Populations - Dynamics Flashcards
Describe the effects of individual age, size & life history on population growth
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).
Calculate life history table values & define attributes
Try practice problems in text book
Describe how/why populations fluctuate over time/space
Populations fluctuate based on their age structure - age structure influences birth rate.
Physical environment and life history strategies will also influence survival rates
Link concepts from population growth, physical environment, etc. to explain population dynamics… give examples
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.
Determining specific ages can be difficult…
Define age and stage models
Age model: how many years old an organism is
Stage model: stage of life - ex. juvenile or adult
What are the three types of survivorship curves? What insight do they provide into the ecology & behaviour of the species?
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)
Static vs. cohort life tables - what are they used for?
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.
Most populations self-regulate around…
1/2 k
Allee effect
Decreasing population leads to decreasing growth rate. This means that a minimum population is required for sustainability.
Fecundity
Reproductive capacity
Determinate growth
Growth stops at maturity where there is relatively constant fecundity
Indeterminate growth
Growth continues after maturity, and offspring increases with maturity/size
Senescence
Deterioration with age, lower reproduction rates
Define the three types of survivorship curves
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
Define the following terms and give the equation for calculating life tables:
x =
bx =
nx =
lx =
dx =
qx =
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