EE25

Question 1

What are the 2 main kinds of models in ecology?

Answer 1

mechanistic models
aim to explain processes underlying observed patterns
empirical model
show relationships between observed data - eg. popualtion size as a function of rainfall

Question 2

What is the fundemental equation of population dynamics?

Answer 2

Nt+1 = Nt(Bt - Dt +It - Et)
^ population growth
if r>0 = exponential growth

Question 3

How do you model population growth?

Answer 3

dN/dt = rate of change of N
N= current popualtion
r= average number of surviving offspring each individual has/ intrinsic growth rate
dN/dt = rN 
r>0 for species not dying out

Question 4

What factors can stop exponential growth?

Answer 4

weather and environmental variation
lack of food nutrients and water
lack of space/light
disease/parasites
predation

Question 5

What are limiting factors?

Answer 5

stop populations increasing exponentially by reducing growth rate

Question 6

What are regulating factors?

Answer 6

subset of limiting factors that bring populations back to equilibrium

• doesnt only limit populations by causing lower of negative growth when large
• also allows recovery when rate
• can be hard to show that a factor is regulatory but without regulation factors would not persist.

Question 7

What is density dependence?

Answer 7

in order to regulate a population factors must act in a density dependent manner.
as density increases per capita growth rate goes down and individual death probablity goes up.

Question 8

What is the simplistic model of population growth rate?

Answer 8

Change in N = rN

r = intrinsic growth rate

Question 9

What is the carry capacity?

Answer 9

density at which rates equal equilibrium population size

Question 10

What are the main things that affect growth rate in different organisms?

Answer 10

insects = 0% because of space. 37% parasites.
small mammals = 67% due to space, 24% due to food
large mammals = 99% due to food
marine mammals = 0% social
mammals = 0% affected by parasites.