Ecology and Ecosystems

• Ecology studies the relationships between living organisms and their environments.
• Ecologists study ecosystems, which include all the organisms and environmental factors in a specific area.
• An ecosystem can vary in size, from a backyard to the biosphere.
• The biosphere encompasses every part of Earth where organisms can survive, including the crust, waterways, landforms, forests, and atmosphere.
• The biosphere represents all ecosystems on Earth combined.

Factors in an ecosystem

• Ecosystems are divided into biotic and abiotic factors.
• Biotic factors comprise the living and once-living components of an ecosystem.
• Abiotic factors are the nonliving elements, such as air, water, soil, sunlight, temperature, and climate.
• Air, specifically the atmosphere surrounding Earth, constitutes a vital abiotic factor.
• Animals inhale oxygen and exhale carbon dioxide.
• Plants use carbon dioxide, sunlight, and water in photosynthesis to produce sugar for energy.
• After using carbon dioxide, plants release oxygen back into the environment.
• Animals breathe in oxygen for respiration, converting sugar molecules into energy.
• Water is involved in life processes like photosynthesis, respiration, and digestion.
• Plants and animals rely on water for sustenance and shelter
• Water is a habitat for fish, frogs, and other organisms
• Soil consist of rock, mineral particles, water, and dead organisms
• Different soils have different nutrients that influence plant life
• Roots of food can be traced to sunlight
• Plants and algae capture sun's energy to produce chemical energy which animals then consume
• Plants and animals can survive in a certain temperature range
• Temperature can be affected by amount of sunlight a region receives, the angle of that sunlight, elevation, if large bodies of water are nearby, ocean circulation, and more factors
• Climate can be affected by timing and amount of wind and precipitation an ecosystem receives

Biotic Factors

• Biotic factors include living and once-living parts.
• Each organism has a niche, or role, in an ecosystem and lives in a habitat.
• All organisms of a species in an area make up a population
• Different populations of species living in an area are a community

Levels of Organization in an Ecosystem

• Levels of organization from smallest to largest go as follows:
  • Organism: one member of a population (e.g., single lake trout in Lake Michigan)
  • Population: the total number of one type of organism in an area (e.g., all lake trout in Lake Michigan)
  • Community: all populations interacting in an area (e.g., fish, bacteria, leeches, water bugs, algae, and plants in Lake Michigan)
  • Ecosystem: all communities and nonliving factors in an area (e.g., Lake Michigan as a whole)
  • Biome: a region with multiple ecosystems (e.g., temperate deciduous forests)
  • Biosphere: all ecosystems on Earth combined

Populations

• Population density is how closely members of a population live
• Populations are denser when organisms occupy a smaller area
• Populations may clump together or spread out

Limiting factors

• The amount of resources available impacts the number of organisms in populations
• These resources limit the population and are called limiting factors
• Limiting factors include: water, sunlight, food, and living space
• Organisms compete for resources and depend on them for survival

Niche

• To survive, every organism has it's own niche
• A niche includes what and when an organism eats, when it's active, what it uses for shelter, and how it reproduces
• If 2 organisms have the same niche they will be in direct competition with each other

Carrying capacity

• Carrying capacity is the largest number of organisms an ecosystem can support
• An ecosystem's carrying capacity is influenced by limiting factors, as well as the number of other organisms in the ecosystem

Biotic potential

• Biotic potential relates to how quickly a population will grow without limiting factors in ideal conditions
• Dogs have a higher biotic potential than humans because they give birth to several puppies and can also reproduce within a year of being born

Population Growth and Migration

• Population growth rate varies on number of births and deaths
• Population numbers can be affected by migration
• Migration is when a population moves from one habitat to another
• Migration can be caused by permanent changes forcing the population to move elsewhere