Lecture 17: Predator Prey Cycles

Question 1

Competition

Answer 1

-/-
interaction hurts both species

Question 2

Predation

Answer 2

+/-
interaction benefits one species but hurts the other

Question 3

Herbivory

Answer 3

+/-
interaction benefits one species but hurts the other

Question 4

Parasitism

Answer 4

+/-
interaction benefits one species but hurts the other

Question 5

Disease

Answer 5

+/-
interaction benefits one species but hurts the other

Question 6

Mutualism

Answer 6

+/+
each species benefits the other

Question 7

Commensalism

Answer 7

+/0
one species benefits while the other is unaffected

Question 8

Some adaptations in +/- interactions for carnivores and herbivores

Answer 8

jaws and teeth
beaks

Question 9

Some adaptations in +/- interactions for prey and plants

Answer 9

Hiding, including crypsis (hiding through blending into environment)
Mobile escape
Physical protection
Chemical protection

Question 10

Adaptations for +/- interactions for hosts (against disease)

Answer 10

immune system
secondary compounds
defensive symbionts
tough outer layer

Question 11

Some adaptations for escaping from predators

Answer 11

distastefulness and/or toxicity (chemical protection)
Unpalatable (toxic)
Secondary compounds (nicotine, mint, capasicin, alkaoids)
Ex. Ash Juniper, Poison dart frog, milkweed plant

Question 12

Secondary compounds

Answer 12

adaptation used to escape from predators
may be constitutive (always there) or induced (by defoliation or other wounding)
Other factors also affect levels of secondary compounds (ex. tobacco has nicotine when it is grown in poor soil)

Question 13

Adaptations to defend organisms from pathogens (escape from predator)

Answer 13

-immune system (vertebrates)
-secondary compounds (plants)
- defensive, mutualistic symbionts
- tough outer layer (plant, animal)

Question 14

Abiotic selective pressure

Answer 14

Nonliving factor in environment that affect survival of organisms, used for physiological ecology
The stress can lessen with adaptation or acclimation of an organism
Drought –> plants strengthening xylem
Low nitrogen levels –> plants holding onto leaves for longer
Saltiness –> fish drinking more water

Question 15

Biotic selective pressures

Answer 15

Refers to the influence that living organisms have on the survival and reproduction of other organisms in an ecosystem
Can lead to an evolutionary race
Adaptation in one species changes the pressure on the other
Adaptation in the other species changes the pressure on the first etc.
The selective pressure can itself evolve
Leads to Coevolution

Ex. Predation

Question 16

Co-evolution

Answer 16

From biotic selective pressures
Process by which two or more species evolve in response to each other’s selective pressures

Question 17

Ex. Co-evolution Pronghorn Antelope Speed

Answer 17

Speed For mobile escape from predators
Antelopes prey for predators (cougars, wolves, coyotes, bobcats) who are fast for selective pressure on antelopes that can run faster to escape predators
In response to predation pressure, antelopes evolve to become faster and predators become faster to catch prey

Question 18

Ex. Co-evolution for Milkweed and monarch

Answer 18

For every defense that the plant mounts, monarch mounts a counter defense

Plant: dense hairs before leaf (defense themselves against being eaten by insects)
Caterpillar (monarch in larval stage): shaves the hairs (evolved behavior to eat

Plant: toxic latex inside the leaf
Caterpillar: detoxifies it

Question 19

Co-evolution among prey

Answer 19

Warning signals from prey to predator
Can be useful to look like other bad tasting organisms

Question 20

Mullerian mimicry

Answer 20

Example of co-evolution among prey
Unpalatable (toxic) species look like each other
Resemblance benefit species to reinforce avoidance behavior of predators

Question 21

Batesian mimicry

Answer 21

Palatable species (nontoxic) mimics an unpalatable species (toxic)
Able to avoid predation

Question 22

Predator/Prey population dynamics

Answer 22

+/- interaction
Dynamics over years or decades, no/little evolution
Can lead to extinctions of both
Predator/prey or parasite/host
Can cause populations to cycle

Question 23

Lotka Volterra Predator-Prey Model

Answer 23

Prey population (N) grows exponentially (r) in the absence of predators, but decrease through predation that is proportional (a) to the multiplication of their population size (N) and the population size of the predators (P)

Predator population size declines exponentially (m) in the absence of prey, but increases in proportion (b) to the prey consumed

Question 24

Phase plane

Answer 24

A plot of all combinations of P and N with arrows showing the direction of change in P and N over time from each combination of P and N

Question 25

Isoclines

Answer 25

Helpful in making phase plane
Isoclines are the conditions under which one of the population sizes will not change (dN/dt=0 and dP/dt=0, separately)

Question 26

Prey switching

Answer 26

when abundance of prey gets low, predators eat other species
dependence of prey population on plant communities of their prey (trophic cascades)

Question 27

Other reasons predators do not drive prey to extinction

Answer 27

Habitat complexity and limited dispersal
Prey switching by the predator
Spatial refuges
Evolutionary changes in the prey populations

Question 28

Stochastic

Answer 28

randomly determined; having a random probability distribution or pattern that may be analyzed statistically but may not be predicted precisly
Ex. Rainfall

Question 29

Anthropogenic

Answer 29

Originating from human activity
Ex. carbon emissions from humans