showed seeds in floating birds could survive long journeys across the sea.
Nearly all germinated. Peas and vetches alone die after a few days in sea water, but seeds protected in a bird's crop survived.
How did Darwin explain the resemblance between whales and fishes in body shape?
They share a recent ancestor
It is an analogical, adaptive resemblance for swimming
Whales are a type of fish
It is pure coincidence with no cause
Correct! Such adaptive resemblances do not reveal true descent, unlike traits shared by all whales.
It is analogical: both are adapted to swimming. Classification relies on characters that reveal descent, not on similar adaptations.
Well done, you got % right and know your way around Darwin's big idea.
You needed % to pass and got %. Have another go, evolution rewards patience.
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