Question

read each question carefully. write your response in the space provided for each part of each question. answers must be written out in paragraph form. outlines, bulleted lists, or diagrams alone are not acceptable and will not be scored.

scientists interested in the relationship among vision, foraging for food, and fitness studied three isolated populations of a small species of primate whose diet includes small insects and fruit, both of which the animals primarily identify by sight. the three populations were once part of a larger population that was fragmented as a result of habitat destruction by humans. the study populations were selected on the basis of the significantly different vegetation among their current habitats. the scientists analyzed the frequency in each population of each of three alleles of a gene encoding an opsin protein. opsin proteins are important for color vision, and each allele provides maximum sensitivity to a specific wavelength of visible light and thus to certain colors. analysis of the alleles present in each population was performed in two different ways, and the data were combined to calculate the frequencies (table 1).

table 1. frequency of opsin alleles in three populations of a small primate

	frequency (±2seₓ̄)
allele 1	0.60 (.05)	0.80 (.06)	0.25 (.02)
allele 2	0.15 (.02)	0.05 (.01)	0.45 (.03)
allele 3	0.25 (.02)	0.15 (.02)	0.30 (.02)

(a) describe one measure of evolutionary fitness.

note on your ap exam, you will handwrite your responses to free-response questions in a test booklet

the allele frequency in a population.

Explanation:

Evolutionary fitness can be measured by an organism's relative reproductive success, such as the number of viable offspring produced that survive to reproductive age. Another measure is the relative survival rate, where the ability of an organism to survive long enough to reproduce (e.g., surviving to adulthood in a population) is considered. For example, in a population of primates, a primate with higher fitness would produce more offspring that themselves can reproduce, or have a higher chance of surviving environmental challenges to reach reproductive maturity. The previously written "The allele frequency in a population" is incorrect as allele frequency is a measure of genetic variation, not fitness directly. Fitness relates to an organism's ability to pass on its genes, often through reproduction and survival of offspring.

Answer:

One measure of evolutionary fitness is the number of viable offspring an organism produces that survive to reproductive age. For example, in the primate populations studied, a primate with higher fitness would have more offspring that themselves are able to reproduce, as this reflects the organism’s success in passing on its genes to the next generation. Another valid measure is the relative survival rate, such as the probability of an organism surviving to reproductive maturity (e.g., surviving from birth to adulthood) compared to others in the population, as survival is a prerequisite for reproduction and passing on genetic material.