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- Population Growth - Factors that Affect Population Growth - Human Population Growth - Changes to Resources - Biodiversity
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population
every species member in given location
geographic range
pop. location affects size
more resources = more organisms
density
amount of organisms in given area
distribution
how spaced out the organisms are within their boundaries
uniform
evenly spread throughout
competition for resources
maximizes space between
random
unpredictable distribution
less individual interactions
*least common ex: dandelion seeds
clumped
clustered together
clusters around resources
*most common
growth rate
population size change over time
increase, decrease, no change
age structure
male+female at each age
immature: before breeding
mature: breeding
*allows predictions on growth/reductions
birth rate
num of births/time
death rate
num of death/time
growth rate
birth rate - death rate
immigration
individuals going into population
emigration
individuals exiting population
effects of population factors
every factor must be considered
they can oppose or support each other
ex: birth=death, immigration>emigration → growth
exponential growth
rapid growth
ideal conditions+unlimited resources
logarithmic growth
phases of growth
*exponential growth is unsustainable
phase 1
lag phase; slow growth
phase 2
log phase; exponential growth
phase 3
population disruption; slower growth
phase 4
no size net growth *brith=death, em. = imm.
carrying capacity
max num of organisms in species habitat can handle
*factors reduce capacity
limiting factors
affect population’s environment, controlling population
biotic limiting factors
competitors
predators
parasites+pathogens
abiotic limiting factors
weather
natural disasters
density-dependent competition
when density is too high for food, water, mates, etc
intra: within species, inter: between species
affect death+birth rates, emigration
limited resources → competition
predation
predator kills prey, prey population decreases
*herbivores predators to plants
predation effects
decreased prey → decreased predator → increased prey → increased predator
disease
parasites+pathogens
high population density makes spreading easier from close contact
*epidemics: a lot of animal/plants
density-independent factors
limits population regardless of density *random
weather: hurricanes, droughts, floods
natural disasters: fires, volcanoes, earthquakes
*affects entire population equally
human population growth
slow growth
500 BC increased more
industrial revolution (exponential growth)
to 7 billion people
human growth reasons
sturdy shelters]
weather protection
comfortable living at diff temps/precipitation
easy food access
agriculture reduced migration
less energy for getting food
healthcare/sanitation
avoiding diseases
increase life expectancy
human growth limits
competition
war (many deaths)
limited resources
water+food lack
starvation/malnutrition
disease
pathogens, viruses, bacteria
*pandemics constantly monitered
demography
study of human populations
birth/death rates, life expectancy, age structure
demographic transition
change from high birth/death rates to low
1: high, high (no change)
2: high, falling (improved living conditions)
3: falling, low (waiting longer for children)
4 low, low (stable)
*more developed countries are higher up in their transitions
age structure diagram
evaluates ages for population changes+predicts future changes
organized by age+sex
*male/female age diffs, females usually live longer
rectangular shape
evenly spread across ages
stable; no significant growth (ex: austrailia)
triangular shape
more young than old people
population will grow once young people mature (ex: angola)
urbanization
creation of cities
displaces flora+fauna
destroys habitat/environment
produces waste
urban sprawl
spread pf urbanized areas
industrial growth
building factories
similar to urbanization
burns fossil fuels
produces hazardous waste
agriculture
farming
high water demands
soil nutrient depletion from crop monoculture
burns fossil fuels
fertilizer+pesticide waste
erosion
removal of soil by wind (becomes drier when carried to diff places) and water (less plants allows water to run through soil)
*loss+redeposition is a major issue for ecosystems
desertification
dry flat farmland to desert
depletion
nutrients+water removed
*avoided with planting a variety, resting soil
monoculture: repeated crop planted
animal grazing: animals destroy plants
deforestation
clearing of trees
agriculture, urbanization, wood
increases erosion+soil depletion from absence of trees/roots
*destroys habitat/allows erosion
water pollution
*only 2% freshwater
sewage: a lot of nitrogen+bacteria
certain O2 consuming algae thrive from nitrogen, taking O2 from others
point source
clear, single pollution source
non-point source
multiple smaller sources without clear contributor
ex: pesticides, organic chemicals
biomagnification
pollutant concentration as it travels up food chain
biomagnification example
low concentration in water, higher in plants (take in a lot of water)
consumer gains more pollutant from eating many plants
add. magnification as consumers eat more of each other
water oversuse
water is a limited resources, and must be conserved
air pollution
*usually non-point (industrial waste+fossil fuels)
smog: thick haze of pollutants over cities
acid rain: nitrogen+sulfur with water vapor to nitric+sulfuric acids which falls as precipitation
greenhouse gasses: contribute to climate change by trapping heat
ozone (O3) layer
O3 absorbs sun UV radiation+protects from radiation
1970’s: hole in ozone layer over Austrailia discovered
linked to CFCs (chloroflurocarbons), in aerosol, fridges, freezers
montreal protocol: banned most CFC *concentration lessened, hole stopped growing
NASA climate change study
global warming: average global temp increase
severe weather/precipitation, sea levels increasing from ice levels melting
2007 IPCC climate change study
shorter hibernation
dealer flowering seasons
linked to greenhouse gasses trapping heat
fossil fuels → more greenhouse gases
deforestation → less plants to take in CO2
*still being researched, sustainability is vital
biodiversity
variation of all organisms in biosphere
ecosystem diversity: habitats+communities
species diversity: species amount+types
genetic diversity: in/between species
undiscovered species
more than half species undiscovered
90% of arachnid species undiscovered
950,000 insects species known, 9 mil unknown
healthy ecosystems
balance of all present species
*slight changes have drastic changes
medecine
animals+plants produce compounds/treatments
agriculture
selective breeding strengthens wanted traits in crops (disease resistance)
development (agriculture/urban)
disrupts habitat/ecosystems
habitat fragmentation
smaller habitat pieces from broken ecosystem communities
over-hunting/fishing
reduces biodiversity (extinct)
invasive species (out-competes native species)
*limits now on over-hunting species
pollution
damage to environment+ecosystem
climate change
severe weather changes, sea levels increasing, ice levels decreasing, global warming
*sea ice loss → polar bears displaced
diversity hotspots
areas where greater amount of species are threatened
*most in Pacific Ocean, at least 1 in each continent
species preservation
endangered species bred+matured, then released into wild to increase numbers *zoos+aquariums
ecosystem preservation
focuses on entire hot spots → entire group+natural interactions (learning about ecosystem through organism in natural habitat) *national parks, reforestation areas, reserves, marine sanctuaries
people+preservation balance
rewards for inconvenience/cost of efforts
financial credit for hybrid cars, solar panels
tourist areas from preservation sites for profit
biosphere reserves
encourages preservation
sustainable technology development
conservation policy creation
human+organism needs balanced
*World Network of Biosphere Reserves allocate and organize such responsibilities
development (agriculture/urban)
disrupts ecosystems, habitats