Interactions Among Living Things

Environment & Ecology Environment = all living (biotic) and nonliving (abiotic) that an organism reacts with. An environment provides all resources needed to live and grow. Living things that share an environment also affect one another. All organisms of an environment are interconnected. Ecology – study of the relationships of organisms and their environment. Ecologists – the scientists who study ecology.

Biotic & Abiotic Biotic Abiotic Birds/Animals Tree/Grass Worm Bacteria Insects Abiotic Soil Sun

Levels in Environments Ecologists organize the relationships of organisms into four levels: Individual – A single member of a species. Populations – a group of individuals from the same species living in a specific area at the same time. Community – All the interacting populations of species in an environment. Ecosystem – Made up of both the community of organisms in an area and their abiotic surroundings.

Forest Ecosystem Community Population Individual

Habitat vs. Niche Habitats – The place in which an organism lives. Provides everything an organism needs for its survival. Populations of different specials avoid fighting over resources by using them in different ways. Niche – The unique strategy a species has for survival, its occupation or job. Two organisms may share a habitat but NOT a niche! Death with occur to one of the organisms.

Feeding Levels What process does this best represent? Producers – (autotrophs, “self-feeders”) The source of all food in an ecosystem! Use photosynthesis to make their own food Green plants and certain microorganisms. What process does this best represent? What is the primary source of all energy in an ecosystem? Photosynthesis: Energy + CO2+ H2O = O2 + Glucose SUN

Feeding Levels Consumers Feed directly or indirectly on producers. DO NOT have the ability to make their own food. 4 Types: Herbivores – plant eaters ONLY Ex. Rabbit, mouse, grasshopper Carnivores – meat eaters Ex. Eagle, lion, tiger Omnivores – eat both plants and animals Ex. People Scavengers – eat dead organisms Ex. Hyenas, vultures, crows

Feeding Levels Decomposers Break down dead organisms into simpler substances (decay). “Nature’s recyclers” Ex. Mold, mushrooms, worms and bacteria

Producers Herbivore Carnivore Omnivore Decomposer Trees Squirrel Robin Worm Grass Blue Jay Bacteria Leaves Woodpecker Beetle

Food Chains and Webs The flow of energy through an ecosystem. Direct link of one organism to another in a feeding pathway (trophic level). Food Web All feeding relationships within an ecosystem.

Energy Levels The location of an organism in a feeding level crates energy levels: How much energy is obtained by an organism from the food it consumes. 10% Rule – Only 10% of the energy a food resource has goes to the consumer. Energy decreases!

Relationships Among Populations Communities are made up of many populations that share the same resources. Organisms within these communities coexist by having one of three different types of relationship: Symbiosis Competition Predation

Symbiosis A close relationship between individuals of two or more species. Symbiosis = Greek Syn = “together” and bios = “life” Can occur in 3 ways: One lives near the other. One lives on the other. One lives in the other.

Symbiosis Ex – bee & flower pollen. Commensalism: one benefits and the other is unharmed. Ex – Sea anemone & fish Mutualism: Both benefit Ex – bee & flower pollen. Parasitism: One benefits, the other is harmed. Ex – tick on dog

Competition When two species struggle for the same limited resources. Each is hurt by the presence of the other. The ability to compete and win is one of the most important causes of evolution by natural selection. fight over food, water, shelter or breeding rights.

Predation When one organism kills and eats another organism. Involves two individuals: Predators - organisms that catch, kill and eat other organisms. Prey – those organisms being killed and eaten. Importance: Reduces size of prey population. Maintains diversity of an ecosystem.

Predator/Prey Relationships Who is the predator? Who is the prey? As the wolf population increases, what happens to the moose population, from 1970-1980? If another predator of the moose moved into this area, what do you think would happen to the wolf population? What is this called? Wolves Moose Decreases Decrease – not enough food for both Competition