Download reproductive isolation

Speciation and Adaptive Radiation
Speciation

Speciation is a name given to the
theoretical process of creating a new
species from pre-existing species of
organism through modes of natural
selection.

Can not be done by means of artificial
selection of different existing species.
Niche
Niche is the word used to describe the
combination of an organism’s
“profession” and the place where it lives.
 No species can occupy the same niche
 Due to COMPETITION
 Species that fill an unoccupied niche do
so by adaptation  This CREATES
ENTIRELY NEW SPECIES

Speciation Example

According to the fossil record, Dinosaurs
were the dominant species during the
Mesozoic era and mammals were very
few and far between.
 But around the time when the
dinosaurs died out, new mammal
species seemed to appear from
nowhere…likely due to speciation and
newly opened niches.
Adaptive Radiation
Reproductive Isolation

Segregation of a
population of species
that DO NOT
interbreed
 Need Physical/
Behavioral Barriers.
 If not isolated 
Blending of genes 
No New Specie

If two populations become dissimilar in
body structure and behavior, particularly
mating behavior, what do you think will
happen to them?
•Decreased chance of breeding…
This is called Behavioral Isolation
Darwin’s Finches-Speciation

STEP 1: FOUNDING
FATHERS AND
MOTHERS
 STEP 2: SEPERATION
OF POPULATIONS
 STEP 3: CHANGES IN
THE GENE POOL
 STEP 4:
REPRODUCTIVE
ISOLATION
 STEP 5: SHARING
THE ISLAND
Darwin’s Finches
Another example

There are many different species of
Galapagos Tortoises alive today (and
many extinct). Each seems to have
been derived by speciation from a
common single ancestor species.
 Under
what circumstances can
two species coexist successfully?
 What
will happen if the niches of
two species are too similar?
 How
might further evolution
occur?