Lecture 12 : Applied evolution

Question 1

where does resistance come from? ( resistance of weeds to herbicides )

Answer 1

1) Pre-existing genetic variation in the population
2) Gene flow
* ‘Epidemic spread’ of resistance from one region to the next
3) New mutations
* In very large populations new, simple mutations may be introduced at a high rate

Question 2

How can we lessen herbicide resistance

Answer 2

1. Multi-herbicide treatment:
   Makes new adaptation less likely Requires more complex adaptation
   Rotation of different kinds of herbicides Weeds regularly hit by different selection pressures
   BUT: could select for generalized resistance

Question 2

How can we lessen herbicide resistance

Answer 2

1. Multi-herbicide treatment:
   Makes new adaptation less likely Requires more complex adaptation
2. Rotation of different kinds of herbicides
   Weeds are regularly hit by different selection pressures
   BUT: could select for generalized resistance

Question 3

what are some evolution-proof solutions to the prevention of malaria

Answer 3

• Tailor insecticide application to knowledge of mosquito generation times & spatial distributions
• Goal: minimize selection for mosquito resistance
  while still reducing malaria transmission

Question 4

Extinction…go for it

Answer 4

• Extinction is the permanent elimination of a species
• Extinction is a normal evolutionary process
  – 99% of all species that have ever lived are now extinct
  – In undisturbed ecosystems, extinction rates have been estimated at 1 species lost every 10 years
• Astoundingly increased rates of extinction during the past century
  – Massive habitat destruction, particularly in tropical regions
  – At least 4,000-6,000 species per year

Question 5

Genetic issues in conservation biology

Answer 5

• Loss of genetic diversity
• Loss of heterozygosity
• Inbreeding depression
• Fixation of deleterious alleles
  *Inability of populations to adapt