What is Ecology?
Ecology Definition - the study of interactions among organisms and between organisms in their environment
Levels of organizationA single member of a species is known as an individual
Populations are groups of individualsCommunities are grouping of different populations
An ecosystem includes a community and its surroundings
A biome is a group of ecosystems with the same type of climate
A biosphere would be the entire planet
Energy Flow
ProducersQ: What do we call organisms that make their own food?
A: Autotrophs
Q: What process do plants undergo to make their own food?
A: Photosynthesis
Q: What’s the equation for photosynthesis?
A: 6CO2 + 6H2O + sunlight C6H12O6 + 6O2
ConsumersQ: What do we call an organism that consumes its food?
A: Heterotroph
There are four types of heterotrophs, depending on where the organism’s energy (i.e. food) comes from: CarnivoresHerbivoresOmnivoresDecomposers
ConsumersQ: Where does a carnivore get its energy?A: From meat only
Q: What are some examples of carnivores?A: Lion, cheetah, jaguar, leopard
ConsumersQ: Where does an herbivore get its energy?A: Only vegetables/grains/fruits, etc (i.e. non-meat eater)
Q: What are some examples of herbivores?A: Deer, rabbits, horses, zebra
ConsumersQ: Where does an omnivore get its energy?A: From both meat and vegetables/grains/fruit, etc
Q: What are some examples of omnivores?A: Bears, chimpanzees, pigs, various birds
ConsumersQ: Where does a decomposer get its energy?A: From breaking down dead organic matter
Q: What are some examples of decomposers?A: Bacteria, fungi (mushrooms), earthworms
Food ChainsThe levels of a food chain include:
First level – producer – autotroph that makes food
Second level – primary consumer – herbivore that eats producer
Third level – secondary consumer – carnivore that eats herbivore
Fourth level – tertiary consumer – carnivore that eats secondary consumer
Food ChainsEx:
Producer – grass that photosynthesizesPrimary consumer – rabbit that eats the grass
Secondary consumer – fox that eats the rabbit
Tertiary consumer – wolf that eats the fox
Food Chains Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)
Energy is transferred by organisms eating and being eaten
Energy transfer is represented by arrows going in the direction of the energy’s movement
Food websA food web links all the food chains in a ecosystem together
More complex interactions than unidirectional flow of food chains
In reality, the interactions between predators and prey in an ecosystem’s exists as a food web instead of a food chain
Tertiary Consumer
Secondary Consumer
Producer
Primary Consumer
Energy PyramidsEach step in the food chain is called a trophic level
Producers are the first trophic levelConsumers make up the second, third or higher trophic level
Energy PyramidEnergy pyramid – only 10% of energy is transferred from one trophic level to the next Energy is used up by the organism’s metabolism and/or released as heat
Amount of energy available in this tropic level
The Role of Climate
Biotic vs. Abiotic factorsBiotic factor –influences/interactions of living organisms
Abiotic factor – physical, non-living influence that affect an ecosystem
Q: What are some biotic factors that affect a forest?
A: Birds, insects, deer, grass, trees
Q: What are some abiotic factors that affect a forest?
A: Temperature, precipitation, wind, soil type
Biotic vs. Abiotic Factors
Biotic Factors
Abiotic Factors
Biotic + Abiotic Factors Together = Ecosystem
Community InteractionsCompetition PredationSymbiosis
MutualismCommensalismParasitism
CompetitionDefinition – organisms of the same or different species attempt to use the same ecological resource
Competitive exclusion principle – no two species can occupy the same niche in the same habitat at the same time; one species will outcompete the otherNiche – range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
PredationDefinition – one organism captures and feeds on another
Predator benefits, prey does not
SymbiosisDefinition – close, long-term relationship between two organisms
There are 3 kinds: MutualismCommensalismParasitism
*Notes on chartExamples: PowerPoint
Mutualism Definition – both species benefit, neither species is harmed
Ex: flowers and pollinating insectsQ: How do flowers benefit?
A: Insects carry pollen to another plant
Q: How to insects benefit?
A: Consume nectar of flower
Commensalism Definition – one member benefits, the other is neither helped nor harmed
Ex: barnacles on whales Q: How do the barnacles benefit?A: They get a place to live!
The whale is neither helped nor harmed by the barnacles
ParasitismDefinition – one organism benefits, the other organism is harmed
The parasite normally lives on (tick) or in (tapeworm) the host
Ex: mosquito on human Q: How does the mosquito benefit?
A: Sucks the blood from human
Human is harmed – transmission of disease
How Populations Grow
Characteristics of PopulationsPopulation
Growth
can be
represented bycharacterized by characterized by represented by
which cause a
Exponentialgrowth
Logisticgrowth
Fallinggrowth rate
S-shapedcurve
Limits ongrowth
No limits on growth
J-shapedcurve
Constantgrowth rate
Unlimitedresources
Population GrowthThree factors affect population size
1. Number of births2. Number of deaths3. Number of individuals that enter or leave pop. Immigration – into area Emigration – out of area
Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially
Population increases indefinitely without stopping
Agriculturebegins
Plowingand irrigation
Bubonicplague
IndustrialRevolutionbegins
Human Population Growth
Logistic GrowthAs resources become limited, the growth of a population slows or stops
Carrying capacity (K) – largest number of individuals a given environment can support
Once the population reaches its carrying capacity, the population size stays the same
Practice Problem
Q: What type of growth is depicted in this graph?
A: Logistic
Q: What’s a carrying capacity?A: Maximum number of organisms an environment can support
Practice Problem
Q: What’s the carrying capacity of this population?
A: Around 65 rabbits
Q: When did this population reach its carrying capacity?
A: Around August 1
Practice Problem
Q: What should be the title for the x-axis?
A: Months
Q: What might be a good title for this graph?
A: Logistic growth of a population of rabbits over 5 months
Practice Problem
Q: Do you see a problem with the scale on the x-axis?
A: July isn’t included!
Limits to Growth
Imagine a small island that has a population of five rabbits. Does how the factor affects the rabbits depend on the size of the population, or will the factor affect the rabbits in the same way, regardless of the population size?
a. climateb. food supplyc. predation
Now imagine another small island that has a population of 500 rabbits. How would the same factors affect this population?
Which of the factors depend on population size? Which factors do not depend on population size?
Limiting Factors Limits to Growth1.Density-Dependent Factors – limiting factor that depends on the populations size
Predation (predator-prey relationships), food supply
Disease
2.Density-Independent Factors – limiting factor that affects all populations in a similar way, regardless of the population size
Weather, natural disaster Seasonal cycles
Density-Dependent FactorPredator-prey relationshipQ: What happens to the wolf population (predators) with an increase in deer population (prey)? Why?
A: Wolf population increases because their food source, deer, increased
Q: What happens to the deer population in response to an increase in wolf population? Why?
A: Deer population decreases because there are more wolves to hunt the deer
Density-Dependent FactorPredator-prey relationshipQ: What happens when the deer population decreases?
A: The wolf population decreases because they don’t have as much food (deer)
Q: What happens when the wolf population decreases?
A: The deer population increases because they don’t have as many predators (wolves)
Cycle/relationship between predator (wolf) and prey (deer)
Density IndependentAffect all populations in similar ways regardless of the population size
Unusual weather, natural disasters, seasonal cycles
Some human activities: cutting down forests, damming rivers etc.
CoevolutionDefinition- a long term change that takes place in two species because of their close interactions with one another.
Examples:Acacia tree and antsFlowers and pollinators (e.g., hummingbirds long beak and nectar)
Newts and garter snakes- see videos:Newt humorNewt versus garter snake