Ch. 10 Lecture

Question 1

What PROCESSES determine current population size (Nt)?

Answer 1

Dispersal, Survival Patterns, and Age Distribution

Question 2

current population size equation

Answer 2

N_t=N_t-1+(B-D)+(I-E)

N_t: current population size

N_t-1: previous population size

B: # births

D: # deaths

I: # immigrants/joiners

E: # emigrants/leave

Question 3

Dispersal

Answer 3

(I-E)

• move from where they were born to a new area
• variable within species AND among populations
• dispersal barriers at edge of Habitat Tolerance Range

Question 4

Survival Patterns

Answer 4

(B-D)

• Survivorship Curves
• Life Tables

Question 5

Age Distribution

Answer 5

(B-D)

reflects:

• history of survival (high/low periods)
• periods of successful reproduction
• population growth potential

Question 6

Growth Potential

Answer 6

are older individuals replacing themselves or not?

Question 7

Survivorship Curves: horizontal line

Answer 7

high survivorship

Question 8

Survivorship Curves: vertical line

Answer 8

low survivorship

Question 9

Survivorship Curves: diagonal line

Answer 9

steady survivorship

Question 10

Survivorship Curves: Type I

Answer 10

high => low survivorship.

most individuals die later in life

Question 11

Survivorship Curves: Type II

Answer 11

steady survivorship.

uniform rate of decline

Question 12

Survivorship Curves: Type III

Answer 12

low => high survivorship.

huge decline in young

Question 13

Survivorship Curves: Axes

Answer 13

X-axis: Life span

Y-axis: number of survivors (N_x)

Question 14

Survivorship Curve: r-selected species

Answer 14

Type III

Question 15

Survivorship Curve: k-selected species

Answer 15

Type I

Question 16

How do we estimate patterns of survival?

Answer 16

Life Tables

Question 17

Life Tables

Answer 17

Provide picture of survival and mortality in populations.

Explore pop. dynamics in context of:

• birth
• death
• survivorship
• age distribution

Question 18

Types of Life Tables

Answer 18

Cohort v. Static

Question 19

Cohort (Dynamic) Life Table

Answer 19

• identify individuals BORN AT SAME TIME and keep records from birth to death
• useful for PLANTS and SESSILE organisms (immobile) or relatively SHORT-LIVED species

Question 20

Cohort (Dynamic) Life Table: components

Answer 20

• Age (x)
• Number Alive (N_x)
• Survivorship (I_x)
• Mortality Rate (M_x)
• Survival Rate (S_x)

Question 21

Cohort Age Class

Answer 21

census interval (x to x+1)

Question 22

Mortality Rate

Answer 22

M_x=(N_x-N_x+1)/N_x

Question 23

Survivorship

Answer 23

I_x=N_x/N₀

Question 24

Survival Rate

Answer 24

S_x=I₀-M_x

Question 25

What is a useful tool for inferring population processes?

Answer 25

Life Tables

Question 26

Static Life Table

Answer 26

• record AGE AT DEATH of individuals within a certain TIME PERIOD
• differs from the cohort methods because individuals are BORN AT DIFFERENT TIMES
• useful for MOBILE and LONG-LIVED organisms
• must be able to age organism at death!

Question 27

Why are there so few young cottonwoods in the Rio Grande population?

Answer 27

Population has not reproduced for over a decade!

• seeds germinate in flood plains (spring floods also reduce competition for cottonwood seedlings)
• seasonal flooding has been disrupted by dams

Question 28

How to make a life table:

Answer 28

Record # individuals alive (N_x) in each age class => Cohort

OR

Record # deaths in each age class => Static

Question 29

Static Life Table: components

Answer 29

1. age interval
2. # dying during interval
3. # surviving at beginning of interval
4. # surviving as fraction of newborn (1st #3)
5. mortality rate (#2/#3)