EE Lecture 8: Evolution in Action Flashcards

1
Q

what shows that humans are still evolving

A

the evoln of resistance to Plasmodium vivax in Madagascar

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2
Q

what is the Plasmodium vivax resistance due to

A

the absence of the Duffy (Fy) blood group from the surface of RBCs -> in individuals of African descent

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3
Q

what does the absence of Duffy (Fy) blood group from the surface of RBCs cause

A

resistance to Plasmodium vivax

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4
Q

what does the Duffy null mutation result in

A

loss of DARC expression

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5
Q

what is a loss of DARC expression caused by

A

Duffy-null mutation

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6
Q

what does Plasmodium vivax require to enter and infect RBCs

A

requires DARC protein

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7
Q

what could have been the selection pressure that drove the fixation of the Duffy null allele in sub-Saharan allele

A

Vivax malaria

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8
Q

what is the Bantu expansion

A

West African farmers across Africa and went to Madagascar, became resistant

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9
Q

what is the Austronesian expansion

A

E.Africa expansion all across East as well as into Madagascar -> not resistant

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10
Q

what two major expansions are involved in the evolution of Plasmodium vivax resistance

A

the Bantu expansion

the Austronesian expansion

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11
Q

what is the Malagasy popn composed of

A
ADMIXED POP:
Bantu people (from West Africa) with the Duffy-null allele and Austronesian people (from E.Africa) who brought the vivax malaria
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12
Q

what best explains the high frequency of the Duffy - null allele in Madagasca

A

positive selection for malaria resistance drove fixation of the Duffy-null allele in mainland sub-Saharan Africa

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13
Q

where were the Bantu of Madagascar from

A

West Africa

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14
Q

where were the Austronesians of Madagascar from

A

East Africa

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15
Q

what two pops does the Malagasy pop consist of

A

Bantu and Austronesians

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16
Q

what methods of sequencing were used to collect data for this experiment

A

SNP Genotyping with asn Affymetrix 10k Chip that took 11.5k SNPs per sample

17
Q

discuss the observed Duffy null frequency

A

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

18
Q

how many SNPs per sample do Affymetrix 10k Chips take

A

11.5K

19
Q

where did the Bantu population move to in Madagascar

A

the moved to the South Coast

20
Q

where did the Austronesian popn move to in madagascar

A

moved to the Merina

21
Q

which pop mainly in Merina

A

Austronesian

22
Q

which pop mainly in South Coast

A

Bantu

23
Q

which area in Madagascar had higher Duffy null frequency

A

South coast where its primarily Bantu

24
Q

why was it concluded that Duffy-Null allele shows positive selecton

A

because both areas (Merina and S.Coast) showed greater freq than predicted with genetic drift alone - POSITIVE SELECTION

25
Q

what were the main conclusions of the experiment to show natural selecton still exists

A

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