A small bird that lives in an island-confined habitat has individuals with varying beak sizes from .....?

Question

...extremely small, medium,and very long.These birds feed primarily on insects to trees and dirt requiring the beaks to workout the insects.A major freeze during the winter has killed off many of the insects in the topsoil this bird naturally feeds on so they are left with their prey that live in the nearby warmer trees.The birds with the largest beaks have the advantage of having acces to these "hard reached" insects and change the gene pool of this species due to their perpetuation and the loss of the birds whom could not reach their only food source.
1.which is the type of natural selection exibited in this example?
a.stabilizing b.directional c.extreme d.disruptive e.none of the above
2.in the next generation the offspring will primarily consistof individuals with what relative size of beaks?
a.none b.small c.medium d.large e.they all died
3.The new stress on this organism in it's environment is what?
a.pollution b.new predator c.excessive hunting d.loss of major food source

Answer 1

Read over what you wrote - the answers are all there for you (although it is perhaps not as clear an example as one would like). Summarize your information: What beak sizes are used to feed on what type of food? What has happened to change the normal selection of food types, and what food types are still available? Would some beak sizes give an advantage to their owners? If so, you might expect those birds to have a better chance of surviving and passing on their genes the next year, right? Question 1 you should be able to work out by thinking about what happens to the population of these birds: assume that 1/3 have beaks of each of the three sizes - make a graph of that (beak size vs. number of birds - make up numbers; it's OK as long as they're about equal), then make up a similar graph showing the number of birds with each kind of beak after the winter (again, use your imagination to give you the sorts of numbers you think should work). Compare the graphs and see how the population changed - that should give you a good indication of the answer. You should be able to answer question 2 from the second one of those graphs, and the answer to question 3 is right there in your initial explanation - what happened to put pressure on the bird population?
Oh, and Ian - I refer you to Peter Grant's work on the Galapagos Finches; some interesting reading there.

Answer 2

Its a dumb question. The topsoil would be warmer than the trees. The birds with small beaks would become canibals rather than starve and insects would repopulate within a few months. Beak size is clearly not a dominant gene so those birds would repopulate as well.

Its bad science and I can't be bothered with it.

Answer 3

If you had listened to your lecturer during these discussions you would already know the answers .So don't expect help from me , other than there would be no difference in the next generation because natural selection in this case takes hundreds if not thousands of years

Answer 4

the 2nd component to your question does not make experience. Do you mean "what's the evolutionary benefit of homosexuality?" i might wager this is a thank you to maintain our inhabitants down. human beings have unfold like an epidemic around the earth, as a species we would desire to decelerate slightly or there wont be any room left!

Answer 5

keep away from my cat