Lecture 18: Population Ecology Flashcards
Ecology
What distinct interaction is characterized by the organisms interacting with the non-living components?
Abiotic
Ecology
What is referred to when considering biotic interactions?
How organisms interact with other organisms
Ecology
What is metapopulation?
Includes: (2)
Group SPATIALLY seperated sub-populations of the same species which interact at some level.
Includes: Movement (emigration/immigration) + mating!
Population space
A bunch of sheeps from the North Pole arrive in Quebec, what phenonmenon is referred to here and why?
Immigration: influx of new individuals from other areas.
Population space
Simon and his family move to Spain, what phenomenon is referred to here?
Emigration: movement of individuals out of a population and into other locations.
Ecology
Biogeography is the study of the ____ of ____ over ____ and ____.
Biogeography is the study of the distribution of biodiversity over space and time.
Ecology
What is known as the area where a particular species can be found during its lifetime, including where individuals or communities may migrate/hibernate?
species RANGE.
Species Range
When considering species range, what are the positive and negative effects of BIOTIC INTERACTIONS?
- Positive effect?
- Negative effect?
Biotic interactions:
- Positive effect: interdependent species within the actual range (ex: food source).
- Negative effect of predators, parasites, disease and competitor.
Species range
When considering species range, what factors set the range limit for the abiotic interactions?
Physical or chemical factors.
Ex: temp, water availibility, pH…
Metapopulation within a heterogeneous landscape
What are 3 patterns of dispersion within a population’s geographic range?
1 - 2 - 3
- Clumped (mini groups)
- Random
- Uniform (even caused by competition…)
Population size
How tf do you do sampling?
2 STEPS!
- Count number of individuals in randomly selected plots (quadrats) of same dimension.
- If density constant, extend this density obtained from the plots to entire area.
Population size
What are the six steps to the MARK-RECAPTURE technique?
1 - 2 - 3 - 4 - 5 - 6
- Capture random sample (s)
- Mark + release them.
- Wait for them to mix within population randomly.
- Capture second sample (n)
- Count number of marked animals in second capture (x) and number of unmarked animals.
- Total population size N = sn/x
Mark-recapture example!
180 dolphins were “visually” marked. After waiting 2-3 weeks for individuals to mix back into population, 44 dolphins were encountered, 7 of which had already been identified. What is the size of the population?
Use equation!
N = sn/x
N = (180)(44)/7
N = 1100 individuals
Population dynamics
What are two factors that can cause a population to grow?
1 - 2?
- Birth rates exceed death rates
- Immigration > Emigration
Population dynamics
What is known as a population whose members all have access to abundant food + free to reproduce at their physiological capacity. UNCONTROLLED, UNLIMITED!!
Exponential population growth
Population dynamics - Exponential population growth
Under Exponential population growth, the per capita rate of increase may assume the …
Maximum rate for the species (rmax)
rmax = dN/dt
- dN: change pop. size.
- dt: time interval.
Population dynamics
Although the rate of increase is constant, the population accumulates MORE new individuals per unit of time when it is …
LARGE than when it is small.
Population growth
Processes that are influenced by population density are said to be…
Processes that are NOT influenced by population density are said to be…
Processes that are influenced by population density are said to be density dependent – disproportionally affected.
Processes that are not influenced by population density are said to be density independent – 1 woman producing offspring.
Density Dependent processes
DEATH RATES:
Context: As ____ increases, the amount of ____ available ____.
This increases: ____ ____.
Result: The ____ competitors will ____ the others, leading to the ____ of the ____ competitors.
THIS IS A DENSITY DEPENDENT PROCESS.
DEATH RATES:
Context: As density increases, the amount of resources available decreases.
This increases: intraspecific competition (compete for limited resources in same species).
Result: The better competitors will outcompete the others, leading to the death of the poorer competitors.
THIS IS A DENSITY DEPENDENT PROCESS.
Density dependent processes
As death rates increase, what can spread?
- What is referred to as the threshold host density (Nt)?
As density increases, the rate at which certain diseases can spread also increases.
- Threshold host density (Nt) = minimum concentration of individuals necessary to sustain given disease.
Density dependent processes
IMMIGRATION AND EMIGRATION:
- High pop. density = … immigration.
- High pop. density = … emigration.
THIS IS A DENSITY DEPENDENT PROCESS.
- High pop. density = DECREASES immigration.
- High pop. density = INCREASES emigration.
THIS IS A DENSITY DEPENDENT PROCESS.
Population dynamics
When you consider the exponential growth model, is it realistic to think that resources will always be unlimited? If not, what is the name of the phenomenon that limits this?
Not realistic, rare that unlimited resources in the real world. Hence, CARRYING CAPACITY (k) is the maximum population size that a particular environment can sustain.
K flattens the curve, reaches a MAXIMUM.
Population dynamics
What is the logistic population growth model?
- 2 things are incorporated!
- Incorporates the change in growth rate as the population nears the carrying capacity.
- As carrying capacity is reached, per capita rate of increase approaches ZERO.
Population dynamics - relationships between concepts!
- When the population size (N) is small and the carrying capacity (K) is high, (K-N) / K ≈ 1. HENCE, per capita rate of increase…
- When the population size (N) is large and the carrying capacity (K) is small, (K-N) / K ≈ 0.. HENCE, per capita rate of increase…
Tf is the formula?
- When the population size (N) is small and the carrying capacity (K) is high, (K-N) / K ≈ 1. HENCE, per capita rate of increase approaches the maximum rate of increase rmax.
- When the population size (N) is large and the carrying capacity (K) is small, (K-N) / K ≈ 0.. HENCE, per capita rate of increase is SMALL.
Formula: dN/dtN = r ((k-N)/k)
Demographics
What is known as the study of the vital statistics of populations and how they change over time?
Demography
Demographics
What is a life table in demography: ____ - ____ summaries of the ____ pattern of a ____. Follows the fate of a cohort.
Life table: age-specific summaries of the survival pattern of a population.
