Intro to Ecology
What is Ecology??
The study of interactions that take place between organisms and their environment.
It explains how living organisms affect each other and the world they live in.
Habitat & NicheHabitat is the place an organism lives
Niche is an organism’s total way of life
The Nonliving Environment Abiotic factors- the
nonliving parts of an organism’s environment.
Examples:air currents, temperature, moisture, light, Soil nutrients.
The Living Environment
Biotic factors- all the living components of an environment.
All organisms are affected by both biotic and abiotic factors in their niches
Abiotic or Biotic?
Biotic
Abiotic or Biotic?
Abiotic
Abiotic or Biotic?
Abiotic
Abiotic or Biotic?
Biotic
Human Impact
What are humans doing to the ecosystems of the world?
What have humans done? ozone layer - created a hole
is this layer that protects us from UV radiation due to Chlorofluorocarbon (CFCs)
greenhouse effect- this NATURAL effect keeps the Earth warm, but due to pollution, humans are amplifying this effect and making it warmer than usual (overloading the carbon cycle with too much CO2, a greenhouse gas)
Smog and acid precipitation are caused by air pollution
What have humans done?
All of these things have had a hand in changing ecosystems and communities world wide
Many Ecologist study human impact on communities by looking at: Biological magnification Keystone species Bioindicators
Biological magnification
Land and water pollution can be a big problem for many organisms Chemical that we use on farms and in our homes can
be toxic to wildlife Many chemicals that enter an ecosystem
undergo biological magnification, a process in which chemicals become more concentrated as they move up the food chain
Fewer amounts of predators at higher levels means more poison in each organism
Keystone species
These are species that can affect many other species in a community
When these species become extinct, or scarce, the entire community changes and usually many species disappear
Increase biodiversity
Keystone Species Sea Otters were hunted to near
extinction in the Pacific Ocean until people realized that their disappearance caused everything in their food chain to disappear
Bioindicators
These are species that are especially sensitive to change
Frogs are bioindicators because they live in or around water (which is where pollutants tend to accumulate) and they absorb gases through their skin
Many people believe that the world wide decline in frog populations is an indicator of population declines in other species
Sustainability Means the ability to meet human needs in such
a way that the human population can be maintained indefinitelyTo do this, we need to make sure our
resources (like food, space and water) will always be available
This includes keeping the Earth healthy and maintaining biodiversity
Biodiversity- refers to the variety of forms of life in an area
If we keep doing what we are doing this is not going to happen
Growth Rate
Growth rate- the amount by which a population size changes over a given timeIn order for a population to grow, the birth
rate (number of individuals born) must be greater than the death rate (number that die)
Population size constantly changes in any given population due to changes in growth rates
Can populations grow infinitely? NOOO!!
Every ecosystem has a Carrying capacity This is the maximum number of
organisms that can be supported in a given habitat.
The carrying capacity of a habitat is based on limiting factors
What are limiting factors? Any factor that restrains the growth of a
population. For example…Space, Food, Water, or Soil Nutrients
When limiting factors become scarce, organisms begin to compete for them. In this competition, some will win (survive) and some will lose (die)This can also cause a population to declineNo ecosystem can support an infinite amount
of organisms…eventually there is a limit. When limiting factors run out, carrying capacity
is reached and populations decline
Population Ecology
Population Ecology
Population Ecologists study many factors dealing with population, the three most important are…population density growth rateCarrying capacity
Population Density
Population density measures how crowded a population is
The population density of the US is about 30 people per square kilometer (0.6 mi2)
In Japan it is 337 people/km2
(Data from 2003)
Levels of Organization Ecologists have organized
species interactions into different levels
1st Level of Organization
Organism:An individual living thing
2nd Level of Organization
• Population:A group of the same species, which live in the same area and interbreed
3rd Level of OrganizationCommunity:
All the populations of different species that live in the same place at the same time.
4th Level of OrganizationEcosystem: the
community AND the abiotic factors of an area.
5th Level of Organization Biosphere:
The portion of Earth that supports life.It is about 20 km (13
mi) wide from deepest parts of ocean to 8-10 km above the surface
If the Earth were an apple, the biosphere would be the skin
Levels of Organization
OrganismPopulationCommunityEcosystem Biosphere
Energy Relationships Vocab
Producers are the autotrophs of an environmentMostly by photosynthesis
Consumers are the heterotrophs of the environment. They can be…Herbivores- which eat producersCarnivores- which eat other consumersOmnivores- which eat producers and
consumers
Energy Relationships Vocab
Primary comsumer- eats producer Secondary consumer- eats primary Tertiary consumer- eats secondary Detritivores - (Decomposers) - Break
down complex molecules in dead organic matter into smaller molecules They are responsible for recycling many
nutrients into the soil
Food Chains
Food Chains- A single pathway of energy relationships among organisms in an ecosystem
Food Chains The arrows DO NOT merely show what
gets eatenThe purpose of the arrows is to show where
the energy is goingScientists refer to eating as an energy
transfer, because when one organism eats another, the main goal is to get energy from the organism.
SO, the arrow points at the organism that GETS the ENERGY (the organism doing the eating)
Food Webs
Food chains are a very inaccurate depiction of feeding relationships in an ecosystem…Food webs are more accurate
Food webs are interrelated food chains of an ecosystem
Make a food chain from this food web
Food Webs Decomposers are
sometimes shown in food chains and food websEventually all
organisms give their remaining energy to decomposers
Trophic Levels Each organism in a food chain or web
represents a trophic levelThe trophic level is an organisms position in a
sequence of energy transfers (in a food chain or web)
Notice Higher on the food chain means higher trophic level
Trophic Levels A top level carnivore
means that NOTHING in that environment is able to eat it.
Organism CAN be at more than one level In this diagram, a fox
eats a snake, but it eats insects also, it would be both a secondary and tertiary consumer
In real life, many organisms are at 2 or more levels.
Energy Transfers Producers add biomass (Organic material)
to environmentsThey are always at the bottom of the food
chain or web.So they are the origin of the energy BUT…Producers get their energy from the
sunSo, THE SUN IS THE ULTIMATE
SOURCE OF ENERGY IN ALMOST ALL ECOSYSTEMS
Energy Transfers Energy transfers within
an environment are often shown using an Energy Pyramid:
Notice that energy is lost as you move up the pyramid
Notice also that low trophic levels are at the bottom and higher levels are at the top
Energy Transfers
Very little energy (10%) is transferred when one organism eats another. Why is this?Not all organisms are eaten at any given levelConsumers cannot break down all of the
organic material in their foodOrganisms use the energy they make or
consume for themselves and do not store it, some of the energy organisms consume is lost as heat during digestion
Stored Energy at each level
Stored Energy at each level
Energy Transfers
This low rate of energy transfer if the reason that as you move up a food chain, there are less organisms at higher trophic levelsThere is not enough energy to
support the organisms at higher levels
Less organisms at the top means less biomass
Nutrient Cycling
Atoms around today have been the same since the beginning of life on Earth
These atoms are constantly being used, reused, and recycled. (CYCLED)
Theses cycles are called biogeochemical cycles
The Carbon Cycle
CO2 is taken out of the air by plants (photosynthesis)
CO2 is put in the air by burning, decomposition, and respiration
Remember, the organic molecules that make us (proteins, carbs, fats, nucleic acids) are made of carbon, which we get by eating
How are humans overloadingthe carbon cycle?
Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. Without it and other greenhouse gases,
Earth would be a frozen world. But humans have burned so much
fuel that there is about 30% more carbon dioxide in the air today than there was about 150 years ago. The atmosphere has not held this much carbon for at least 420,000 years according to data from ice cores.
Water Cycle- important words to know Transpiration- when plants lose water
(usually through stomata) Evaporation- water turns from liquid to
gas Runoff- when water runs across land
(possibly picking up pollutants, like fertilizer)
Nitrogen Cycle
Even though the air is mostly N2 gas, many organisms cannot use it.Without nitrogen, no protein or nucleic
acids! Plants get N with the help of bacteria and
soil/fertilizers Animals get N by eating it When living things die, decomposers return
the nitrogen in their bodies to the soil
Community Ecology
Looks at the interactions of different populations within an ecosystem
Species Interactions In Communities
There are 5 major types of Interactions
1. Predator-Prey
2. Competition
3. Parasitism
4. Mutualism
5. Commensalism
Predator-Prey The prey is the organism that is eaten The predator is the organism that does the
eatingExamples:
Lions eating Zebras Snakes eating Mice Birds eating insects
Predator and Prey Populations rise and fall with
each other
Competition Competition occurs when two or more
organisms attempt to use the same limited resource.A limited resource is any resource that may
run out.Examples:
Hyenas fight with lions over the same animals
Two cacti that are side by side compete for water
Symbiosis
Close association between two or more organisms of different species living together
3 typesParasitismMutualismCommensalism
Parasitism Parasitism is the relationship between a
parasite and a host. A Parasite is an organism that lives in or on
another organism and feeds on it without immediately killing it.Examples: ticks, fleas, blood-sucking
leaches, and mistletoeThe organism that the parasite feeds on is
called the HostThe host is harmed in parasitism.
Mutualism Mutualism is a cooperative partnership between
two species in which both species benefit.An example is the bacteria in your intestines and
you. Billions of bacteria live in your intestines. They help break down food you would
otherwise not be able to digest. They also produce beneficial substances,
such as Vitamin K for you. In return, you give them a warm, dark, food-
rich environment.
Commensalism Commensalism is a relationship in which one
species benefits from another species and the other is neither harmed nor helped
Example: Remoras and SharksThe remoras attach to the sharks and feed
on scraps left over from the sharks meals.The shark is neither harmed nor helped by
this relationship
Relationship Organism #1 Organism #2
Commensalism + 0Mutualism + +Parasitism + -
Predator Prey + -Competition - -
Great White Shark eating Seal
Lion eating Zebra
Clown Fish live in Anemone, the anemone is neither harmed nor helped by the fish
The Acacia Tree provides shelter for the ants and the ants protect the tree from other insects
Honey guideThese birds will lead people and other mammals to honey and after the mammal opens the bee hive to get the honey, the bird feeds on the bee larvae
Tapeworm
Dodder plant- poisons and eventually kills the plant it grows on
Ecological Succession
The gradual, sequential growth of a community is called ecological successionThe first species to grow in succession is
called the pioneer speciesPioneer species are typically small, grow
quickly, good at growing under harsh conditions, and good at dispersing offspring
Primary Succession No true soil is present
before Primary Succession Because of this it
is slower than secondary
Occurs on newly exposed or created land- like land under melting ice caps or islands formed by volcanoes
Primary Succession Lichens are usually the
pioneer species They break down the rocks
into dirt and when they die, they leave behind organic material, which will be broken down by decomposers This creates soil which is
basically dirt, minerals, and organic material
This process takes thousands of years
Primary Succession
Secondary Succession
This happens after an existing community is disrupted by a disturbance like a fire
Soil is already present Grasses and weeds tend to be the pioneer
species After many years bigger plants will begin to grow This process takes about 100 years
Secondary Succession
When does succession end?
When it reaches a climax communityThis is simply a stable end pointAt this point, the community remains relatively
stable assuming there are no more disturbances
Ecosystem Ecology
Biomes
What is a biome? A very large climatic region that contains a
number of smaller, but related ecosystems in it.
Tundra Found in North Freezing temps for most of the time, little rain Has permafrost (a permanent layer of frozen
soil) Due to the permafrost and a short growing
season, there are few or no trees in the tundra Characterized by small plants, like grasses, and
mainly small mammals
Tundra
Anaktuvuk Pass, Alaska
Arctic Fox
From left: tundra near Churchill, Manitoba, Canada; tundra in the Arctic National Wildlife Refuge, Alaska.
Tropical Rain Forests Found near the
equator Over 200cm of rain
each year, consistent warm temps
This biome gets the most rain and supports the greatest variety of life
Tropical Rain Forests
Rainforest in Malaysia on the island of Borneo
Amazon and Amazon River
Bengal Tiger
Temperate Forests
70-150cm of rain, moderate temperatures, 4 distinct seasons
Can be coniferous or deciduous based on the trees that grow thereConiferous- seeds in cones and tend to
be evergreenDeciduous- Shed their leaves each year
Temperate Forests
Deciduous
CONIFEROUS Rainforest
Coyote
Taiga
Found south of Tundra Also called Boreal Forest Very cold (but warmer than Tundra), long
winters; summers relatively wet and warm Animals in this biome often migrate or
hibernate during winter
Taiga
White Spruce taiga, Denali Highway, Alaska Range, Alaska
Lakes and other waterbodies are very common. The Helvetinjärvi National Park, Finland, is located in the southern boreal forest.[
Bobcat
American Black Bear
Grasslands
3 varieties: Temperate grasslands, savanna, and chaparral
Other names include steppes, prairies, pampas and veldts
25-75 cm rain per year, moderate to warm temps
Characterized by grasses dominating, few or no trees
Grasslands
Steppe
prairie
Mongolian Gerbil
Saker Falcon
Northern Lynx
savanna
Deserts Receive less than 25cm of rain each year Can be hot or cold Temperatures can vary greatly from day to
night (the dirt does not trap heat well, which is what warms ecosystems at night)
Desert Kangaroo RatBobcat
Hot Desert Plant Adaptations
Waxy cuticles Tiny hairs and light greens prevent
some heat absorption Keep stomata half closed or only
take in CO2 at night to avoid water loss
Barrel Cactus
Palo Verde
Hot Desert Animal Adaptations
Animals tend to be small Some are able to get the water they need
from food Nocturnal- only out at night in hot deserts Burrowers
Desert Tortoise
Sonoran Desert ToadThorny Devil
Ocean Zones
Ocean Zones Aphotic- no light, no photosynthesis; organisms
here typically feed on falling dead organisms from above
Photic- has sunlight Intertidal- area of the shoreline covered during high
tide and exposed during low; has organisms that are adapted to periodic exposure to air
Neritic- shallow water above the continental shelf; most productive zone; upwelling carries nutrients from deep waters making it nutrient rich.; this is where coral reefs form in tropical areas
Ocean Zones Oceanic- deep parts of
ocean/open sea; fewer species than neritic, nutrient levels low, ½ the photosynthesis that happens on Earth happens in the ocean;
Pelagic- open ocean Benthic- ocean floor;
diverse life can be found living near sea floor volcanic vents
Estuaries Where rivers meet oceans Salt water mixes with fresh Inhabitants are well adapted to changing
temp and salt conditions
Estuary of Klamath River, Oregon River Nith estuary, Scotland
Lakes Eutrophic
rich in organic matter and vegetation, murky and have a lot of bacteria which
eventually use all of the oxygen and that can cause the animal life to die
Lakes naturally become this way over time Oligotrophic
Not a lot of organic matter and vegetationwaters are clearerStill supports fish and other life
Wetlands
Areas of land covered in freshwater for at least part of the year
Main types are marshes and swamps Wetlands filter pollutants from water; they
prevent flooding by taking in large amount of water
Las Vegas has wetlands, which is the area that most of our rainwater drains to (which is the reason it stays wet)