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 how 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 micro-organisms--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
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 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
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
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
Buildup of a pollutant in organisms at higher trophic levels in a food chain ppm=parts per million
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