Much appreciated help needed for another question

Hi there
I am answering 2019 Question 2 Genetic variation

My answer below just addresses the first two bullet points os just need feedback on first two bullet points.

I was a bit confused by the marking schedule because the question refers to the gene pool, which would be the North and South Island birds combined. Migration, which is the movement between populations, would result in alleles moving between North and South Island. So migration, in this case, would only result in the increase of genetic diversity (due to new allele combination), not the loss, because the question is in reference to the gene pool as a whole. Alleles are not moving out of the gene pool; they are just moving between populations within the gene pool. The marking schedule is different from my thought process.

Another thing I was a little confused about is marking schuele refer to the 7000 population as small. I was looking online and it says that a minimum of 500 individuals in a population is enough to reduce genetic drift. Marking schedule says the opposite. By NCEA standards what should I consider a small population?

My answer: Allele frequency is the amount of times a particular allele occurs in a gene pool. Gene pool is the total number of alleles present in a population. Migration is the movement of alleles from one population to another.

Migration between the North and South Islands positively affects the karearea gene pool as a whole by increasing genetic diversity. The total population size is 7000, hypothetically we are going to assume 3500 live on the North Island and 3500 live on the South Island. If migration did not occur, then the 3500 birds on each island would just be limited to themself. Now that migration does occur, there are 7000 birds, so there are more mating options which increases genetic diversity and introduces North Island alleles to South Island and South Island alleles to North Island.
Females tend to migrate to new areas, if both males and females stayed in the same area, breeding would be limited to the mates in the areas. With limiting mating partners this would increase the chance of inbreeding which would reduce genetic diversity. Therefore through migration, chances of inbreeding is reduced, which is beneficial to the gene pool.

Genetic drift is the random change in alleles, generally resulting in the loss of alleles. As the population of the karearea is above 500, genetic drift won’t have a significant impact on the population. The random death of an individual is unlikely to completely take out an allele due to the buffer in individuals. If some individual dies, it is easy for the population to return to the original allele frequency through breeding.

Thank you very much any help will be appreciated

Almost true. However, I think you missed the point where the question resource states, only the females migrate.
There are some possible outcomes as a result of this, and it can lead to Natural Selection occurring.
Also, note the way the question is worded:
an explanation of how migration AND genetic drift “may” affect the kārearea’s gene pool

To fully unpack this question (and segue it to the E) you would have to start considering how those two processes will affect BOTH the North and South Island populations.
The key word in there being “may” implies you have to consider the implications that since only the females are able to migrate, this will impose a selection of different adaptations (check the schedule for the suggested phenotypes) that are beneficial in North and South island (due to the environment).

While you are correct, this question is a more about how the population may eventually diverge in to two separate populations (the North and South - which should form your E discussion). While the answer does not specifically go into this (Covered in Level 3 - AS3.6 Speciation) aspects of Natural Selection (beneficial alleles that help the organism to have a better survival chance in its environment, thus passing on those beneficial alleles, thus increasing the allele frequency of said alleles) are expected coverage at Level 2.

Unfortunately I am unable to give you a quantitative figure to make that decision.
In reality, it is quite difficult to decide how big is sufficient, because it depends on many factors for that species (eg, breeding frequency, mating habits, number of offspring, etc…).
What I would urge you to do however, is to READ the information in the resource carefully. Have a look at the third paragraph:
Population size is estimated at 7000. Genetic analysis has found that gene flow occurs between North and South Island populations, and the population has low genetic diversity.

That last sentence says the population has low genetic diversity.
At this point, I’d overlook the 7000 figure and work my answer around the fact that the resource has clearly stated the population already has a low genetic diversity.

Hope that helps.

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