Download Biology 11 The Fit Bird Gets the Worm! Name: Chap 14 ANSWER

Biology 11
Chap 14
p 296, 305-7
The Fit Bird Gets the Worm!
ANSWER KEY
Name: ______________
Date: _______________
Block:_____
1. Which utensil was the most successful at collecting:
a) Pasta: _____
b) Styrofoam:_______ c) String:______
2. Relating this activity to Darwin’s finches, what did part of each bird’s body
did the different utensils represent? utensils represented different beaks
3. How many different alleles (ie different versions of the same gene) were
present for the “bird population” in this activity? 4 different alleles
4a. Which utensil collected the most food in total?
b. What does this suggest about the fitness of the “birds” with this “trait”?
Explain using the meaning of fitness. Birds that were able to collect the most
food had the highest fitness because they were the best suited to their
environment and most likely to survive and pass on their genes
c. What does this suggest about the presence of this allele (trait) in future
populations. Is it likely to become more or less common? Explain how you know.
The allele (beak type) that caught the most food is most likely to become a
trait that is more common because those birds are eating enough food to
survive, reproduce and pass that specific trait on.
5. If the birds picked up the least amount of food in total eventually died of
starvation what phenotype (physical appearance) would you expect in future
populations of these birds?
The birds that died due to starvation would not pass on their genes for that
specific beak type therefore the future population of birds would be missing
that specific beak type or have very few of it.
6. How does Natural Selection relate to this activity? Explain in detail.
The type of trait that is passed on, depends on it being well suited to its
environment. Beak types that allow the most food to be caught ensure that
the bird will survive and pass on that that trait. Therefore, due to being well
suited to it’s environment that trait is “naturally” selected for.
7. Darwin’s finches are typically used as an example of how new
species form.
No two species can occupy the same niche in the same location for
a long period of time or the more efficient one will drive the other
to extinction. In the case of these birds what conditions might
lead to speciation? How do the mechanisms of gene flow and
genetic drift relate?
A random event such as a storm could have sent some of the
finches to new and different islands- this would be an example of
gene flow (immigration). Colonization occurs when new niches are
available and can be taken over. Because Darwin’s finches all have
different beak types they were able to spread out and make use of
the different new niches available. Because the islands are
separated by water, the different groups of finches on different
islands cannot interbreed (reproductive isolation occurs) and natural
selection acts to select for the trait that is best suited to that
specific niche. Over time both geographic barriers, behavioural
barriers and reproductive isolation lead to the formation of new
species.