Lecture 8: Mechanisms of evolution

Question 1

Evolution:

Answer 1

Any change in gene frequency

Question 2

Gene frequency:

Answer 2

The relative proportional representation of a gene in a population

Question 3

When calculating gene frequency of alleles if it changes then

Answer 3

evolution has occurred

Question 4

Mendelian Inheritance; important points

Answer 4

1) Heredity is NOT blending
2) Acquired traits are not inherited
3) It does not produce a directional change in gene frequencies

Question 5

Mendelians experiment was about

Answer 5

PEAS

Question 6

Weismanns Principle:

Answer 6

Germ cells –> Germ cells –> Germ cells
\ \ \
SOMA SOMA SOMA

Question 7

Germ Cells:

Answer 7

any biological cell that gives rise to the gametes of an organism that reproduces sexually

Question 8

Soma:

Answer 8

cell body

Question 9

The Central Dogma:

Answer 9

DNA –> DNA –> DNA
\ \ \
Protein Protein Protein

Question 10

Hardy-Weinburg Equilibrium:

Answer 10

the gene frequency in a population that is not evolving

Question 11

At H-W Equilibrium

Answer 11

The gene frequency does not change

-i.e. there is no evolution

Question 12

Conditions for the H-W equilibrium

Answer 12

1) Infinite population size (therefore no genetic drift)
2) No mutation
3) No selection
4) Mendelian inheritance
5) Random mating

Question 13

Genetic drift:

Answer 13

Genetic drift occurs because Mendelian Inheritance is not exact

Question 14

Genetic drift is more likely to occur in _____ ______

Answer 14

Small population

• if population <100 drift is v. important
• if population is >100,000 drift is negligible

Question 15

E.g. of Genetic Drift

Answer 15

Human blood groups in Italy.
-between villages blood group frequencies vary a LOT!
BUT between cities blood group frequencies are v similar

Question 16

Mutation:

Answer 16

a heritable change in genetic material

Question 17

Mutation might involve:

Answer 17

• change in chromosome

- change in a single gene

Question 18

Mutation as a mechanism of evolution:

Answer 18

occurs at a very slow rate so is relatively unimportant as a mechanism of evolution

Question 19

Non-mendelian Inheritance

Answer 19

• Meiotic drive
• Molecular drive
• Inheritance of Acquired Characertistics (lamarckism)

Question 20

Meiotic drive

Answer 20

MD genes distort gene segregation so that gametes that don’t carry the MD genes die.
-MD is rare so is relatively unimportant as a mechanism of evolution

Question 21

Molecular Drive:

Answer 21

MD genes are able to convert slightly different genes into identical copies of themselves.
-MD is rare so is relatively unimportant as a mechanism of evolution

Question 22

Inheritance of Acquired characteristics

Answer 22

LAMARCKISM

-doesnt work = NO MECHANISM

Question 23

when does selection occur?

Answer 23

when genotypes differ in their ability to pass genes on to the next generation

Question 24

types of selection:

Answer 24

1) Artificial selection
2) ) Natural selection
3) Sexual selection

Question 25

Artificial selection:

Answer 25

Chosen by man, keep reproducing idealistic traits

Question 26

Natural selection:

Answer 26

survival! those traits aiding survival will be reproduced & passed on-survival of the fittest

Question 27

Sexual selection:

Answer 27

e.g. males fighting / growing extensive tail feathers to attract mates. Unappealing mates will not reproduce