A Finch Population with Heritable Variation in Beak Size Arrives

question 20

Multiple Choice

A finch population with heritable variation in beak size arrives on an island where only large seeds are available as a food source. Describe the process of natural selection that would follow.

• A) Finches with smaller beaks would grow larger beaks so that they could eat the large seeds. All birds will reproduce and the frequency of large beaks within the population will increase.
• B) Finches with larger beaks will more easily eat the large seeds and are thus more likely to survive and produce offspring with similarly large beaks. The frequency of large beaks within the population will increase.
• C) All of the finches with small and medium beaks will soon die; all of the finches with large beaks will survive. The frequency of large beaks within the population will increase.
• D) Finches with smaller beaks would grow larger beaks so that they could eat the large seeds. Only these birds that grew larger beaks will reproduce and the frequency of large beaks within the population will increase.
• E) Finches with larger beaks will more easily eat the large seeds and not need to reproduce. On an island where only large seeds are available for food, those birds with large beaks will more easily manipulate the food, outcompete those birds with smaller beaks, and have more time to reproduce. Birds with smaller beaks must work harder obtaining food and thus have less time to reproduce. The next generation of birds will be comprised mostly of birds with larger beaks.

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Definitions:

Coefficient Of Variation

A standardized measure of the dispersion of a probability distribution or frequency distribution, calculated as the ratio of the standard deviation to the mean.

Standard Deviation

A measure that quantifies the amount of variation or dispersion of a set of data values, indicating how much the individual data points differ from the mean.

Median

The middle value or point in a data set, where half the data lies above and half below it.

Empirical Rules

Statistical rules that allow for the determination of probability within a normal distribution, stating percentages of data that lie within certain standard deviations from the mean.