Lecture 5-6: Population Ecology

Question 1

Why do we care about population numbers?

Answer 1

• Conservation (to see what species are vulnerable for extinction)
• to see available resources
• (health) to measure danger of potential viruses

Question 2

When are differential equations suited for population

Answer 2

when the population growth is continuous

Question 3

Difference equations

Answer 3

discrete model
best used for episodic reproduction

Question 4

Continuous time model

Answer 4

N= (No) . e^rt

Question 5

Discrete time model

Answer 5

N= (No) . theta^t

Question 6

what is the relationship between theta and r?

Answer 6

theta = e^r
r= ln (theta)

Question 7

What keeps populations from exploding or going extinct?

Answer 7

• density dependent regulation
• how the population numbers affect population growth
• the population grows faster when the population Is smaller because of the abundance of resources

Question 8

Model of density dependent equation

Answer 8

Dn/Dt= rN (1-R/k)

Question 9

Describe variables in Nt= (KNo)e^rt/ K+No (e^rt-1)
What is this equation?

Answer 9

K= carrying capacity
No= initial population
r= instantaneous rate of increase
t= time over timestamp
this is the sigmoid growth curve with an s shape

Question 10

What does the inflection point represent in the sigmoid growth curve

Answer 10

• when population starts to grow slower

Question 11

allee effect

Answer 11

• when, in small populations, there are negative effects on population growth due to difficulty to reproduce
  example” meerkats

Question 12

Fecundity

Answer 12

how many daughters a mother will produce in her lifespan

Question 13

Survivorship

Answer 13

Chances of survival to the next timestamp

Question 14

Components of a life history strategy

Answer 14

• reproduction timing (episodic or continuous)
• number of offspring
  -parental investment
• lifespan

Question 15

Life tables

Answer 15

Data summarizing life events of individual and when they typically occur

Question 16

Survivorship schedule

Answer 16

Lx denotes likelihood of being alive at next Time stamp

Question 17

Fecundity schedule

Answer 17

Mx denotes expected daughters mother will produce

Question 18

Cost of reproduction

Answer 18

(Fecundity)- (Survivorship)

Question 19

Net Reproduction Rate

Answer 19

Ro= ∑Mx . Lx
Mx denotes number of offspring produced if she isn’t expected to die early

Lx accounts for if she does die early

Question 20

Generation Time

Answer 20

Average age female gives birth

T=∑LxMx/Ro

Question 21

Semalparity

Answer 21

When species undergo reproduction at once right before they die
examples: salmon