Speciation Flashcards
What are fossils?
Fossils are the preserved remains or traces of dead organisms. They are found in rocks.
What can fossils be formed from?
Hard body parts, such as bones and shell - don’t decay easily or are replaced by other materials as they decay. Parts of organisms which haven’t decayed, for example dead animals and plants - can be preserved.
Casts or impressions, such as footprints or burrows - these become covered by layers of sediment, which eventually become rock.
What can dead animals and plant be preserved in (to become fossils)?
Amber (hardened tree resin)
Peat bogs
Tar pits
Ice
In which type of rock are the simplest organisms found?
Fossils of the simplest organisms are found in the oldest rocks.
In which type of rock are the most complex organisms found?
Fossils of more complex organisms are found in the newest rocks.
Do fossils support the theory of evolution?
Yes
What is the theory of evolution?
The theory of evolution states that simple life forms gradually evolved into more complex ones.
Why do scientists study fossils?
By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth.
How can new species arise?
New species can arise as a result of isolation. This is where two populations of a species become geographically separated.
How can new species arise (2)?
Genetic variation
Natural selection
Speciation
What is genetic variation?
Genetic variation is where each population has a wide range of alleles that control their characteristics
What is natural selection?
Natural selection is where the alleles which help an organism to survive are selected in each population
What is speciation?
Speciation is where the populations become so different that successful interbreeding cannot happen anymore.
