Interactions of Life

Chapter 24

Living Earth• The part of Earth that supports life is called

the biosphere.– Top portion of the crust, all the waters and the

atmosphere that surrounds Earth.– The biosphere is made up of different

environments that are home to different kinds of organisms.• Desert environments vs. tropical environments.

Ecology: the study of interactions that occur among organisms and their environment

• An ecosystem is all the organisms living in an area as well as the nonliving parts of that environment.– A population is made up of all the organisms in an

ecosystem that belong to the same species.• All of the grasshoppers in the prairie.

– A community is all the population of all species living in an ecosystem.• All of the bison, grasshoppers, birds, etc. in the prairie.

Each organism in an ecosystem needs a place to live…

• Habitat – the place where an organism lives.– In the rainforest, some birds

live inside of dead trees while salamanders live beneath fallen leaves and twigs.

– An organism’s habitat provides the kinds of food and shelter, the temperature and the amount of moisture the organism needs to survive.

Biosphere Ecosystem

CommunityPopulation

Ecology Flow Chart

Biosphere Ecosystem Community Population

1. Pick an ecosystem (Tropical rainforest, Subtropical savannas, Deserts and semi-deserts, Oceans, Temperate grasslands, Temperate forests, Coniferous forests, Alpine and polar regions)

2. Create an ecology flowchart using irregular shapes.3. Start big (at biosphere) and “zoom in” (to population)4. Make sure you keep in mind the climate of your ecosystem and all

of the living organisms that would be involved.5. Underneath each picture, write a caption so that I know what I’m

looking at and so I know that you know what each level is.

Populations

• Competition: when two or more organisms seek the same resource at the same time.– Competition for food, living space, or

other resources can limit a population’s size.

– Competition is usually most intense between members of the same species.• why?

• Population size indicates whether a population is healthy and growing.

• Population density is the size of a population that occupies a specific area.

Elements that affect population size…

• Limiting factor: any living or nonliving feature that restricts the number of individuals in a population.

• Carrying capacity: the largest number of individuals of one species that an ecosystem can support.

• Biotic potential: the highest rate of reproduction under ideal conditions.– Pumpkins vs. peaches

• Birth and death rates• Movement of organisms into or out

of an area.

Interactions within communities

• Producers: organisms that use an outside energy source (like the sun) to make energy-rich molecules.– Plants use photosynthesis

• Consumers: organisms that cannot make their own energy-rich molecules and instead obtain energy by eating other organisms.– 4 types of consumers

Four types of Consumers

• Herbivores: eat plants– Deer and rabbits

• Carnivores: eat animals– Frogs and lions

• Omnivores: eat both plants and animals– Pigs and humans

• Decomposers: eat dead organisms– Earthworms and bacteria

Food Chain!

• Food chain: a model that shows the feeding relationships among the organisms in an ecosystem.

Can’t we all just get along?

• Symbiosis: any close relationship between species.– Mutualism: a symbiotic relationship in which both

species benefit.– Commensalism: a symbiotic relationship in which

one organism benefits and the other is not affected.

– Parasitism: a symbiotic relationship in which one organism benefits and the other is harmed.

Can’t we all just get along?

• Niche: an organism’s role in its environment, including its habitat and food, and how it avoids danger, finds a mate and cares for its young.– Predator and Prey!!

• Predator: consumer that captures and eats other consumers.• Prey: The organism that is captured by the predator.• Predators limit the size of prey populations, increasing the

number of different species that can live in an ecosystem.

– Cooperative actions improve a species’ survival• One deer warns others of predators in the area• Individual ants perform different tasks required for the

survival of all