CHAPTER 6 Population Ecology Flashcards
The way we measure additions of this type is with the natality rate (also called the birth rate)
BIRTH
This is the permanent arrival of new individuals into the population.
IMMIGRATION
This is the permanent movement of individuals out of a population.
EMIGRATION
We measure this with the mortality rate (also called the death rate).
DEATH
A group of individuals of the same species that live within a particular area and interact with one another.
population
The study population in relation to environment, including environmental influences density, distribution, age structure and abundance.
Population Ecology
- In species that reproduce sexually, a population might be defined as the group of individuals that interact by _______.
- In species that reproduce asexually, a population must be defined by other kinds of interactions, such as ____ for common sources of food.
interbreeding
competition
- Population ____ the number of individuals in the population
- Population ____ the number of individuals per unit of area.
size
density
- geographic area where individuals of a species occur.
- the number of individuals of a species that are found in a given area
distribution
abundance
Distribution and abundance change over time and space
Pattern of spacing of individuals within the boundaries of the population
** Clumped – most common
*Usually because of resources
*Humans
**Uniform
*Interactions between the individuals in the population
*Territoriality
** Random
*Inconsistent
*Plants – windblown seeds
dispersion
Population Growth Rate
BR
DR
M
AS
SC
- Birth Rate - fecundity
- Death Rate - mortality
- Migration (immigration & emigration)
- Age Structure
- Survivorship Curves (patterns of mortality)
Relative number of individuals at each age group
Used to project future population growth
“pyramid” shaped
AGE STRUCTURE
Greater number of young individuals means greater potential for growth.
Survivorship Curves
Shows the number of individuals alive during each stage of life
Type I – few offspring
- _____ death rates at beginning of life
- _____ of parental care
Type II - _____ offspring
- _____ death rate at all age groups
Type III – lots offspring
- _____ death rates at beginning of life
- _____ parental care
Low
Lots
medium
Consistent
High
Little or no
describes populations that increase in numbers without any limits to their growth. (J-shaped curve)
-The per capita growth rate stays the same, making population grow faster as they gets larger.
Exponential growth
introduces limits to reproductive growth that become more intense as the population size increases. (S-shaped curve)
Logistic growth
increases continually without limiting factors – assumes resources are unlimited
The larger the population becomes the faster it grows
Unregulated growth
Occurs in populations that colonize a new or unfilled environment
exponential model
But realistically, populations cannot grow exponentially forever…
AS THE DENSITY CHANGES , IT HAS AN IMPACT ON COMPETION FOR FOOD RESOURCES.
is anything that constrains a population’s size and slows or stops it from growing. Some examples of limiting factors are biotic, like food, mates, and competition with other organisms for resources.
refers to any of the factors (variables) in an environment capable of limiting a process, such as the growth, abundance, or distribution of a population of organisms in an ecosystem. —– may be density-dependent or density-independent.
Limiting factor
2 Categories of limiting factors
Birth rate and death rate change with population size
The larger the population gets the more competition
Resources
Territoriality
Disease
Predation
Toxic waste (metabolic)
Intrinsic Factors
density-dependent factors
2 Categories of limiting factors
Size of the population does not effect the birth rate or death rate
Natural disasters – will occur regardless of population size
Fire
Flood
Weather
density-independent factors
Population Growth
- account for limiting factors and limited resources
- the number of individuals that can occupy the habitat (K)
logistic model
carrying capacity
The per capita growth rate gets smaller as the population approaches carrying capacity (K)
logistic growth
Reproductive Strategies - Selection
Maximum growth rate below carrying capacity
* Exponential growth
* Opportunistic populations
* Early reproduction
* Semelparity
* Short life span
* High mortality rate
* Little or no parental care
* Large numbers of offspring
Fish
Grasshoppers
Flies
r-selected
Reproductive Strategies - Selection
Maximizes population size at or near carrying capacity
* Logistic growth
* Equilibrial populations
* Late reproduction
* Iteroparity
* Long life span
* Low mortality rate
* Lots of parental care
* Few offspring
Sharks
Elephants
Humans
k-selected
Reproduction
Determined by the tradeoff between birth rate and survival probability
** ________ – 1 single large reproductive effort
* Harsh environments
* Low survival rate for long periods of time
* Insects, annual plants, salmon
** ________ – multiple smaller reproductive effort
* Occurs in organisms that survive for long periods of time once established
* Mammals, perennial plants
Semelparity
Iteroparity
