Determining Population size and Density Flashcards
Population size
The number of individuals of the same species living within a specific area
Population density
Number of individuals per unit volume or area
What are the mathematical methods used to calculate and estimate the population size?
- Transects
- Quadrats
- Mark-recapture
When is using transects useful?
When the density of the species is low or large and easy to spot organisms.
When is using quadrats useful?
Useful for sessile organisms or ones that move very little.
When is using mark-recapture useful?
When the animals are hard to reach or migratory. It is an indirect determination of population size.
How does mark-recapture work?
Animals are trapped temporarily marked using a tag or a transmitter and then released. Traps are placed weeks later the proportion of marked versus unmarked animals are analyzed and an estimate is developed.
What are the three types of population distribution?
- Uniform distribution
- Random distribution
- Clumped distribution
Uniform distribution
- when nutrients are evenly distributed but scarce
- eliminates competition
- species can mark their territories by releasing chemicals
Random distribution
- resources are evenly distributed however they are plentiful
- no need for defence or competition
Clumped distribution
- uneven distribution of resources
- organisms that partake in positive interactions ex. protection from predators or hunting in groups
Fecundity
The number of offspring produced by a female over her lifetime
Fecundity tends to be…
inversely proportional to the amount of care and investment that the oarents provide to the offspring due to the fact that reproduction is a high-energy task
What is fecundity also proportional to?
Fecundity is also inversely proportional to survival.
How many types of survival patterns are there?
There are three types:
- Type I
- Type II
- Type III
