Food Chain Simulation • Each person in your group will choose to be 1 of the following: • A Snake • A Mouse • A Hawk • Grass
Sunny D Energy Flow • If you are the grass, take the cup of Sunny D. • Mouse gets cup #2 • Snake gets cup #3 • Hawk gets cup #4 • Grass – pour SD into the mouse’s cup up to the line. • Mouse – pour SD into the snake’s cup up to the line. • Snake – pour SD into the hawk’s cup up to the line. GO IN ORDER – DO NOT SKIP STEPS!
Food Chain & Energy Flow Simulation • In the end, who gained the most energy? The Grass! • Where did the energy come from? The Sun! • Who gained the least amount of energy? The Hawk! The higher you are in the food chain, the less energy you’re getting from your food!
Only 10% of the total energy available goes to the next level! Energy goes from the Producers to the first level consumers
We’ve seen feeding relationships & how energy flows through trophic levels in an environment.How do populations behave in response to the environment? What types of things affect populations?
Changes in Population Size • Birth Rate: the major way organisms are added to a population • Death Rate: the major way organisms are removed from a population Great Horned Owl & babies
Death Rate vs. Birth Rate • What will happen to a population if the death rate is faster than the birth rate? The population can become extinct!
Death Rate vs. Birth Rate • What will happen to a population if the birth rate is faster than the death rate? The population can become overpopulated!
Changes in Population Size • Immigration: organisms entering a population coming IN to • Emigration: organisms leaving a population Exiting
In most populations, the birth & death rate are about equal. What keeps a population from getting tooBIG?
Limiting Factors • Something that keeps a population from increasing in size • Food, space, weather conditions • Factors can be: • Density Dependent • Density Independent
Density Dependent • Population size depends on how many organisms are in a defined space • Competition for resources (like food) keeps numbers down. Snowshoe Rabbit Canadian Lynx
When the rabbit population increases, the Lynx population will begin to increases, too, because there is more food.
As the Lynx population begins to thrive, they over eat, decreasing the rabbit population, in turn hurting themselves.
Density Independent • Populations are affected no matter what the original population size was. • Usually caused by environmental changes, such as temperature, drought, natural disasters
Consider a population of sparrows. If there’s a huge storm, it will kill 10% of the population (the size of the population doesn’t matter – it’s still 10%).
Carrying Capacity • The population size of the species that the environment can support • Based on food, habitat, water, etc.
Once the population size gets to a certain point, disease will spread more easily, & the population will need to compete for food & resources. This keeps populations from getting too large.
Community Interactions Remember! A community is all of the populations of different species that live in the same place at the same time!
Competition • Competing for resources • Food, shelter, space, mates
Predation • One organism hunts and feeds on another organism.
Symbiosis • The relationship between 2 different species living closely together • Mutualism • Parasitism • Commensalism Lichen Mycorrhizae
Mutualism • Both species benefit from the relationship Clownfish live within sea anemones, which normally sting other fish. The fish gets protection, & the anemone benefits because the clownfish keep it clean of bacteria.
Mutualism Hummingbirds pollinate flowers. The hummingbirds get food, while helping the flowers reproduce!
Parasitism • One organism gains benefits at the other’s expense! Here, a leech sucks the blood of a human.
Parasitism A wasp lays its eggs in the larva of another insect (a Boll Weevil). When the wasp eggs hatch, they feed on the Boll Weevil!
Commensalism • One species benefits & the other is neither hurt nor helped. Epiphytes are plants that grow on other plants without harming them. They never set roots in the ground!
Commensalism Moss growing on a tree
When grazing cows walk around, they disturb the ground, which stirs up insects. Birds follow the cows and eat these insects. • Mutualism • Parasitism • Commensalism Commensalism
Shrimp living in the ocean eat ectoparasites off of larger fish. The shrimp get a meal and the larger fish get rid of a parasite. • Mutualism • Parasitism • Commensalism Mutualism
A botfly lays maggots inside a man’s head, providing shelter and nutrition for its young. • Mutualism • Parasitism • Commensalism Parasitism
Before you leave, answer the following question on a sheet of paper (share!): Is mycorrhizae an example of mutualism, parasitism, or commensalism? Explain your answer!