APES Unit 1.1

Introduction to Ecosystems

Ecosystem

A community of biotic organisms interacting with the abiotic components of their environment as a system through various nutrient and energy cycles.

Organism

A living thing that can function on its own.

Species

A group of organisms that can interbreed and produce fertile offspring, sharing common characteristics like genetic makeup, chemistry, and behavior.

Intraspecific

Within the same species.

Interspecific

Between different species.

Population

Organisms of the same species that interact with each other and occupy a specific area.

Community

Populations of different species.

Ecological Niche

1. Specific area within a habitat occupied by an organism

2. Function of that organism within its ecological community

What are characteristics of a niche?

1. Habitat

2. Interactions with biotic and abiotic factors

3. Place/role in the food web

4. Type and amount of resources available

Generalist species

1. Able to survive on a wide variety of food resources

2. Able to withstand a wide range of environmental conditions

3. Live in broad niches

Ex. cockroaches, humans, and mice

Specialist species

1. Specific/limited number of prey

2. Prone to extinction, sensitive to environmental change

3. Live in narrow niches; eg. pandas

Ex. Giant Pandas, Koalas, and Mountain Gorillas

Which type of species has the advantage when environmental conditions are stable and why?

Specialist species since there are few competitors because each species occupies its own unique niche (also called Competitive Exclusion Principle).

Which type of species has the advantage when habitats are subject to rapid changes and why?

Generalist species because they are more adaptable.

Symbiosis

Any type of close and long-term biological interaction between two different biological organisms of the same or different species.

Obligatory symbiosis

One or both of the organisms entirely depends on the other for survival.

Facultative symbiosis

The organisms can generally live independently.

Amensalism

The interaction between 2 species where 1 suffers and the other is not affected.

Example of amensalism

The black walnut tree releases a chemical that kills neighboring plants.

Commensalism

The interaction between 2 species where one organism benefits and the other is not affected.

What could commensalism look like?

• using another organism for transportation

• using another organism for housing

• using something that another organism created (shells)

Competition

1. can be either intraspecific or interspecific

The driving force of evolution

competition

Intraspecific competition causes…

organisms best suited for survival

Mutualism

The interarcuon between both species where both benefit.

Example of mutualism

bees gather nectar for food and flowering plants get to reproduce because of pollination

Parasitism

The interaction between 2 species where one is benefited and the other is harmed.

Ectoparasites

Live on the surface of the host, like ticks and fleas

Endoparasites

Live within their hosts, like tapeworms

Epiparasites

Feed on other parasites. ex. protozoan living in the digestive tract of a flea living on a dog.

Predator

hunt and kill prey

Opportunistic predators

kill and eat almost anything (alligators, dogs)

Specialist predators

only prey upon certain organisms (anteaters)

Saprotrophism

saprotrophs obtain their nutrients from dead/decaying plants + animals through absorption of soluble organic compounds

Examples of saprotrophs

Vultures, dung beetles, many fungi + bacteria

Law of tolerance

The existence, abundance, and distribution of species depends on the tolerance level of each species to both physical and chemical factors.

Limiting factors

Any abiotic factor that limits or percents the growth of a population.

Examples of living factors

1. level of soil nutrients

2. available amount of water + light

3. temperature

4. water pH

Morphological portioning

2 species share the same resource but have evolved slightly different structures to utilize it.

Example of morphological partioning

2 different species of bees have evolved different shaped mouth parts to utilize various size flowers of the same species.

Spatial partioning

When competing species use the same resource by occupying different areas or habitats within the range of occurrence of the resource.

Example of spatial partioning

different fish species feeding at different depths in a lake

Temporal partioning

Two species use same resource at different times.

Example of temporal partioning

One species of spiny mouse feeds on insects during say while another spiny mouse species feeds at night.