Lecture 19 owls and parasites

Question 1

Parasitism (2)

Answer 1

*parasitism is the most common way of life
*over 40% of all animals are parasites

Question 2

Parasite definition

Answer 2

An organism which lives at least part of its life cycle on or within another organism (the host), can be
specialist or generalist. Obtains part of its nutritional requirement or needs from its
host

Question 3

Community on an individual host (3)

Answer 3

On a mouse there may be

ectoparasites in the form of lice and flees
Macroparasites in the from of nematodes and tapeworms
Microparasites in the from of protozoa and bacteria

Question 4

Pathogen definition

Answer 4

an agent that causes disease in a host.Often includes viruses, bacteria, sometimes prions are
include

Question 5

Parasite key roles in the ecosystem (3)

Answer 5

*Maintain genetic diversity within a species - as individuals with a low resistance to parasites often fail to reproduce
*Mediate competition
*alter a communities abundance and dynamics

Question 6

Snowy owls sexual dimorphism (2)

Answer 6

*Females are larger
*Males are more white, however both sexes decrease in coloration with age
*Females are likely darker to enhance camouflage while nesting and males are likely brighter to advertise their age/breeding ability

Question 7

Irruptive migration (5)

Answer 7

*Snowy owl migration is based on food = irruptive migration
*High energy cost from flying around
*Beneficial to this specialist species to ensure abundance of food
*Breeding sites of snowy owls had high numbers of lemmings
*Possible that owls move north until they find a suitable site

Question 8

Snowy owl diet

Answer 8

*Snowy owls broaden their diet in the winter time, becoming more generalist feeders

*Terrestrial: small mammals (lemmings, voles) remain the primary prey. Also ptarmigans & hares

*Marine: rely on sea birds