Question

Scientists in the galapagos islands observed that over the span of twenty years, a population of finches responded to competition over food resources with. a) Decreased competition for food

b) Evolutionary changes in beak size
c) Increased availability of nesting sites
d) Migration to new habitats

Answer 1

Over twenty years, finches in the Galápagos Islands exhibited evolutionary changes in beak size due to natural selection in response to the availability of seeds during different environmental conditions, as documented by Peter and Rosemary Grant.

Step-by-step explanation:

Scientists observed that over a span of twenty years, a population of finches in the Galápagos Islands responded to competition over food resources with evolutionary changes in beak size. Studies by Peter and Rosemary Grant provided evidence for this swift evolutionary change as a result of natural selection. During a drought, there were fewer seeds available and finches with bigger beaks that could eat these remaining, often larger seeds, were more likely to survive and reproduce. Consequently, within just two years, the average beak size in the population increased, demonstrating a rapid evolutionary response to environmental changes.

Another significant finding was during an El Niño period, when rainfall increased and large seeds became scarce, favoring small-billed finches that could eat the more abundant small, soft seeds. This led to an evolutionary shift towards smaller beak sizes in the finch population, as those with smaller beaks had more offspring. The ability of finches to rapidly adapt their beak size to the changing availability of seeds is a compelling demonstration of natural selection in action.

Summarizing, the observation conducted on the finches' beak size provided a contemporary example of evolution by natural selection, supported by clear evidence in the physical traits of a population in response to environmental changes and food resource availability.

Answer 2

The population of Galápagos finches responded to food resource competition with evolutionary changes in beak size due to natural selection. Big-beaked finches thrived during droughts by eating larger seeds, while during wet periods, small-beaked birds had an advantage.

Step-by-step explanation:

Over a span of twenty years, a population of Galápagos finches responded to competition over food resources by experiencing evolutionary changes in beak size. This is a classic example of natural selection where food scarcity due to environmental changes like droughts has led to the survival and reproduction of finches with larger beaks. These finches were able to eat a wider variety of seeds, including larger and harder ones, which allowed them to survive when the smaller-seeded food sources were scarce.

During periods of abundant rainfall due to El Niño, smaller seeds were plentiful, and as a result, small-beaked birds had a survival advantage. Conversely, during droughts, larger seeds remained, giving an advantage to birds with larger beaks. Over time, this selective pressure changed the average beak size in the populations, providing a clear example of evolution by natural selection, as discovered by researchers Peter and Rosemary Grant during their extensive studies of these bird populations since 1976.