Week 11 Flashcards

Question

What is the relationship between H.sapiens and other hominins?

Answer 1

Replaced archaic forms of hominins – with some inter breeding H. Sapiens – lone survivors of extinct radiation of bipedal African hominins

Answer 2

Approx 10,000

Answer 3

6 % sequence divergence All humans – closely related!

Answer 4

mtDNA – pairwise comparison between random individuals within each species

Answer 5

Gorrillas - 22% Bonobos - 11% Western chimpazee - 16%

Answer 6

Genetic variation – Fst between populations Worldwide Fst = 0.15; so 80% of variation found within populations and only 20% among populations

Answer 7

Human genetic variation cannot be subdivided into sharply defined discrete races Most of what variation there is was left in Africa

Answer 8

Subtle differences exist in alleles frequencies at specific loci between populations. Accumulated - determine statistical genetic differences between populations

Answer 9

Western and Southern Europe + Africa Northern Europe + Eastern Europe + Iran Australia

Answer 10

Distinct unique genetic groups in Cornwall, Devon, Northern Wales, 2 in southern wales

Answer 11

Global Fst – 0.15 - low levels of gene flow since human expansion Ca. one individual per generation between continents No obstacle to changes being caused by selection

Answer 12

Expected distribution of Fst of loci across the genome because of drift (without selection) vs observed distribution More loci with higher Fst’s than expected = identifies genes under selection

Answer 13

Lactose tolerance

Answer 14

Lactose – nutritional carbohydrate in milk Broken into glucose/galactose by Lactase Only active up to weaning age in other mammals Most humans (70%) cannot digest Lactose – intolerant to large amounts of unfermented milk

Answer 15

Persistence of lactase into older age – Northern European populations Polymorphism upstream of the LCT gene – associated with lactase persistence Frequency of the polymorphism – matches geographical distribution of dairy production

Answer 16

Lactase persistence allele – In European humans, = recently single mutation Found in haplotypes (sections of linked genes) that are homogenous over long sections of genome – recombination hasn’t had time to break up ancestral sequence

Answer 17

Length of haplotype – consistent with origin of this variant 10,000 years ago Roughly when dairy cattle farming became established in Europe

Answer 18

* Dark skin = ancestral in humans – protects against Ultra-Violet radiation (UV) But some UV – required – for synthesis of Vitamin D Pale skin evolved – avoids Vitamin D deficiencies at higher latitudes Skin colour closely related to regional levels of UV Alleles at various specific pigmentation loci – closely associated with light skin

Answer 19

Influence HIV/AIDS has on human evolution

Answer 20

Some geneotypes make a person more susceptible to HIV compared to others The more susceptible the reduced number of children compared to genes that offer resistance

Answer 21

In South Africa - 20% pop have HIV Most common susceptible genotype - 0.8 children Most common resistant genotype - 1.3 children Other South African population lower amount of HIV Most common susceptible genotype - 0.97 children Most common resistant genotype - 1.1 children South African population with higher amount of HIV Most common susceptible genotype - 0.7 children Most common resistant genotype - 1.38 children There is stronger selection in populations where HIV is more prevalent