Imagine a population of newts that have been co-occurring with predator snakes f
ID: 165012 • Letter: I
Question
Imagine a population of newts that have been co-occurring with predator snakes for a long period of time (many hundreds of generations). If the snakes in the community suddenly go extinct (due to an outside cause, e.g. human activity), what do you think would happen to the newts over the next several generations?
a. There would be selection against the production of TTX because it is costly, so it would decline over time.
b. TTX production would remain the same because it is not favored or disfavored by selection.
c. The level of TTX production over time is unpredictable because it will evolve only by drift.
d. TTX production will increase because newts it is costly to stop the synthesis of TTX.
Explanation / Answer
Answer: (a) There would be selection against the production of TTX because it is costly, so it would decline over time.
It has been investigated and found that where low toxicity newts occur, the snakes in the area have low resistance to TTX. Newts of intermediate toxicity occur with snakes of intermediate resistance.
In Texada Island of British Columbia, the newts are non toxic while the snakes are non resistant.
So, this leads to the conclusion that natural selection will act against the production of TTX (since they are no more required) when the predator snakes become extinct.