What might happen to a group of large-beaked finches which are blown by a hurricane to an island without vegetation capable of producing thick nut-like seeds?

 

Answer:

Two things might happen to the large-beaked finches:

• They may go extinct.
• They may go through another round of evolution by natural selection, leaving only the variants that are adapted to the current vegetation.

Genetic drift is a phenomenon wherein a new population arises from a small group of individuals that has been separated from a large population. The large-beaked finches that are separated into an island by a hurricane experienced a specific type of genetic drift called the founder effect in which the small group was separated from the main population of large-beaked finches. 

The individuals in the original population have large beaks that are fit for feeding on thick, nut-like seeds, which might be abundant in their habitats. Because the new habitat (island) lacks vegetations bearing this kind of seed, the finches would starve. This lack of resource acts as an evolutionary pressure leading to natural selection.

One characteristic of the founder effect is the possible dramatic decline in genetic diversity, which is a key factor for a species to survive natural selection. Because the isolated finches have large beaks, the limited genetic variability for beak size and shape may cause the population to struggle to survive. This leads to a couple of possible scenarios:

1. All the finches might starve and die. The strong evolutionary pressure (i.e., lack of appropriate food) and lack of genetic variability (i.e., there is only one type of beak fit for one type of food) would lead to natural selection selecting against all the individuals, which means that no individual would be able to survive and reproduce, essentially wiping that population off the island. This, however, does not mean the species is extinct because it is a founder population, which means that the original population is still alive.
2. If some individuals are able to live off other foodstuff, then those individuals have a chance to survive, reproduce, and evolve. Diversity is a key component of a species' survival through natural selection because in a highly diverse population, any one individual may have traits that allow it to survive. In this case, there might be a few finches that have different beak shapes (e.g., smaller, narrower beaks) that can be fit for feeding on other foods such as insects and other types of seeds. Through time, these individuals would be able to survive and reproduce, while the exclusively large-beaked ones would die. If the differential beak shape and size is heritable, then the surviving finches would carry these traits to succeeding generations. As time passes and more adaptive beak shapes and sizes arise, new species would form within the island.