Community Ecology

Ecological Niche Ecological Niche – The role a certain species plays in an ecosystem How does it: Interact with other organisms Interact with abiotic factors What sort of things may these include?

Example: American Alligator

Alligator: Resources Resources that it uses: Opportunistic Feeders: Fish, Turtles, Smaller Gators, Small Mammals, Birds So what? Gators eating these animals keeps populations of dozens of other species in check

Alligator: Interactions Alligators are not aggressive unless threatened Opportunistic feeders and will attack if hungry, and within striking range Known to attack pets, livestock, and humans

Alligator: Cycling of Matter Contribute to food chain as top predator

Human hunting has jeopardized alligator populations Gators hunted for meat, skin, and for sport Killing alligators effects the ecosystem How?

Competitive Exclusion Principle AKA – Gause’s Principle When 2 species compete for the same resources, one is more likely to be more successful The result will be in the second species being eliminated Basically: 2 animals cannot occupy the same niche

Resource Partitioning Some animals appear to compete for the same resources, however when examined closely, they occupy slightly different niches Examples: Anole Lizards in the rain forest Warblers in the same tree

Character Displacement AKA – Niche Shift Due to resource partitioning, organisms may adapt differently to their ‘micro-niches’ This would result in less competition, and eventually evolution divergent

Realized vs. Fundamental Niche Fundamental Niche – The niche an organism occupies when no competition is present Realized Niche – The niche an organism occupies when competition is present (NO niche overlap)

Energy Flow All living things need energy in order to survive Energy flows throughout the biosphere to all living things Energy needs to be put into a living system, otherwise it cannot function (DNW) What energy is constantly put into the biosphere?

Producers Autotrophs – Organisms that produce their own food Because they make their own food, they are also called producers

Producers Producers are the base of all ecosystems on earth Producers directly and indirectly produce all the food that goes into an ecosystem

Producers The most well known autotrophs used solar energy and use Photosynthesis When sunlight is not present, autotrophs use chemicals to produce food in a process called chemosynthesis

Consumers Heterotrophs – Organisms that must consume other organisms to obtain energy These are also known as consumers (DNW) There are many different categories of heterotrophs

Herbivores – Organisms that obtain energy by eating only plants

Carnivores – Organisms that obtain energy by consuming animals

Omnivores Omnivores – Organisms that obtain energy by consuming both plants and animals

Scavengers/Detritivores Scavengers/Detritivores – Organisms that feed on the tissue of dead organisms

Decomposers Decomposers – Organisms that break down organic matter into simple nutrients or fertilizers

Trophic levels Energy moves from one organism to another when it is eaten Each step in this transfer of energy Is known as a trophic level Main trophic levels Producers Consumers Decomposers

Energy Flow It is impossible to obtain all the energy in an organism When a rabbit eats grass, it does not obtain all of the energy in the grass When a hawk eats the rabbit, it does not obtain all the energy in the rabbit About 10% of energy is transferred from one trophic level to the next This is known as the 10% law

Food Chain Energy flow from 1 trophic level to the next is called a food chain A food chain is simplified Only one organism at each level are shown

Food Chains Typical food chain order: Producers (Autotrophs) Primary consumers (Eat autotrophs) Secondary consumers (Eat primary consumers) Tertiary consumers (Eat secondary consumers) Decomposers (Break down anything dead)

Food Chain - Example

Food Web Animals typically eat more than just one organism Food webs show a greater variety in the diets of organisms

Arrows The arrows point in the direction that the energy is transferred Basically, the arrows point from the prey, to the predator

Ecological Pyramid Shows the relationship between consumers and producers at different trophic levels in an ecosystem Shows the relative amounts of energy at each trophic level Shows what levels have the most energy and highest # of organisms

Ecological Pyramid

Symbiosis Symbiosis – a close and permanent association between different organisms There are three main categories of symbiosis: Commensalism Mutualism Parasitism

Commensalism – When one organism benefits, and the other is unaffected

Mutualism – When both organisms benefit

Parasitism – When one organism benefits, and the other is harmed

Coevolution Animals interacting with one another over long periods of time have led to coevolution Examples: Secondary Compounds Camouflage Aposematic (Warning) Coloration Mimicry

Secondary Compounds Secondary Compounds – Toxic chemicals produced in plants that are harmful/distasteful to herbivores Examples: Nicotine Poison Oak/Ivy Mustard oil=Toxic to insects Hotness of Peppers

Camouflage Camouflage – Any color, pattern, or shape that enables an organism to blend in with its surroundings

Aposomatic Coloration A conspicuous pattern of coloration that warns other animals that they should not be eaten Poisonous Stinging Bad Tasting

Mimicry Mimicry – When two or more species resemble one another 2 types: Mullerian Mimicry – Animals with similar defenses have similar coloration Batesian Mimicry – When animals with no defenses resemble organisms that do have a defense mechanism

Mullerian Batesian