Darwin's finches are an example of adaptive radiation, the evolution of an animal or plant group into different types adapted to specialized ways of life. Their common ancestor arrived on the Galapagos about two million years ago. Over time, Darwin's finches have evolved into 15 recognized species differing in body size, beak shape, song and feeding behavior. The picture here shows finches with four different types of beaks. What statement best represents how one species of finches became many?
Responses
A In order to survive, the finches with different beaks flew to the island with the best food source for each beak type. Over time they evolved into different species.In order to survive, the finches with different beaks flew to the island with the best food source for each beak type. Over time they evolved into different species.
B The finches became isolated from one another on different islands. Finches developed the beaks that would best help them survive, over time evolving into different species.The finches became isolated from one another on different islands. Finches developed the beaks that would best help them survive, over time evolving into different species.
C Each island was different and presented different food sources, there were already different finches on each of the islands, over time scientists were able to better assess these differences, cataloging the different species.Each island was different and presented different food sources, there were already different finches on each of the islands, over time scientists were able to better assess these differences, cataloging the different species.
D The finches became isolated from one another on different islands. Because each island was different and presented different food sources, those finches with the beak type best fit for each island ecosystem survived to reproduce, over time evolving into different species.
D The finches became isolated from one another on different islands. Because each island was different and presented different food sources, those finches with the beak type best fit for each island ecosystem survived to reproduce, over time evolving into different species.
The correct answer is D. The finches became isolated from one another on different islands. Because each island was different and presented different food sources, those finches with the beak type best fit for each island ecosystem survived to reproduce, over time evolving into different species.
To understand why this is the correct answer, we should consider the concept of natural selection. Natural selection is the process by which individuals with traits that are better suited to their environment are more likely to survive and reproduce.
In the case of Darwin's finches, the different islands in the Galapagos presented varying food sources and environmental conditions. When finches with different beak types arrived on different islands, they were subjected to different selective pressures. Those finches with beak types that were well-suited for the available food sources on their respective islands had a higher chance of survival and reproduction.
Over generations, the finches with beak types that allowed them to effectively utilize the available food sources were more successful in passing on their genetic traits. Through this process of natural selection, the populations on each island gradually diverged and evolved into different species.
It is important to note that the initial diversification of the finches likely occurred through the process of adaptive radiation, where a common ancestor species diversified into multiple species, each adapted to a specific ecological niche. This initial diversification was then further reinforced by the isolation of populations on different islands and the resulting divergence in their beak morphology and feeding behavior.
Therefore, option D accurately represents how one species of finches became many, highlighting the important roles of isolation, different food sources, and natural selection in driving the evolution and speciation of Darwin's finches on the Galapagos Islands.