[Campbell Biology P.567] Based on the provided data table, analyze the trends in kdr genotyp... | Practice Question
Based on the provided data table, analyze the trends in kdr genotype frequencies for Anopheles gambiae and Anopheles coluzzii from Pre-2006 to Post-2006. Which of the following statements accurately describes these trends and their implications for insecticide resistance?
A: In Anopheles gambiae, the frequency of the r/r genotype significantly increased from 2006 to Post-2006, suggesting rapid selection for resistance. In Anopheles coluzzii, the r allele was initially absent but became highly prevalent by Post-2006, likely due to transfer.
B: The +/+ genotype frequency decreased substantially in both Anopheles gambiae and Anopheles coluzzii over time, indicating a general decline in non-resistant individuals. However, the r/r genotype only increased in Anopheles gambiae.
C: Hybrids primarily carried the +/+ genotype in 2006, indicating they are not a significant factor in the spread of resistance alleles. Both parent species showed minor fluctuations in kdr frequencies but no clear trend towards increased resistance.
D: The increase in r/r genotype was consistent across all species and time periods, suggesting a uniform selection pressure favoring resistance. The r allele was always present at low frequencies in Anopheles coluzzii.
Explanation
For Anopheles gambiae, the r/r frequency increased dramatically from 30.4% in 2006 to 90.5% in Post-2006. For Anopheles coluzzii, the r allele was completely absent 0% in Pre-2006 and 2006, but by Post-2006, the r/r genotype appeared and reached 31.3%, indicating a significant spread of the resistance allele, likely through transfer from hybrids as suggested in the text.