After a winter ice storm, 25 parrots are found sheltering in a tool shed. Ana traps the parrots, weighs them (average weight = 36 grams) and then feeds them. The next morning she find that 6 of the parrots have died. She weighs the dead ones (average weight = 20 grams) and the remaining parrots (average weight = 44 grams) She continues to feed the remaining parrots. In spring time, the parrots nest and have a total of 35 offspring. She keeps the offspring and releases the adults. The next winter she weighs the 35 parrots she kept and find that their average weight is 38 grams. What was the parrots response to selection (R)?
To calculate the parrots' response to selection (R), we need to compare the average weight of the offspring from the second generation to the average weight of the adults from the first generation.
The average weight of the offspring in the second generation is given as 38 grams. This is the selected trait we are considering.
Now, let's break down the information given in the problem step by step:
1. Initial population: After the ice storm, there were 25 parrots with an average weight of 36 grams. Six parrots died, so the remaining parrots (adults) had an average weight of 44 grams.
2. Reproduction: The adults nested and had 35 offspring.
To calculate the parrots' response to selection (R), we use the formula: R = (S' - S) / S
Where:
- R is the response to selection
- S' is the average weight of the offspring (38 grams)
- S is the average weight of the adults (44 grams)
Plugging in the values, we get: R = (38 - 44) / 44
Simplifying, R = -6 / 44
Therefore, the parrots' response to selection (R) is approximately -0.136. This indicates a decrease in average weight from the adults to the offspring.