Part C
What percentage of sheep had a body height of 1.2 meters or more 30 years ago? How does it differ from the present data? Does this data support your argument regarding the type of selection occurring?
Part D
Submit height data from 200 female sheep during both years but didn't notice a significant
Answer (1)
Calculate the percentage of sheep with a body height of 1.2 meters or more 30 years ago: P 30 = 200 120 × 100 = 60% .
Calculate the percentage of sheep with a body height of 1.2 meters or more presently: P p rese n t = 200 140 × 100 = 70% .
Calculate the difference between the two percentages: D = P p rese n t − P 30 = 70 − 60 = 10% .
The data suggests directional selection is occurring, favoring taller sheep. \boxed{10\%}$ ### Explanation 1. Calculate percentage 30 years ago First, let's calculate the percentage of sheep with a body height of 1.2 meters or more 30 years ago. We have height data from 200 female sheep. By counting how many sheep had a height of 1.2 meters or more, we find that 120 sheep met this criterion. Therefore, the percentage is calculated as follows: P_{{30}} = \frac{{120}}{{200}} \times 100 = 60 S o , 60 P_{{present}} = \frac{{140}}{{200}} \times 100 = 70 S o , 70 D = P_{{present}} - P_{{30}} = 70 - 60 = 10 The percentage of sheep with a body height of 1.2 meters or more has increased by 10% over the past 30 years.
Analyze the type of selection The increase in the percentage of sheep with a body height of 1.2 meters or more suggests that directional selection may be occurring. Directional selection favors individuals with traits at one end of the spectrum, causing a shift in the population's genetic variance toward the favored trait. In this case, it appears that there is a selection pressure favoring taller sheep, leading to a higher proportion of sheep with a body height of 1.2 meters or more in the present population compared to 30 years ago.
Examples
Understanding how traits change in a population over time is crucial in agriculture. For example, if farmers selectively breed sheep for increased wool production or meat yield, they are essentially applying directional selection. By tracking changes in body size or other relevant traits, farmers can assess the effectiveness of their breeding programs and make informed decisions to optimize their livestock production.
