More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved.
Similarities/differences
allow classification
Annotations:
1) Plants make their own food and are fixed to the ground
2) Animals move about and can't make their own food
3) Microorganisms are different to plants & animals
Evolutionary and ecological relationships
Evolutionary
Annotations:
* Species wich similar characteristics - similar genes because they share common ancestor (closely related), often look alike and live in similar habitat
* Genetically different species can look alike too
* Evolutionary trees show common ancestors/ relationships between organisms (more recent, more closely related)
Ecological
Annotations:
* Organisms in same environment with similar characteristics - might be in competition
* Differences between organisms in same environment can show predator-prey relationships
Natural Selection
Charles Darwin's idea
1) Individuals within species show variation due to differences in genes
2) Individuals with characteristics that make them better adapted to environment
have better chance of survival - more likely to breed successfully
3) Useful genes more likely to
be passed on to next generation
Mutations
Mutation: Change in organism's DNA
Mostly, mutations have no effect but can be
beneficial i.e. produce useful characteristic
Beneficial mutation
more likely to be passed
on by natural selection
Over time, beneficial mutation
will accumulate in a population
Darwin's idea was very
controversial at the time...
Wasn't enough evidence to
convince many scientists
Annotations:
Not many other studies had been done into how organisms change over time
No good explanation of how
appeared or passed on - didn't
know about genes/mutations
Went against
religious beliefs -
no need for God
Lamarck
Argued that if
characteristic was used a
lot it would become more
developed in its lifetime
Believed
acquired
characteristics
would be passed
onto next
generation
Evidence
Lamarck's hypothesis rejected
- experiments didn't support
Discovery of genetics supported Darwin's idea
Annotations:
Provided explanation of how organisms born with beneficial characteristics can pass them on (via their genes)