Ecology Review

What Is Life? 8 Life Characteristics Made of one or more CELLS (cell theory) Displays organization (atoms  organism) Metabolism (Acquire Materials and Energy) Maintains homeostasis Grows & Develops Respond to Stimuli Reproduce Adaptations evolve over time

Ecology The study of the interaction of living things with each other physical environment From Greek “oikos” – a place to live “logos” - study

Energy pyramid On average only 10% of energy at one trophic level is available to the next

Biotic factors of an ecosystem Population All the members of the same species that inhabit a particular area Community All of the members of all species that inhabit a particular area Ecosystem All Biotic and abiotic factors

Abiotic Factors (nonliving components) ____________ Ex. Biotic Factors (living components) _______________ Ex.

Biosphere All of Earth’s ecosystems Lithosphere - land Hydrosphere - water Atmosphere - air

Biome Characteristics Composed of large regions. Certain plant & animal species. Have specific climate with similar plants and animal adaptations.

Categories of Biomes Tundra Taiga Grasslands Deserts Deciduous Forests Tropical Rainforests Other Biomes Chaparral Savanna Coniferous Forest

Biomes of the world

Decomposers Soil nutrients Simple Food chain

Categories of Biotic Organisms Producer Consumer autotrophs -plants in most ecosystems -phytoplankton (protists, bacteria) -chemosynthesis or photosynthesis 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2

Decomposers saprophytes -external digestion -mostly bacteria and fungi detritivores -feed on partially decomposed matter -e.g. crabs, termites, worms scavengers -e.g. vultures, crows, lobsters

Consumers heterotrophs -feed on producers or consumers herbivores -plant eaters -primary consumers carnivores -meat eaters -secondary (tertiary) consumers omnivores -eat both plants and animals

Trophic Levels = all organisms feeding at a particular level (refer to energy pyramid: > 4 levels hard to support)

Food Web – a summary of the feeding relationships in a community

Trophic level – position in the food chain –basal (lowest level) –intermediate – act as predators and prey –top predators – have no predators

Keystone Predator – one that has a dominant effect on community composition –reduce competition among prey species –allow poorer competitors to persist Top predators aren’t always keystone predators –abundance –feeding patterns

Stability in Food Webs A community is stable if –it doesn’t change much in response to environmental changes, or –it returns to its previous state after a disturbance Early models suggested that larger food webs are unstable

Current view: more diverse food webs are more stable –more species = weaker interactions on average –species influenced by many weak interactions have more stable populations than species with few strong interactions Field research suggests most interactions in nature are weak.

Carnivores Herbivores Producers No predators Limited only by food Limited by predation Limited by competition and resources