Population Drift Impact Analysis
Genetic drift is a mechanism of evolution characterized by random fluctuations in allele frequencies from one generation to the next. The magnitude of this random drift is inversely proportional to population size; it is stronger in smaller populations.
In this scenario:
- Population M has a size of NM = 100 individuals.
- Population N has a size of NN = 1000 individuals.
- Starting allele frequencies are $p = 0.5$ and $q = 0.5$ in both populations.
- The time frame is 100 generations, with no selection acting on the populations.
Due to its smaller size, population M will experience stronger genetic drift than population N. Stronger drift causes allele frequencies ($p$ and $q$) to deviate more significantly and randomly from their initial values over time.
Heterozygosity is quantified as $2pq$. This value is maximized when $p = q = 0.5$ (yielding $2 \times 0.5 \times 0.5 = 0.5$) and decreases as allele frequencies become unequal (i.e., move away from 0.5 towards 0 or 1).
Since genetic drift is stronger in population M, its allele frequencies ($p$ and $q$) are expected to diverge more from 0.5 compared to population N after 100 generations. Consequently, the heterozygosity ($2pq$) in population M is expected to decrease more substantially than in population N.
Therefore, $2pq$ in population M is expected to be lower than $2pq$ in population N.
Important Questions from Genetic drift
- Which one of the following statements about genetic drift is accurate?
- A few years ago, a very small population of zebrafish became isolated by a newly built dam. As a result, which statement is most likely to be true about this population of zebrafish now?
- Which two of the following processes can result in a decline in heterozygosity in populations?
I) inbreeding; II) genetic drift; III) mutation; IV) random mating In a population of birds on an island, the average beak size reduced over one generation. A researcher estimated the association between beak size and relative fitness, shown in the graph. The estimated slope was –0.05 with a 95% confidence interval of -0.15 to 0.09.
Which one of the following evolutionary processes acting on beak size is the most likely reason for the observed reduction in beak size?
- Two isolated populations X and Y have 100 and 10000 individuals, respectively. Both populations have the same starting allele frequencies of p=0.5 and q=0.5. After 1000 generations of genetic drift, which of the following statements is true about the heterozygosity at this locus in these two populations?
