Lecture 12 - Applied Evolution

Question 1

how can resistance to insecticides or herbicides be introduced to a population?

Answer 1

• pre-existing genetic variation in the population
• new mutations
• gene flow

Question 2

The best management strategy for stopping pesticide resistance, depends on how the resistance ____________

Answer 2

evolved or came to be

Question 3

if pre-existing genetic variation is the reason for genetic resistance, what do we do?

Answer 3

• nothing we can do it already exists but can try to stop it from spreading

Question 4

if new mutations are the reason for genetic resistance, what do we do?

Answer 4

keep population small so that there are less possibilities for mutation

Question 5

if gene flow is the reason for genetic resistance, what do we do?

Answer 5

keeps populations separate like stop sharing equipment

Question 6

which type of reproduction usually has more resistance variation? outcrossing or selfing?

Answer 6

outcrossing

Question 7

what methods can help stop herbicide resistance?

Answer 7

• multi-herbicide treatment
• rotation of different kinds of herbicides

Question 8

what is multi-herbicide treatment, what does it do?

Answer 8

• treatment with more than 1 chemical
• unlikely that mutations to survive all chemicals will arise at the same time
• thus new adaptations are less likely
• requires a more complex adaptation

Question 9

what is rotation of herbicides?

Answer 9

• weeds are regularly hit by different selection pressures on rotation
• could select for generalized resistance

Question 10

what is responsive alternation? how effective is it?

Answer 10

apply one insecticide and wait for the entire population to be resistant and grow a little then hit it with another so that all of the individuals die
- can evolve treatment to the other insecticide
- not really a good strategy

Question 11

what is a mosaic application of insecticide?

Answer 11

• apply different insecticides to different geographic area
• effectiveness depends on spatial scale
• if dispersal is smaller than the mosaic it can select for local adaptations
• if dispersal is greater than the mosaic scale can be effective
• multiple intergenerational killing at the family or colony level

Question 12

what is period application?

Answer 12

apply insecticide every so often and switch which one given
- if generation is shorter than application period will take longer but still effective
- if generation time short can be effective too
- multiple intergenerational killing at the family of colony level

Question 13

combination insecticide method

Answer 13

both insecticides at the same place at the same time
- super effective according to current research
- multiple intragenerational killing at the individual level

Question 14

how is evolution used in management of HIV?

Answer 14

• to hinder virus replication but cant eradicate the virus completely
• multi-drug cocktail
• evolutionary toggling

Question 15

multi-drug cocktail

Answer 15

• multiple harmful drugs at the same time
• single mutations unlikely to confer resistance to multiple drugs with different mechanisms of action
• causes lower viral loads making multiple mutations less likely

Question 16

evolutionary toggling (HIV)

Answer 16

• once resistance evolves, stop taking the drug,
• resistance has a cost so non-resistant forms will then dominate
• re-apply drug, reducing virus levels
• repeat

Question 17

how is cancer treatment being rethought?

Answer 17

• strong, prolonged selection pressure using the same chemotherapy drugs may not be the best solution as it selects for resistance
• cycling drugs, multidrug cocktails, and lower doses of drugs might be a better option but ethical consideration make tests of theory for human application challenging

Question 18

Chytrid fungus epidemic

Answer 18

• humans moved fungus around likely causing huge die offs
• a fungus colonizes frog skin
  frogs use skin to breathe so prevent their breathing eventually killing them
• frogs are showing evolution to chytrid so hopefully they can recover

Question 19

what are genetic issues in conservation biology? (5)

Answer 19

• loss of genetic diversity
• loss of heterozygosity
• inbreeding depression
• fixation of deleterious alleles
• inability of populations to adapt
• often results from bottle neck and makes hard for populations to bounce back

Question 20

what does the likelihood of an evolutionary rescue from adaptation to occur depend on? (3)

Answer 20

• population size
• beneficial mutation rate
• how much fitness was reduced
• can create a 3D model of likelihood