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Flashcards in Evolution Deck (23)
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1

evolution

change in allele frequencies in populations over successive generations

2

gene

"locus" (region) of DNA

3

Alleles

alternative forms of the same gene

4

Biological fitness

ability of an organism to produce surviving offspring

5

Adaptation

heritable trait that increases the fitness of an individual in a particular environment compared to other individuals that don't have this trait

6

the 5 key mechanisms of evolution

- mutation
- genetic drift
- natural selection
- sexual selection
- gene flow

7

what is the ultimate source of all genetic variation?

mutations

8

effects of mutations

by changing the genetic code new alleles are generated which can...
- change amino acid sequences or alter gene expressions

9

most mutations decrease

fitness

10

genetic drift

random changes in allele frequency

11

genetic drift is stronger in

smaller populations

12

example of genetic drift

walking and randomly stepping and killing a bunch of bugs

13

when do you expect strong effects of genetic drift?

population bottlenecks - when species go close to extinction

14

when do you expect strong effects of genetic drift?

founder effect: new island - first few animals arrive on island and repopulate

15

Natural selection was discovered by

Charles Darwin and Alfred Wallace

16

Natural selection is the idea that

traits that improve survival/reproduction should increase in frequency through time

17

Example of natural selection in nature

Daphne Major drought

18

Daphne major drought

- drastic ecological changes led to a decrease in seed abundance
- little soft seeds dried out and only the hard large seeds were left
- high mortality of darwin finches because all their food was gone
- finches with larger beaks were more likely to survive
- traits are heritable: relationships between beak size of parents and off spring

19

intra-sexual

male-male competition

20

inter sexual

female choice

21

natural and sexual selection often act in...

opposition to each other

22

Gene flow

movements of genes among populations

23

gene flow tends to oppose divergent

natural selection