Populations - Dynamics

Question 1

Describe the effects of individual age, size & life history on population growth

Answer 1

Population growth is affected by per capita reproduction rates. An individual’s reproduction rate is affected by age (ex. decreases with senescence), size (ex. larger individuals have more offspring), and life history (ex. fecundity).

Question 2

Calculate life history table values & define attributes

Answer 2

Try practice problems in text book

Question 3

Describe how/why populations fluctuate over time/space

Answer 3

Populations fluctuate based on their age structure - age structure influences birth rate.

Physical environment and life history strategies will also influence survival rates

Question 4

Link concepts from population growth, physical environment, etc. to explain population dynamics… give examples

Answer 4

The physical environment limits population growth because resources are finite.
Examples:
If plenty of resources, population grows.
If predator population proliferates, prey populations will drop in response.
If vegetation is lost, herbivore populations will drop.

Question 5

Determining specific ages can be difficult…
Define age and stage models

Answer 5

Age model: how many years old an organism is

Stage model: stage of life - ex. juvenile or adult

Question 6

What are the three types of survivorship curves? What insight do they provide into the ecology & behaviour of the species?

Answer 6

Type I: high survival when young (high parental care), high mortality when old (limited by senescence, not lack of resources)

Type II: Constant rate of mortality (death mainly caused by lack of resources and disease)

Type III: High mortality when young (low parental care), low mortality once established (maturity brings protection)

Question 7

Static vs. cohort life tables - what are they used for?

Answer 7

Static life tables: tracks the same group over their lifespan

Cohort: takes a one time snapshot of a sub-sample at all life stages

Life tables are used to organize data for estimating survivorship & population growth.

Question 8

Most populations self-regulate around…

Answer 8

1/2 k

Question 9

Allee effect

Answer 9

Decreasing population leads to decreasing growth rate. This means that a minimum population is required for sustainability.

Question 10

Fecundity

Answer 10

Reproductive capacity

Question 11

Determinate growth

Answer 11

Growth stops at maturity where there is relatively constant fecundity

Question 12

Indeterminate growth

Answer 12

Growth continues after maturity, and offspring increases with maturity/size

Question 13

Senescence

Answer 13

Deterioration with age, lower reproduction rates

Question 14

Define the three types of survivorship curves

Answer 14

Type I: High survival when young, high mortality when old

Type II: Constant rate of mortality throughout life span

Type III: Mortality high when young, but low when old

Question 15

Define the following terms and give the equation for calculating life tables:

x =
bx =
nx =
lx =
dx =
qx =

Answer 15

lx: l1 = n1 / n0
dx: d1 = n1 – n2
qx: q1 = d1 /n1

x = age class
bx = age specific fecundity (females only)
nx = number of individuals in an age class
lx = age specific survival
dx = number that died
qx = age specific mortality rate

Question 16

Cohort life table

Answer 16

Monitors fate of all individuals born at the same time.

Question 17

Static life table

Answer 17

Subsample of the population at one time point, estimate fates based on numbers at certain age classes

Question 18

How can age be determined?

Answer 18

Usually defined by the study (ex. juvenile vs. adult based on plumage or size)