1. Darwin: a reluctant rebel
Darwin and Evolution
Darwin: a reluctant rebel

2. History of Evolutionary Thought
Carolus Linnaeus ( )
Taxonomist
Binomial Nomenclature
Agreed with the “fixity of species” theory

3. LaMarck Organisms adapted to their environments by acquiring traits
change in their life time
Disuse organisms lost parts because they did not use them — like the missing eyes & digestive system of the tapeworm
Perfection with Use & Need the constant use of an organ leads that organ to increase in size — like the muscles of a blacksmith or the large ears of a night-flying bat
transmit acquired characteristics to next generation
Lamarck noted how well-adapted organisms were to their environments, and believed that fossils could be understood as less perfect forms which had perished in the struggle for increasing perfection. He explained adaptation as a result of change caused by environmental pressures.

4. LaMarckian vs. Darwinian view
in reaching higher vegetation giraffes stretch their necks & transmits the acquired longer neck to offspring
Darwin
giraffes born with longer necks survive better & leave more offspring who inherit their long necks 

6. Charles Darwin 1809-1882 British naturalist
Proposed the idea of evolution by natural selection
Collected clear evidence to support his ideas
What did Darwin say?
What evidence supports Evolution by Natural Selection?
What impact did Evolution have on biology?

7. Voyage of the HMS Beagle
Invited to travel around the world
(22 years old!)
makes many observations of nature
main mission of the Beagle was to chart South American coastline
After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world.
FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain.
Darwin noted that the plants and animals of South America were very distinct from those of Europe
Robert Fitzroy

8. Voyage of the HMS Beagle
Stopped in Galapagos Islands
500 miles off coast of Ecuador
The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin.
On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland.
It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands

9. Galapagos
Recent volcanic origin most of animal species on the Galápagos live nowhere else in world, but they resemble species living on South American mainland.
500 miles west of mainland

10. Unique species
Show Campbell videos!!!

11. Darwin found… birds
Finch?
Sparrow?
Woodpecker?
Warbler?
Collected many different birds on the Galapagos Islands.
Thought he found very different kinds…
Finch?
Sparrow?
Woodpecker?
Warbler?

12. But Darwin found… a lot of finches
Darwin was amazed to find out:
All 14 species of birds were finches…
But there is only one species of finch on the mainland!
Large Ground Finch
Finch?
Sparrow?
Woodpecker?
Warbler?
Small Ground Finch
Finch?
Sparrow?
How did one species of finches become so many different species now?
Warbler Finch
Veg. Tree Finch
Woodpecker?
Warbler?

13. Tree Thinking Descendant species Ancestral species Large-seed eater?
Large Ground Finch
Small-seed eater?
Small Ground Finch
Darwin noted that the plants and animals of South America were very distinct from those of Europe.
Organisms from temperate regions of South America were more similar to those from the tropics of South America than to those from temperate regions of Europe.
Further, South American fossils more closely resembled modern species from that continent than those from Europe.
Warbler?
Warbler Finch
Leaf-browser?
Veg. Tree Finch

14. Correlation of species to food source
Seed eaters
Flower eaters
Insect eaters
Rapid speciation: new species filling new niches, because they inherited successful adaptations.
Adaptive radiation

15. Correlation of species to food source
More observations…
Correlation of species to food source

16. Natural Selection
gradual, non-random process by which biological traits become either more or less common in a population
mechanism that drives evolution
Evolution = change in a species over many gnerations (long period of time)/ accumulation of adaptations
There is variation in traits.
Caused by mutations in DNA
Caused by inheritance of dominant/recessive alleles = different phenotypes
Only organisms that are “best fit” for the environment survive, reproduce, and pass on their traits to offspring.

17. Natural Selection: 4 steps
Natural Variation exists in nature
Competition - Organisms struggle for survival: more organisms are produced than the environment can support
Survival of the fittest: Only the best adapted survives. Adaptations are important
Organisms change over time in response to the environment: organisms change but they have a common descent – they have common ancestors

18. Adaptations: inherited characteristics that allow individuals to “do better” in their environment. Adaptations increase their chance of survival and reproduction

19. Artificial selection This is not just a process of the past…
It is all around us today

20. Selective breeding

21. Natural Selection vs. Artificial Selection
Artificial Selection: nature provides variation, and humans select variations that we find useful (domestic animals and crops)
Natural Selection: the environment is the selective force. Only those organisms that are well adapted will survive in the wild.

22. Sexual Selection