4.1.2 OUTLINE THE MECHANISM OF NATURAL SELECTION ANS A POSSIBLE DRIVING FORCE FOR SPECIATION
Natural selection
Evolution
Natural selection
Speciation
A species
: the process where individuals best suited to their environment survive and go on to reproduce so successful genes
are passed on to the next generation.
: a process by which new species are formed by successful genes being passed on to the next generation, changing
the gene pool and ultimately leading to a new species.
: a group of organisms that can interbreed and produce fertile offspring.
: the development of new species over very long periods of geological time.
The theory of evolution was suggested by …
He noted that:
All species tend to …
–produce.
This means there is …
for resources and a struggle for …
.
Species show …
, and so he concluded that those best adapted to their environment …
and these can then go on to
.
Successful genes are therefore …
This is called natural selection.
Over time changes in the species’ gene pool leads to …
Artificial selection is selective breeding – this is when humans choose animals to breed together because of their…
Darwin’s theory is often called ‘survival of the fittest’. Why?
Finches adapted to their individual island environments by …
Tortoises with long necks were more successful because….
This meant that on some Galapagos Islands tortoise shells
Lizards that learnt to swim were more successful because
4.1.3 State that isolation can lead to different species being produced that are unable to interbreed to
yield fertile offspring.
Isolation is the process of two populations becoming cut off from each other. They can be cut off
geographically, genetically, behaviourally or reproductively.
This can lead to new species being formed:
When there is a barrier between species. This is called ………………………………………………………………………………. .
What happened on the Galapagos Islands? What was the barrier?
When the appearance or behaviour of species changes so much that the males and females are no longer attracted
to each other and can’t breed. This is called ………………………………………………………………………………….. .
What happened with fruit flies?
It can also happen if two populations can no longer breed together e.g. poodle and a ………………………………… .