What is the impact of natural selection on medium ground finches during a prolonged drought?

The impact of natural selection on medium ground finches during a prolonged drought is best observed through the survival advantages that beak size confers in relation to available food sources. During such drought conditions, small seeds, which are typically more abundant in normal circumstances, become scarce. As a result, finches with larger beaks have an advantage because they are better equipped to crack open and access the larger, tougher seeds that may still be available.

This survival advantage leads to higher rates of reproduction for those individuals with larger beaks, allowing their traits to be passed on to future generations. Over time, this results in an increased frequency of larger beak sizes within the population, driven by natural selection as those individuals are more likely to survive drought conditions and successfully reproduce. This process is a classic example of how environmental pressures can shape the evolutionary trajectory of a species, demonstrating the role of natural selection in promoting traits that enhance survival and reproduction.