A population of snails is preyed on by birds that break the snails open on rocks, eat the soft bodies, and leave the shells. The snails occur in both striped and unstriped forms. In one area, researchers counted both live snails and broken shells. Their data are summarized below: Which snail form seems better adapted to this environment? Why? Predict how the frequencies of striped and unstriped snails might change in the future.

Verified step by step guidance

1. Examine the data provided in the table. Note that the table includes counts of living snails and broken shells for both striped and unstriped forms, along with the percentage of striped snails in each category.
2. Compare the percentages of striped snails in the 'Living' and 'Broken' categories. The percentage of striped snails is higher in the 'Broken' category (56.3%) compared to the 'Living' category (47.1%), suggesting striped snails are more frequently preyed upon.
3. Interpret the data: Since striped snails are more likely to be found in the 'Broken' category, it indicates that striped snails may be less adapted to avoiding predation in this environment compared to unstriped snails.
4. Predict future changes in frequencies: Over time, if predation continues to favor unstriped snails, the frequency of unstriped snails in the population may increase, while the frequency of striped snails may decrease due to selective pressure.
5. Conclude that the unstriped form seems better adapted to this environment because it is less frequently preyed upon, as evidenced by the lower percentage of unstriped snails in the 'Broken' category.

Key Concepts

Natural Selection

Natural selection is a fundamental mechanism of evolution where individuals with traits better suited to their environment tend to survive and reproduce more than those without such traits. In this scenario, the predation of snails by birds may favor one form over the other, influencing which traits are passed on to future generations.

Phenotypic Variation

Phenotypic variation refers to the observable differences in traits among individuals in a population, such as the striped and unstriped forms of snails. This variation is crucial for natural selection, as it provides the raw material for evolutionary change, allowing certain traits to become more common if they confer a survival advantage.

Population Dynamics

Population dynamics is the study of how and why populations change over time, including factors like birth rates, death rates, and predation. In this case, understanding how the frequencies of striped and unstriped snails might change involves analyzing the impact of predation on their survival and reproduction, which can lead to shifts in population structure.