Chapter 20 Flashcards
Most Common pattern of distribution
clumped
Least common pattern of distribution
random
Factors affecting population growth
birth rate
death rate
immigration
emigration
population explosion
rapid increase in population that’s too fast to be contained
population crash
rapid decrease in population
Biotic Potential
the highest possible per capita growth rate
Lag phase
slow population growth due to few individuals able to reproduce
Exponential growth phase
(r)
rapid population growth due to much higher birth rate then death rate
Stationary Phase
birth and death rates are equal
Carrying Capacity
(k)
theoretical maximum sustainable population
Density Dependent Factors
biotic factors that limit the carrying capacity
predators, parasites, disease
Density Independent Factors
abiotic factors that limit carrying capacity
droughts, floods, fires
Environmental Resistance
total affect of all limiting factors (biotic and abiotic)
r Selected Strategies
species that produce close to their biotic potential
short life span
many offspring
affected by density independent factors
exp mouse
k Selected Strategies
populations which live close to their carrying capacity
larger
less offspring
affected by density dependent factors
elephant
Open populations
changes through immigration and emigration and birth/death rates
Closed populations
only change through birth and death rates not immigration and emigration
community
interacting populations within a given area
Intraspecific competition
competition within a species for resources
affected by density dependent factors
Interspecific competition
competition btw species for resources
includes invasive species
Competitive exclusions principle
no two species can occupy the same niche n a community
Defences Against Consumers
poor taste like poison
physical protection like thorns
protective camouflage
Batesian Mimicry
harmless animals evolve to look like harmful ones
Mullerian Mimicry
2 harmfully animals evolve to look like each other
Symbiosis
relationship between two species
mutualism
both species benefit
commensalism
one benefits and the other isn’t harmed
parasitism
one benefits and the host is harmed
succesion
change in an ecosystem over time
driven by abiotic and biotic factors
Primary Succession
begins where no soil is present to begin with, takes a long time
pioneer community are the first organisms to populate this area
climax community: the stable community the eventually developed
Secondary Succession
begins when soil is present but the old community has been destroyed, occurs faster the primary succession
includes pioneer species and the climax community
Age pyramids
triangle: rapid population growth
rectangle: stable population
inverted triangle: decreasing population
