Crash Course Ecology

Crash Course Ecology
Notes Created By Jack Lance

The History of Life on Earth

● About 4 billion years ago, when the Earth’s first oceans formed, life
happened via the bonding and reactions of molecules found in the
water. We don’t know how it happened, but it did.
● First life was likely a grouping of chemicals surrounding a
membrane, because as we know, phospholipids (being
hydrophobic) spontaneously form bilayers when in water.
○ Over time, these likely transformed into amino acids, and
eventually RNA.
● These collections of chemicals trapped in membranes, called
protobionts, most likely began to grow, split and replicate until
some copying error gave way to DNA nucleotides, which is a much
more stable repository for genetic material than RNA because it is
double stranded, not single stranded (RNA).
● First living things were Prokaryotes, singlecelled organisms with
no nuclei, that were probably very similar to the archaea we find
living today in hydrothermal vents, sulfur hot springs, etc..
(Extremophiles)
○ likely showed up around 3.93.5 billion years ago during the
Archaean Eon. The first of 3 eons in Earth’s history.
■ The Archaean
■ The Proterozoic
■ The Phanerozoic
● These are broken up into Eras, Periods and
Epochs
○ From 3.53.1 billion years ago, prokaryotes were all alone on
Earth, but then the amount of Oxygen in the atmosphere shot
from 010% in a very short period of time (geologically
speaking).

■ Likely produced by a new prokaryote, Cyanobacteria,
which figured out how to make its own food through
Photosynthesis.
■ This Oxygen Revolution killed off many prokaryotes
that had evolved without Oxygen
○ About 2.1 billion years ago, a new kind of organism
appeared Eukaryotes. These include (today) all plants and
animals.

■ the Eukaryotes likely evolved through a process called
Endosymbiosis, in which one prokaryote parasitized
another, resulting in a mutual relationship and
Mitochondria.
○ About 1.5 billion years ago, Multicellular eukaryotic
organisms begin showing up, the very first likely being algae.

○ Around 535 million years ago, the Eukaryotes went berserk.
■ This is known as the Cambrian Explosion. A major
biological goldenage when the diversity of all animal life
on Earth ‘exploded’.
■ Creatures began to use minerals to create shells,
skeletal structures, claws and defensive plates.
○ This brought about the dawn of the Phanerozoic Eon
■ The one we are in currently
○ Around 500 million years ago, during the Ordovician Period,
plants, animals and fungi started colonizing the land (likely
to escape predation).
○ During the Devonian Period, about 365 million years ago,
Tetrapods (4legged vertebrates) and Arthropods began
showing up on land.
○ The Carboniferous Period, that extended from 359299
million years ago, heralded a major development of plants.
■ The forests were so dense and widespread that they
made all the fossil fuels we now use.
■ These forests created so much oxygen that the
atmosphere was around 35% O2, rather than today’s
21%
■ This O2 cooled the planet, crashing the entire system.
○ During the Permian Period, 299251 million years ago, all
the landmasses of the world joined to form one giant continent
we know as Pangea.
■ We begin to see Gymnosperms (the first plants with
seeds), and Archosaurs.
■ About 252 million years ago, the PermianTriassic
Extinction took place.
● 96% of all marine species and 70% of terrestrial
vertebrate went extinct, and is the only known
mass extinction of insects (57% of all taxonomic
families and 83% of all genera went extinct)

● The most significant extinction event on the plant.
Ever.
● Dawned the age of the Dinosaurs. Not much
competition allowed evolution to fill many available
niches (a combination of biotic and abiotic
resources that a species could use to survive).
○ During the Jurassic Period, about 199145 million years
ago, large herbivorous dinosaurs and smaller carnivorous
dinosaurs were roaming the Earth. (There were also
mammals, small, but still there)
■ 65 million years ago, all the Dinosaurs went extinct
(currently only theories suggest why), except for their
surviving descendants the birds.
○ About 100 million years ago, Angiosperms, or flowering
plants, appeared. Flying insects evolved with them, providing
an ideal vehicle for reproduction.
■ Coevolution
○ On a geological scale, that brings us up to now.

Population Ecology

● Population Ecology: Groups within a species and how they interact
and live together in one geographic area.
○ Fundamental Principles of Population Ecology include:
■ A population is just a group of individuals of one
species who interact regularly
■ How often organisms interact has a lot to do with
Geography. You compete with those closer to you for
food, living space, reproductive privileges, etc..
■ Population Density, or how many of a population are in
a specific area that might come into contact with each
other.

■ Geographic Arrangement of individuals within the
population. This is also known as Dispersion.
■ Population Growth.
● All kinds of factors drive this:
○ Fecundity (how many offspring an individual
can have)
○ Limiting Factors, the biotic and abiotic
factors that limit population growth.
○ Niche Requirements
○ Mates and Mating
● Categorized into:
○ DensityDependent(Is the population being
controlled by how many individuals are in
it?) limit growth due to environmental stress
caused by population size.
○ DensityIndependent(Is the population
being controlled by something else?) limit
growth due to external factors like a volcanic
eruption, monsoon, etc..
● Carrying Capacity is the Number or individuals
that a habitat can sustain with the resources
available. Once Density Dependent limiting
factors kick in, that’s a pretty good sign of a
population reaching its carrying capacity.
■ Any population of anything, according to math, will grow
exponentially until, for some reason, it can’t
anymore.
● Known as Exponential Growth.
○ The population grows at a rate proportional to
the size of the population.
● Once the population reaches these limiting factors,
it will only experience Logistic Growth.

○ This means that the population is limited to
the carrying capacity of its habitat.

■ Mathematical Equation for population growth:
● R = (Natality Mortality)/(N)
● R refers to Rate of growth
● N refers to Initial Population Size

And as for Growth over a Period:

● Community Ecology: Focused on groups of different organisms
living together, and figuring out how they influence each other.
● Ecosystem Ecology: The study of how all living and nonliving
things interact within an entire ecosystem.

Human Population Growth

● Since about 1650, Human population has been undergoing the
longest period of exponential growth of any large animal in
history.
○ In 1650, there were about 500 million people on the planet
○ By 1850 the population had doubled to 1 billion
○ Doubled again just 80 years later
○ Doubled again just 45 years later
○ Now well past 7 billion and counting
● Perennial problem in nature and in our lives:
○ Quality or Quantity?
○ All organisms make a similar choice through how they
reproduce:
■ R vs K Selection Theory

● R vs K Selection Theory states that some organisms reproduce in
a way that aims for huge, exponential growth, while others aim for
a smaller, more intimate relationship with their offspring. (K
reproducers are typically content only creating enough offspring to
hit the Carrying Capacity of their habitat)
○ Rselected species produce very rapidly and do not invest
time in raising offspring. R standing for the ‘maximum rate of
a population’.
○ Kselected species only produce a few offspring within their
lifetime, and invest a lot of time and energy raising them. K
standing for ‘Carrying Capacity’.
○ Most animals aren’t very strongly K or R selected. It’s
more of a spectrum: Some organisms usually small ones
tend to reproduce more on the R side, while larger
organisms tend to reproduce more on the K side. Most
species are somewhere in the middle.
○ Contradiction of Humans = We tend to reproduce and raise
our offspring in a Kselected manner, yet over the past 300+
years, our population curve looks suspiciously like that of an
Rselected Species.

■ Even then, most exponential growth rates, even for
RSelected species, usually do not go on for 350
years.
■ We’ve been able to do this because we learned how to
eliminate limiting factors that would’ve plateaued
(made us reach our carrying capacity) and eventually
diminished our population.
● Agricultural advances
● Medical advances
● Not being so Disgusting! (Sewage)
● Adapting to Inhospitable Places
○ Ecological Footprint: Calculation of how much land and how
many resources each person on the planet requires to live.
■ Varies geographically and determined by lifestyle.

Community Ecology

● Competition: Because there is a finite amount of resources on the
planet, evolution drives us to compete for them so that we can
live long enough to reproduce.
○ Important part of how different species interact when their
habitats overlap. These interactions define Ecological
Communities
● Interspecific Competition: When communities of the similar
species compete for the same resources needed for their survival
and continued population growth. i.e. weeds competing with
sunflowers for the nutrients and water in soil.
● Finite Resources are typically limiting factors in competition.
● Competitive Exclusion: When one species eliminates another
competing for the same resources.
○ When two species are competing for the same resources, one
of them will eventually be more successful, and eliminate
the other.

○ Not all resources are limiting.
○ Most species, even ones that are nearly identical, are
adaptable enough to find a way to survive in the face of
competition.
■ This is done by finding an ecological niche. the sum of
all resources, both biotic and abiotic, that a species use
in it’s environment.
● Fundamental Niche: an Ideal niche in which a species can live the
way it naturally wants to should there be no competition. Few
species ever achieve this.
● Most species, in order to avoid competitive exclusion and
continue living, take up a Realized Niche Or, the niche in which a
species lives in the presence of competitive exclusion.
● Canadian Ecologist, Robert Macarthur, made a discovery that
made him one of the most influential ecologists of the 20th century.
○ While researching at Yale in 1958, he studied 5 species of
warblers that live in coniferous forests. At the time, because
of the sheer amount of warblers living in the same area, many
ecologists thought they occupied the same ecological niche.
○ Macarthur studied the birds for many seasons, dividing
individual trees different warblers lived in, and observed
that each species of warbler divided it’s time differently
among the various parts of the tree.
○ The warblers had different hunting and foraging habits, and
even bred at different times of the year so that their highest
food requirements didn’t overlap.
○ This was the first recorded observation of a Realized Niche.
■ This phenomenon is now known as Resource
Partitioning. (when similar species settle into separate
niches that let them coexist)
● Mutualism: When two species benefit by forming relationships
through conflictavoidance. Both provide a service, and both
benefit.

○ Obligate Mutualism: relationship in which one species would
die if the other was not there.
● Commensalism: Relationship in which One species benefits, and
the other is unaffected/neutral toward the relationship.

Community Ecology II: Predation

● Herbivory: Predation in which an organism eats primary
producers
● Parasitism: Predation in which organisms derive energy from a
host, usually harming it, and sometimes killing it in the process.
● The need to survive causes predator and prey to adapt to develop
both weapons and defenses in a neverending evolutionary change.
○ Hunting and feeding adaptations for predators
○ Detection, Capture and Handling adaptations for prey
■ To avoid Detection, some creatures have developed
Cryptic Coloration (camouflage)
■ Avoiding Capture, some animals have developed speed
advantages, and some find safety in numbers (like
Bison), forming giant herds.
■ Preventing Handling can appear in many ways, such as
plants growing thorns, creating sap that traps
insects, chemical weapons like the tobacco plant’s
nicotine, Aposematic Coloration (Warning Coloration),
Mullerian Mimicry (alike coloring of similar types of
poisonous species), Batesian Mimicry (The copying a
poisonous creature’s appearance by nonthreatening
creatures)

Ecological Succession

● Primary Succession: Happens during a large ecological event, such
as a volcanic eruption, glacial freeze, asteroid impact, superstorm,
etc.. When organisms populate an area for the first time.
○ Advantage = No competition (Pioneer Species =
prokaryotes/protists)
○ Exclusively plants, typically with windborne seeds like
lycophytes.
○ Objective = to build/rebuild soils
○ Takes a very, very long time.

● Secondary Succession: Once the soils are ready, larger plants are
able to move in and repopulate. Usually the first response after a
smaller disturbance like a flood or fire.
○ These small disturbances that stimulate secondary
succession lead to development of a Microclimate (a small
climate in the area of succession that slightly differs from the
climate around it).

○ This microclimate leads to different niches, plant populations,
animal populations, and can even change the ecosystem
within its area.

● Climax Community Model: Observation in which communities
show a tendency to morph over time, changing until it becomes a
Climax Community, in which it would have a predictable
assemblage of species that would remain stable until the next major
disturbance.
○ Stochasticity: Randomness. Prevents us from ever knowing
exactly what a community will look like after a disturbance.
Element of unpredictable variability.
○ Ecosystem Stabilization: Issue because ecological
communities can never really become ‘stable’, as there is
always some aspect of change occurring.
○ We can tell that an ecosystem is in later stages of succession
determinant upon its level of Biodiversity.
■ High Biodiversity: When there are many niches that are
occupied by organisms.

● Only way for there to be High BioD, is for an
Ecosystem to have thousands of communities,
meaning it is in the latter stages of succession.

● Intermediate Disturbance Hypothesis: Theory that intermediate
disturbances (not too big, not too little), are ideal for the overall
development of a community and Ecosystem.
○ More niches = more Biodiversity; more Biodiversity = more
stability and healthier ecosystems.

Ecosystem Ecology

● Defining an Ecosystem: A collection of living and nonliving things
that interact with each other in a certain way.
○ Simultaneously It depends
■ Want to know how energy and materials come in and
move through a tree with a specific community of insect
protists in it? That is an ecosystem, etc...
■ Ecosystem can be measured via
● Biomass: The total weight of all living things within
the ecosystem.
● Productivity: How much stuff is produced and how
quickly it grows back.
● Retention
■ Where do the materials come from? (Water, Nitrogen,
Phosphorus, etc..)
● Energy
○ Law of conservation of matter; same goes for
an ecosystem.

● All energy (food)  in an ecosystem move through it indefinitely via
transference in Trophic levels.

○ Primary source of Energy: Solar/Photosynthesis via Primary
Producers
■ Primary Producers are then consumed by
Heterotrophs (Herbivores), aka Primary Consumers.
■ Primary Consumers then Eaten by Secondary
Consumers and so on, until Decomposers (Detrivores)
eat the dead consumers.
■ Efficiency of energy transference:
○ 1/10 of energy is transferred to the
consumer.

● Unfortunately, if there are toxins involved, they do
not abide by energy’s law of transference, and
simply accumulate into the consuming organism.
○ Known as Bioaccumulation

Biogeochemical Cycles

● Hydrologic Cycle: How water moves on, above, and below the
surface of the Earth driven by energy supplied by the Sun and the
Wind.
○ Easy to think of all the water on Earth as held in reservoirs.
■ The Ocean
■ The Atmosphere (clouds)
■ The Polar Ice Caps
■ So not only does water cycle through different places,
but also takes different forms at different places in the
cycle (liquid, solid, gas).
○ No Beginning or End
○ 1)Precipitation

■ Rain , Hail, Snow, etc.. Happens when water in the
atmosphere condenses from a gas to a liquid and
occasionally a solid.
● (Opposite of condensation is evaporation, and
when a substance converts straight from a solid to
a gas, that’s sublimation, and the opposite of this
is deposition)
● Condensation is responsible for clouds, which
happens when air containing water vapor rises and
cools or is compressed to the point where it can no
longer be a gas. At this point, the vapor forms
droplets.
● Wind moves clouds, and as water in clouds keeps
condensing and getting heavier, gravity eventually
takes over and pulls the condensed droplets to the
ground in the form of rain, snow, hail, etc…
● Gravity continues to work, pulling the water to its
final resting place, typically the lowest nearby point.
This is called runoff. Or the water is pulled
underground.
● Most water is pulled through runoff after
precipitation until it eventually reaches the ocean.

● The Carbon Cycle:
○ Carbon absorbed by plants has 3 possible fates
■ It can be respired back into the atmosphere
■ It can be eaten by an animal
■ Or it can be present when the plant dies.

*So what are Nitrogen and Phosphorus used for?
● Animals are 3% Nitrogen and 1% Phosphorus
● We need Nitrogen to make Amino
Acids>Proteins>Bodies>DNA & RNA
● DNA and RNA also require Phosphorus
○ ATP, and Phospholipid Bilayer

Nitrogen Cycle
● Nitrogen Gas (N2) makes up about 78% of the atmosphere
○ Unfortunately, it is made up of two N atoms stuck together with
a triple bond. Very hard to break.
● Plants need help to assimilate the N2, and receive that help via
Nitrogen Fixation.
○ Using NitrogenFixing Bacteria. Found in soil or water, or in
symbiotic relationships with root systems in Legumes.
○ These bacteria convert N2 into Ammonia (NH3), which then
becomes Ammonium (NH4+) when mixed with water, which
can be used by plants.
○ They do this with a special enzyme Nitrogenase which is the
only biological enzyme that can break that triple bond.
○ Ammonia can also be made by Decomposers like fungi when
breaking down dead organic matter (proteins and DNA). Once
this happens, other Nitrifying Bacteria can take this ammonia
and convert it into Nitrates (NO3)>3 Oxygen atoms attached
to a Nitrogen atom, as well as Nitrites (NO2)
■ These are even easier than Ammonium for plants to
assimilate
● Other ways to break the bonds between the N atoms include
○ Lightning
○ Synthetic fixation (fertilizers)
● The cycle continues (Bacteria>Plants>Animals>Decomposers)
UNTIL that Nitrogen finds itself in Denitrifying Bacteria, whose job
it is to metabolize the Nitrogen Oxides back into Nitrogen Gas.

○ This process uses a special enzyme called Nitrate
Reductase.

The Phosphorus Cycle
● Concentrated in the Lithosphere.
○ Rocks containing inorganic phosphates (especially
sedimentary originating in old ocean floors and lakes)
○ Not many rockeating bacteria on Earth, only Lithotrophs, so
bacteria do little to expose the phosphorus
● When the rocks are reexposed (from underwater), and water
erodes them, some of the phosphates are dissolved into the water.
○ These dissolved phosphates are immediately available to, and
assimilated by plants, which are then eaten by animals.

○ As in the Nitrogen cycle, decomposers then release the
phosphorus back into the soil and water via decomposing
dead organic organisms.
○ Decomposed phosphate is Immediately reassimilated back
into plants, and the cycle goes on.
● Once that atom of phosphorus makes it way into some body of
water, it can cycle around the organisms there for 100,000 years.
○ Eventually it will make its way into something that dies and
falls into a hole so deep that decomposers can’t survive there
and becomes sedimentation, which builds into
rocks>mountains>erosion>water
● Humans have introduced synthetic fertilizers, containing lots and
lots of nitrogen and phosphorus but too much of a good thing is
bad. This poses intense ecological stress on ecosystems.

Human Impacts on the Environment

● Human behaviour and lifestyle has already driven nearly 1,000 plant
and animal species (to date) into extinction most of them over the
last century.
● Ecosystem Services: Benefits the natural world provides us for
free, typically things that we could never, ever duplicate on our own.
○ Thus, having Ecosystems and keeping them intact is not only
important for the organisms who live in them, but also for us.
○ These services can be broken up into 4 categories
■ Support Services create and replenish the foundation
of the Earth’s biological systems. (recycling the
compounds that are necessary for life through the
biogeochemical cycles, forming new soils, producing
oxygen)
■ Provisioning Services providing the raw materials we
need to live. (The ocean providing food, rivers give
water, plant fiber for clothing and shelter, sources of fuel
in the form of biomass, hydropower, fossil fuels)
■ Regulating Services Decomposers converting waste to
energy, plants filtering water and air, producing oxygen
and absorbing CO2, etc..
■ (Cultural Services) Ecosystems Just Being
Awesome It’s nice to be surrounded by other living
things, healthy ecosystems give us places to play,
inspiration, grounds for education through study. Less
tangible, but still important cultural services.
● Ecosystems with High Biodiversity are much more resilient to and
capable of handling that ‘neverending change’, as well as being
able to handle disturbances much better.
○ In a High Biodiversity ecosystem, if you take one species out
of the mix, it’s less likely that the ecosystem will collapse.

● Best way to see how we affect the environment is through how we
affect biodiversity.
○ Unfortunately, we have already endangered most of the
highest biodiversity ecosystems on the planet.
● Top Five ways that humans are messing up the Environment:
○ 1) Deforestation we currently cut through 8,000 hectares of
trees a day to provide land to graze cattle on, and to harvest
wood
○ 2) Desertification Can be a sideeffect of Deforestation, in
which dry, unproductive landscapes spread. Driven along by
additional factors like overgrazing and overirrigation.
■ Overirrigation can cause Desertification because when
we use groundwater to irrigate crops, the natural salts in
that groundwater build up in the soil, eventually making it
so salty that nothing can grow.
■ Over time, ecosystems near deserts become overtaxed,
and the desert is able to spread into it.
○ 3) Global Warming Increase of CO2 in the atmosphere while
decrease in the area of forests and lush ecosystems that
provide regulation = bad. Melting Sea Ice leads to less habitat
for polar bears, seals and sea birds. More temperate animals
are moving closer to the poles, and hotter, drier conditions are
causing more fires.
■ Biggest problem with this is the timeframe of the
disturbance. Changes like this have happened in the
past, but took place over millennia, allowing organisms
time to adapt, while these changes are taking place over
our individual lifetimes.
○ 4) Introducing NonNative Species Both intentionally and
unintentionally, this can lead to invasive species, rapid niche
changes, and ecosystem entropy.

○ 5) Overharvesting Overfishing the oceans to meet growing
demand for popular fish species, overhunting predators like
wolves to protect livestock.
● Pollution Any substance that’s in the wrong place or in the wrong
concentrations in the environment.
○ Trash in the environment Pollution
○ Chemicals in the environment (both naturally occurring and
synthetic) Real killers.
○ We tend to think of pollution as chemicals made in large
chemical processing plants, and these are definitely a
problem, BUT, natural compounds in wrong concentrations
can do just as much damage.
● One of the main ways we are altering the concentrations of natural
compounds is by messing with the biogeochemical cycles.
○ Most obvious cycle we’re altering = Carbon Cycle
○ Cycle keeps going on, but problem is that we’re overloading it
by digging up and burning carbonrich coal, oil and gas.
○ Also been tampering with Nitrogen and Phosphorus cycles,
via increasing concentrations in the environment by creating
synthetic fertilizers that can spread nutrients into the water,
leading to large algal blooms that ‘chokeout’ the rest of the
plants and animals in the stream.
■ Also cause Dead Zones, in which decomposers try to
decompose the algae after it has used up all of the
nitrogen and phosphorus, but require Oxygen to do so,
taking it out of the water, thereby killing most of the other
living organisms in that area that require oxygen.
● Important Natural Pollutants
○ Cyanide (used in mining operations for ore extraction, leading
to hazardous waste that never really goes away)
○ Mercury (Supertoxic, naturally occurring metal found in coal
among other places, and doesn’t do anything while
underground in coal seams, but when that coal is burned to

make electricity it’s released into the air. It then falls onto the
land, making its way to groundwater, and eventually into the
food chain (specifically marine).
○ Sulfur Dioxide & Nitrogen Dioxide (Naturally sourced from
volcanic eruptions and the waste of some algae and bacteria)
but we release millions of tons of this stuff every year by
burning fossil fuels. When they react with compounds in the
atmosphere, they turn into sulfuric acid and nitric acid,
returning to the surface as acid rain.
● Important Synthetic Chemicals
○ Endocrine Disruptors (EDC) put in pharmaceuticals,
pesticides and plastics. I.E. BPA, which is found in plastics
and leach into our drinks. When they are excreted back into
the environment, typically in waterways in high concentrations,
animals end up absorbing them.
■ These alter an animal’s Endocrine (hormone) system,
and have led to male fish with female reproductive tracts,
or testes that make eggs.
■ Unknown effects on humans thus far, but research is
progressing.

Conservation and Restoration Ecology

● Conservation Biology
○ Involves measuring the biodiversity of an ecosystem and
determining how to protect it.
● Restoration Ecology
○ The science of restoring broken ecosystems. For example
taking an interrupted, polluted river, and turning it into a
functioning ecosystem again.
○ To fix something that’s broken, you have to understand what
made it work to begin with. Practicality.

■ The glue that holds every ecosystem together is
Biodiversity.
■ Biodiversity can mean many different things, though. It’s
generally referring to species diversity.
■ In addition to species diversity, ecologists look at
genetic diversity within a species as a whole and
between populations.
○ Genetic Diversity is important because it allows a species to
adapt to new situations and disturbances like disease and
climate change.
○ Ecosystem Diversity is the variety of different ecosystems
within an area.
■ A large forest, for example, can host several different
ecosystems, like wetland, alpine, and aquatic.

○ Small Population Conservation focuses on identifying
species and populations that are miniscule, and attempts to
increase their numbers and genetic diversity.
■ When a population is small and has low biodiversity, its
very probable that it will soon die out, so when a
population is suffering from inbreeding or genetic drift
(a shift in it’s overall genetic makeup), this leads to even
less diversity>lower natality rates>higher mortality
rates>even smaller population.
● This is known as an Extinction Vortex
■ So how small is too small? Ecologists figure this out by
calculating whats called the Minimum Viable
Population, which is the smallest size at which a
population can survive and sustain itself.
■ To calculate this, you need to find out a species real
breeding population and then you figure out everything
you can about that species life history:
● How long they live

● Who gets to breed the most
● How often they can create offspring, etc..

○ Declining Population Conservation focuses on populations
whose numbers are in decline no matter how large the original
population was.
■ First one must determine whether the population is
actually declining
■ Then you have to determine how large the population
historically was and what its requirements were
■ Finally, you must determine what is causing the decline
and figure out how to address it

○ Of course, we can’t really bring an ecosystem exactly back to
the way it used to be, but through these sciences, we can get
rid of the problems they are facing and recreate some of the
elements that the ecosystem needs to function properly.
■ Structural Restoration is the removal and cleanup of
whatever human impact was causing the problem, and
the rebuilding of the historical natural structure.

■ Bioremediation recruits organisms temporarily to help
remove toxins, like bacteria that eat wastes or plants that
leach out metals from tainted soils.
■ Biological Augmentation is a somewhat more
‘invasive’ method of restoration in which rather than
removing harmful substances, organisms are added to
the ecosystem to restore materials that are gone.
● i.e. plants that help fix nitrogen like beans, acacia
trees and lupine are often used to replenish
nitrogen in soils that have been damaged by things
like mining and overfarming.
● Problems can lead to introduction of an invasive
species
○ i.e. 1930’s Australia introduction of cane
toads to control beetles. Not only are they
toxic, but they’re everywhere now, and
poison native species like dingos that try to
eat them.
■ Thus, its just easier to Protect Ecosystems rather than
trying to fix them.

Sources and Citations

1. Crash Course Ecology
a. Crash Course Ecology. Hank Green. Crash Course Ecology
Series, 20122013. Web. 10 Feb. 2015.
<https://www.youtube.com/watch?v=sjEPkjp3u4&index=1&list
=PL8dPuuaLjXtNdTKZkV_GiIYXpV9w4WxbX>

Crash Course Ecology

More Related Content

What's hot

Viewers also liked

Similar to Crash Course Ecology

Recently uploaded

Crash Course Ecology