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1

What are the top produced & sold crops of the world?

- maize
- wheat
- rice

2

maize, wheat, rice account for __% of food energy intake by humans

60

3

Where is the "fertile crescent"

near the east (between Africa & Asia)

4

What idea did Vavilov come up with?

Center of Origins
"Vavilov centers of diversity"

5

Center of origins / Vavilov center of diversity

crops originate in areas where the diversity of their wild relatives is greatest

6

Contribution from Lysenko

discovered "vernalization"

7

Vernalization

induce early flowering in biennial crops by applying cold treatment
- flowers will delay flowering until they have experienced "winter"
- epigenetics: methylate flowering time genes so they remember to flower early

8

biennial crops

flowers every other year

9

Consequence of Lysenko's stupidity?

- Lamarck > Darwin
- train southern crops to grow in the north
- death of evolutionary geneticists, scientists
- catastrophic crop failures & famines

10

2 things that happen during the domestication of crops

1. severe bottleneck
2. strong artificial selection

11

consequences of domestication

reduced genetic variation

12

ways to measure genetic variation

H: heterozygousity
P: polymorphism
pi: number of nucleotide differences per site, for any randomly sampled pair of nucleotides (genetic diversity)

13

how is genetic variation maintained?

BIO120??

14

how is genetic variation generated?

BIO120??

15

why do we care about genetic variation in crops?

1. understand artificial selection used by our ancestors
2. future improvement of crops
3. pest & pathogen management

16

maize was domesticated from...

teosinte

17

what was demostrated by Stephen Wright's study on maize?

- there was selection
- 43% loss of genetic variation
- genetic diversity of teosinte vs. maize fall below the "no consequence of selection" slope
- many used to have nucleotide differences, but not anymore due to genetic drift & bottleneck

18

what do both bottlenecks & selection do?

reduce Ne

19

Ne

= effective population size
= members of the population who successfully reproduced
= size of ideal population where every adult reproduces, and genetic drift is the same as a real population

20

N

= census size
= total number of adults in a pop'n

21

rate of drift =

rate of decline in heterozygosity over time

22

____ size is most important for evolutionary analysis

effective

23

Why does N != Ne?

- not everyone has same number of kids
- unequal sex ratio
- overlapping generations
- fluctuations in population size

24

does Ne << N happen in the absence of selection?

yes

25

what effect does selection have on Ne?

make it even smaller (some will be better mates than others)

26

Ne is measured as a ___ across the genome, or ____

- species average
- for each gene separately

27

what are the 2 views of domestication?

1. bottleneck affects entire genome, and all loci are affected
2. ^ & selection forces on certain loci reduce Ne (for those loci) in addition to the reduction felt by the entire genome

28


bottlenecks have ___-wide effects on Ne

genome

29

Artificial selection should lead to additional ___ in Ne that are ____ specific

reduction; locus

30

how do we see if artificial selection?

look for genes that show evidence of a more severe bottleneck than that is typical of the rest of the genome