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Lab: A Step in Speciation
What is a species?
Species: organisms that can interbreed and
produce fertile offspring.
What are subspecies?
Subspecies: members of the same species
that are geographically isolated from each
other and look different.
Question
What happens to different subspecies when
they are geographically isolated from each
other?
Hypothesis
IF subspecies are geographically isolated,
THEN that will lead to speciation or the
formation of a new species.
Procedure
1.
2.
3.
Plot out your grid map according to the
instructions.
Once that is done, place the salamander
pictures in their proper locations on the
map.
Answer analysis questions.
Analysis – Part A
1.
2.
3.
No, areas without salamanders probably are dry
or desert like. Also, human populations might
disrupt their habitats.
Mountain areas, except for in mountainous
desert areas.
Yes, subspecies are geographical variations with
in a species. Subspecies closer together should
be more similar to each other than to those
further away. You can see similarities among
coastal forms versus inland forms (closest to
ancestral species = E.e. picta).
Analysis Part A (cont.)
4.
5.
Spotted forms tend to be inland and
unspotted forms along the coast, except in
southern California where both spotted
and unspotted occur together.
Both populations occur in the same area in
southwestern California.
Analysis - Part B
1.
They are genetic intergrades (hybrids)
between subspecies.
Analysis – Part B (cont.)
2. An intergrade between E.e. eschscholtzii
and E.e. xanthopica
-yellow eye patch disappears
-less orange coloration on belly
-dots on sides (yellow, black)
-tip of tail lighter
Analysis – Part B (cont.)
3. They are geographically isolated by several
hundred miles.
4. To find any intergrades and to see if two
subspecies occupied the same region.
5. There are no intergrades – more
collections needed?
Analysis – Part B (cont.)
6.
7.
Population E.e. klauberi because this is the
only form without intergrades.
Between populations E.e. klauberi and E.e.
croceator.
Analysis – Part B (cont.)
8. The map shows intergrades
between all the subspecies
except the two that exist in
southern California. It
appears that speciation has
taken place down the
coastal and inland mountain
ranges. Before data on the
intergrades was collected it
would be easy to think that
the two southern subspecies
were different species.
Analysis – Part B (cont.)
9. It would break the chain of interbreeding
subspecies E.e. eschscholtzii and E.e. klauberia in
the southern end of the range. This would
produce two reproductively isolated populations –
two species.