ecology

ecology

Scientific study of living organisms and their relationships with the environment

levels of organization

individual → population → community → ecosystem → biome → biosphere

population

one species (group of similar organisms that can breed and produce fertile offspring) living in a particular area

community

different populations in one defined area

biome

group of ecosystems with same climate and similar communities

biosphere

all parts of the Earth where life exists including land, water, and air

atmosphere

air

lithosphere

land

hydrosphere

water

methods of study used by ecologists

·      Observing

·      Experimenting

·      Modeling

biodiversity

more biodiversity=more variety

keystone species

species that holds ecosystem together-connected to many other species

Ecosystem energy flow

the main source of energy for all life on earth is the sun, but less than 1% is used by living things

Producers/Autotrophs

·      Capture energy from sunlight or chemicals and use that energy to produce food

·      Assemble inorganic compounds into organic molecules (includes plants, some algae, some bacteria)

·      Best known autotrophs harness solar energy using photosynthesis

·      Adds oxygen to, and removes carbon dioxide from the earth’s atmosphere

·      Occurs on land and in water

chemosynthesis

·      Produce carbohydrates using inorganic molecules (chemical energy) without light

·      Occurs with some types of bacteria in deep ocean, hot springs,…

Consumers/Heterotrophs

·      Get energy from other organisms

·      Herbivores—eat plants

·      Carnivores—eat animals

·      Omnivores—eat both

·      Decomposers—type of detritivore that breaks down organic matter

·      Detritivores—eat dead matter

feeding relationships

·      Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)

food chains

A series of steps in which organisms transfer energy by eating and being eaten

trophic levels

Steps in food chain; 1^st trophic level is producer; 2^nd and up are consumers

food webs

link all the food chains in an ecosystem together

Specialist

organism that only eats from one source

Generalist

organism that has many food sources

Biogeochemical cycles

·      Matter is recycled in ecosystems and converted to usable chemical form by organisms

·      Water and nutrients pass through the environment and organisms in cycles

Hydrologic/water cycle

condensation, transpiration, precipitation, evaporation, percolation

Oxygen cycle

photosynthesis, cellular respiration, cycled with other nutrients—such as nitrates, carbon dioxide, phosphates

Carbon cycle

cellular respiration, photosynthesis, consumption, decomposition, erosion (limestone—calcium carbonate), volcanic activity, fossil fuels, combustion

Nitrogen cycle

lightning, nitrification, denitrification, ammonification, decomposition, nitrogen fixation, excretion, assimilation, fertilizers, consumption

Phosphorus Cycle

weathering, erosion, decomposition, consumption, assimilation

Primary productivity

Rate organic matter is created by producers

Limiting nutrient

Nutrient in scarce amounts so productivity is slowed down or stopped completely

Ecological Pyramids

shows amount of energy or matter within each trophic level

Pyramid of numbers

shows the relative number of individual organisms at each trophic level

Energy pyramid

shows the relative amount of energy available at each trophic level

Biomass pyramid

represents the amount of living organic matter at each trophic level, typically, the greatest biomass is at the base of the pyramid

Ecosystem

Organisms interacting with each other & the environment

Abiotic

non-living

Biotic

living

Ecological niche

the job of the organism within the ecosystem—full range of physical, behavioral, and biological conditions it lives in and how it uses those conditions

Competitive exclusion principle

no two species can share the same niche in the same habitat—one will be pushes elsewhere or become extinct

Niche partitioning

divide the niche

Evolutionary response

divergent evolution

Ecological Equivalents

species occupying similar niches but in different locations—result of convergent evolution

Competition

organisms attempt to use the same resource at the same time; one wins and one loses and doesn’t survive

·      Infraspecific vs Interspecific Competition

Predation

predator captures and feeds on another organism (prey)

Symbiosis

two or more species live together in a close relationship

Mutualism

both species benefit

Commensalism

one species benefits and the other isn’t helped or harmed

Parasitism

one species is helped and the other is harmed (doesn’t die immediately)

Demography

study of populations in ecosystems

Dispersion

Arrangement of population'

a.     Clumped (for mating, resources,…)

b.     Uniform (due to intraspecies competition for resources and territory; ex: penguins)

c.     Random (wind dispersed seeds)

Growth patterns

Affected by number of births, deaths, and number that enter or leave a population

Exponential growth

reproduction at a dramatic rate

Uniform dispersion

due to intraspecies competition for resources and territory; ex: penguins

Random dispersion

ex: wind dispersed seeds

Logistic growth

population’s growth slows or stops after exponential growth when carrying capacity is reached (S curve)

Survivorship Curves

type 1, type 2, type 3

Type 1

survive to old age generally (humans and large mammals)

type 2

equal rate throughout life (small mammals, birds, reptiles)

type 3

high birth and infant mortality rate (invertebrates, fish, amphibians, plants)

What could cause a decrease in population growth

·      Food supply decrease

·      Predators

·      Competition

·      Lack of space

·      Disease

·      Weather changes

·      Human activities

·      Natural disasters

Ecological succession

changes that occur over time in an ecosystem

Primary succession

occurs where no soil existed—new islands, volcanoes, melting glaciers, landslides, tsunamis…

Secondary succession

existing community is disturbed, but not soil—forest fire, plowing and clearing of land, hurricanes…