Lesson 9: predator prey dynamics

What do species interactions affect? what can it lead to

Species interactiosn affect individuals, populations, an communtieis, and can lead to evolutionary change

What is a trophic interaction vs non trophic

Tropic (feeding) non trophic (competitive and facilitaative)

Is symbyosis positive or nwgative

It can be positive or negative, it is where multipple species line in close physical and or physiological contact

What is competition 

(-,-) 

Non-trophic interaction; two or more species overlap in the use of limiting resources, negatively affecting groth, reproudction, and or survival 

Describe positive interactions. What are the two types of positive interactions

aka facilitations, at least one species benefits, neither are harmed

Mutualism: both species beneift, sometimes it is highly dependent (+,+)

Commensalism: One species benefit, the other is unaffected (+,0)

What is amensalism

One species is harmed, the other if unaffected (-,0)

What is predation, what are the three types

Predation: individuals of one species (predators) kill and.or consume individuals of another species

Carnivory: predation and prey are animals

Herbivory: predator is an animal, prey are plants or algae

Paratism: predatro (a parasite) lives symbiotically on or in the prey (its host) and consumers certain tissues, may not kill the host. Some parsites are pathogens that cause disease

What are parasitoids 

Insects that lay egs on or in another insect host 

Would can losing top predators do

losing top predators causes surge in smaller predators (mesopredators) and ecosystem can collapse

cascading negative effects of meso predators happen

Why is the world green

Pre\dators have indirect positive affects on platns bc herbivores eat plants and the predators eat herbivores

How do yellow stone wolves show top down? how did otters show it

reintroducing wolves caused increase in in plants, beasvers, bison by reducing elk population.

Sea otters: eat on urchins. urchins take over kep forrests. Sea otters help production and diversity.

The oscillating population cycles of hare and lynx

Every 10 years, there is a spike in hare populatio. Every 10 years thre is also a lynx spike but it is slightly after

What is the lotka volterra oredatir prey mide,

dN/dt = rN -aNP

N = number of prey

P = number of predators

r = popultaion growth rate

a = capture effieiceny

Predator mdoel

dP/dt = baNP - mP

b=effieiceny of prey conversion to predator offspirng

a = cpture effeiciny

m=mortality rate

N = numer of prey

p = number of predators

What does zero growth isolcine predict 

Predicts change in predator and prey populations at specific thresholds

When does the prey population increase and decrease

Prey population decreases if P>r/a, so if the predator population is bigger than the population growth rate over captrue efficiency (top of the zero growth isocline)

Prey population increases if P < r/a, so if the population is beneath the zero growth isocline

When does predator population decrease, when does it increase

Predator population decreases if N <m/ba so if prey population is less than m/ba

Predator population increases if N > m/ba, so if prey population is more than m/ba

How far apart are the predator prey cycoles from each other

½ cycle off each other