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Transcript of Ecology
The study of living systems and their interactions
with each other and the environment around them.
No man is an island ~ John Donne
a group of organisms of the same species
living in the same area, using the same resources
and affected by the same factors & stresses
Examining how a group of populations in a particular area interact with each other (predation & competition for example) and how these interactions affect community structure & organization.
Biotic Factors - living/organic components of an ecosystem that affect organisms (predator/prey/parasites/mates/disease/etc.)
Abiotic Factors - nonliving components of an ecosystem that affect organisms (water/oxygen/nutrients/space/etc.)
Factors that Describe a Population
size - birth/immigration - death/emmigration
range - migration area/environmental limitations
distribution - clumped, uniform, random
density - concentration in an area
Population Growth Factors
sex ratio - #females is more important
generation time - flies=days, humans=years
age structure - how many of each age
type I - few children/high survival rate
type II - litters of offspring/half survive
type III - millions of offspring/high mortality rate (few survive)
Different strategies for Survival:
K selected - like type I
r selected - like type III
Tradeoff - # and size of offspring vs. survival of offspring or parent. Produce more offspring costs energy but you don't have to take care of them VS. produce few offspring (risky) so you must devote time & energy to make sure they survive.
Exponential Growth - unrealistic for the long term because of limiting factors (space, mates, food, time, money, etc.
Logistic Growth - slowing as it reaches its carrying capacity (K) due to limited resources, sometimes fast, growing populations (r-selected) overshoot this and then experience a population crash or die-off period before becoming stable.
Wealthiest 20% consumes over 86% of the world's resources
Competitive Exclusion Principle
Niche is area & resources used by a species
Realized or Actual Niche depends on other species
No 2 similar species can occupy the same niche
Microhabitats eliminate competition
Characterizing a Community
Composition - dominant species, biomass
Keystone Species - lynchpin of foodweb
Succession - Primary, Secondary and Climax community
Symbiotic Interactions include: mutualism, commensalism, parasitism & competition (predator/prey)
Camouflage: cryptic and aposymatic coloration, batesian and mullerian mimicry.
Drives Co-evolution of species b/c they affect the survival of one another
Green Parrot Snake
Loss of Biodiversity
what is the survival strategy of this species?
what does it gain by using this strategy?
what does it cost the species? Tradeoff...
loss of community stability
increased chance of collapse
artificial selection of humans
loss of a single species results in the collapse or major disruption of a community because they prey on the dominant species and keep them under control. These species can often be indicators of the health of an entire community.
Glacial rock or volcanic erruptions stripped bare of all life & soil (organic material)
Fire or other natural disaster will leave much of the soil intact so first growth is annual plants not lichen/mosses as in Primary Succession.
populations are dynamic, they change over time because their environment is changing. Darwin said populations produce more individuals than the environment can support. How is this important in driving the evolution of a species?
One population can influence the survival of another. Those who survive are those best adapted to the environmental conditions at that time. Adding or removing species affects the evolution of others in that community. Discuss one way in which humans have influenced this.
a self-contained environment including all the biotic and abiotic factors.
Trophic Levels (Greek origin - feeding)
Producers - plants & other autotrophs
Consumers - primary, secondary, tertiary, etc. all heterotrophs
Decomposers - bacteria, earthworms, nematodes, etc. that break down dead material back into usable organic nutrients
Energy Source - the sun (or in some cases, heat from the earth)
3 Major Types:
Numbers - how many individuals at each trophic level.
Biomass - mass of each trophic level
Energy - available at each level
Nitrates in Runoff
40% more water lost
60% more nitrates lost
10% more calcium lost
removal of primary producers reduces...
Breaking the water cycle could have disasterous effects for the entire ecosystem
Carbohydrates, Lipids, Nucleic Acids & Proteins are all based on Carbon skeletons.
Respiration puts CO2 into the atmosphere
Photosynthesis pulls it back out and converts it into organic forms we can use again (molecules listed above)
Nitrogen-fixing bacteria live in nodules of legume plants (legumes include beans, peanuts and lentils)
These bacteria change the structure of Nitrogen into a form plants can absorb and thus the entire food chain.
Why we need P
Phosphorous helps us...
build bone mass - Ca10[PO4]6[0H]2 is the chemical formula for the crystaline deposit in bone
generate ATP - adenosine triphosphate which is form of energy used by cells
hot summers/cold winters
rich soil/good for crops
very cold, long winters, fair soil
pine trees, caribou, wolves, moose, bear, rabbits and lynx
permafrost - layer of permanently frozen soil, no trees
caribou, artic foxes, snowy owls
arid, low rainfall, poor soil, extreme temps (night/day)
cacti, jackrabbits, owls, kangaroo rats, lizards, snakes, tortoises
high rainfall and temp., poor soil
Temperate Deciduous Forest
moderate amount of rain, warm summers/cold winters
deer, wolves, bear, small mammals, birds
Large regions classified by their climates & plant life. Distribution depends on their latitudes. Similar biomes can be found at similar latitudes both north and south of the equator.
-> DNA & RNA
Gross Primary Production
total primary production of an ecosystem
Net Primary Production
Gross production minus the cost of respiration by consumers
Toxins build up in a foodweb becoming more highly concentrated higher up the foodchain
Top predators are most affected because they receive the most concentrated doses.
A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria.
Dominant Species - largest biomass