Marion Petrie's Mate Preferences

Marion Petrie began her controlled breeding experiment with peacock offspring by observing peahen mate preferences in Whipsnade Park, UK. Observations showed that peahens appeared to have a preference for peacocks with more elaborate trains (i.e. larger in size and more eyespots). Petrie was interested in finding out why the peahens were mostly attracted to the peacocks with the most elaborate trains in this population. To test this idea, Petrie took eight males of different attractiveness from Whipsnade Park and separated them into individual pens. She then placed four females in each peacock’s hen at random – there were 32 peahens total used in this experiment. Petrie’s hope was that the peahens would mate with the peacock so that she could …show more content…
From the data that Petrie collected, she found that there were differences in the growth among the fathers, the sons, and daughters. Taking into account this detail from the data, Petrie conducted a multiple regression analysis, and found that the tarsus length, the train length, and the size of the eye spots on the father’s train affected the size of the offspring. These variables along with the hatch date and egg weight – which are an important factor in this experiment because if the eggs hatch early, they are more likely to be smaller in size—were entered into the multiple regression analysis. It was determined that males who had larger eye-spots had larger offspring. It could also be speculated that the females who mated with the males with more attractive trains produced larger eggs. Petrie later released some of the offspring back into Whipsnade Park and observed for two years. After the two-year period, Petrie found that only 41% of the offspring originally introduced into the park were present, and the larger the birds were at introduction, the more likely they were to have survived after two …show more content…
Because females that mated with males with a larger train produced larger, more successful offspring, it would make sense that males who possess larger trains produce offspring that have a better survival rate. Although the survival rate of the offspring released into Whipsnade Park for two years was 41%, it seems likely that if the surviving birds mated with other good quality birds (i.e. peacocks with large trains and multiple eyespots), their offspring would have a higher success rate for survival. As with all natural things, natural selection selects for those individuals that are most likely to survive in a particular environment. The offspring that do survive and are capable of reproducing will do so and thus produce more successful offspring. I would assume that the reason female peacocks do not have tails is because it is not genetically coded for them to posses them. Because the females are typically the ones who pursue their mate, it makes more sense that the males would need a trait that makes them aesthetically pleasing to the