Why can’t genetic drift be answer to this? (1 Viewer)

jimmysmith560

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I believe it's because the predator (birds) acts as a selection pressure, which reduces the number of dark beetles over time.

Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). This definition therefore suggests that genetic drift would not be something that applies to this question, making D the correct answer.
 

Hivaclibtibcharkwa

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I believe it's because the predator (birds) acts as a selection pressure, which reduces the number of dark beetles over time.

Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance (sampling error). This definition therefore suggests that genetic drift would not be something that applies to this question, making D the correct answer.
But isn’t the bird causing a change in allele frequencies over generations? So can’t it be classified as genetic drift
 

jimmysmith560

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But isn’t the bird causing a change in allele frequencies over generations? So can’t it be classified as genetic drift
This is an example of a scenario that is similar to the question:

1626922713407.png

As you can see, selection pressure here occurs in a very similar manner to the question (less dark beetles compared to less tan mice).

Genetic drift occurs due to chance (sampling error). It also occurs in all populations of non-infinite size, but its effects are strongest in small populations. The bird is causing selection pressure which I believe is because it is specifically targeting dark beetles instead of the light ones, giving light beetles an increased chance of surviving over others.
 

Eagle Mum

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Jimmysmith560 is absolutely correct.
A change in allele frequency is an effect of both genetic drift and/or selection pressure, but the two causes are completely different. Genetic drift occurs even in isolated populations irrespective of external factors. Selection pressure is from external factors.

In scientific study, as much as possible, try to work out cause, effect & correlation in system(s).
 

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