Beak of the Finch

The Beak of the Finch
1. Daphne Major
This chapter is dedicated to studying what Darwin could not, the actual evolutionary process at work. It uses the work of two evolutionists (the Grants) on Daphne Major to illustrate the process and describes islands as a perfect setting for studying natural selection.
2. What Darwin Saw
The Grant study is praised and a picture of the Daphne island begin this chapter. Then it details how Darwin ignores the finches in favor of more adventurous creatures, and in keeping with his education in religious literature. Predecessors to Darwin noticed variation but thought they were deviant from the perfect form. The process of discovery that drew Darwin into the field of inquiry is described.
3. Infinite Variety
Barnacles excited Darwin enough for him to study their intricate variation for seven years even without the expectation to see speciation occurring! The thirteen finches Darwin collected were of a single family and four species; the difficulty in telling them apart is stated in this quote: “’Only God and Peter Grand can recognize Darwin’s finches’” (43). The beginning of the Grant’s study is described and the condition of the finches is told by anecdote to be very naïve.
4. Darwin’s Beaks
The tradition of natural theology acquired from Paley inspired Darwin’s work. Then the variation in beaks is described and Darwin’s response to this variation is given. David Lack intended to disagree with the idea that beak variations are adaptively useful but reconsidered when he studied them more closely. The Grants have identified the number and distribution of seeds on the Daphne island through laborious work. They also chronicled the war with the spiny weed, caltrop; a perfect example of the minor differences that dictate survival.
5. A special Providence
The drought and its impact on Daphne is described. Finches failed to breed and molt as a result of diminishing food supply. Only one in seven finches survived and most of these were the larger male birds. The first rainfall draws male finches to the highest point on the island to sing in the rain  Their population had been changed by the drought.
6. Darwin’s Forces
Trevor notices that generally small juvenile finches survive while large die. Sexual selection is genetic death. This pressure was evident in the population of finches due to the disparity between the sexes. Endler’s guppy study is given as evidence of sexual selection in competition with natural selection. There is a paradox of directional selection towards large finches that still allows small finches to survive and reproduce.
7. Twenty-five Thousand Darwins
El Nino visits the Galapagos while Gibbs is on watch and he hopes for extraordinary selection event as the population of finches exploded and the island fauna changed radically with all the rain. The result was that big birds with big beaks were selected against and the directional selection favored small birds with small beaks. A sparrow study experienced similar results. These results changed the way we look at the fossil record.
8. Princeton
The Grants are going to compile the data from the finch watches on Daphne and they will take a year to complete the task. They discuss the many birds in terms of best breeders and survivors. Their analysis shows odd population results where hybrids survive and reproduce better than pure breed finches.
9. Creation by Variation
The process of evolution is happening now, and we can observe it even though Darwin did not conceive of this being possible. Then the chapter discusses how evolution through natural selection results in speciation. It begins with objections to selection and moves to Darwin drawing the “coral of life” which would become the tree of life. Darwin saw each species as marooned; its own island.
10. The Ever-Turning Sword
Species that evolve in isolation can meet again to compete. The exceptional survive and flourish giving rise to divergence; adding to the twigs on the tree of life. The Grants saw that finches specialize when in the dry season to ensure they can compete for food. Dolph did studies that resulted in a new way to see the pressures on finches with an adaptive landscape that has a peak fitness and a valley of the unfit. The character of divergence is subtle but present as selection dictates where along the peak a species is.
11. Invisible Coasts
The impact of hybrids on evolution is discussed as Darwin did not think that hybrids added to it. Pearl, a researcher, came to believe that hybridization played a large role after working with breeders. The Grants observed many barriers on Daphne and saw its impact on speciation.
12. Cosmic Partings
This chapter investigates adaptations that occur at an appreciable rate. It also looks at the impact of adaptions on populations, in how they create new species. The example of fruit fly populations reacting to bacterial infection is explored.