Genes in populations 3

Question 1

roughly when did hominids and other great apes diverge?

Answer 1

5.7 million years ago

Question 2

what are the 2 arguments for where humans arose?

Answer 2

multi regional vs out of Africa

Question 3

what is the multi regional theory?

Answer 3

a single population spread over many continents connected by gene flow with high genetic diversity and transitioned from H. erectus to H. sapiens

Question 4

what is the out of Africa theory?

Answer 4

humans originated out of a limited area of Africa with a low genetic diversity H. sapiens replaced H.erectus

Question 5

2 pieces of evidence to support out of Africa model

Answer 5

1) compared to our closest relatives humans are not very diverse
2) all alleles share a common ancestor

Question 6

5 features of mitochondrial DNA

Answer 6

1) found in both sexes
2) maternally inherited only
3) small molecules
4) high mutation rate
5) many copies per cell

Question 7

3 features of Y chromosome DNA

Answer 7

1) found in males only
2) paternally inherited only
3) do not recombine with X chromosome

Question 8

when did humans emerge in Africa and when did they spread?

Answer 8

the emerged 120-140 thousand years ago and they spread 30-80 thousand years ago

Question 9

what is evidence go show that skin colour is adaptive?

Answer 9

dark skin in Africa to protect from UV - little Vitamin D produced so more needed in diet
light skin in Europe due to high grain diet with low vitamin D and low UV levels

Question 10

what is the gene best studied for pigmentation?

Answer 10

MCR1

Question 11

how is lactase persistent inherited?

Answer 11

autosomal dominant mendelian trait - persistance allele is dominant to lactose intolerance allele

Question 12

what are heterozygotes to cystic fibrosis resistant to?

Answer 12

cholera and typhoid

Question 13

why is there a higher frequency of cystic fibrosis heterozygotes in Europe?

Answer 13

because they are resistant to infectious diseases which are more common in agricultural societies

Question 14

when did agriculture and domestication take place?

Answer 14

within the last 10 thousand years

Question 15

what is cladogenesis?

Answer 15

the formation of a new group of organisms by evolutionary divergence (speciation)

Question 16

what is post zygotic isolation?

Answer 16

a new gene causing sterility or inviability of hybrids and will not spread through a population

Question 17

what is pre zygotic isolation?

Answer 17

a new gene causing an altered mating signal or response also likely to spread through a population

Question 18

what is disruptive selection and how does it cause speciation?

Answer 18

intense competition at high abundance therefore low fitness and weak competition at 2 areas of low competition therefore high fitness of 2 groups forming two species

Question 19

what is assortative mating?

Answer 19

2 distinct groups only breed with themselves

Question 20

what is allopatric speciation?

Answer 20

separation by an ecological barrier

Question 21

what is the founder effect?

Answer 21

where genetic drift can overcome the section of sterile hybrids but only in very small populations

Question 22

what is the Dobzhansky- Muller solution?

Answer 22

traits A and B are both fixated and advantageous to each population but the hybrids of both genes joined together are not advantageous and incompatible

Question 23

what is autopolyploidy?

Answer 23

multiple chromosome sets derived from the same species that produce unstable pairing

Question 24

what is allopolyploidy?

Answer 24

polyploids with chromosome sets derived from different species to produce stable pairing

Question 25

where is polyploidy common?

Answer 25

in plants

Question 26

what may polyploidy result in?

Answer 26

instant speciation

Question 27

what is isolation of a species due to?

Answer 27

incompatibilities between separately evolved traits/genes