Ecology

Characteristics of a balanced ecosystem*:

1. Has a constant source of energy

2. More producers than consumers

3. A complex food web (biodiversity)

4. Nutrient cycles flow uninterrupted

   1. Main cycles include:

      1. Carbon

      2. Nitrogen 

      3. Water

      4. Phosphorus 

   2. (cycle flow depends on decomposers and energy flow)

* It is a self sustaining environment with biotic and abiotic factors interacting 

1. Symbiotic relationships in ecosystems:

   1. Are close relationships between organisms of different species

   2. Organisms in symbiotic relationships tend to co-evolve

2. Prey and predator relationships:

   1. A relationship in which one organism gets killed (prey) by the other (predator) 

   2. Their interaction controls the size of each population

Mutualism:

Something that benefits two organisms in the relationship (+,+)

Parasitism:

A symbiotic relationship in which the parasite benefits and the host is harmed (+,-)

For example: Mosquitoes and humans 

Commensalism: symbiotic relationship in which one organism benefits and the other organism is not benefited or harmed (+)

1. Nutrient Cycles: Describe the transformation of some molecules as they cycle in ecosystems so key elements become available (as a resource) for living things

   1. The main elements involved in cycles are: carbon (C), nitrogen (N), phosphorus (P), hydrogen (H), and oxygen (O). 

   2. If they are not recycled they would be available for:

      1. Daily life functions, and to build tissues 

2. Nutrients circulate in ecosystems through cycles that include the following processes

   1. Biological 

   2. Geological

   3. Man made 

   4. Physical and chemical 

What is the difference between habitat and niche?

Habitat is the physical space where an organism lives

Niche: is like the job of a particular species, no two species have the same niche. It is the description of a species range of biological and physical activities in an ecosystem. Includes interactions with other species: Trophic/feeding relations, resources it uses, reproduction, and habitat

Resources (limit species population):

All the things necessary for the species survival. Can be renewable (cycle) or nonrenewable (soil) (once used they are gone)

Competition (shapes species niche):

Competition drives the division of resources 

EX: warbler species, or plants in a forest

Competitive exclusion:

When two species attempt to use the same resource the less competitive species do nor survive. Invasive species have competitive advantage in ecosystems.

Keystone species:

Are species that have an important role in maintaining the structure of a community

Variables affecting population growth:

• Resources available

  • Food 

  • Space

  • water

• Diseases

• Natural disasters 

  • Climate change

• Imbalance in relationships in the community 

  • Number of prey/predators

  • Introduction of invasive species

• Man made disasters

  • Fires

  • Oil spills

  • Wars

• Immigration (decreases population numbers)

• Migration (increases population numbers)

• Death rate

• Birth rate

What are the effects that human population growth has on the ecosystem?

• Pollution

• Water 

  • Plastic

  • Toxic waste

• Air 

  • Combustion of fossil fuels

• Soil

  • Fertilizers

  • Pesticides 

• Deforestation

  • Loss of habitats (leads to decrease in biodiversity which leads to ecosystem’s collapse

• Man made disasters

  • War

  • Disease