Read the instructions for this self-checked activity. Type in your response to each question, and check your answers. At the end of the activity, write a brief evaluation of your work.
Activity:
In this activity, you'll analyze and interpret data about a population. A scientist has been monitoring the height of a small population of wild sheep for 30 years. He monitored 200 adult male sheep from each year and then broke down their height into ranges. Study the data in the chart, and then answer the questions that follow.
| Height | Less than 1 m | 1 m - 1.19 m | 1.2 m - 1.4 m | Greater than 1.4 m |
| --------------- | ------------- | ------------ | ------------- | ------------------ |
| 30 Years Ago | 45 | 110 | 40 | 5 |
| Present Data | 15 | 84 | 75 | 26 |
Answer (2)
Calculate the percentages of sheep in each height range for both time periods.
Compare the percentages to identify changes in height distribution.
Observe a decrease in shorter sheep and an increase in taller sheep.
Conclude that the sheep population has become taller over the past 30 years.
Explanation
Analyze the problem and data We are given a table showing the height distribution of a wild sheep population 30 years ago and at present. The data represents the number of sheep in each height range, with a total of 200 adult male sheep monitored each year. Our goal is to analyze and interpret this data to understand how the height distribution has changed over the 30-year period.
Calculate percentages First, let's calculate the percentages of sheep in each height range for both time periods. This will make it easier to compare the distributions. From the tool, we have the following percentages:
30 Years Ago:
Less than 1 m: 22.5%
1 m - 1.19 m: 55.0%
1.2 m - 1.4 m: 20.0%
Greater than 1.4 m: 2.5%
Present Data:
Less than 1 m: 7.5%
1 m - 1.19 m: 42.0%
1.2 m - 1.4 m: 37.5%
Greater than 1.4 m: 13.0%
Compare the percentages Now, let's compare the percentages to identify the changes in height distribution:
Less than 1 m: The percentage of sheep shorter than 1 m has decreased from 22.5% to 7.5%.
1 m - 1.19 m: The percentage of sheep in this range has decreased from 55.0% to 42.0%.
1.2 m - 1.4 m: The percentage of sheep in this range has increased from 20.0% to 37.5%.
Greater than 1.4 m: The percentage of sheep taller than 1.4 m has increased significantly from 2.5% to 13.0%.
Analyze the changes From the comparison, we can observe a clear shift in the height distribution of the sheep population. There is a decrease in the proportion of shorter sheep (less than 1.19 m) and an increase in the proportion of taller sheep (1.2 m and above). This suggests that the sheep population has, on average, become taller over the past 30 years.
Interpret possible reasons Possible reasons for this change in height distribution could include:
Environmental factors: Changes in food availability, climate, or habitat could favor taller sheep.
Genetic changes: Natural selection or genetic drift could have led to an increase in the genes associated with greater height.
Reduced competition: If the population size decreased or the environment changed to reduce competition, the sheep might have better access to resources, leading to increased growth.
It's important to note that these are just possible explanations, and further research would be needed to determine the exact causes of the observed changes.
Examples
Understanding how populations change over time is crucial in ecology and conservation. For example, if we observe a decrease in the size of fish in a lake, it could indicate overfishing or changes in the lake's ecosystem. By analyzing such data, we can implement appropriate management strategies to protect the fish population and maintain the health of the ecosystem. Similarly, in agriculture, monitoring the size and yield of crops can help farmers optimize their farming practices and adapt to changing environmental conditions.
Over the past 30 years, the height distribution of the sheep population has shifted, with a decrease in shorter sheep and an increase in taller sheep. This suggests the population has generally become taller. Possible reasons for this change include environmental improvements, genetic factors, and reduced competition for resources.
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