lecture 13: What is a population? Flashcards
What is a population?
A group of individuals of a single species inhabiting a specific area
What are some characteristics that all populations have?
- Density
- Distribution
- Other demographic charactersitics
What is Density in regards to a population?
- number of individuals per unit area
What is Distribution in regards to a population?
Size, shape, and location of area occupied by population
What are the other demographic characteristics held by a population
Age & sex ratios, birth & death rates, immigration and emigration rates, growth rates.
What is absolute density?
The number of individuals of a population per unit area
What is ecological density?
The number of individuals of a population per unit area of suitable habitat
(moose per hectare of forest)
What limits a populations distribution?
The geographic distribution of a population is limited by the physical environment.
So a species can only live in areas where its niche requirements are fulfilled.
What are the three reasons why species aren’t living in all spaces?
why are they isolated to only certain locations
- All organisms have limited energy and resourses
- it takes extra energy to survive and reproduce in region on the edge of their niche
- Therefore, organisms don’t usually bother spreading out
What dose teh dispersal of a population affect?
It can alter the distributions and local population densities
What are the two major categories of dispersal?
immigration: Movement into a local population
Emigration: movement out of a local population.
Is migration dispersal?
no
What is migration?
Migration is the seasonal movement of individuals from one location to another.
What is dispersal?
The permanent movement from one population to another
What is the issue with killer bees that have been moving up from central america?
Aggressive compared to standard farm bees
Can create larger colonies because of an excess of food
Also form massive swarms to protect their hives.
In theory, Dispersal will allows a species range to move along with what?
The climate that their niche is within.
What is the leading force of population dynamics?
Climate.
What is dispersal a response of?
Changing of food supply
What are the two responses seen by predators when food supply is altered?
Functional response
Numerical response
What is a numerical response?
Change in density of predator populations in response to changes in prey density.
What are the two drivers of numerical responses?
Reproduction & Dispersal
What is a reproduction based numerical response?
Time lag between peak prey population and peak predator population.
What is a Dispersal based numerical response
no time lag between peak predator and prey populations.
Mountain pine beetle is spreading to
Alberta, wreaking havoc along the way.
What do you think the driving factor of their
dispersal is?
A. They are a non-native species, like the
Africanized honey bee example
B. Climate change, like the maple and
hemlock example
C. Food availability, like the kestrel/owl and
vole example
B. Climate change, like the maple and
hemlock example
What is a meta population?
A meta-population is made up of a group of subpopulations living on patches of habitat connected by an exchange of individuals.
What is a requirement for meta populations to form?
The populations need to be able to disperse from one population to another.
If there is no dispersal between populations, then can it be considered a meta population?
No it cannot,
What are the characteristics of a distribution pattern within a small scale
On smaller scales (< few hundred meters), the
individuals of a population are distributed in
patterns that may appear to be random,
regular/even, or clumped.
What are the characteristics of a distribution pattern within a large scale
The populations are clumped. (around areas of ideal conditions)
this is over an area which there is substantial environmental change
What is a random distribution?
Seen within small scales,
individuals have an equal change of living anywhere within an area.
What is a regular distribution?
Seen within small scales,
Individuals are uniformly spaced.
What is clumped distribution?
Seen within small scales,
individuals have a higher probability of being in some areas versus others.
What is the common understanding of large scale distributions of populations?
They are populations that are distributed over scales in which there is significant environmental variation
True or false:
All populations have characteristics such as
density, distribution, and demographics
True
True or false:
Density is defined as the number of individuals
per unit area. Can be measured as absolute
density (/area) or as ecological density
(/habitat area)
True
