Question 1: Why was there so much debate over whether natural selection could give rise to new species?
There was much debate over whether natural selection could give rise to new species because the idea seemed so farfetched. Darwin himself even questioned this himself in The Origin of Species asking, “Can we believe that natural selection could produce, on the one hand, an organ of trifling importance, such as the tail of the giraffe, which serves as a fly-flapper, and, on the other hand, an organ so wonderful as the eye?” He questioned the amount and variation of complexity that natural selection could produce. Surely it could produce minor variations in species, such as the size of the beaks of finches, but he questioned whether it could really yield whole new species.
Even Darwin’s friends whom were scientists did not agree that natural selection could give rise to new species. His friend Hooker said that he was trying to account for too much with natural selection. Huxley gave a speech about evolution, “The Coming of Age of the Origin of Species,” without even mentioning the idea of natural selection. In general, people accepted the idea of evolution, but did not accept Darwin’s idea of natural selection as the cause for it. Especially after Darwin died, people simply thought it was too radical of an idea and that there must be another explanation for evolution. An exhibit made at the British Museum’s Natural History Building in honor of Darwin even dismissed the idea of natural selection and “survival of the fittest.” It was just an idea people were not ready to accept at the time.
Question 2: What is adaptive radiation?
Adaptive radiation is a way of describing how one species diverges into several species to adapt to the environment. This process is driven by natural selection. In the case of the Galapagos finches, it was found that there are three species of land finches. Dolph decided to test the theory of adaptive radiation by entering information into a computer accounting for the environment of the island. This data included the size of seeds, how big the beak of a finch needed to be to crack a certain seeds, and how many seeds it takes to feed a finch, among other information. He processed the information to calculate how many finches a hypothetical island could support, given finches with various beak sizes.
The computer produced a graph which showed three peaks with deep valleys in-between them. These peaks meant that three species with specific beak sizes would emerge to adapt to the environment. Three different species could survive given the types and amount of seeds. Each of their beaks would have to be highly specific to survive on the certain seeds available. This also supports that the idea that one species of finch could have evolved into the three species found on the island. Variation from generation to generation would produce finches with beaks better or worse suited for the seeds available. Through time, the one species of finch would diverge into three different species in order to make full use of the food provided on the island.