Evolution- 4.5 Succession Flashcards
5.1- Succession, 5.2- Extinction
What is succession?
Succession is the gradual change in the mix of species in an area over time following a disturbance.
How do organisms influence succession?
Organisms change the environment, making it more suitable for other species to be introduced, leading to changes in the species composition over time.
What is primary succession?
Primary succession occurs in barren landscapes with no soil, such as bare rock from a volcanic eruption or retreating glacier. It involves colonization by pioneer species and proceeds very slowly.
What are the stages of primary succession?
1) Pioneer Step: Pioneer species (e.g., lichen or moss) colonize the barren landscape and form soil.
2) Immature Phase: Species like plants begin to migrate and increase diversity.
3) Environmental Change: Each new species alters the environment, facilitating the arrival of others.
4) Competition: Larger organisms outcompete smaller ones, altering the environment.
5) Climax Community: A stable, mature ecological community is established.
What is secondary succession?
Secondary succession occurs after a natural disaster or disturbance that leaves the soil intact, such as a fire, flood, or cyclone. It is faster than primary succession.
What are the stages of secondary succession?
1) Disturbance: A natural disaster or disturbance destroys a climax community, but soil remains.
2) Immature Phase: Species recolonize the area, starting with plants.
3) Environmental Change: Each new species alters the environment, facilitating others.
4) Competition: Larger organisms outcompete smaller ones.
5) Climax Community: A stable, mature ecological community forms.
What is extinction?
Extinction occurs when all members of a species die out.
Why are species with low genetic diversity at a higher risk of extinction?
Species with low genetic diversity are more vulnerable to changes in the environment or selection pressures, making it harder for them to adapt and increasing the risk of extinction.
