Pages in this set

Page 1

Preview of page 1
Speciation
Biology Revision Presentation

Page 2

Preview of page 2
In any species there
exist groups of
individuals called


demes

Page 3

Preview of page 3
Demes
breed among themselves more
than witht the other individual
members of the population.

Page 4

Preview of page 4
Speciation
is the process by which an new
species with its own distinct gene
pool forms.

Page 5

Preview of page 5
Isolating Mechanisms
are barriers to the passage of
genetic material between demes.
In the long term this can lead to
groups so different that they can be
called separate species.

A new species is unable to breed with
the old species+.
+
OK, so you can have hybrids which are…

Page 6

Preview of page 6
There are a number of
different isolating
mechanisms...
Geographic Isolation & Reproductive Isolation

Page 7

Preview of page 7
Geographic Isolation occurs when a
population is physically split into two or
more demes.

A physical barrier can be anything from a
river to a mountain and everything in
between.

This kind of speciation is allopatric speciation,
it is very likely to occur.

Mountain?
Deme 1
Deme 2

Page 8

Preview of page 8
Reproductive isolation occurs when there are
no physical barriers but two demes cannot
interbreed. This form of speciation is
sympatric speciation.

Numerous mechanisms can cause
reproductive isolation.

Page 9

Preview of page 9
This occurs when
animals which have
Behavioral elaborate
courtship
isolation behaviours cannot
elicit the required
response in their
potential partner.

Page 10

Preview of page 10
Mechanical Occurs where
mating pairs are

isolation. unable to couple
successfully.

Comments

jo

It won't open?

Similar Biology resources:

See all Biology resources »See all resources »