Marcus is studying Midwestern grasslands. He observed that average yearly temperatures have been increasing and average yearly precipitation has been decreasing; he hypothesizes that these environmental changes might affect biodiversity. What experimental design might Marcus use to test his hypothesis and what data might he record?
a
Over two years, Marcus will evaluate the amount of grassland in a one-acre section of protected grassland. Using field cameras, he will survey the number of prairie dogs and coyotes, and he will use computer software to evaluate the amount of runoff. Observations that the amount of grassland decreases; the numbers of prairie dogs and coyotes also decrease; and runoff increases in the area would support his hypothesis.
b
Over two months, Marcus will evaluate the amount of grassland in a one-acre section of grassland surrounded by urban development. Using field cameras, he will survey the number of antelope and prairie dogs, and he will use computer software to evaluate the amount of runoff. Observations that the amount of grassland decreases; the numbers of antelope decrease; the numbers of prairie dogs increase; and runoff decreases in the area would support his hypothesis.
c
Over two years, Marcus will evaluate the amount of grassland in a one-acre section of protected grassland and an area of desert. Using field cameras, he will survey the number of mice and snakes, and he will use computer software to evaluate the amount of runoff. Observations that the amount of grassland decreases and the amount of desert increases; the numbers of mice decrease; the snakes increase; and runoff increases in the desert area and in the grassland area would support his hypothesis.
d
Over two months, Marcus will evaluate the amount of grassland in a one-acre section of protected grassland and a one-acre section of deciduous forest. Using small-area estimation, he will survey the number of crickets and mice, and he will use GIS software data to evaluate the amount of pollution in the region. Observations that the amount of grassland decreases and the amount of deciduous forest increases; the numbers of crickets decreases; the numbers of mice increases; and there is more pollution in the grassland ecosystem would support his hypothesis.
The most appropriate experimental design for Marcus to test his hypothesis would be option b. This design involves evaluating the amount of grassland in a one-acre section of grassland surrounded by urban development. Marcus would use field cameras to survey the number of antelope and prairie dogs, and computer software to evaluate the amount of runoff.
The data that Marcus would record would include the following:
- Amount of grassland in the one-acre section at the beginning and end of the experiment
- Number of antelope observed using the field cameras
- Number of prairie dogs observed using the field cameras
- Amount of runoff measured using the computer software
Observations that support Marcus's hypothesis would include:
- Decrease in the amount of grassland
- Decrease in the number of antelope
- Increase in the number of prairie dogs
- Decrease in runoff in the area
Option A: Over two years, Marcus will evaluate the amount of grassland in a one-acre section of protected grassland. Using field cameras, he will survey the number of prairie dogs and coyotes, and he will use computer software to evaluate the amount of runoff. Observations that the amount of grassland decreases; the numbers of prairie dogs and coyotes also decrease; and runoff increases in the area would support his hypothesis.
In this experimental design, Marcus will monitor the changes in grassland area, populations of prairie dogs and coyotes, and the amount of runoff over a two-year period. By using field cameras, he can observe the changes visually, and by using computer software, he can evaluate the quantitative data related to runoff. If the amount of grassland decreases, indicating habitat loss, and the populations of prairie dogs and coyotes also decrease, it suggests a decline in biodiversity. Additionally, an increase in runoff can indicate changes in the water cycle, potentially affecting the grassland ecosystem.
By comparing these observations over time, Marcus can determine whether the environmental changes, such as increased temperatures and decreased precipitation, have had an impact on biodiversity in the Midwestern grasslands.