Lesson 3 of an A Level teaching resource, produced in conjunction with the Charles Darwin Trust, that uses Darwin's work on pigeon breeding and the work of contemporary scientists to explore genetics and evolution. This third lesson covers the topic of speciation. The accompanying teacher's notes can be found on our website at www.linnean.org/funkypigeons

1. Funky Pigeons
Revealing the biology of
inheritance and
selection
Lesson 3
Speciation
Picture courtesy John Ross: darwinspigeons.com

2. City versus country bird
news.bbc.co.uk/1/hi/wales/mid/8079539.stm
Can birds change their tune?
The role of song in bird ecology
Listen to the song of city and
country Great Tits:
• Consider how the songs are
different.
• Consider why the songs are
different and why song is
important to birds.
• Summarise the ideas from
the news clip.
Picture by Sławek Staszczuk (commons.wikimedia.org)

3. Galápagos Islands
Courtesy NASA

4. “When I see these Islands in sight of each other and
possessed of but a scanty stock of animals, tenanted by
these birds but slightly differing in structure and filling
the same place in Nature, I must suspect they are only
varieties… If there is the slightest foundation for these
remarks, the Zoology of Archipelagoes will be well worth
examining; for such facts would undermine the stability
of species.”
Charles Darwin
Beagle Notebooks, 1835
Darwin’s notes

5. Darwin’s mockingbirds

6. “These birds are closely allied in
appearance to the Thenca of
Chile… I have specimens from
four of the larger Islands; the
specimens from Chatham and
Albemarle Island appear to be
the same, but the other two are
different. In each Island each
kind is exclusively found; habits
of all are indistinguishable.”
Charles Darwin
Ornithological Notes, 1835
Darwin’s Big Idea
Species can and do change
Three mockingbirds Darwin collected from
the Galápagos Islands in 1835
© The Trustees of the Natural History Museum, London

7. “I never dreamed that islands,
about fifty or sixty miles apart,
and most of them in sight of
each other, formed of precisely
the same rocks, placed under a
similar climate, rising to a nearly
equal height, would have been
differently tenanted.”
Charles Darwin
The Voyage of the Beagle, 1845
Darwin on the Galápagos Islands

8. Variation in finches
Picture by V. Boehm (flickr.com)

9. Rosemary and Peter Grant
© Peter and Rosemary Grant © Peter and Rosemary Grant
© Peter and Rosemary GrantPicture by Sally Taylor (flickr.com)

10. • Selection pressure
• Stabilising selection
• Geographical isolation
• Reproductive isolation
• Genetic drift
• Sympatric speciation
• Allopatric speciation
• Inbreeding
• Assortative mating
Keywords