ECOLOGY PART I

Definitions: Ecology = branch of biology that deals with interactions between organisms and their environment and interactions among organisms biotic factors = living factors in the environment abiotic factors = physical factors in the environment limiting factor = physical factor in the environment that limits population growth

Abiotic factors include: light intensity and duration varies with latitude influences plant life and animal hibernation and migration water has photic zone (where light penetrates) water has aphotic zone (no light) heterotrophs and chemotrophs

Abiotic factors include: 2. temperature varies with latitude and altitude Water precipitation varies region to region influenced by mountains and oceans

Abiotic factors include: soil and minerals soil layers topsoil – organic matter, living organisms, plant liter (humus) subsoil – rock particles, mineral and nutrients rock from bedrock below

Biotic relationships: populations individuals of a certain species in an area example = bullfrogs in a pond community different populations in a given area example = bullfrogs, algae, fish in a pond ecosystem community and physical environment including biotic and abiotic factors

Biosphere: portion of the earth’s surface where living things exist (about 20 km thick) includes: lithosphere – solid surfaces of the earth hydrosphere – water (on, under, and vapor over) atmosphere – air mass

Complete worksheet ECOSYSTEMS On page 2 in your packet

Nutritional Relationships

Autotrophic (producers) Organisms that make their own food using CO2 Most use photosynthesis, a few use chemosynthesis This provides food for the heterotrophs

Heterotrophs (Consumers) Organisms that cannot synthesize their own food Herbivores Carnivores Omnivores Saprobes

Herbivores feed only on plants rabbits, cattle, deer, sheep, horses

Carnivores feed on other animals (meat eaters) Predators –attack and kill prey (lions, hawks, wolves) Scavengers – feed on dead animals that they find (vultures, hyenas)

Omnivores feed on plants and animals (bears, humans)

Saprobes (decomposers) organisms that obtain nutrients by breaking down remains of dead plants and animals (fungi and mushrooms)

Predator population follows prey population Predator – Prey Curve Predator population follows prey population

Symbiotic Relationships organisms that live in close association with each other and at least one benefits Mutualism Commensalism Parasitism

Mutualism: both organisms benefit Termites and digestive organisms Cows and digestive organisms Lichens (algae and fungal cells) Peas, clover, alfalfa (legumes) have nodules of bacteria on their roots that convert nitrogen gas into nitrogen in the soil that can be absorbed by the plants The alga provides food for the fungus, which then envelops the alga, providing shelter and nutrients.

Commensalism one organism benefits and the other is not affected Pilot fish and sharks Barnacles on the body of a whale

Parasitism one organism benefits and the other is harmed Parasite and host Can cause slight damage – some can kill Tape worm in animals Mistletoe and Indian pipe in plants

Competition in ecosystems Habitat – where an organism lives Niche – role of the species in their ecosystem When niches overlap –competition begins Intraspecific (within a species) Interspecific (between species)

ENERGY FLOW Food Chains Food Webs

producer consumer consumer consumer Food Chains producer consumer consumer consumer (grass) (grasshopper) (frog) (hawk)

Food Webs Shows all of the food chains in a community

Pyramid of Numbers

Lowest level is most numerous, most energy, most biomass Pyramid of Numbers TOP 3RD ORDER 2ND ORDER 1ST ORDER HERBIVORS GREEN PLANTS NUTRIENTS CARNIVORS PRODUCERS Lowest level is most numerous, most energy, most biomass

Numbers decrease going up the pyramid Energy decreases going up the pyramid Only about 10% of the total energy is passed level to level Total biomass decreases going up the pyramid Each level going up supports less numbers and less biomass 3rd level Consumer Secondary Consumers Primary consumers producers

Complete worksheet ECOSYSTEMS On pages 6 and 7 in your packet