Chapter 13How Ecosystems Change

College Bound Biology Mr. McCloskey

Section 2Ecosystem Development and

Change

Ecosystem Lifestyles

• Niche = The sum of an organism’s interactions with its physical environment and with other organisms.

Job #1 Bring minerals to the surface

Job #2 Carry dead material underground

Job #3 Helps water and gases penetrate soil

Ecosystem Lifestyles

• Fundamental Niche = The total niche that an organism could potentially use within an ecosystem.

Competing Organisms Coevolve• Competition = A situation in nature when

two or more organisms attempt to use the same resource.

Shallow water and deep water barnacles compete to take hold of the rocks.

Competing Organisms Coevolve• Realized Niche = The part of a

fundamental niche that an organism actually occupies as a direct result of competition.

Competition can cause changes in an ecosystem

• Competitive exclusion = The process in which two species fighting for the same resource results in one species losing and dying out within the ecosystem.

Competition and Ecosystem Development

• Competition is often seen when a disturbance creates new habitat.

Competition and Ecosystem Development

• Glaciers recede

Competition and Ecosystem Development

• Yosemite Fires

Competition and Ecosystem Development

• Tornadoes

Competition Drives Change in a Developing Ecosystem

• The first species to enter the new habitat are small, fast growing plants. These are known as the SETTLERS or PIONEERS.

Competition Drives Change in a Developing Ecosystem

• These small plants (pioneers) help to improve the soil ecosystem and allow other plants to come in and grow.

Competition Drives Change in a Developing Ecosystem

• Succession = The regular progression of species replacement in a developing ecosystem

Competition Drives Change in a Developing Ecosystem

• Primary Succession = When succession takes place on land where nothing has ever grown before.

Competition Drives Change in a Developing Ecosystem

• Secondary succession = Succession taking place in areas where there has been previous growth like an abandoned farm filed or forest clearing.

Ecosystem Stability

• Stability = The ability of the later stages of succession to resist disturbances.

• Early succession = low stability

• Later succession = more stability

• Final community = most stable

What factors promote stability?

Answer = Diversity!!!

More diverse ecosystems are more stable. The web of interactions makes them more likely to handle distrubances.

What factors promote stability?• Keystone Species = A species whose

niche affects many others in the ecosystem and that cannot be readily replaced if lost.

Why are some Ecosystems More Diverse Than Others?

Answer = The size of the ecosystemReducing the size of an ecosystem reduces the variety of physical habitats.

National Parks!!!!

Why are some Ecosystems More Diverse Than Others?

• Answer = The latitude of the ecosystem

Latitude has a great influence on ecosystems because both moisture and temperature vary with the distance from the equator.

The tropics are warm and moist and have long growing seasons with lost of rain.

There is also little variation in the temperature from day to day and year to year. Therefore, there are lots of species coevolving.