Lab Manual

Question 1

How do you measure selection?

Answer 1

measure target trait frequency and reproductive success of individuals with variations of target trait

Question 2

What is absolute fitness?

Answer 2

total number of an offspring of an individual

Question 3

What is relative fitness?

Answer 3

total number of offspring divided by average number of offspring produced by a population

Question 4

What kind of graph would show directional selection?

Answer 4

positive linear line = high fitness, negative linear line = low fitness

Question 5

What kind of graph would show stabilizing selection?

Answer 5

positive parabola, intermediate values favourable

Question 6

What kind of graph would show disruptive selection?

Answer 6

negative parabola, extreme values favourable

Question 7

What kind of graph would show no selection?

Answer 7

flat line

Question 8

Which length growing season would plants be more successful in before a drought?

Answer 8

long growing season

Question 9

Which length growing season would plants be more successful in after a drought?

Answer 9

short growing season

Question 10

What is a mutualism?

Answer 10

an interaction between two species where they both benefit

Question 11

What is the mutualism between medicago and rhizobia?

Answer 11

rhizobia convert N2 into NH3 for medicago which grow in nitrogen poor soil and are endocytosed to form nodules on their root systems using a flavonoid/nod factor interaction

Question 12

What are intermediate nodules?

Answer 12

nodules that can continue to grow in size but are unable to reproduce

Question 13

What are determinate nodules?

Answer 13

nodules that stop growing about a week after infection

Question 14

Which rhizobial genes are involved in symbiosis?

Answer 14

symbiosis island, located in plasmid, can be horizontally transferred

Question 15

What is a mechanism for detecting cheating rhizobia?

Answer 15

partner-choice: allocating less resources to those who weren’t fixing nitrogen efficiently
for the plant, rewarding those who did

Question 16

How is partner choice detected?

Answer 16

biomass of non-fixing rhizobia nodules are smaller than those that do

Question 17

Which rhizobia are antibiotic resistant/susceptible?

Answer 17

mutualists are susceptible and can only grow outside zone of inhibition, cheaters are resistant and can grow around antibiotic disc

Question 18

What medical-rhizobia interactions are seen in low nitrogen environments?

Answer 18

more nodules formed because plants need to take the chance of engulfing cheaters to get nitrogen

Question 19

What medical-rhizobia interactions are seen in high nitrogen environments?

Answer 19

less nodules formed because plants can get nitrogen for themselves, less cheaters because rhizobia have less at stake and higher chances of living comfortably

Question 20

What is inclusive fitness?

Answer 20

sum of direct and indirect fitness

Question 21

What is greenbeard selection?

Answer 21

altruistic behaviour dedicated to unrelated individuals with similar traits

Question 22

What behaviour can be seen in yeast individuals carrying the FLO1 locus?

Answer 22

yeast cells will flocculate, making them less susceptible to chemical and environmental stress

Question 23

If all strains tested were to flocculate, which plates would they grow on?

Answer 23

A: YPD; B: YPD, G418; C: none

Question 24

If the strains tested were to flocculate only with kin, which plates would they grow on?

Answer 24

A: YPD; B: YPD, G418; C: none

Question 25

If the strains tested were to flocculate based only on relatedness at the FLO1 locus, which plates would they grow on?

Answer 25

A: none; B: YPD, G418; C: YPD, G418, Ura

Question 26

If a phenotypic trait is under negative directional selection, which individuals will have the highest relative fitness in the population?

Answer 26

Individuals with the lowest value of the trait

Question 27

What side effect does flocculating have on yeast?

Answer 27

slower growth rate

Question 28

Where will antibiotic resistant bacteria grow in relation to an antibiotic disc?

Answer 28

around the edges