Pop Ecology

Question 1

Population ecology focus

Answer 1

Factors affect pop size

Question 2

Unique features of pops

7

Answer 2

• Distribution
• Structure ( age structure, sex ratio)
• size (N)
• Density (N/ area)
• Growth rate (r)
• Pattern of growth ( logistical/ exponential)
• Life history traits

Question 3

Pop size

Answer 3

• numbers individuals in pop

Question 4

Pop density

Answer 4

• number individuals in area ( volume )

Question 5

Estimating pop size

Answer 5

Moving?

Yes: mark recapture

No: quadrant sampling

Question 6

Range of tolerance

Answer 6

Range abiotic where organisms can survive

Question 7

Limits of tolerance

Answer 7

• upper/ lower limits particular (usually abiotic) factor where organisms survive

Question 8

Geographic range

Answer 8

Where species live

Question 9

How to do mark recapturing

Answer 9

1 visit: mark individuals

2 visit: capture and count how many are marked

(#marked 1 (M)/ estimated pop size (Ñ) ) =
( # marked 2 (m) / total captured 2 ( n))

N= M*n/m

Question 10

Assumptions for mark recapturing ?

4

Answer 10

1) pop closed so N constant ( no birth/ death, move in/ out pop)
2) all same change be caught
3) marking don’t affect later catchability
4) don’t loss mark

Question 11

Pop size (N) changes with time (4 factors and formula)

Answer 11

1) #births (increase N)
2) #deaths ( decrease N)
3) # immigrations (increase )
4) leaving ( emigrating) ( decrease)

N(t) = N (original) + B - D + I - E

Question 12

How calculate pop parameters

2

Answer 12

Per capita ( per person ) basis

• let compare did pop sizes

Question 13

Birth / death rates

3

Answer 13

b = B/N

d = D/N

Abs number births / deaths = B/D

range 0 to 1

Question 14

What is r ( intrinsic growth )

1 and formula and 3

Answer 14

• per capita growth rate

r= b-d

b>d , r>0, pop increase
b< d , r< 0 , pop decrease
b=d, r=0 , pop doesn’t change

Question 15

Patterns of growth

Answer 15

Logistical and exponential

Question 16

Exponential growth

6

Answer 16

• J- shape
• resources not (yet) limited
• typically found: few individuals found new pop / bottleneck and start recovery with lots resources
• r density independent
• # individuals added pop is function (N)
• # individuals added depends on r

Question 17

Logistics growth

6

Answer 17

• realistic, eventually runout resources
• growth rate level ~ 0
• max pop size specific environment can support (K)
• initial growth exponential
• r decreases as pop increases / resources limited
• r density dependent

Question 18

Carrying capacity

Answer 18

• max pop size specific environment can support (K)
• not constant, depends variables
• can change with time/location

Question 19

What pop density is r highest?

3

Answer 19

Low pop density

Small N (K-N)/K = K/K = exponential

• r smaller, eventually fluctuates around 0

Question 20

2 factors prevent exponential pop growth

2 with 3 and 1

Answer 20

Density dependent: - often biotic ( composition)

• less E reproduction, less reproductive success, less survival
• less births, more deaths

Density independent: - often abiotic ( natural disasters, cold snaps )

Hint: more likely happen if pop increases

Question 21

Life history traits

1+ 8 eg

Answer 21

Life stages ( birth —> growth —> reproduction—> death)

• age specific survivorship
• age first reproduction
• sex ratio offspring
• reproductive lifespan
• # offspring
• size offspring
• amount parent care
• growth rate

Question 22

Survivorship curves and 3 types

Answer 22

• # individuals surviving as function age1) increase survivorship till old ( large mammals)
  2) steady survivorship ( some birds , lizards , rodents )
  3) decreases survivorship when young ( sea turtles, fish , plants )

Question 23

Life history traits and natural selection

Answer 23

• LHT linked fitness
• can’t max all LHT same time ( lots babies and care)
• NS max total lifetime fitness

Question 24

K- selected

7

Answer 24

K: little offspring and high survivorship

• stable environment
• high competition
• long lifespan
• type 1 survivorship
• reproduce more/ equal 1
• few big offspring

Question 25

r - selected

8

Answer 25

r: lot offspring and low survivorship
- unstable/ unpredictable envious
- short lifespan
- type 2 survivorship curve
- sex maturity fast
- max r
- usually reproduce once
- lots small babies