Unit 2: Population Ecology Flashcards
What is Population?
a group of individuals of the same species that live in the same area at the same time, also may potentially interact with each other
Can defining a population border be difficult?
Yes
Species exist as Metapopulation. What is Metapopulation?
a population of populations, connected by migration or gene flow
What is Population Size?
(N) the number of population members in a habitat at the same time
What are methods for determining Population Size (N)?
- count all individuals in the populations
- sub-sample and extrapolate
- mark-recapture
Is the method: “count all individuals in the population” for determining (N) possible?
It is usually not possible, except for those endangered species
What are the different types in the method: “sub-sample and extrapolate”?
Quadrat & Transect
What is a Quadrat sample?
square made of various materials used to determine population size and density in slow moving or stationary organisms
What is a Transect sample?
a path along which one counts and records occurrences of the objects of study
What are the potential difficulties if the “sub-sample and extrapolate” method?
- over what area do you extrapolate
- Heterogenous habitat
- movement of individuals
What is Mark-Recapture?
technique used to determine populations size in mobile organisms
What is the mark step in Mark-Recapture?
catch some individuals and mark them
What is the recapture step in Mark-Recapture?
return later, catch some individuals, tally number marked and unmarked
How do you estimate population size based on Mark-Recapture?
N = Mn/m
(N = estimate population size
M = number marked sample 1
m = number marked in recapture sample 2
n = total in recapture sample 2)
What assumptions are made about Mark-Recapture?
- individuals not moving in/out of study area
- individuals mix between captures
- no catch bias
- individuals do no learn to avoid/seek traps
- no change in survival rate for marked individuals
