3.1 How Changes Occur Naturally in Ecosystems Flashcards
What is natural selection? Explain how this would work and give an example.
- process (proposed by Darwin) where environmental factors favour the selection of fit individuals
- individuals with advantages are better able to reproduce and pass along their traits
- eg. a salmon with a slightly larger tail may be able to swim faster or further in a river
- individuals with unfavourable traits have a less chance of reproducing and passing along their traits
- eg. a salmon with a small fin may not be able to spawn because it can’t swim to the correct location
How is the Galapagos finch an example of natural selection? (2)
- there are 13 species of finch on Galapagos Islands that developed from a single species on the mainland
- each species has a unique characteristic, such as differently sized beaks, which allow it to thrive in its own niche and not compete with other finches for resources
What is adaptive radiation?
The process by which members of a species adapt to a variety of habitats
What is ecological Succession?
- the process of gradual change that occurs when organisms colonize a habitat, modify it, and are forced out by a new species better adapted to the new altered environment
- changes that take place over time in the types of organisms that live in the area
What are the two types of ecological succession?
- primary succession
- secondary succession
What is primary succession? Give and example.
- occurs in areas where no soil exist
- eg. bare rock exposed after a glacier retreats or formed when lava has cooled
What are pioneer species? What do they do and where do they come from?
- the first organisms to survive and reproduce
- they alter the abiotic and biotic environment so that other organisms can survive there, and eventually, combined with the weathering of rock, they form soil
- wind carries spores of lichens and organisms that can survive
What are lichens?
A simple slow-growing plant that typically forms a low crustlike, leaflike, or branching growth on rocks, walls, and trees
What are the stages of primary succession? (6)
- pioneer organisms arrive
- pioneer organisms and the weathering of rock create soil
- the soil improves, allowing plats to grow and animals to appear
- seeds of trees germinate and the first trees (such as deciduous trees) create shade, further changing the abiotic conditions
- as more niches are created, there is a greater diversity of animals and more complex food webs
- the environment reaches climax or mature community
What is a climax/mature community? (2)
- where a stable group of two or more species is able to survive and reproduce indefinitely in the same habitat
- the final stage of succession
What is secondary succession? Give an example of what it would follow.
- occurs after a major disturbance in an area that already has soil and once had living organisms
- a forest fire
How is secondary succession different from primary? What is so important about the soil?
- secondary is much more rapid than primary
- soil contains seeds, micro-organisms, earthworms, and insects
What does ecological stability in a community mean?
Populations are able to return to their previous state from before they were disturbed
What natural events can effect marine mature communities? (2)
- changes in ocean current patterns
- extreme weathers
When does flooding occur and what does it do?
- flooding occurs in locations where water levels change rapidly, climate change and global warming may be increasing incidents of flooding
- can cause soil erosion and spread pollutants and harmful bacteria associated with wastes
