Chapter 16: Parasitism

Question 1

Parasitism?

Answer 1

• live on or in host organism for some period in a symbiotic relationship. Obligate relationship for parasite

Question 2

symbiosis ?

Answer 2

intimate and protracted association between two organs of different species

Question 3

Transmission of parasites? (two ways)

Answer 3

• direct transmission between hosts by direct contact with artier or through air, water
• OR intermediate vector eg lyme disease (ticks), malaria (mosquitoes )

Question 4

Multiple Hosts?

Answer 4

• some species have an intermediate host and definite reach maturity

Question 5

Effects of parasites on host populations:

- three?

Answer 5

A. Large impacts, especially in populations with no evolved defences
B. Density dependent regulators. Outbreaks when host density
C. Selective agent mortality protect

*mechanism that can keep a population in check

Question 6

Invasive species?

Answer 6

• big problem because they can bring along with them some new parasite not common to the area

Question 7

Size of area?

Answer 7

• small area and high [] of individuals high density = disease/parasites transfer much easier
• not only competition for resources
• elderly ad sick/ stressed more.

Question 8

Evolution of parasitism when host defences can evolve to counter negative impacts?

Answer 8

• may result in commensalism: relationship between two species in which one benefits without significantly affecting the other
• relationships may become more beneficial to both (mutual exploitation)

Question 9

Mutualism?

Answer 9

• relationship benefits both species. Can be obligate (one dependent on the other) or facultative (can live without)
• common and ecologically important
• digestive system of herbivores contain bacteria and protozoa that carry out termination and break down of pant material
• Mutualism are also involved in the uptake of night N95 of chamber

Question 10

Is destination between host and parasite distinct?

Answer 10

not always coral with zooanthellae

Question 11

Examples of non symbiotic relationship and mutualism?

Answer 11

plat pollinator relationship and seed dispersal

Question 12

How do we know if it is mutualistic?

Answer 12

• hard to tell

- but benefits must outwear costs to each single species

Question 13

Case Study: Ants and bullhorn acacia ?

Answer 13

Psudomyrex ants live in hollow thorns in acacia
Acacia have foliar nectaries and Beltian bodies (leaflet tips that provide oils and protein) that provide food for ants
Ants aggressively defend acacia against herbivores (insects and mammals) and other plants
Ants need the acacia. Does the acacia need ants?

**plant and an animal living together
ants live in the hollow thorns …ant feeds on nectaries and gets protection from it
the ants defend the plant from other herbivores
ants need it for a food supply and the acacia does need the ants via protection

Question 14

Why do acacia can better with ants?

Answer 14

• also reduced compeition from other plants
• does not have the cyanogenic compounds many acacia do…Acacia shoots without ants have larger number of herbivorous insect s
• *those who’d let acacia come in and eventual