Speciation Flashcards
Where does evidence of early forms of life come from?
Fossils
What might changes in the environment do to plants and animals?
Cause them to die out, eventually becoming extinct
What are fossils?
The remains of dead organisms from many years ago, found in rocks
How can fossils be formed?
- From the hard parts of animals that don’t decay easily
- From parts of organisms that have not decayed because there aren’t the needed conditions
- When parts of the organism are replaced by other materials as they decay
- As preserved traces of organisms (footprints, burrows)
What does soft bodied forms of life mean?
That they have left few traces behind, and the traces they did leave have been destroyed by geological activity
What can we learn from fossils?
How little organisms have changed as life developed on Earth
How is extinction caused?
- Changes to the environment over time
- New predators
- New diseases
- New more successful competitors
- A single catastrophic event (collisions with asteroids)
- Through the cyclical nature of speciation
What do new species arise as a result of?
- Isolation
- Genetic Variation
- Natural Selection
- Speciation
What is isolation?
Two populations of a species become separated (geographically)
What is genetic variation?
Each population has a wide range of alleles that control their characteristics
What is natural selection?
In each population, the alleles that control characteristics which help the organism survive are selected
What is speciation?
The populations become so different that successful interbreeding is no longer possible
