Lecture 20 - Predation, Parasitism And Disease

What does the lokta-volterra model predict for predator-prey interactions?

Coupled lagged population cycles

True Or False: lynx-hare cycles are complex in nature

True

What are 2 additional factors of lynx hare cycles?

1. Damage of plants due to heavy browsing (caused by hares/ herbivores)

2. social stresses in overcrowded hare populations

Prey are under stronger selection for ________

Defenses

True Or False: Predators have ________ selection for counter defenses

Weaker

True Or False: Prey are under stronger selection than predators

True

How does an imbalance in selection affect predators and preys

Predators: evolve slower

Prey: evolve faster

If competition tends to decrease biodiversity explain how the predator-prey relationship in Paine Piaster’s experiment increases biodiversity

Mussels are great predators and they often outcompete other invertebrates in their area. The predator-prey relationship between the starfish and mussels keeps the mussels population in check. This also means the the level of biodiversity is maintained when more mussels are eaten because it lowers the level of competition between those species.

What Is The Enemy Release Hypothesis?

(Ask’s why invader species are so much impactful (harmful/beneficial) when their not in their natural habitat)

• Invaders have fewer natural enemies when they immigrate compared to their native area

True Or False: Parasites have simple life cycles

False, they’re very complex

Define: Direct Life Cycles

Parasites that only need a single host species to complete their life cycle

Define: Complex life cycles

Parasites require 2 or more host species in order to complete their life cycle

Define: Vectors

Hosts that transport parasites to their next host

Define: Reservoirs

Animals species that carry diseases and parasites in the long term (without getting very sick)

What Are The 2 Different Possible Outcomes Of How Disease Risk Affects Communities?

1. Dilution effect

2. Amplification Effect

Define: Dilution effect

When host diversity dilutes the disease risk from spreading

Define: Amplification effect

Risk increases when there are more host or vector species for diseases to infect

True Or False: There Are Less Diverse Pathogens In Temperate Places

False, there are more diverse pathogens

Ex. Malaria