Verbal-modern-Day Evolution name: Date: P: Malaria, being the #1 killer of humans in the history of our species, is of grave concern, especially in tropical arears. Malaria is transmitted to humans via mosquito bites. Unfortunately, mosquitoes are becoming resistant to insecticides, using a resurgence in malaria. Investigators wondered whether alleles encoding resistance to insecticides have been sferred between closely related species of Anopheles. The analysis of DNA can detect the transfer of resistance alleles between closely related mosquito species. To find out whether such transfers have occurred, DNA was analyzed from two species of mosquitoes that transmit malaria (Anopheles gambiae and A. coluzzii) and from A. gambiae x A. coluzzii hybrids. A. gambiae +/+ +/+ +/ r/r Pre-2008 4 6 3 2008 7 7 6 Post-2008 4 4 54 Hybrids +/+ +/n r/r 2008 9 6 0 A. coluzzii +/+ +/r T/T Pre-2008 2008 229 0 0 68 6 0 80 124 92 Post-2008 Table 1: Genotype data of the Anopheles mosquitoes. Resistance to DDT and other insecticides in Anopheles is affected by a sodium channel gene, kdr. The r allele of this gene confers resistance, while the wild type (+/+) genotype is not resistant. Researchers sequenced the kdr gene from mosquitoes collected in Mali during three time periods: pre-2008 (2004 and 2006), 2008, and post-2008 (2011–2014). A. gambiae and A. coluzzii were collected during all three time periods, but their hybrids only occurred in 2008, the first year that insecticide-treated bed nets were used to reduce the spread of malaria. A likely explanation is that the introduction of the treated bed nets may have briefly favored hybrid individuals, which are usually at a selective disadvantage. A. gambiae Pre-2008 2008 Post-2008 A. coluzzii Pre-2008 2008 Post-2008 +/+ +/+ +/r r/r r/r +/r Table 2: Genotype frequencies of the different genotypes of the Anopheles mosquitoes. 1. State the null and alternative hypothesis of the scientists. Null: Alternative: 2. [SP4] Complete the second table by calculating the genotype frequencies in each species for each time period. 3. [SP5] Describe the change in kdr genotype frequencies over time in A. gambiae. Propose a hypothesis with explanation to account for the observation./n4. [SP5] Describe the change in kdr genotype frequencies over time in A. coluzzii. Propose a hypothesis with explanation that accounts for the observation. 5. [SP5] Explain whether the data indicate that hybridization can lead to the transfer of adaptive alleles. Provide reasoning for your answer. 6. [SP6] Predict how the transfer of the r allele to A. coluzzii populations could affect the number of malaria cases in the years immediately following the transfer.

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