ECOLOGY Ecology The study of organisms and their

ECOLOGY

Ecology • The study of organisms and their interactions with the environment • The biosphere is all the land, water and air in which organisms live. • All the living parts of an environment are called biotic factors. The nonliving parts are called abiotic factors (ex: water, light, etc. )

Levels of Organization in the Biosphere • Population: consists of all the members of a single species that live in one area • Community: all populations that live and interact in one environment • Ecosystem: community + abiotic factors; ex: forest, desert, ocean

Cycles • Matter is recycled within and between ecosystems • Biogeochemical cycles show matter cycles through the biosphere • There are 4 types of cycles: – Water cycle – Carbon cycle – Nitrogen cycle – Phosphorous cycle

Some Terms • Habitat: type of environment in which a particular species lives • Niche: full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions • Biodiversity: the variety of life--the different plants, animals and microorganisms--and the ecosystems of which they are a part

Food Synthesis • Photosynthesis: use of light energy to make food; process used by plants, algae and some bacteria • Chemosynthesis: use of chemical energy to make food; process used by some bacteria

Remember • Autotrophs: use light energy to make their own food; also called producers • Heterotrophs: can’t make their own food; also called consumers

Types of Heterotrophs • Herbivores: eat plants • Carnivores: eat animals • Omnivores: eat both plants and animals • Decomposers: break down organic matter • Scavengers: eat tissues of dead animals

Community Interactions • Competition: organisms attempt to use an ecological resource in the same place at the same time • Symbiosis: any relationship in which 2 species live closely together • Predation: interaction in which one organism (predator) captures and feeds on another organism (prey)

Types of Symbiotic Relationships • Mutualism: both organisms benefit • Parasitism: one organism benefits while the other is harmed • Commensalism: one organism benefits while the other is neither harmed nor benefited

Food Chains • A food chain models the flow of energy through organisms in a community • The flow is in one direction • Each step in the transfer of energy and matter in an ecological community is called a trophic level • Only 10% of the energy from one level is transferred to the level above it

F O O D C H A I N

Food Web • Shows how food chains are connected

Ecological Pyramids • Show the relationship between producers and consumers at the trophic levels in an ecosystem • There are 3 types of pyramids: – Energy Pyramid – Biomass Pyramid – Pyramid of Numbers

Growth Rate • Growth rate = change in the number of individuals divided by the time period • Factors that play a role in growth rate: – Birth rate – Immigration—movement of individuals into an area – Emigration—movement of individuals out of an area – Death rate

Exponential Growth • Occurs when individuals • • in a population reproduce at a constant rate Under ideal conditions with unlimited resources, a population will grow exponentially As resources become less available, the growth of a population slows or stops The red bracket shows the area of the graph that represents exponential growth.

Carrying Capacity • The number of individuals • in a population that an environment can support over a relatively long period of time Determined by limiting factors • Limiting factors are biotic and abiotic resources in the environment that limit the size of a population The red bracket shows the area of the graph that represents the carrying capacity.

Density-Dependent Limiting Factors • Factors that become limiting only when the population is large • They include: – Living space – Disease – Competition – Predation

Density-Independent Limiting Factors • Factors that affect all populations in the same way, regardless of their size • They include: – Weather – Seasonal cycles – Natural disasters

Ecological Succession • As an ecosystem changes, older inhabitants gradually die out and new organisms move in • This series of predictable changes that occurs in a community over time is called ecological succession • There are 2 types: – Primary succession – Secondary succession

Primary Succession • Occurs where no soil exists • Ex: occurs on surfaces formed by volcanic eruptions or on bare rock exposed when glaciers melt

Primary Succession

Secondary Succession • Occurs when a disturbance of some kind changes an existing community without removing the soil • Ex: wildfires burn woodlands or field is cleared for farming and then abandoned

Secondary Succession

Biological Magnification • Buildup of a pollutant in organisms at higher trophic levels in a food chain ppm=parts per million