Question

Even though I know what random selection, directional selection, stabilizing selection, disruptive selection and sexual selection are I can not understant what does Starlings producing five eggs in each clutch has to do with it.
In my final I got this question and I don't know if I got it right because I had to guess. The question said something like "starlings produce five or six eggs (I don't remember the exact number) in each clutch and I was supposed to say which type of selection (random,directional, etc..) was that. Please tell me why will any of those answers make sense.

Answer 1

Not sure... but if I have to guess, I'd say positive directional selection because 5 or 6 eggs seem like a big number. Positive directional selection favors those have higher trait values, in this case, they produce more eggs, thus have higher fitness than other Starlings which produce less than 5 or 6 eggs.

I'm not so sure because the information given is very little... when I learned about this topic, my teacher usually provides a bar graph showing different trait values and their fitness... for example, if having 5 or 6 eggs would show highest fitness, then it would be stabilizing. If having more than 6 eggs generate higher fitness than those produce 6 eggs, then it's positive directional selection. However, I know this is definitely not a sexual selection case.

Sorry, it's not much help... but I saw no one else answered it after you posted a couple times, so I might as well give you my opinion.