Population Distributions

What are some factors that can prevent a population from persisting in an area?

Competitors

Predators

Pathogens

What can create geographic ranges?

Small-scale variations in the environment

What is a general rule regarding population distributions?

Populations can grow larger in more suitable habitats

How does the ecological envelope differ from the realized niche?

One describes the predicted conditions, while the other one describes the conditions that currently exist

What does the total abundance of a population provide?

A measure of whether a population is thriving or on the brink of extinction

How is the population density calculated?

Dividing the abundance by area

What happens when the population density is greater than what the habitat can support?

Some individuals must leave or the population will experience lower growth and survival

Where does the largest density of individuals typically occur?

Near the center of a population’s geographic range

What are the different types of population dispersion?

Clustered

Evenly Spaced

Random

Why is random dispersion not common?

Non-random environmental heterogeneity

What does dispersal allow for?

Allows species to colonize areas outside of their geographic ranges

What can dispersal help avoid?

Areas of high competition or high predation risk

What is the size of a defined space related to?

The abundance and density of the population

What are the different types of surveys that can be made?

Area- and Volume-Based

Line-Transect

Mark-Recapture

What are some of the ways individuals can be quantified?

Census

Survey

Measuring how far individuals travel from a single source location

What do populations with a high abundance also have?

Large geographic ranges

What is the density of a population negatively correlated with?

The body size of the species

What type of habitats do individuals choose whenever possible?

Habitats that provide the most energy

What are some factors that fitness is determined by?

Maximizing resources

Predator presence

Territory owners

What happens when individuals frequently disperse among subpopulations?

The whole population functions as a single structure