What is Ecology? Ecology Definition - the study of interactions among organisms and between...

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