EE Lecture 8: Evolution in Action Flashcards
what shows that humans are still evolving
the evoln of resistance to Plasmodium vivax in Madagascar
what is the Plasmodium vivax resistance due to
the absence of the Duffy (Fy) blood group from the surface of RBCs -> in individuals of African descent
what does the absence of Duffy (Fy) blood group from the surface of RBCs cause
resistance to Plasmodium vivax
what does the Duffy null mutation result in
loss of DARC expression
what is a loss of DARC expression caused by
Duffy-null mutation
what does Plasmodium vivax require to enter and infect RBCs
requires DARC protein
what could have been the selection pressure that drove the fixation of the Duffy null allele in sub-Saharan allele
Vivax malaria
what is the Bantu expansion
West African farmers across Africa and went to Madagascar, became resistant
what is the Austronesian expansion
E.Africa expansion all across East as well as into Madagascar -> not resistant
what two major expansions are involved in the evolution of Plasmodium vivax resistance
the Bantu expansion
the Austronesian expansion
what is the Malagasy popn composed of
ADMIXED POP: Bantu people (from West Africa) with the Duffy-null allele and Austronesian people (from E.Africa) who brought the vivax malaria
what best explains the high frequency of the Duffy - null allele in Madagasca
positive selection for malaria resistance drove fixation of the Duffy-null allele in mainland sub-Saharan Africa
where were the Bantu of Madagascar from
West Africa
where were the Austronesians of Madagascar from
East Africa
what two pops does the Malagasy pop consist of
Bantu and Austronesians
what methods of sequencing were used to collect data for this experiment
SNP Genotyping with asn Affymetrix 10k Chip that took 11.5k SNPs per sample
discuss the observed Duffy null frequency
observed Duffy null frequency showed a higher freq on the South Coast (primarily Bantu) than in the Merina (primarily Austronesian) but both showed greate frequency than predicted with genetic drift alone
how many SNPs per sample do Affymetrix 10k Chips take
11.5K
where did the Bantu population move to in Madagascar
the moved to the South Coast
where did the Austronesian popn move to in madagascar
moved to the Merina
which pop mainly in Merina
Austronesian
which pop mainly in South Coast
Bantu
which area in Madagascar had higher Duffy null frequency
South coast where its primarily Bantu
why was it concluded that Duffy-Null allele shows positive selecton
because both areas (Merina and S.Coast) showed greater freq than predicted with genetic drift alone - POSITIVE SELECTION
what were the main conclusions of the experiment to show natural selecton still exists
Duffy-null freq higher than expected in Madagascar
Freq increase only explained by gen drift under extreme demographic histories
ovserved gen diversity greater than expected given extreme demographic histories
vivax malaria resistance 23% to 61%
Conclusion: NATURAL SELECTION FOR DUFFY NULL ALLELE
