What did Darwin observe regarding finches on different islands in the Galapagos? Different beak sizes led to birds singing different songs, which he found led to assortative mating. Different beak sizes and shapes were adapted to fit well with the available food. O Darwin observed that offspring of finches had similar sized beaks as their parents. O Finches could easily hop over to different islands and would quickly find new niches. 20 988 114 4 Indoor Playground with Wheels

Peter and Rosemary Grant of Princeton University have studied the ecology and evolution of finches on the Galapagos Islands since the early 1970s. They have shown that finches with large bills (as measured by bill depth; see Figure) can eat both small seeds and large seeds, but finches with small bills can only eat small seeds. In 1977, a severe drought on the island of Daphne Major reduced seed production by plants. After the birds consumed whatever small seeds they found, only large seeds were still available. The resulting food shortage killed a majority of the medium ground finches (Geospizafortis) on Daphne Major; their population plummeted from 751 in 1976 to just 90 in 1978. The Grants research also documented a change in the distributions of bill depths in the birds from 1976 to 1978, as illustrated in the graphs to the right. In light of what you now know about the relationship between bill size and food size for these birds, interpret the change illustrated in the graph. What type of natural selection does this example illustrate? Source: P. R. Grant. 1986. Ecology and Evolution of Darwins Finches. Princeton University Press.

Darwin hypothesized that new species could appear gradually through small changes in an ancestral species. What experiment did he conduct to test this hypothesis? the breeding of finches O the breeding of pigeons the observation of humans the observation of dog breeds

Darwin’s finches have different beaks in terms of size and shape to be able to eat different food sources like insects, nectar, and seeds. Cactus finches have longer, more pointed beaks to probe cactus flowers compared to their relatives, the ground finches. If a plant disease killed a large portion of the cacti on the Galapagos islands, what would the future populations of finches look like in terms of beak size and shape? Use your knowledge of natural selection to determine which option is most likely. Ground finches would survive and pass on their shorter and wider beaks, so there would be a higher proportion of finches in future generations that have short and wide beaks. Ground finches would survive and pass on their beaks, but they would mate with the remaining cactus finches, creating a new hybrid that is somewhere between short versus long and narrow versus wide. Cactus finches would compete for food with ground finches and exhibit resource partitioning, so the beaks…