Lecture 11- Chapter 13

Question 1

The Trillions of Bacteria Help To

Answer 1

• digest food
• synthesoze certain vitamins

Question 2

Parasitism Key Concept 1

Answer 2

• Parasites typically feed on only one or a few host species
• Parasites have to withstand being exposed by their host

Question 3

Microscopic Ectoparasite

Answer 3

1. Scabies or the itch mite
2. Athlete’s foot

Question 4

Endoparasites

Answer 4

• live inside their hosts
• eg; Tapeworms (greys anatomy)

Question 5

Scolex

Answer 5

• suckers and hooks attach to the intestinal wall

Question 6

Parasitism Key Concept 2

Answer 6

• Hosts have mechanisms for defending themselves against parasites
• parasites have mechanisms for overcoming host defences

Question 7

Host Species

Answer 7

• have multiple parasite species

Question 8

Parasitism Key Concept 3

Answer 8

• Hosts and parasite populations can evolve together, each in response to selection pressure imposed by the other.
• Nematoid refers to a worm
• Strong selection on parasites from hosts, and hosts have a strong selection on parasites

Question 9

Coevolution

Answer 9

• Rabbits are more resistant, and the virus is less lethal
• Rabit mortality rate goes down after multiple epidemics
  - Evolution of building resistance to myxoma virus
  - Coevolution between the host and parasite

Question 10

Parasitism Key Concept 4

Answer 10

• Hosts and parasites can have important effects on each other’s population dynamics
• Environment consists of 2 populations:
  1. Host population
  2. Parasite Population

Question 11

Parasitism Key Concept 5

Answer 11

• Parasites can alter the outcomes of species interactions, thereby causing communities to change.
  - Parasites can alter the physical environment
• Ecosystem engineers: coral reef
• With the keystone species removed from the community we see a shift in alternative stable states

Question 12

The Plague

Answer 12

• have reduced the world population from 475 million to 350-375 million in the 14th century