Name: __________________________________
Period:_____
Allopatric & Sympatric Speciation
Part I: Allopatric Speciation
Learning Objectives
By completing this exercise, you should:
 Know what allopatric speciation involves.
 Appreciate why geographical barriers play an important role in this type of speciation.
 Be able to explain how allopatric speciation is the evolution of new species in populations that are
geographically isolated from one another.
Procedure
1. Study the diagram below of allopatric and sympatric speciation.
2. Working in pairs, cut out each box and decide which statements are closely related.
3. Lay out the statements in the order which tells the story of allopatric speciation. If it helps, stick the
statements onto a sheet of poster paper and make little drawings to help clarify your thoughts.
a. There are some statements that are very similar, but you must use them all.
b. Be prepared to explain why you grouped the statements as you did.
c. Can you explain how variation occurs and why it is important?
4. When you are satisfied with your arrangement and can answer 3b and 3c above, call your teacher over
to have it checked and your claim evaluated.
Teacher Initials: _______
Part II: Sympatric Speciation
Learning Objectives
By completing this exercise, you should:
 Know the definition of sympatric speciation and by carrying out the research activity be able to give at least two
examples of this type of evolution.
 Know that there are likely to be behavioural or ecological barriers in place to prevent gene exchange within a
given area.
o Behavioural barriers, such as breeding patterns or rituals, and
o Ecological barriers, such as food availability, may operate in sympatric speciation.
 Be able to explain how sympatric speciation is the evolution of new species in populations that live in the same
geographic area.
Procedure
Sympatric speciation is where new species evolve from a single species whilst inhabiting the same geographic region. The
areas may overlap or be within the same boundary.
The above definition raises the question of how speciation can occur within a population of interbreeding individuals.
1. Find out what sort of ecological and behavioural barriers lead to speciation within the same geographical area.
Clearly explain what the selection pressures are and how this affects the phenotype of the emerging new species.
a. The medium ground finch, cichlid fish and apple maggot flies of North America would make a good
starting point (ex. type ‘ground finch and sympatric speciation’ into your search engine).
b. Present your findings in a written report of no more than one page. Labelled diagrams with accompanying
explanations are acceptable.
Allopatric Speciation Statements
Species
generally give
rise to fertile
offspring.
Isolation of a
group of
individuals due
to mountain
ranges, oceans
or migration.
Best adapted
survive
(survival of the
fittest).
Over time and
many
generations
different
characteristics
begin to
emerge.
Starting off
with one
population, a
common gene
pool.
Species are
populations
within which
genes are free
to mix by
interbreeding.
Less wellNew or
adapted
favourable
organisms fail
alleles are
to pass on their
passed onto the
alleles to the
next
next
generation.
generation.
Environmental
selection
pressures are
different for
each group.
Genetic
differences,
due to
mutations in
the separated
populations,
begin to
accumulate.
Individuals
within a
population may
not be able to
compete as
well as others.
The original
environment
may be very
different from
the isolated
area.
Geographical
barriers
prevent
interbreeding
of populations.
Healthiest or
best
individuals
will be the
most likely to
breed.
New
phenotypes
gradually
appear in the
population.
Genetic drift
(random
mutations/
differences)
occurs
independently.
Healthiest or
best
individuals
will be the
most likely to
breed.
Individuals
within a
Different
Mutations give population may
mutations arise
rise to different become better
in different
phenotypes.
at exploiting
populations.
their
environment.
Mutations
occurring in
each
population will
be different.
Usually a good
correlation
with the
phenotype
(underlying
new alleles)
and the
environment.
Members of
Evolution
the different
Often isolated occurs and new
populations
may become so populations are
biological
very small.
distinct that
species are
formed.
they can no
longer breed.