Chapter 2 Flashcards
Lag Stage
Slow growth, many resources, few individals
Exponential Stage
Population growing at its biotic potential (fast growth), found in lab conditions
Equilibrium Stage
No growth, meets environmental resistance (birth rate=death rate) many limiting factors, habitat at carrying capacity
How do we count organisms?
a) direct observation
b) indirect observation: tracks, nests, burrows, scat
Transects
A long narrow rectangular area used for sampling a population
Used: specie density is low & organisms are large
Quadrats
An area of specific size used for sampling a population in a square sampling area
Mark Recapture
A method where animals are caught, marked, released and caught again
Accuracy is dependant on 5 factors:
a) equal chances of catching marked and unmarked individuals
b) no animals can come or go
c) time is given to randomly disperse
d) no negative effect on captured animals
e) animals do not lose tag
Distribution Patterns
Determined by 2 factors:
1) distribution of ressources
2) interactions among members of a population
Clumped Distribution
- Ressource Distribution: uneven
- Ressource abundance: Varies
- Interactions: Positive
Uniform Distribution
- Resource Distribution: even
- Resource abundance: scarce
- Interactions: negative
Random Distribution
- Ressource Distribution: uniform
- Resource abundance: abundant
- Interactions: neutral
Environmental Resistance
Sum total of all limiting factors in a population that keep population below carrying capacity
Environmental Resistance= Density dependant (biotic)+ density independent (abiotic)
Demographie
The study of population changes (pop size and density)
B-BR increases
D-DR decreases
I-Immigration increases
E-Emmigration decreases
Population Explosion
population that grows fast before it can be obtained
Unlimited Environments
- unlimited resources
- species reach biotic potential
- growth is exponential
- biotic potential=average # of offspring produced /yr
- produces J shaped curve
Biotic Potential Factors
- number of offspring
- number of offspring that survive to reproduce
- age of reproductive maturity
- number of times individual reproduce in their lifetime
- lifespan of individual
Limited Enviroments
- limited resources
- occurs in natural populations
- produces S shaped curve
S shaped curve
3 stages:
- lag
- exponential
- equilibrium
Habitat at carrying capacity
J shaped curve
2 stages
- lag
- exponential
found in lab conditions
Carrying Capacity
The maximum population size a habitat can contain over a period of time
flat line
can change
Density Dependant Factors
A factor that affects the growth of a population to a greater extent when there is an increased number of individuals
- biotic factors
- low density-little effect on population
- high density- high effect on population
Density Independent Factors
A factor that effects population growth the same way regardless of the number of individuals
-abiotic factors
Survivorship Curve
Graph that shows a proportion of species alive at different ages
Type 3- High probability of surviving early in life but a rapid decline
Type 1- High survival early and into middle age few survive at old age
R strategy
- short lifespan
- early reproductive stage
- produce large numbers of young
- little or no parental care
- unstable environments
- smaller organisms
- exceeds carrying capacity then crashes
K strategy
- long lifespan
- late reproductive age
- produce few young
- parental care is present
- often exist in stable environments
- larger organisms
- exist close to carrying capacity without crashing
Competition
Occurs between or among things that are trying to use the same limited resources
Intraspecefic
- Between 1 species
- Density dependant factors
Interspecific
- between 2 or more diff species
- density independent
2 possibilities:
a) niches are identical
b) niches are non identical
Predator & Prey Interactions
constant cycle, more prey predators increase, more predators prey decrease
Symbiotic Interactions
A direct or close relationship between individuals of different species that live close together
Mutualism
both partners benefit
ex: bee and flower
Commensalism
one organism benefits while the other is not affected
ex: cattle and egrets
Parasitism
one organism benefits while the other is harmed
ex: human and mosquito
Invasive species
An organism that causes economic or ecological harm i. a new environment where it is not native
Damage of invasive species
a) outcompetes native species really quick and can cause extinction
b) reduce biodiversity less biodiversity causing monoculture
c) can upset balance of food eb
Ways to control invasive species
a) pesticides and herbicides
b) biological control: introduce other organisms into the food web that are predators or parasites of the pest
